onecoolmint

Hi guys,



I have an '89 GXL with about ~159k on it. It's pretty much always run fine (flooded twice in the last 5 years). It's behaving badly now, and the dealer is wanting to tell me that it needs a new engine. I'm not completely sold on that being the problem, so wanted to see if any of you have had any similar experience and/or ideas. Here's the history:



About two weeks ago, I started it up to go to work one morning, and a few hundred yards after I left the house, the voltage gauge slammed all the way to the top and the idiot lights all came on. In fear of boiling the battery, I drove it back to the house and had it towed to the shop. They said it was the alternator that was bad and they replaced it. That fixed the overcharging.



I drove it for about a week and it was fine. Then one morning I drove it to work fine, but when I went to drive home after work things were not fine. I started it up and it started but ran *very* rough. It had a bit of a rattling/knocking sound, and as soon as I took my foot all the way off the gas, it died. Attempting to start it a second time, it flooded badly and would not start. I had it towed to the shop and they kept it for 3 days. They cleared the fuel from the engine and replaced the thermostat (they said it was failing, but I'd never had any cooling problems with the car before. at least it was a cheap part).



Anyway, I got the car back, drove it for about 5 days, in which everything was fine. The car started fine, had good power at both low and high RPMs. Then the exact same problem happened again (drove fine to work in the morning, went to start it up in the afternoon after work and it ran very rough then wouldn't start a 2nd time). So I had it towed back to the shop again, telling them the same thing happened. They've had it for a couple of days now, and are attributing the problem to low compression, which I assume means new engine time.



I'm wondering if there could be something else that's the problem though. Could some wiring have been harmed while the alternator was overcharging? The reason I wonder is that I had never had the problem until the alternator overcharged. Since then, it's happened twice in two weeks.



Thanks a bunch,

mint

1988RedT2

I don't know, but I wouldn't invest in a new engine until after I saw a compression test. Sounds like it could be something else, possibly related to your original alternator problem. Did they do a compression test? If so, have you seen the printout?



How is the battery? Good, or barely cranks it over?

onecoolmint

Hi, thanks much for your response.



I haven't been back to the shop yet to see if they have a compression printout. They called on Friday afternoon saying they were "pretty sure" it was low compression causing the behavior, but they didn't have any numbers or anything (it was just the customer service guy I talked to though, not the mechanic). They said they'd look at it some more on Saturday and call me again on Monday morning. I'm a little leery of what they're saying, because last time they changed the thermostat (which didn't seem like it should have been related to the problem) and didn't even check the compression.



The battery is totally fine, it cranks over no problem and passed the amperage test last time it was there. And in between the two "rough start" times, it drove great. Started good, plenty of power, no charging issues.



I'll definitely ask them for the compression test numbers if they try to sell me on a new motor. Any other tips on what I should ask them about?



Thanks again for responding -- much appreciated!

mint

onecoolmint

Hi guys,



I got the numbers back from the compression test:



Front Rotor: 6.1, 6.3, 6.1

Rear Rotor: 5.1, 5.0, 5.2



Do these sound normal, somewhat low, dangerously low, etc.?



I'm having a bit of trouble relating the compression back to the original problem. Aside from the overcharge time and the two rough-start times, the car has started and run normally. That's to say that the car starts fine, power is good at low RPM and high RPM, gas mileage is normal (18-19mpg around town), and it idles very smoothly at ~800rpm once the engine is warm. Does it make sense that the two rough-starts would be attributed to a compression problem?



Not wanting to pay for a new engine if there's something else that's semi-likely to cause these symptoms.



Thanks a bunch!

mint

Baldy

I'm wondering, would an open injector cause this? Could that happen intermittently?

confab

What units are the numbers in? PSI? KG/cm^2? Nm? That makes a big difference in interpreting. However, they're all pretty even. So unless you have two bad housings I wouldn't worry about the compression too much. I think they need to look a little deeper.

onecoolmint

Hi guys, thanks much for the replies.



The compression readings are in kg/cm^2.



The shop still has my car, and they say they're not able to get it to start at all now. They're still claiming low compression and saying it needs a new engine.



I traded a few emails with Pineapple Racing, and they say the compression itself probably isn't low enough to cause the car not to start. But that that the compression may be amplifying the real problem, whatever it may be.



I'm worried that even if I get a new engine, it might not solve the problem (e.g. if it's caused by a faulty fuel injector or an ignition problem or a fuel pump or something else).



Does anyone have a rotary mechanic in the Portland, OR area that they recommend? I used to take the car to Chris at GT Garage, but as far as I know he's not around anymore..?



Thanks again!

mint

onecoolmint

Also wanted to add that the cranking speed for the compression check was 245 RPM.



Thanks,

mint

compnut21

I my opinion it sounds like a faulty ecu. It could have been harmed when it was overcharging, but intermittent issues and only at certain times makes me think moisture related issues or dry solder joints. See if your passenger floor is wet and try another ecu. I can easily say the motor is not at fault.



p.s. The compression numbers are fine.

turborotor

No one suggested to check for vacumm leaks. Any vacumm leaks past the AFM would cause the car to run rough or not start.