compression test results are in. see page 2.

[88bonnsse]

Put in new plugs at least.

o.k cool.. but any thoughts on the compression test results ?

[00Beast]

I'm not an expert on the results. It's good that they're all within a few percent, means you don't have a bent rod or one piston with bad rings, but I don't know what a good L36 reads.

[willwren]

Your motor is toast. Your rings are shot, causing MAJOR blow-by. Your PCV isn't big enough to handle it all.

Start looking for a new motor or car ASAP. I'd be concerned with a 10% change between dry and wet tests on a 3800. Your motor was severely abused at some point. I've NEVER seen ring/cylinder wear anywhere near the numbers you report.

When I say toast, I mean TOAST.

This is the cause of all your symptoms. The idiots at Firestone should STILL have checked compression before guessing.

[1oldman]

I think you did a dang good job performing the compression test. Too bad it won't help the rings, but you did good!!!!! - BC

[88bonnsse]

Your motor is toast. Your rings are shot, causing MAJOR blow-by. Your PCV isn't big enough to handle it all.

Start looking for a new motor or car ASAP. I'd be concerned with a 10% change between dry and wet tests on a 3800. Your motor was severely abused at some point. I've NEVER seen ring/cylinder wear anywhere near the numbers you report.

When I say toast, I mean TOAST.

This is the cause of all your symptoms. The idiots at Firestone should STILL have checked compression before guessing.

what numbers are bad ? the wet or the dry test numbers ? of just the fact that the difference between the 2 test is so huge..?


so its a gaurentee my motor is shot ? it lasted 3 yrs already like this... hopefully it last another 3-weeoks to 3 months so i can get a motor..

http://allentown.craigslist.org/pts/2318401454.html


its still in the car, i called him on monday of this week. he said for $350 i get the entire complet motor with everything on it. and i can here it run and rev the engine. i just cant drive the car cause it only goes in reverse... so what do you think will ? is the price worth it ?
what do you think about this ?

[Mechanical Mike]

How much oil did you put in each cylinder for the wet test?

[RJolly87]

How much oil did you put in each cylinder for the wet test?

I was curious about this as well.

[Jrs3800]

The ash on the plugs as well as the low dry test readings lead me to believe the rings are shot... I would expect to see 170-190 dry on a 9.4 : 1 compression motor...

[willwren]

Your dry numbers are far too low to be considered good. And they are all equally bad. The fact that it rose at all wet is an indication your rings are shot, not your valves. Had the numbers not changed, your low compression would have been due to valve, seat, or stem seal wear.

I also suspect you used way too much oil in your wet test, but it doesn't really matter in the long run. Add the plug evidence in, and the deal is sealed.

[88bonnsse]

How much oil did you put in each cylinder for the wet test?

i had a 6 ounce squirt bottle, used about an ounce in each cylinder..

[88bonnsse]

The ash on the plugs as well as the low dry test readings lead me to believe the rings are shot... I would expect to see 170-190 dry on a 9.4 : 1 compression motor...

150 psi is what i thought it was normally.. i seen that on a site with 95 bonneville specs..


and i also seen this.. on another site...


Comments (100)

Comment by:
symons
5/8/2011
12:32 AM I have a 1996 3800 it makes a wisteling sound after it run for a few seconds and if you remove the oil fill cap the engine will kill. I have already installed new pcv and new orings this did not help.Took it to a GM dealer they also have no idea what is wrong. Could this be the plastic tube that goes to the pcv bad up the intake?

[harofreak00]

How much oil did you put in each cylinder for the wet test?

i had a 6 ounce squirt bottle, used about an ounce in each cylinder..

Did you not watch the video you posted?

here is the video.. good video too for anyone who wants to learn how to do this.
http://www.youtube.com/watch?v=X_tbksFY ... 11F3F2282C

You only needed a few drops, not an ounce. You probably put in about 500x too much oil. But, like willwren said:

I also suspect you used way too much oil in your wet test, but it doesn't really matter in the long run. Add the plug evidence in, and the deal is sealed.

