Shawnmark

Hey guys. I'm having some problems with my 83 RX7. Its completely stock, non turbo 12a. I picked it up about 4 days ago, and it was running like a champ when i bought it. Two days ago, i was giving it its daily start up, and after it warmed up, i decided to take it up and down the street. After cruising for a good 20 minutes, i decided to open it up a little bit, so i took it to 5.5K rpm's in first, and 4000 in second. By that time i was already back at my destination, but when i clutched in, i heard a terrible rattle, and the engine nearly stalled. I limped it back to its parking spot, and popped the hood, fearing the worst. The rattle has not returned, but the engine shakes terrible. I'm speculating that the rattle i heard was the engine mount destroying itself, seeing as the engine shakes unnaturally when the cars idling. The bigger problem is that it appears that one rotor is not firing. I pulled the plugs and they were pretty fouled up, and the prongs are pretty gone. It idled a little rough, but i figured that was because of the frozen air pump. (I've simply removed the belt, planing to fix it as soon as i have the money.)

I'm pretty worried that I've destroyed my engine days after buying the car. I really hope thats not the case, because I've quickly fallen in love with the car, and a new engine is a long way away financially for me.

t_g_farrell

iTrader: (1)

You need to do a ghetto compression check. By that I mean pull the leading
plug on each rotor and spin the motor by hand and make sure you hear 3 even puffs
as the rotor makes its roatation. That will rule out internal issues (at least serious ones).

Sounds like you need new plugs at a minimum based on that description. Get new plugs
and try it out again.

Shawnmark

Hey, thanks for the feedback. Once it warms up a little bit outside i'll go try that ghetto compression check. The fact that the car is still running makes me feel like not all is lost. I don't actually have the money for new plugs at the moment, because i spent all my money on the car. (I expected problems, but i did not expect the engine to give me trouble after two days. I'm admittedly ill prepared to take care of this car.)

Kentetsu

Running it up through the rpms like that, then immediately having an issue like stalling, sounds like a bad fuel filter.

However, shaking at idle like you describe sounds like you may have tossed an apex seal (blown motor). Perform the compression test as advised. If the motor is bad, then watch the for sale sections of the forums, Craig's list, maybe call a few junkyards, to find a used replacement. They can usually be found for 2 or 3 hundred bucks.

If the compression test turns out to be good, the replace the fuel filter (3 bucks and 15 minutes) and procede with the normal tune up items. One of the best things you will be able to do for the car is to pick up a can of Seafoam and put it in the gas tank. Rotaries are prone to carbon buildup in the apex seals, which can reduce compression and eventually even destroy a motor. The Seafoam will take care of that and restore the performance of the motor.

Let us know how the compression test turns out, and good luck.








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Shawnmark

Well, what i said about stalling, it happened when i clutched in to make a turn, so the engine dropped down to idle, and thats when it almost stalled and started to shake. If i tossed an apex, would i not hear it? I have not been able to get my buddy to come over with his tools yet, so i have not had a chance to try the compression test. Also, today my electric system was acting a bit fennecy. From what I've read, my battery cables might be shot. I tried to jump start the car, and when cranking the engine the voltage dropped down to around 8 or 9 volts.

Also, when it comes to the engine, would it be better to do a rebuild, or just buy a new one?

Kentetsu

Rebuild or replace? That will totally be dependant upon your budget.

Battery cables are a common problem with these cars. You can get heavy gauge replacements pretty cheap from places like Autozone. Grab them off the shelf, rather than asking at the parts counter. Just make sure the length is correct. I did mine and it made a big improvement.

Shawnmark

Well i did the poor mans compression test today. The front rotor appears to have compression, although i could not really spin the engine fast enough to hear how many puffs it was making, that side still runs, so i assume it has compression on all three. The rear rotor does not seem to have any compression what so ever. I did not hear anything coming from that side. I'm going to be borrowing a compression tester from a friend as soon as i can.

Something a friend told me is that i might have seized an Apex. He knows his RX7's, and was the one who recommended i join this community. He said that it might be fixable, and that i should ask you guys what the best way to free it up would be. I've been searching a bit and all i've really been able to find is the ATF treatment. Anyone else got suggestions? I'm sure this has been experienced by quite a few people.

orion84gsl

iTrader: (5)

Seafoam will do the same job of freeing up a stuck apex seal as ATF.

You will not necessarily hear an apex seal failing. My 12A tossed an apex seal in the rear rotor last year, and the only way I could tell is because when I tried to take off from a light the car had almost no power and sounded like a lawnmower.

Another way to check compression is to crank the engine with the leading plugs out. Same idea as turning it with a ratchet but it'll spin faster, and the puffs will be a little louder and more noticeable if one face isn't getting compression. This is how I figured out my rear rotor was toast. If it's not a seal issue, this will do no harm to the engine, if it is, well that rotor and housing are likely garbage anyway.

Kentetsu

Also, keep in mind that if the engine is flooded, it will have no compression to speak of. The fact that the rear rotor had no puffs at all would lead me to believe that it is simply flooded.

Usually, when performing the compression test on a rotor with a bad apex seal, you will still hear puffs of air. The only difference will be in the rythm of the puffs. Hard to explain, but its kind of like this:

Good rotor: puff..puff..puff..puff
Bad rotor: puff.....puff......puff......puff

So it really helps if you compare front to back and check for the rythm of the puffs.

No puffs at all would imply either a flooded engine, or no apex seals at all. Losing all of the apex seals is not unheard of, but it is rare.

Rotaries love Seafoam! Stay away from the ATF treatment, just use the Seafoam instead. It will not damage the soft seals in the motor (much debate over whether or not ATF will harm them), and it won't foul your spark plugs either. I also use it to deflood rotaries with great success, just dump an ounce or so down the carb and crank it over.