onecoolmint

Hi guys,

I have an '89 GXL with about 155k on it. I've owned it for about 8 years and it's been a great car. Other than a couple of small things (needed brakes and mufflers), it's needed very little maintenance. It's flooded a handful of times but nothing that letting it sit for a few hours didn't fix.

Recently, though, I had a few problems. The local dealer is telling me that it needs a new engine, but I'm not convinced so hoping maybe some of you have had similar experiences to share or ideas on what the problem could be.

About a month ago, as I was driving to work, the car decided to start overcharging (voltage meter went to the top and all the idiot lights came on). This only happened a few hundred yards away from my house, so I drove it back home and had it towed to the shop. They replaced the alternator and that seemed to fix the overcharging problem.

I drove it for about a week without issue. One day I drove it to work and it was fine. When I started it up to go home after work, though, it had a problem. It started the first time, but it ran *very* rough. It sounded funny and was very uneven/shaky. I thought I'd maybe lost a rotor. I let my foot off the gas after a few seconds, and it died immediately. I tried to start it again but it wouldn't start. It cranked over fine but wouldn't start up. I had it towed to the shop, and they said it was severely flooded. They cleared the flooding and said that they noticed the thermostat was broken causing the car to overheat while they idled it (I'd never had a cooling problem prior to this so I'm suspicious). Anyway, they said it was fixed and gave it back to me.

I drove it back and forth to work for several days, and it seemed fine. Then about 10 days later the exact same thing happened (very rough start after work, died when I let off the gas, then flooded badly and wouldn't restart). I had it towed to the shop again. They're now claiming that this is happening because of low compression, and that I need to replace the engine.

The compression numbers they gave me are:
Front rotor: 6.2, 6.3, 6.1
Back rotor: 5.1, 5.0, 5.2

Do these numbers sound normal, or a little low, or very low?

Other than the the two times it rough-started, the car has run fine. It starts fine, has good power at low and high RPMs, gets normal gas mileage, and idles beautifully at ~800RPM when the engine is warm. So I'm a little hesitant to believe that low compression is the cause, because symptoms are intermittent.

Are there other problems that are likely to cause this kind of behavior? Fuel injector problem or vacuum leak or ignition problem or something else? Could something have been damaged when it was overcharging, maybe a wiring harness or something?

Please let me know.

Thanks a bunch!
mint

prime

If its intermittent I wouldn't be inclined to think its low compression, though I'm unsure as to a secondary cause. I'm new to rotaries myself, as you can see by my post count. However I can say that a N/A Rotary has somewhere between a 9.1:1 and a 9.4:1 compression ratio. Those numbers are WAY to low for a N/A. If its a Turbo, thats a different story. I don't think the compression for turboed cars is decreased that much, but I do know it is lower than the N/A engines.

I'm pretty sure all GXL models are N/A, so those numbers are very low for your engine. Unless the casing is exploded or theres a huge line gouged around the rotors on the inside, I don't see you needing to replace it though. I'm sure another more experienced member of the forum could help you chase down a more probable cause.

What I will say is that whoever is working on your engine probably doesn't have the experience to guarantee any repair, so they're recommending the entire engine be replaced due to liability concerns. If they replace the whole damn thing crate, they don't have to worry about whether or not that know how to fix it, it'll just run. Theoretically.

onecoolmint

Thanks prime. I talked to the shop and they said that the compression test was done on a warm engine and the cranking speed during the test was 245 RPM. Does that say anything as to the numbers? You're correct, the car is a non-turbo.

Is it possible the ECU could be giving some incorrect fuel mix signal intermittently that would cause the problem I'm seeing?

Thanks again!
mint

btbaus

iTrader: (3)

how long since youve had a tune up??? perhaps the fuel pump strainer is clogged a bit.... is your check engine light on??

onecoolmint

Hi btbaus, thanks much for your response.

The car was tuned up probably about 6 months ago (beginning of the summer).
The check engine light has never come on, it always ran fine until the overcharging happened.