[willwren]

The PCV dispersion tube in the intake doesn't matter at all if it were missing or fell off in there. The PCV will still flow just fine. Start coming to grips with the fact that your motor is toast. We've very clearly laid out the diagnosis based on your troubleshooting.

[88bonnsse]

The PCV dispersion tube in the intake doesn't matter at all if it were missing or fell off in there. The PCV will still flow just fine. Start coming to grips with the fact that your motor is toast. We've very clearly laid out the diagnosis based on your troubleshooting.

:(


update: hey will, i just called my local star pontiac dealer and spoke with the service department.

i explained to them my entire problem and even the numbers from the compression test.

they said my motor has plenty of compression and is good, they said the loud whistle noise my motor makes untill the oil cal is removed is due to a bad vaccuum hose, or air inductoion chamber i think he said.. he said my motor is fine, dont buy another one... i would be wasting my money..


and this came from a 37 yr certified gm technician. im gettin both my motor is good and its not good. dont no really what to do....................

[Mechanical Mike]

I'm confused about something. If he has massive blow-by then shouldn't he be feeling pressure at the filler instead of suction?

[95naSTA]

I had similar numbers when I did a compression test a few years back. My rings were also shot. I did get a spare motor but I wanted to see how long it would last like that. 40k later it was still running when I finally pulled it.

[willwren]

Forget the certified GM Mechanic. The 'acceptable' specs on compression per GM are very low. 99.9% of the motors on this Forum are significantly higher, and your plug condition sealed the deal. GM mechanics work on all types of motors, and don't have the luxury of specializing on the 3800 family alone. The 3800 is a notoriously 'tight' motor when compared to all others made by GM divisions. It's a unique animal.

Your compression sucks, you have the symptoms, your compression numbers back it up, and the plugs seal it's fate.

[88bonnsse]

Forget the certified GM Mechanic. The 'acceptable' specs on compression per GM are very low. 99.9% of the motors on this Forum are significantly higher, and your plug condition sealed the deal. GM mechanics work on all types of motors, and don't have the luxury of specializing on the 3800 family alone. The 3800 is a notoriously 'tight' motor when compared to all others made by GM divisions. It's a unique animal.

Your compression sucks, you have the symptoms, your compression numbers back it up, and the plugs seal it's fate.

my plugs looked used i.m.o.. not burnt up.. they are 4 yr old plugs with 40k on them.. i figured they looked normal for that kinda miles on them..


i mean my car does not drive bad at all in any sense or way. it drives perfect, good pedal response, no shaking in the motor, nothing.......

if my motor was shot then wouldnt i have some signs or symptoms besides just a whistle noise after 3 yrs ? i mean really it cant just be *shoot* but still running *dang* near perfect..




quote - 95nasta
i had similar numbers when I did a compression test a few years back. My rings were also shot. I did get a spare motor but I wanted to see how long it would last like that. 40k later it was still running when I finally pulled it.

what were your symptoms that made you do a compression test ? im curious.

[RJolly87]

You have had 2 admins tell you what is going on with your engine. Admins who know the 3800 like the back of their hand. You have testimony of one driver who had similar compression numbers, who also said that he ran it for 40k miles without issue. What does low compression mean really? The engine is not as good as it could be, and is on its way out. It very well could hang in there for another 100k miles, it could begin dropping more compression tomorrow, or start coming apart, no body knows. Because it runs good now does that change anything? No. Will you arguing about it change anything? No. Are you welcome to throw more money at it and go about figuring it out your own way? Yup, but don't complain if you come back to the same diagnosis, and are out money. Can you prove many experienced members and mechanics wrong? Please do, we are here to learn, but remember, we have seen just about everything.

[willwren]

My bad. I wish you would have told us what you wanted to hear sooner. Let me correct myself (and ignore my posts, jrs3800's posts, and 95naSta's posts in this topic):

Your compression is normal. Exactly what we would expect to see. It has nothing to do with the symptoms you described. I'd call your compression numbers factory normal +40%. Great motor. It should last you forever. Ignore your other symptoms leading up to our incorrect conclusion, that's also perfectly normal behavior for your engine.

In the future, tell us in your original post what you want to hear. It sucks to have to waste 3 pages just to get to that point.