I have a few questions on compression issues

1. What neglect do previous owners do to these cars to cause premature low compression?

2. Last year my 90 GXL blew a rear apex seal causing low compression, 172,000, didnt have time to fix her yet so I bought an 88 vert, which now has no compression in rear rotor also, 118,500, all same symptoms afterwards except that with the 90, i had popping in the exhaust, which I didnt have with the 88. Can someone explain why that is so?

3. Will the poor mans comp test work when looking to buy another G2? Will it tell me how good or how bad the comp is, or will it just tell me good or bad period?

4. Is there a way for me to tell what caused my low compression to occur?

5. My add coolant had come on right before, but i never had any white smoke or leaks, so where the hell did it go?

 

sorry 1 more.

How can you do a poor mans comp test on a car that does not crank?

 

No poor mans compression test on a car that doesnt crank.

 

not change the oil regularly would kill the engine sooner

and revving it when its cold could also do that

I think the oil changes are the most important thing.

 

Leaving the stock exhaust catalytic converters on after 85-120K miles. The old owners will let the catalytic converters clog, they'll notice a sharp drop in power, they don't check exchaut backpressure (any muffer shop can do that easy) and they still don't change the OEM cats. Then the engine premiturely fails and they wonder why.

Also if they don't change the coolant regularly and/or don't verify the PH Levels & corrosition resistance. The OEM radiator gets clogged & they overheat the engine.

You should always install an aftermarket temp gague on any sports car for piece of mind anyway.

Most 2nd gens will always have a small pop/backfire during high RPM shifts, but these cars have a decelleration & afterburn system that helps control backfiring & popping in the exhaust. You can troubleshoot this by downloading the FSM (factory service manual) from www.teamfc3s.org.

Also if your car is running rich the backfiring will increase, which is a sign you need a FULL tuneup.

Warm up the car, shutdown, Pull the EGI fuse to kill the ignition, remove the leading sparkplug, and listen for 3 strong air pulses as you attempt to crank the car. The pulses should be VERY loud & even. Repeat for the rear rotor chamber as well.

Low or NO compression? Your suppose to do a compression test when the engine is hot to obtain the "hot compression numbers." And that's with a REAL rotary compression tester, not the el-cheezy handheld piston compression tester.

True Low compression (ie not partially flooded or 0 compression flooded) on a low miles engine usually happens because you've 1) stresses the APEX seals by a clogged exhaust, ran the engine lean too many times 2) let the car sit too long without prepping the car for storage 3) poor rebuild or 4) damaged rotor chambers by sucking something in the engine 5) previous owner "grannied" the car and caused excessive carbon buildup inside the engine.

Leaked out when the coolant system was pressurized at higher RPMs (like on the freeway). Check for bubbles in the coolant system when the car is running anway though.

 

Letting the engine sit, or not driving regularly, is the main cause of low/no compression. The seals have to move up and down as the engine rotates. When you shut an engine down, randomly 1 or 2 seals may be compressed inward, and 1 or 2 may be extended outward. After a while, little bits of carbon the engine has built up inside the seal grooves will tend to make the seal stick in place. From there, if you try and make the engine work again, you'll sometimes get seals that won't move freely in and out (causing low compression, because the seal doesnt press out fully anymore), and sometimes even a siezed engine (because an extended seal won't compress back in).

Even in cases where you do get the engine running again after sitting for a long time, often seals break shortly thereafter...most likely because it was binded up as mentioned above, and finally flexed and broke.

 

And if your engine is going, and the car is in good shape, why not contact the man in the post above me (Kevin @ rotary ressurection).. it'd be cheaper than a new car most likely, and you know that you have a properly built engine then

 

yea dont rev it when its cold. thats how i lost my apex seals. AND i stay in central florida. so warm it up before you do anything