How To Buy An '86-'92 Non-Turbo RX-7
So you want to buy an RX-7? Good! You'll be happy you did, as long as the car you get is in good shape. However, in order to pick the right car you must know what to look for. Don't count on a mechanic to know how to inspect the RX-7. Most are not versed in the rotary engine, and have no idea about the intricacies of these cars. A good inspection is easy to perform though, even if you have only very basic mechanical skills.
This list covers the non-turbo (naturally aspirated, or "NA") second generation RX-7. If you are looking for a turbo, most of this stuff still applies, but there are additional steps to take. Please see How To Buy An '86-'92 Turbo RX-7 after reading this document for additional turbo related information.
The first thing you want to look at is the body. It's condition will tell you about the rest of the car. For example, if it is dirty and dull, you can assume that the previous owner did not take very much pride in his/her can and did therefore not give the body and paint the attention it deserved. Odds are you will find many other things wrong with such a car, so keep your guard up. If things look decent, you can make a more detailed inspection.
- The Paint
- The factory paint on the 2nd Gen. RX-7 is actually very good, and if cared for properly will still be in good shape. Look for peeling clear coat and paint, which can signal a cheap repaint. This may be due to standard wear or something like accident damage. Drips and runs should not exist, and will again be a signal of a cheap repaint. Odds are that cheap paint will become a problem in a few years when it starts to chip, flake and peel.
- The Body
- Look for the obvious first: big dents, dings, rust, etc. Dents and dings can be repaired fairly easily if they are small, but larger ones will be a hassle. Rust is bad, period. Realistically, all cars will acquire rust after a few years on the road, but it should not be excessive. Look under the car with a flashlight. There should not be any holes in the floor, sills, or frame rails (that are not factory). Such damage is expensive to repair as the interior must be removed so new panels can be welded in. Also look for bent frame or welding, which can be a signal of previous repairs. If the frame is bent or crushed, the car has been in an accident and it would be a good idea to get the alignment checked by a frame shop. Rust on RX-7s is common at the edges of the rear wheel wells, along the bottom of the doors and on the bottom of the front fenders. Areas that are a little tougher to see are the "dogleg" area just at the front of the rear wheel wells where the inner body meets the outer panels (look for rust just behind the subframe mounts) and the area between the frame and rear seats/storage bin. If possible, remove the front wheel well plastic guards and look toward the rear of the car. You will probably see some significant rust where the firewall meats the underside. It may even have rusted though. This is very common, but can probably be used as a bargaining chip. Check also to see if some sort of rust protection has been used over the years. If you look on the door sills, you will see several black rubber plugs. If these are new looking, you can assume that they have been replaced when the rust protection was applied as the old ones usually break.
Previous accident damage is a little harder to find. Look for discoloured or distorted areas, or places where things just don't quite match up. RX-7s have some subtle compound curves which are hard to replicate with body filler. You may be able to notice it where the trim attaches to the body as that area has a sharp curve the body fillers do not like. Don't immediately discount a car that has accident damage. If it was repaired correctly and wasn't too severe to begin with it should be OK. You might want to have a body shop look at it though. They will literally be able to tell by looking at it. Look on the underside for weld lines that can signal either accident damage or rust repairs. If you find these, then it's best to have a competent body shop examine the car if you are unsure how to interpret what you see. Poor welding/fitment on replaced panels can come back to haunt you in a few years as the weld lines rust if not properly treated.
Rust behind the tail lights in the interior is common due to leaking gaskets, but it certainly should not be rusted though. The licence plate surround at the rear likes to rust at the top due to exposed unpainted metal.
- A common failure on RX-7s is the drivers door lock. There are several failure modes, but most of them result in the driver being locked out of the car. Look for evidence of forceful entry, such as damaged window seals. If the handle or lock was replaced and not rekeyed, you will have a different key for the drivers door and for the ignition. Not really a problem, but very annoying in a car that is supposed to be one-key. Needless to say, all locks and handles should work properly. In some cars, there is a hatch release under the drivers seat. It should work, as should the fuel door release right beside it. If they don't, the cable my be broken. This is annoying to replace, and it is even more annoying to have to pry the fuel door open with your key. The rear hatch glass is heavy, so make sure the gas struts are in good working order. The hatch should spring up when released, and stay up on it's own when opened fully. Check the latches and strikers for evidence of being greased with a white lithium grease.