The shop still has my car now, and they say they can't get it to start at all, and are still pushing for me to get a new engine. I'm concerned that the problem lies somewhere other than the engine itself, though (fuel injector, ignition, etc.), and that it may still exist even if I did get the engine replaced.

Can anyone recommend a good rotary shop in the Portland, OR area that might be able to have a look at it?

datz

I'm pretty sure all GXL models are N/A


???

SCCAIT7

First red flag ... If this is not a rotory shop ... How did they do a compression test? You CANNOT, CANNNOT, CANNNNNOT use a conventional compression tester ... I don't care how good someone says they are - ill bet you a case of your favorite beer (shipped to your location) I get a different compresion reading with the Mazda compression tester than they do with their Autozone/Snapon/Matco/MAC piston engine tester!!!

I have brought cars back from being "severly" flooded that have sat for 6 months. I would suggest bringing the car home. Pull the plugs out and report on their condition. Be sure you do this with the engine cold. I would bet you have a fouled or bad plug(s)

The injectors in our cars are FAMOUS for leaking down after you shut the engine off. They simply get old and don't hold the fuel pressure - This leaks down into the housings and causing a flooded/ing condition. Then when you go to start the car the computer sees cold engine - FUEL and puts more fuel in there. Anyway ... I had/have this problem with my car even with new injectors. I ended up putting a fuel pump swtich in line and I turn it off for 5 seconds before turning the engine off. Then turn it on for 5 seconds before starting.

onecoolmint

Hi SCCAIT7, thanks much for replying.

The shop I brought it to is a Mazda dealer. Sorry, I should have mentioned that in my original post. They said they did use the Mazda factory compression tester, so the numbers might be accurate. On the other hand, I don't believe any of their mechanics are really rotary experts. Their first response after checking the compression was "we think it's probably a bad apex seal", which doesn't seem to match up at all with the compression numbers they gave me. Their diagnosis hasn't seemed too certain. Something to the effect of "we can't find anything else, so it must need a new engine".

One more small bit of info -- they said the cranking speed for the compression test was 245 RPM.

Interestingly, the first time it happened, the dealer only kept the car for about half a day. They said they cleared the flooding, and I took the car and it drove fine for a over a week. The second time it happened, the symptoms were *exactly* the same, yet now they say they still can't get the car to start at all (they've had it for well over a week).

Does it make sense that the two rough starts/idles be caused by a leaking injector? That's to say - would the flaky injector cause the very rough idle and subsequent stall when I let off the gas? If so, is there any way to test the injector to to rule it in/out as the problem part?


Thanks again!

prime

Yes, replace the injectors. Actually, to be totally sure, you could overhaul your whole fuel system. But to keep it simple, fuel pump, fuel filter, make sure the lines aren't kinked, and replace the injectors. It COULD need new apex seals, but that needs a rebuild, not a new engine. A new engine for bad seals is a little nuts, these things should have new seals every 60,000 kilometers.

Bad seals, on every rotor, could explain those compression numbers. However I find it sketchy that they said they tested on a warm engine. First off, you don't do compression tests on a warm engine. A warm engine will give you an entirely different, and unreliable result, as a cold engine test. The an engine is not thermally efficient, it heats and cools unevenly. Technically speaking your engine should have better compression when warm and there's a lot of oil in evidence.

Testing a warm engine doesn't give you a thorough baseline reading. Also unless these ****'s have giant heated blankets I don't see how they're getting an engine that won't start warm, I've got alarm bells goin off in my brain mate.

A rough idle could also be caused by low oil pressure, IE a broken oil pump, not enough lube in there. It could be the reason for the low compression in that the lack of oil very quickly ruined the seals. It could even explain why it happened a second time after everything was checked over the first time. You practically have to rebuild the engine, take the engine apart, to get to and check the oil pump. And given the nature of our rotary engines, a busted oil pump would be a very bloody bad thing.

I'm not really sure what else to tell you without taking a look at the car myself.

EDIT - Also, you could drain the fuel tank. If you have a bad water mixture or something forigne in your tank, that could do it to. You might try just starting it up with a full tank. The water shoulder stay at the top, away from the pump, and if it runs ok then you know that's your issue.