NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   -   Is Engine Dead (https://www.nopistons.com/2nd-generation-specific-17/engine-dead-12537/)

rpm 02-19-2003 02:20 AM

Hi all. First time user to the site. Glad to see there are other enthusiasts out there. I just picked up a 1988 RX-7 SE non turbo manual transmission for $175.00! The owner of the shop said that it was a customers car and the engine was shot. I planned on replacing the engine, but it runs! I drove it on and off the trailer, and into the shop. It runs rough and doesn't seem to idle. The battery was also dead so I had to jump it. It starts right up. The first thing I'm going to try is new plugs and a battery. It doesn't smoke or smell like anti-freeze or oil. I checked the oil and anti-freeze, both were full and looked new. The air cleaner also was in great shape. The shop owner didn't know rotaries and from the sound of it didn't even pull a plug, just assumed it was dead. Quote: "Those rotaries only last 60k." The car has 118k, he state it already had a different engine 67k ago. I have a '79 RX-7 since '89, and my dad bought his new in late '78. Never had any trouble. I also change an engine in a '86 back in '96, so I'm familiar w/ the engine components. Is the engine dead? What should I check? How do I check compression or a bad apex seal? Any help would be appreciated. Thanks in advance.

phinsup 02-19-2003 02:29 AM

Check for compression. you should get three compression spikes, if you have a gauge that holds the compression, just open the valve and have someone crank it over.

bradley87se 02-19-2003 10:36 PM

Keep checking the coolant...from what ive heard it leaks slowly. Definately go with the compression test though. Either way only 175$ is cheap as balls.

rpm 02-19-2003 10:41 PM

The new plugs and battery did nothing to improve, but the plugs were worn out. I'm next going to try and check compression. Has anybody had a plugged up catalytic convertor that caused power loss? I had this happen on a Saab 900. What about faulty MASS sensor? Thanks, Ryan. BTW I cleaned the interior, looks better already.

pengaru 02-20-2003 01:48 AM

clogged cat will cause problems, but you can usually tell by high operating temps and/or glowing cat/manifold...



any old compression checker will work, but most piston motor checkers retain the pressure to hold a peak value, this is kindof useless when you're trying to get 3 readings from a single spark plug hole as on a rotary engine. So you have to remove the schraeder valve used to hold the pressure, so the needle can bounce with each rotor face. Looking for nice even bounces, somewhere between 60-150psi depending _greatly_ on rpm

most important is that there are 3 seperate spikes, and relatively even per rotor housing. Personally, I would crank for 15 seconds, and count the spikes during the 15 seconds. Multiple that # by 4 and you have your rpm count for a nice relatively useful compression check.



if compression checks out, other things would be coolant system pressure check, and if that checks out, and the car isnt low on oil and/or blowing oil smoke... she's probably something usable.



how's the oil pressure when you get her running?

rpm 02-20-2003 01:23 PM

Oil pressure is normal. I'm going to try the compression test next. Thanks a lot.

rpm 02-23-2003 11:55 PM

I checked the compression. 3 even spikes and 95psi in the front. No compression in the rear rotor. I am trying the ATF trick in the rear rotor as I have nothing to lose before pulling the engine. Any one know of a good source for a used engine. I'd love to keep the car but I have a '79 RX-7, 3 other vehicles and a motor cycle, so my plan is to put an engine in and sell it. Thanks.

rotary>piston 02-23-2003 11:59 PM

put some atf in the engine, if it doesn't get any better then you've probably got a blown seal. Do a comp. test though, make sure before you junk the engine.

rotary>piston 02-24-2003 02:02 AM

sorry, didn't see that last post

rpm 02-24-2003 02:20 AM

I've been looking at past posts about stuck apex seals. Any one had luck freeing them up when they had zero compression using the ATF trick? Is it common for the seals to stick from carbon build up in one rotor?

Racer X 02-24-2003 02:23 AM


Originally Posted by rpm' date='Feb 24 2003, 12:20 AM
I've been looking at past posts about stuck apex seals. Any one had luck freeing them up when they had zero compression using the ATF trick? Is it common for the seals to stick from carbon build up in one rotor?

I've heard it frees them up but how much depends on how stuck they were and if they arent siezed to the rotor.I don't think you will gain more than 20 psi at the most using the ATF trick.But what do you have to lose tho?

Racer X 02-24-2003 02:24 AM


Originally Posted by rpm' date='Feb 23 2003, 09:55 PM
I checked the compression. 3 even spikes and 95psi in the front. No compression in the rear rotor. I am trying the ATF trick in the rear rotor as I have nothing to lose before pulling the engine. Any one know of a good source for a used engine. I'd love to keep the car but I have a '79 RX-7, 3 other vehicles and a motor cycle, so my plan is to put an engine in and sell it. Thanks.

Damn you almost have as many vehicles as J9FD3S.https://www.nopistons.com/forums/pub...#>/biggrin.png

rpm 02-27-2003 01:01 AM

Thanks for the replies everyone. As an update the rear rotor apex seals are shot. I found an engine with 52k on it that I will be putting in the car. I also scored 15 inch BBS wheels for the car. They are actually the wheels I bought for a 1986 RX-7 in '99. I sold the car, but saw it DOA in a driveway for the past year in town. The engine I put in the car in '96 died, but he was willing to sell the wheels. I actually bought and sold that '86 twice--long story. Also considering putting a custom paint job on this car (Myself), maybe the new RX-8 red. Problem is that I'm not going to want to sell it when I'm done. Well, at least it will be another RX-7 revived and back on the road. https://www.nopistons.com/forums/pub...#>/biggrin.png

HeffSpooled 02-27-2003 03:49 AM

Thanks for posting the update. So many threads have no conclusion. Was it a broken apex seal(s)? Did you manage to eyeball it through the exhaust port?

rpm 02-27-2003 10:27 AM

I tried the ATF trick, let it sit for 3 days, no change. I will look at it throught the exhaust port when I pull it out. I was also thinking of using the old engine for a practice rebuild. It sounds like a lot of people are rebuilding them themselves now.


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