- The manual windows are very reliable. The electric windows do a have a few quirks. If they move up slowly and/or need assistance, the tracks probably need to be cleaned and regreased. If they don't work at all, suspect the switches. The motors rarely go bad. Electrical problems will be discussed in their own section.
Once you are sure the body is in good shape, you can move onto the engine. Contrary to popular belief, the rotary is a very reliable engine if cared for properly. This is of course true of any engine, but the rotary is more sensitive to poor maintenance. Most mechanics (even Mazda mechanics) don't know what they are doing, so it is up to you to make the decisions. There are some fairly simple checks that can be done and they will be a very good indication on the condition of the engine.
- Engine Bay
- Take a quick look at the engine bay. There shouldn't be anything obviously wrong. No severe rust (although rust is common on the alternator, air pump, exhaust, under the break and clutch master cylinders and near the cold start assist tank), fluid leaks or frayed wires. You may spot some oil leaking from under the oil filter. This is the oil pressure sender and leaks around that area are common. Leaks are common also where the oil filter pedestal mounts as there are two o-rings for sealing that can wear out over time. It's an easy fix but a bit of a pain due to limited access. Check the belts to see if they are brittle or frayed. Also look at the condition of the hoses to make sure they are not cracked or broken. The idea here is to just get a general idea on the condition of things.
- The next most important thing to check is compression. This will give you an idea of the current internal condition of the engine, but cannot predict future events. The best way to have compression checked is to find a Mazda dealer with the special tester. A standard compression gauge will work, but can be inaccurate if uses improperly. Good compression is a 7 or higher on the Mazda tester, and higher than 85 PSI on a standard gauge. Do two tests, one with the engine cold and one with the engine warm. A "poor mans's compression test" is outlined on my Is My Engine Blown? page.
- Starting/Warm Up
- Get there first thing in the morning and start the engine. This guarantees a cold start. It should immediately rev to around 3000 RPM for about 20 seconds, then drop to 1500 RPM, and then slowly come to a solid 750RPM idle after it has warmed up (about 5 minutes). The idle should be smooth, not rough and surging. Applying the brake should not bring down the idle, nor should turning on the A/C. If it does, the BAC valve may be defective or sticking. After the car has fully warmed up, shut it off, wait 15 minutes (look at some other part of the car) and then try to restart it. If it doesn't fire right up it may be flooded. This is a standard problem, but a pain to fix as the usual cause is leaking fuel injectors. Use this as a bargaining chip to bring the price of the car down a few hundred dollars. If you do the fix yourself, you should spend just about that much.
While the car is warming up, you may want to remove the rad cap and take a look. The coolant level should be pretty close to the top. Also, there should be no bubbles seen. If you see a steady stream of bubbles coming from somewhere else in the system, and it increases as the RPM of the engine does, there is an internal coolant leak. Avoid the car unless you plan on rebuilding the engine soon.
Needless to say, if the "Check Engine" light comes on, there is a problem somewhere.
- Oil Consumption
- Rotary engines are designed to burn oil. A small amount of oil is injected into the intake and the intake area of the rotor housings which helps to lubricate the apex seals and allow the engine to build compression. This oil is not recovered and thus burned as part of the combustion cycle. These engines are not two stroke engines. Ask the seller about the oil consumption history. If he or she proudly states that the car never burns any oil, they are either lying or there is a serious problem with the metering oil pump, the lines or the oil injectors. Either way, I would look very suspiciously at the car from now on. There are procedures for testing the metering oil pump and related hardware, but they are beyond the capacity of the standard inspection. In this case, you can only guess at the condition of the engine. Finding oil containers in the car is a good sign and proves that the seller is just lying to try to make a sale. If the engine has chronically low compression and floods easily the oil injection system may have been malfunctioning for a long time. For the record, mechanical '86-88 metering oil pumps are more reliable then the electronic '89-91 pumps. Suspect a failure in the metering oil system if the rear rotor has low compression but the front is fine. Normal oil consumption for these cars is about 1 quart per 1000 miles, but this will vary depending on how spirited your driving is.
