Help! 96 3.8 V-6 engine "Locked down"
08-27-2006, 04:54 PM
#21
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Originally Posted by Goatcrazy
OK, here'* the results: 
I performed the steps that I described in my post, and when I turned the engine over by hand (Turning it with a ratchet as fast as I could go). The engine rotated freely and made no unusual noises.
I then "bumped" the engine with the starter a few times until I saw oil pressure show up on the guage, then cranked it freely and no unusual noises, oil pressure good, all seemed well.
Here are the results of the compression test:
#1: 205
#3: 185
#5: 180
#2: 185
#4: 205
#6: 170 * Very litte oil added to this cylinder
The numbers are slightly out of the 10% spec, but given the fact that each cylinder had varying amounts of oil added, and the vehicle has 240K miles on it, I think that the results are good...
What should I do from here? The intake manifold kit comes with all required gaskets for re-installation. Should I use those or step-up to a fel-pro set based on other people'* experience?
Also, I originally intended on replacing the timing chain soon, and I was thinking about doing it now, but I think that I won't for two reasons:
1) If the engine does have bearing problems I don't want to sink any more money into it than I have to. I want to watch it for a while, and if it looks good after a month then I'll go back and replace the chain.
2) I diddn't want to create to many potential problems at the same time, when then complicates the troubleshooting process (ie: rough running engine - is it a vacuum leak, timing off, cam/crank position sensor problem, etc etc )
What are your thoughts?
I performed the steps that I described in my post, and when I turned the engine over by hand (Turning it with a ratchet as fast as I could go). The engine rotated freely and made no unusual noises.
I then "bumped" the engine with the starter a few times until I saw oil pressure show up on the guage, then cranked it freely and no unusual noises, oil pressure good, all seemed well.
Here are the results of the compression test:
#1: 205
#3: 185
#5: 180
#2: 185
#4: 205
#6: 170 * Very litte oil added to this cylinder
The numbers are slightly out of the 10% spec, but given the fact that each cylinder had varying amounts of oil added, and the vehicle has 240K miles on it, I think that the results are good...
What should I do from here? The intake manifold kit comes with all required gaskets for re-installation. Should I use those or step-up to a fel-pro set based on other people'* experience?
Also, I originally intended on replacing the timing chain soon, and I was thinking about doing it now, but I think that I won't for two reasons:
1) If the engine does have bearing problems I don't want to sink any more money into it than I have to. I want to watch it for a while, and if it looks good after a month then I'll go back and replace the chain.
2) I diddn't want to create to many potential problems at the same time, when then complicates the troubleshooting process (ie: rough running engine - is it a vacuum leak, timing off, cam/crank position sensor problem, etc etc )
What are your thoughts?
The UIM gasket that comes with the Dorman is fine. But you will want to change out the LIM gaskets, too. Best to use the Aluminum GM gaskets for that.
If you have the time and energy, you could just do the UIM first, run it and see if it'* OK, then go in again and do the LIM gaskets. The UIM gasket and throttle body gasket are re-usable.
But it is not advisable to ignore the LIM gaskets. They will fail and destroy your engine in the same way. Fel-Pro LIMs will cost you $40 and GM Al-frame LIMs will cost you $60.
Have you read this topic yet? http://www.bonnevilleclub.com/forum/...e=article&k=38
If not, you really need to.
08-31-2006, 01:24 PM
#22
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Well, I got the Bonnie back together again. I replaced the UIM, gaskets, spark plugs & wires and it fired up as if nothing ever happened...
It burned antifreze HEAVILY when I initially started it....I had to Idle/drive for about 20 minutes for it to clear up. As soon as the smoke thinned from the tailpipe, I changed the oil again (#2 in 8 miles of driving) and the oil was really thin. The original oil change after the incident looked better than that...
My check engine light is on now...From the previous posts I assume that the lead oxy sensor is blown out & needs to be replaced. That one doesn't cause drivability problems, so I'll sit on that for a while while I monitor the health of the engine...
Engine temps OK, oil pressure OK. Runs smooth as ever...
I'll probably drive it for a few days and do a final oil change and begin monitoring for coolant entry....
Thanks again to all for the quick help!!!!
It burned antifreze HEAVILY when I initially started it....I had to Idle/drive for about 20 minutes for it to clear up. As soon as the smoke thinned from the tailpipe, I changed the oil again (#2 in 8 miles of driving) and the oil was really thin. The original oil change after the incident looked better than that...
My check engine light is on now...From the previous posts I assume that the lead oxy sensor is blown out & needs to be replaced. That one doesn't cause drivability problems, so I'll sit on that for a while while I monitor the health of the engine...
Engine temps OK, oil pressure OK. Runs smooth as ever...
I'll probably drive it for a few days and do a final oil change and begin monitoring for coolant entry....
Thanks again to all for the quick help!!!!
08-31-2006, 02:26 PM
#23
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We are glad to help.. And we hope that we have helped you save an engine.. 
Let us know how it all pans out
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09-01-2006, 12:28 PM
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If the engine holds up for a month, I'm going to call it good, and go back and replace the LIM gaskets, timing chain, and coil packs
If I feel like upgrading the ride of the vehicle from what feels like a '56 Bonneville, back to a '96 model, then I'll replace the struts!
Thanks again for the help!!!
If I feel like upgrading the ride of the vehicle from what feels like a '56 Bonneville, back to a '96 model, then I'll replace the struts!
Thanks again for the help!!!
09-12-2006, 12:36 AM
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Great analysis Bill - I thought the same thing. I do what Wilwren said. DRAIN THAT OIL ASAP! These guys here really know there bonnevilles and they will steer you in the right direction. Great JOB!
Originally Posted by BillBoost37
Sorry to say....but here'* what happened..
Your upper intake ruptured and dumped coolant into the motor. It started running rough from the burning coolant and then as the coolant filled the lower intake ...it overflowed into a couple cylinders and hydrolocked the motor.
You will want to drain and replace the oil as soon as possible as it is probably rusting and corroding your bearings.
Your upper intake ruptured and dumped coolant into the motor. It started running rough from the burning coolant and then as the coolant filled the lower intake ...it overflowed into a couple cylinders and hydrolocked the motor.
You will want to drain and replace the oil as soon as possible as it is probably rusting and corroding your bearings.
09-13-2006, 04:49 PM
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I bought my '97 non-running with 100k miles, and had the same issue. Mine had cracked the front head between two valve seats when it hydrolocked, so I replaced the head, and had 'em both machined, along with all new gaskets and a Dillon upper. It had a recent oil change prior to my purchase, but sat there several days with heavily contaminated oil. After repairing everything, I refilled the oil (had drained it immediately after I got the car), and ran it maybe 1/2 hour. I did a oil/filter change, and drove it for a few days, and changed it again. Oil is cheap, engines are expensive, so I wanted overkill in getting water out of the oil passages! 10k miles later, my engine still runs strong. Best of luck!
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