Need help with engine that won't run

keithert · 10-27-2009, 11:41 PM

My 92 8v has been running fine since I got it a couple months ago. It would start immediately when the key was turned. It started to have a problem where there was loud squeal when the weather was wet. I'm pretty sure this was from the alternator. In diagnosing this I poured a small amount of water on the alternator with the engine running and it immediately started squealing. The next day the engine was very hard to get started. It would make a bucking sound while cranking. I got it started and was able to drive it about a mile before it died and was very hard to start. It did start and I limped it home. Tonight I replaced the alternator but it is still having this issue where it won't start. If I don't give it gas it just cranks indefinitely. If I hold the gas it bucks and will backfire after cranking awhile but will almost start. It almost sounds like the timing is off. But I don't know how pouring a small amount of water on the alternator would cause the timing to go awry. But this started the day after I was messing with the alternator. Any ideas would be much appreciated.

aquanaut20 · 10-28-2009, 01:40 AM

Water on the alternator, whatever posessed you?? Water and electricity dont like each other.

Have you checked the running output of the alternator @ 2000rpm, should be 14.5vdc. if not your battery(12.5vdc at rest) may be in a state of discharge . Delivering enough to crank but not enough to fire the coil.
If you don't have fully rectified charge current, the water may have cracked/damaged the HOT rectifier diodes.

Bex · 10-28-2009, 06:17 AM

Any CEL codes?

keithert · 10-28-2009, 06:38 AM

Quote:

Originally Posted by aquanaut20

Have you checked the running output of the alternator @ 2000rpm, should be 14.5vdc. if not your battery(12.5vdc at rest) may be in a state of discharge . Delivering enough to crank but not enough to fire the coil.
If you don't have fully rectified charge current, the water may have cracked/damaged the HOT rectifier diodes.

Is the rectifier in the alternator? The old alternator has been replaced. I haven't been able to get it started so I can't tell if the CEL is staying on. When it was running poorly the other day the light was not on.

keithert · 10-28-2009, 08:23 AM

I checked the unloaded voltage at the battery and it was 12.75. I then hooked up my portable jump start device and it read 12.99 volts. I couldn't check the voltage while cranking. It did the same thing where it wants to start but won't catch. I'll try to jump it off another car tonight and read the voltage while cranking.

Richard Craneum · 10-28-2009, 10:23 AM

Check your Valve Timing. Get a compression tester. You can get from Auto Zone (rental for a deposit that you will get back).

1) Mark all wires (1 through 4) where they go.
2) Take all the plugs out.
3) Screw the Pressure Gauge fitting to the Plug holes.
4) Take the fuel pump fuse off (to avoid fuel been dumped in the intake)
5) Disconnect the Coil Cable to the distributor from the coil itself (just a precaution)
6) Crank the engine with the throttle pressed all the way down (WOT)
7) Give it a good crank (like 6 full rotations)

You should get like 165 PSI or so with the engine cold (I think, Jerry knows the numbers

)

If I am correct and the valves are out of sync, you will not have hardly any good compression (very low, depending how bad are out of time).

If you have an air compressor you can point the engine on TDC for the 1# Cylinder and push air via the Spark Plug hole. It should keep pressure, if leaks out, a valve is open.

I think your problem is not the Alternator, but a Timing Belt issue. When was the last time you replaced it? Is a 60,000 mile intervals by the Owner's Manual.

aquanaut20 · 10-28-2009, 10:49 AM

Look like you have eliminated any power problem, your next move would be to follow Richards excellent diagnostic flow chart.

Let us know the results.. P

keithert · 10-28-2009, 10:56 AM

I have a compression tester. I'll test it tonight if I have time.

Bex · 10-28-2009, 03:11 PM

Quote:

Originally Posted by keithert

I haven't been able to get it started so I can't tell if the CEL is staying on. .

You only need the key in the on position, the car does not have to run for the codes to be recorded. I only mention this as if car sounds like it wants to start but just doesn't catch, could be fuel issue, which ECU would record.

Richard Craneum · 10-28-2009, 03:29 PM

The compression test will tell if the cam is out of whack. If that is the problem, the Ignition Timing will be off too since it uses the Camshaft as a reference.

On the one that you pump air on the cylinders you can hear the air hissing on by the valve that is open, if is not too open.

But be careful, doing this will push the piston down and roll the car. If is in 5th Gear, Chocked and Parking Brake pulled, I think one piston can not do the work with about 100 or so PSIG (no need to go too high).