- It is normal for a rotary engine to let out a few puffs of oil smoke (grey, dark blue) when it is started. This is due to the side oil seals staying in one position and allowing oil to seep past. It isn't anything to really worry about, as long as it does not continue for more than a few seconds. If it does, suspect the oil o-rings as starting to wear/fail. You will use much more oil than normal, and end up trailing huge clouds of smoke behind you. Spark plugs will also foul quickly. On the plus side, smoking engines are a great candidate for a rebuild and most likely the excess oil entering the rotor chambers over the years has prevented extreme wear on the irons and housings.
If the engine is hard to start, stumbles and then billows out huge clouds of white smoke, there is a serious problem. Most likely this condition will also be accompanied by mysterious coolant loss and possible overheating. The reason is that the O-rings around the housings that seal off the water jacket have failed, thus allowing coolant to enter the combustion chamber. This is very bad, and I would avoid the car unless you want to rebuild the engine. Even buying a water-pumper as a rebuild candidate is risky since water in the combustion areas of the engine can cause serious corrosion problems making it less likely you will get a good set of hard parts for a rebuild.
Black or very dark blue smoke is usually excess fuel. The most common cause of this is leaking injectors or a car that is very badly out of tune.
Once the engine has warmed up, hold it at about 6K RPM for 30 seconds then let off the throttle quickly. If you (or someone else) can see smoke coming from the exhaust, the oil seals are probably on their way out.
- If the car has been overheated in the past, or overheats when you are looking at it, just walk away. Overheating is instant death for a rotary engine and is highly likely to be damaging to the engine even after one incident. For '86-88 cars, normal operating temperature is about 1/4 way up the gauge. For '89-92 cars it is about half way. Both gauges will be very slightly higher if the A/C is on. The '86'-88 gauge is relatively linear but the '89-'92 gauge really only has three positions corresponding to the bottom, middle and top. These positions are cold, normal and "new engine".
- Pulsation Damper
- If the car is an '86-88, look at the front of the primary fuel rail. This is where the pulsation damper sits. On the '86-88 cars, these have a tendency to leak, thus spraying fuel onto the exhaust manifold. This causes an engine fire which is very difficult to put out because of the flow of fuel. If it is leaking, don't drive he car, and have it replaced immediately. '89-92 cars don't have this problem as often due to the damper being integral to the fuel rail but they have been known to fail.
- 5th and 6th Ports (Aux ports) and VDI
- All non turbo 13B engines used in the 2nd generation RX-7 have a 6 port induction system. The 5th and 6th ports remain closed below about 3500 RPM, preserving air velocity and running more conservative port timings to help increase low end torque. After that, the ports open up and improve top end horsepower. If the ports are not working properly, you will loose quite a bit of top end punch (the commonly accepted figure is around 25 HP). To test them, first locate the actuators. They are located on either side of the ACV valve above the exhaust manifold. Looking from the passenger side of the engine compartment towards the drivers side, you will see two cylinders with rods sticking out from them. Those are the actuators. Smear some grease on the shafts and after your test drive look to see if the grease has moved. If it has, then the actuators are working. If not, something needs to be repaired. If the car was not driven at high RPM, then most likely the actuators have frozen from age. Removing them and applying penetrating lube usually brings them back to life. If the actual port valves are stuck, the intake manifold probably has to come off.
