Members Brian L. Posted June 16, 2004 Members Share Posted June 16, 2004 I have a friend who is thinking of giving me her 2nd gen rx7. It has some problems and she just wants to get rid of it and get a new car. I have no experience with rotary engines so all you rx7 guys out there give me a hand... Question 1: It starts smoking pretty bad when you rev it up around 5,000 rpm. I have heard rx7's smoke but I don't see them smoking that much. Is there something that goes out in the motor (like the equivelent to rings) that would make it do this? It the motor gone? Question 2: It has been overheated pretty bad I am assuming because the it was a girl driving the car and she just drove it untill it stopped running. Not sure if it is just low fluid/thermostat/water pump because I have not looked at the car. How do those engines handle overheating? Should I not put any money into this car. Or can I just fill up the fluid and get a free car out of it? Thanks for the info. Quote Link to comment Share on other sites More sharing options...
mikeski38 Posted June 16, 2004 Share Posted June 16, 2004 An overheated rotary is a dead rotary. A sure way to kill a rotary is to overheat it. Quote Link to comment Share on other sites More sharing options...
CaptainWho Posted June 16, 2004 Share Posted June 16, 2004 I'll have to agree with mikeski38. It's all too likely that the overheating compromised the side or apex seals. Those are the things that more or less act like rings in a piston engine, and they're very susceptible to overheating. Replacing them requires a full tear down of the engine, which can get expensive. A remanned engine is likely to run you $3k and up, depending on what you have done to it. If she's giving it to you free, why not take it? Just keep in mind you're likely to have at least a couple thousand in it before it's a reliable runner. Quote Link to comment Share on other sites More sharing options...
.RJ Posted June 17, 2004 Share Posted June 17, 2004 If its overheated and smoking, the apex seals are shot, rotor housings are warped, and something wrong with the oil injection pump. If you want to put a new motor in it, it would be a fun car..... Quote Link to comment Share on other sites More sharing options...
Members Brian L. Posted June 17, 2004 Author Members Share Posted June 17, 2004 How much do new motors run for that generation rx7? Quote Link to comment Share on other sites More sharing options...
CaptainWho Posted June 17, 2004 Share Posted June 17, 2004 ISC wants 3500 for an ITS prepped 13B. I don't know what you'd have to pay for a remanned stock 13B. SDJ also rebuilds rotary engines for SCCA use, but his web site doesn't list prices. Quote Link to comment Share on other sites More sharing options...
N1XRR Posted August 16, 2004 Share Posted August 16, 2004 I have a friend who is thinking of giving me her 2nd gen rx7. It has some problems and she just wants to get rid of it and get a new car. I have no experience with rotary engines so all you rx7 guys out there give me a hand... Question 1: It starts smoking pretty bad when you rev it up around 5,000 rpm. I have heard rx7's smoke but I don't see them smoking that much. Is there something that goes out in the motor (like the equivelent to rings) that would make it do this? It the motor gone? Question 2: It has been overheated pretty bad I am assuming because the it was a girl driving the car and she just drove it untill it stopped running. Not sure if it is just low fluid/thermostat/water pump because I have not looked at the car. How do those engines handle overheating? Should I not put any money into this car. Or can I just fill up the fluid and get a free car out of it? Thanks for the info. Hey everyone, I'm new to NASA and saw this posted and wanted to spread some information. First things first, the problem in the 1st question is a symptom of the 2nd. These engines are built in an alternating pattern of aluminum and cast iron. The front, middle and rear housings are all cast iron and the 2nd and 4th housings are aluminum. The rotors are all iron. When you over heat this engine, just like an engine with a cast iron block and aluminum heads, the metals expand differently. That squeezes the oil seals that are on the side of the rotor. What your seeing here is that the seals have been pressed into the rotors. NOTE: These are not the apex seals. Warn out apex seals do not cause the motor to smoke oil like explained...very common misconception. All that being said, the engine may not be totally gone. What causes the oil seals to stick is nothing other than carbon...and these engines tend to build up carbon if not treated properly(redlined frequently). Its a possibility that you can do the "ATF trick" that is well known in the RX7 world. That is, running the engine for 30 seconds or so to heat it up, and then take out the trailing spark plugs(the ones on top) and putting 3-4 ounces of ATF(automatic transmission fluid) directly into the engine. Take out the EGI fuse and turn it over again(with the plugs out) and add another 3-4 ounces. Do that a number of times until all 6 of the rotor faces are bathing in ATF. Now, the actual amount isn't as important as just letting it sit for 24-48 hours. Put the trailing plugs in the car and let it sit. After a couple days, go out and start the car up.....but there is a warning here. Start the car up and drive far far away from where you live. Even better if you can get the car away from your place before starting. Why? It'll smoke....BAD. Thats actually the ATF burning. Your neighbors will call the fire department because they think your cars on fire, seriously. Take it out and let the car get some heat in it. When its warm(after two minutes or so) do 8-10 redline runs and then go home, it won't be smoking anymore. Change the spark plugs as they will be fouled out(use ONLY NGK plugs that are designed for the car). Now, see if the problem persists. If it does, then a new set of seals are in order...but thats at the minimum. The iron housings could be warped so bad that the engine isn't any good. There are quite a few people who'll rebuild engines for around $1000. In all honesty, its not all that hard...but it will cost some money. All new seals will run $300+(depending on what seals need to be replaced and what parts are damaged. A complete seal kit from a company like Atkin's Rotary are $600+. Junkyard engines, on the other hand, are still fairly easy to fine. Infact, you can even buy a Japanese engine for right around $1000 and have the car run just fine. I hope this provides a bit of insight into your situation. Quote Link to comment Share on other sites More sharing options...
0x1 Posted August 16, 2004 Share Posted August 16, 2004 I just wanted to add that you can test the apex seals with a simple compression test. Apex seals can be damaged easily by detonation which occurs more frequently with insufficient cooling. If an apex seal is damaged, two of your combustion chambers will not hold pressure. This can be a good measure of how damaged the motor is. If the apex seals are good and you're getting coolant in the combustion chamber (white smoke out the exhaust), then as said before, you may be able to get away with a $1000 or so rebuild. Either way, it'd probably be a good idea to replace the apex seals and maybe even rotors anyway. Even if you have to drop $2-3k into the car to make it runnable, it would be an awesome car for the money. Here's a good link to info about rotory engines and how they work -> http://auto.howstuffworks.com/rotary-engine.htm Enjoy! Quote Link to comment Share on other sites More sharing options...
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