The '89-'92 engines also have a Variable Dynamic effect Intake (or VDI). This is another valve in the upper intake manifold that opens above about 5000 RPM to allow the pressure waves generated by intake closing to travel through the secondary port runner to the opposite port and force more of the intake charge into that rotor. The valve remains closed at lower RPM to make the secondary runners longer, thus maximizing torque. This actuator is located on the drivers side of the upper intake manifold between the runners, just below the dynamic chamber (plenum box). It can be tested in the same way as the 5th and 6th port actuators. Just make sure you make several runs over 5000 RPM so that the intake valve can open.
The newest second generation RX-7 is already more than 10 years old, so wear in the interior is to be expected. However, there are a few RX-7 issues you should look for.
- The carpets should be relatively clean, and there should be a mat under the passenger and driver's feat. There should be no weird stains on the floor, as those may signal rust problems below (especially if rust coloured). If you see a lot of salt build up behind the seats, expect rust problems. Water tends to collect and remain back there for months at a time if the car is winter driven. Maroon interiors have a tendency to discolour, turning a shade of green if left in the sun. For the most part, the other colours are trouble free. Of course, you want to check the carpet for rips, holes, etc.
- Wear is normal on the seats, as they are often used when driving the car. If the seat is cloth, look for discolouration, ripping, stains, etc. If they are leather, look for cracking and cheap repairs. The seats sit on adjustable tracks so it is a good idea to have a look at them too. They should easily move and not stick. You will probably notice the seat retaining bolts have rusted. This is normal, as long as they haven't rusted through. If they have, repairs will be necessary as the car is not safe to drive with loose seats.
- '86-88 trim is quite brittle and has a tendency to crack. Don't be surprised if the radio surround is broken at the top, the clock/idiot light trim is cracked, the vents on the dash near the doors are loose/missing/cracked and the vents under the windshield are cracked. This is normal in any older car, but much more so in the RX-7. Also, check the steering column cover. It is subject to a to a lot of abuse which tends to destroy the screw holes. For the most part, '89-92 trim is a lot more forgiving and just plain higher quality. Remember that the price of small trim pieces can quickly add up. If replacing trim, you might as well use the '89-92 part (this can require other modifications).
- Automatic Seatbelts
- If the car is equipped with automatic seatbelts, check to see if the recall has been done. If the owner has receipts, then it is easy. Otherwise you will have to take the VIN number to a Mazda dealer and find out if it has been done. If the seatbelts are broken, don't worry as they are under lifetime warranty by Mazda. The current owner may not know this though and it may be a bargaining chip.
- The headliners on these cars are basically trouble free. However, the flip down mirror can become very loose in it's holder. There is a small plastic sphere that will crack over time. This is very annoying as it causes the visors/mirrors to hang down in you or your passenger's field of view.
- If the car is equipped with a sunroof, then make sure it moves freely. It if sticks, chances are it has to be removed, cleaned and regreased. The tracks will build up crud after 10+ years in the weather. It is also common for the sunroof panel to rust around the edges. Leaks are uncommon but can occur.
Here we come to one of the more involved sections, with some of the more potentially irritating problems. Unfortunately, some of the 2nd gen electrical system is of questionable quality and the age of the cars can make these problems worse. '86-88 cars are a little worse then the later cars, but both can have their share of problems. Some are simple to fix, some are expensive. You will have to make the call as to whether a problem is big enough to consider looking at another car. However, odds are that the other will have a few issues itself. Most problems can be traced to bad soldering and/or faulty grounds, but some are just bad design.
- Headlight Switch/Wiring Harness
- By far the most common failure in the RX-7 is the headlight switch and it's associated wiring harness. The basic sequence of events is that the headlight switch dies due to cold solder joints, which then generates excess heat, which then melts the connector and wiring harness. The problem can be repaired by replacing the faulty switch and wiring harness, but with just the switch priced at around $300 this gets expensive fast. Most of the time switches can be found at the wreckers for around $5 though and there are several vendors which offer rebuilt switches and harnesses. The old switch can always be rebuilt if it didn't take it's connector and wiring harness with it when it died. A rebuilt switch, if done properly, is very reliable. To test the switch, just turn on the headlights, try the headlight cleaning switch (just raises the lights without turning them on), and test the defroster switch. If any of them doesn't work, then suspect the switch. If the dash backlighting, headlights or marker lights don't come on then odds are the headlight switch is bad. Also check the dimmer function to make sure the dash/radio lights dim as appropriate.
- Turn Signal Lever/High Beam Switch
- These switches are subject to the same type of failure as the headlight switch, but do not damage the wiring harness when they die. Replacement costs about the same.
- Wiper/Hazard Switch
- This switch will fail as the headlight switch will, but will not damage the harness. Symptoms of it failing are non-working intermittent wipers, non-working hazard lights, wipers that don't park, and of course non operational wipers. Replacement is about the same as the headlight switch and rebuilds are available which correct the original weakness. If the car is not equipped with a rear wiper, there will be an extra switch that apparently does nothing. Tell your friends it engages secret engine modifications.
- Cruise Control Switch
- The cruise switch is trouble free.
- The CPU is located behind the drivers kick panel, hidden by a wiring loom. It controls such things as the turn signals, horn, warning beep, etc. Over time, the poor Mazda solder joints will begin to become intermittent which will result in the malfunctioning of the aforementioned devices. The usual fix is to open up the CPU and resolder all the big joints. This is not an expensive or difficult task to do yourself, but a dealer will want to replace the whole CPU. I don't even want to know what that would cost. Many other seemingly random electrical faults can be traced to this unit.
- Emissions Control Unit (ECU)
- The ECU is the real brains of the car, coordinating everything from spark timing to fuel delivery to idiot light functions. Unfortunately, this device is subject to two types of electrical malfunction. The first is bad solder joints. Go figure, eh? The second is bad grounding. As the car ages, the ground connections dirty up and corrode. This makes them intermittent and high resistance. The effect on the ECU from both these conditions is erratic operation, which can cause all manner of engine related problems. Perhaps one of the most common is the infamous 3800RPM hesitation. Coming up to 3800RPM, the engine may hesitate horribly. This is usually related to ECU problems. Cold solder joints can be repaired by resoldering the ECU and the grounding problem can be fixed by regrounding. A dealer may want to replace the whole unit though, and this would be at great cost and may not cure the problem in the case of bad grounds.
- Dead Horns
- See "CPU". The opposite can be true in that the horns sound continuously. While this may be amusing for a few minutes it becomes less and less amusing the more often it happens.
- Heater/AC/Fan Controls
- The device that controls the heater, A/C and fan is referred to as the logicon. It is subject to the same soldering problem as most other parts in the car. Failures in the logicon show up in several ways. You may not be able to adjust the fan speed, adjust the air mix or change the air outlet locations. There are also several motors that control the flow of air. The one you want to be concerned with is the air mix motor. It controls the ratio of unheated/cooled air to heated/cooled air. If the logicon has fried, it may take the motor with it. If the motor has fried, it may take the logicon with in. You can repair the logicon yourself by resoldering the joints, but beware of price if you take it to a dealer. They will probably want close to $400 for a new one and it will be subject to the same types of failures as the old. Some vendors offer refurbished logicon units that have many of these design faults corrected.
- For the most part, the stereo is trouble free. If it does fail, it will be due to bad soldering. The most common symptom is intermittent sound from one or more speakers, failed displays or inoperative controls. The radio can be repaired, but if it is removed you might as well install a good aftermarket unit. This will probably cost less then replacing it with another Mazda unit.
- Power Antenna
- As with most other power antennas, the unit on the RX-7 takes a lot of abuse and will wear out over time. If the motors runs (which you can hear in the rear drivers side) but the antenna doesn't move, the small plastic push strip has broken or come off the gears. It can usually be repaired with a minimum of fuss. Don't expect to find a good power antenna at the wreckers. If the motor does not run, first check the fuse. It may have been removed to keep the antenna from freezing up in the winter. If the radio is aftermarket and the antenna doesn't work, chances are that the relay required for the ground activated antenna (opposite of normal) was not installed. Oh, and regardless if the antenna is working or not, these cars seem to get horrible radio reception.
- Power Windows
- Over time, the power window switches will tend to build up a carbon coating on the contacts. This usually leads to less than ideal window operation. The fix is to replace the switch, or use fine sandpaper to clean the contacts in the old ones. Personally, I would replace rather then repair as the sand paper will take the nickel coating off of the contacts making the problem reoccur in the future.
- Engine Electrical
- The engine wiring harnesses have to deal with a lot of heat and can thus be subject to extreme wear. Typical areas of concern are where the harness crosses over the exhaust (Mazda, when did that ever seem like a good idea?!) and the connections at/near the battery (corrosion due to battery acid exposure). The harness should be inspected to check for signs of hacking, damaged connectors, mechanical damage due to rubbing and other obvious faults. Disconnecting and checking the inside of several of the weather tight connectors (for example at the ignition coils or the CAS) can reveal potential corrosion issues. It is very common for the non-weather tight (such as the TPS or air temp sensor) connections to at least show some corrosion but massive amounts or terminals coated in a white fuzz are definitely bad signs. The battery cables should be good and tight with a coating of grease with factory style molded lugs and not temporary clamp-on lugs. The main vehicle ground can be found just above the frame rail at the drivers shock tower. It should be sound and corrosion free. Grounding is covered in great detail by my grounding writeup. If there is any aftermarket wiring make sure that it is neat, tidy, secure and not a horrid hack job as it often can be. It helps if the previous owner can provide documentation as to what this wiring is and where it leads.
With a few minor problems, these components of the car are reliable and trouble free. As long as the car has been cared for you shouldn't find any problems in this area.
- Don't be too surprised if the shifter is sloppy. The shifter bushings in these cars will fail over time and need to be replaced. The job is not complicated or expensive and is easily done in an hour. Don't worry to much about it.
- It goes without saying that the transmission should shift smoothly and easily. However, it will feel a little more notchy than other cars. Also, the 2nd gear syncro may be worn out, resulting in a grind when shifting quickly into second. The only way to fix this is to replace or rebuild the transmission. This is a common problem in the 2nd generation RX-7, so don't count on another car's transmission to be perfect either. Another common problem is noise. If the bearings are worn (mostly due to old or no transmission oil) they will provide a constant whine while the car or transmission is in motion. The only cure for this is a transmission rebuild or replacement, which can be expensive. Note that the transmission may last for many more miles with this condition, or it could die next week. To check the level of transmission fluid, jack the car up so that it is raised and level. Now remove the fill plug from the drivers side front of the transmission (right near the starter). Stick in your pinky finger. You should be able to feel the fluid level. If you cannot feel it, the fluid is low and there is a leak somewhere.
At this point all of the 2nd gens on the road are over 10 years old so transmission problems in the non-turbo transmissions are becoming common. These transmissions are generally weaker then the turbo units and will wear more quickly especially if the car is driven hard.
- Make sure the clutch is not excessively worn (slipping) by shifting into a higher gear and then getting on the gas. The RPMs should rise as the car's speed increases. If the speed of the engine spikes but the car accelerates slowly then it is a good indication the clutch is slipping.
- As with any older car, the u-joints on the driveshaft are probably near or already past their useful life. This will show up as a very noticeable vibration when the car is moving. The problem here is that the stock Mazda driveshaft does not have replaceable joints, so you need a whole new driveshaft. However, do not buy the Mazda shaft if you can help it. Get an aftermarket shaft with replaceable joints to avoid this whole problem again. Some shops can replace the u-joints on the stock Mazda shaft if they can source the parts.
- Listen for bumps, thumps and other things. No side of the car should sag, and it should not bounce up and down when you push on it. Excessive nose-dive while braking is bad, as is squatting when accelerating. Both indicate worn springs. You may notice some negative camber in the rear wheels. Toe in may also be present. Most RX-7s have a little negative camber so I wouldn't put too much worry into it. The toe in is due to the Dynamic Tracking Suspension System, and will straighten out when the car begins to move. The shocks should not leak oil, and the springs should not sag. If you can get under the car, pull and push on all the suspension components you can find to check for excessive play. Rubber bushings wear out after many years of service which can cause sloppy handling and strange noises.
On cars so equipped, the AAS (Auto Adjusting Suspension) will probably not work. The system didn't do much anyway. If it doesn't work, odds are it has been disconnected, the struts have been replaced with standard struts (good) or the 10+ year old suspension is just worn out. The system was just a gimmick anyway, and a true sports car does not need such frivilties. Unless you really care about having a perfectly stock car the it is probably not a large concern.
- The car should track straight and no strange sounds should be heard when turning the wheel. If such sounds are heard, the ball joints and/or tie rod ends are probably worn out. They will need to be replaced and the car will have to be aligned.
- Needless to say, the brakes should work. They should feel fairly firm, and not drop straight to the floor. No pulsing should be felt. If they pulse, one of more rotors are warped. The brake lights should come on when the brakes are applied, and the parking brake should firmly hold the car on a hill. Applying the parking brake should also light the "BRAKE" idiot light. On application of the brakes the car should not pull to one side. If the car is equipped with ABS, find a deserted wet spot and slam on the brakes. The ABS should kick in. Also check the fluid. Black brake fluid signals neglect, or a history of cheap brake jobs. Be wary of such a car as there are probably hidden brake problems which will come up the first time you put clean fluid in.
- Tire Wear
- The tires should not show any weird wear patterns. Most likely, the rears will be worn more than the fronts. This is normal for a RWD car as most people don't rotate their tires.
- Jack up each end of the car and try to rip the wheel off with your hands. You shouldn't feel any play or hear any clicking. If you do, the bearings or races are probably worn. One note about the front wheels: the bearing race and hub are integral. That is, if one is bad you have to replace the whole assembly. This can be expensive if you or the shop doing the work does not know the trick to removing the old race. Remember that bearings are a wear item on all cars and will need to be replaced/repacked at some point. Ask when this was last done. At the very least the bearings should have been repacked sometime in their life (really with every major tuneup).
When cars are modified, all bets are off. Modifications fall into a wide range of categories and can thus have a range of effects. Some can improve the overall enjoyability of the car, while others can drastically improve one area while having negative effects on another. If you are looking at a modified car it is best to seek out another enthusiast who is experienced in these areas to help. A few common modifications and hacks will be covered here but due to the wide variety it is impossible to examine every possible situation.
- Probably the most popular rotary modification is exhaust. Look at the system and make sure that it appears to be high quality, does not rattle and is not secured in place with coat hanger wire. Stainless is about a thousand times better then mild steel for longevity and sound quality. Check the flanges for leaks. If you live in an area where emissions is a concern then make sure that the catalytic converters are in place. It is important to listen to the exhaust under a variety of driving conditions to determine if it is sound you can live with. Too loud? is that 12" tip too large? Does the car sound like a Weed Whacker on crack?
- Sometimes the stock metering oil system is removed and instead 2 stroke oil is added to the fuel tank. Some feel that this lubricates the apex seals better, some don't trust the stock system, and sometimes the stock metering pump or lines just fail. Whatever the reason, is this something you can live with? Is it going to be a hassle dealing with 2 stroke oil everytime you fill the car up (in the pouring rain, in your nice suite or while everyone around you is asking "why are you pouring oil into the gas tank?")?
- Removal Of Cold Start Warmup System, Removal Of BAC Valve
- The RX-7 has a system designed to idle the car up when cold. It is responsible for the 1500RPM idle which gradually drops to 750RPM as the car warms up. For some reason, a lot of people remove it. This can make the car an absolute pain in the butt to drive in cold weather as you must now manually idle the car until it warms up. It is my opinion that no good can come from removal of this system and it is a pointless and stupid mod.
Removal of the BAC valve is a similar hack that serves no purpose. It is the BAC valve's job to allow the ECU to control the engine's idle to compensate for various loads like A/C, electrical draws and times when you are not quite as delicate as you should be with the clutch. Removal of the BAC valve means that the ECU can no longer idle the engine and the engine's idle must be raised (generally to around 1000 RPM or slightly higher) mechanically by adjusting the throttle body. Again, it is my opinion that there is no valid reason to remove the BAC valve as only negative effects can result. The good news is that there are a million BAC valves being sold off very cheaply since people keep removing them, so the system is easy to restore.
- The Banjo Bolt Mod
- This one can take some explaining. The fuel pulsation damper in the S4 RX-7s is prone to leaking due to old age. As mentioned previously in this article, this ends up spraying hot fuel on the exhaust manifold which ignites and causes an engine bay fire. To help prevent this, some owners replace the pulsation damper with a standard banjo bolt. This eliminates the pulsation damper function from the fuel system. What this means is that the "water hammer" effect created when the injectors open and close is no longer being absorbed. The jury is still out on whether this is a problem on a stock or near stock car. It is my opinion that this is a hack, and the proper way to deal with a leaking damper is to replace it with another stock or aftermarket unit. While in the great scheme of things the banjo bolt hack is probably not a huge deal in a stock NA or near stock turbo car, it has been attributed to cause engine failure in more highly modified cars due to potential lean spots that can be created. If I was looking at a car with the banjo bolt hack, to me it would signal the need to look more carefully at the rest of the car for stop-gap "fixes".
- Emissions Removal
- Removal of the emissions equipment is another popular modification. Most commonly this is in the form of catalytic converter removal. The result is more power and better throttle response. Of course the downsides are that it is no longer possible to pass an emissions test, the car is louder, smellier and it pollutes more. Whether these are issues for you will depend on your attitude and where you live. Once the cats are removed, many owners also remove the rest of the emissions equipment. There is no power gain to doing this, but many feel that it "uncomplicates" the engine and makes the engine bay cleaner. There can be many downsides depending on exactly what has been done during this removal. If the crankcase purge system has been removed, then you will probably have to deal with emptying a catch can every once and a while, or may have a vacuum line somewhere dumping oil vapor. If the charcoal canister (fuel vapour recovery) has been removed there is likely a lingering odor of fuel around the engine bay, or the vent line has been plugged or relocated under the car. Both are dangerous as fuel vapors vent from this line as the pressure in the fuel tank changes. If emissions equipment has been removed improperly, all manor of drivability problems can be created so it is best to thoroughly check the car or take it to someone who can.
- Electric Fans
- See The Myth Of The Electric Fan.
- Suspension Modifications
- It is hard to totally screw up suspension modifications but it can be done. First, has the car been dropped to some ridiculous ride height? Will it clear curbs and speed bumps? How is the alignment? If the suspension has been modified then getting proper alignment angles can be tricky. How is the ride? Too hard? Too soft? Hard bushings can cause the car to feel like it is falling apart everytime you go over a bump and can introduce all kinds of noises if not kept lubricated. What about the quality of the parts used? Are they name brands such as Racing Beat, Eiboch or Tokico or are they no-name eBay specials?
- Other Modifications
- It is impossible to cover every circumstance so most importantly it is vital to check the quality of the work. That will tell you a lot about how the car will perform. Is any electrical neat, tidy and properly fused? Are joints soldered (good), crimped (acceptable) or just twisted and taped (very bad)? Are things held in place with zip-ties or proper cable clamps? How about the quality of welds on any welded parts? What is the overall impression of the fit and finish? Jagged edges on cuts, sensors and wires dangling instead of being secured and just general sloppy work can indicate that not a lot of thought was put into the work. Is the interior hacked to mount a stereo? Wires running every which way? These are all things that must be considered to get an overall impression of the car.
There, I think that's just about it. Don't take this list to mean that the RX-7 is not a reliable car. For the most part, any used car will have a similar list of quirks. Hell, any new car will have the same thing. Remember the airbag computer failures on the 2001 Impala? Good luck in your search, and happy rotoring.
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