This is a really strange problem, any help would be appreciated......

I was driving down the road the other day, and out of nowhere the car began to run slightly "rough" as if it had an ignition problem. This quickly grew from slightly rough to running as if it were on 3 out of 6 cylinders. Then it died all together. I coasted to a parking lot, and tried cranking over the engine, but it would not start. It cranked freely, but no sign of ignition.

The starter made some grinding noises, then would only "click" when I tried to crank it.

I thought the battery was dead, so I put in a new battery and the same thing, just a "click".

Yesterday I replaced the starter, and noticed that the starter nose cone was broken off which I found extremely odd.

When I tried to crank the engine again, after replacing the starter, all I got was a "Click". Looking into it further, the starter was trying to move the engine, but the engine would not physically turn.

I tried to move the engine by hand, and I noticed that it would move freely in the direction OPPOSITE to engine rotation maybe 180 deg. crank rotation, then bind again. Moving forward it moves freely back to the starting point again. If I rotated the engine back 180 degrees, then tried to crank, it would crank until it moved 180 degrees then stop.

I've never run into this before, what could possibly be going on!!!! I really need to get this car back on the road again!!!

The car is a '96 bonneville with the 3.8 V-6. It has 240K miles on the original drivetrain. The timing chain has NEVER been replaced. The oil level is fine, the car did not overheat at the time of the problem.

I was wondering if the timing chain jumped, which would explain the car originally stalling, and maybe now the valve is in contact with one of the pistons which would explain why the engine only rotates so far.

But I thought the 3.8 V6 engine had clearance between the piston and the valve at full extension...Does anyone know if this is true?

Pleeeeease Help!!!!

 

This is my guess. There is something mechanical blocking the motor from going past the "stuck" point. If you're lucky, it may fall away and allow the motor to turn completely over. Or...it falls away, you start the motor and cause total damage. Picture a rod cap dangling off, or some other nightmare like that.

Perhaps a broken tooth off the cam gear stuck in the chain, maybe one of valves lost it's keeper and the valve fell part way into the combustion chamber. If you're lucky, maybe just something wrong with the belt that will reveal itself as you rotate the crank. Look for the easy stuff first. But I would not try and rotate with the starter.

Try backing the motor BY HAND a full 360 or more, then going forward BY HAND.
Listen for any unusual noises. I would pull the starter again and have someone inspect the ring gear while the motor is rotated, then pull the valve covers and check that all the valves are OK, and the cam turns with the crank.

The fact that it started running rough before it quit means 2 likely suspects: Cam or ignition timing. I'll bet it's the cam

 

OK here's the diagnosis:

It appears that the 3.8 L V-6 [Info from Bonnevilleclub.com] has a factory problem of the upper intake manifold (composite unit) cracking and leaking coolant into the cylinders. When this occurrs, varying problems can occurr from the engine burning coolant slowly to the engine being suddenly filled with fluid, hydrolocking and bending rods.

My case was a mild (if that's possible) one of the last scenario. I removed spark plugs from all the cylinders and turned the engine over by hand. Cylinders #1 and #4 bubbled fluid out when those pistons came to TDC.

I have drained the oil, and it's not milky, but it does have a very thin layer of coolant at the top.

I'm researching what I need to do to make the intake manifold repair.

What other things should I do given the circumstances?

 

Squirt about an ounce of oil into each spark plug hole and rotate slowly by hand. That should keep things from getting worse while you work on the intake.

I just bought a 2000 V6 camaro. Is that intake common on all v6's or just pontiac's bonneville? How common is this problem? Does it happen because of age & heat, or on fairly new motors?

 

Just came back from that Bonneville forum. The intake issue looks to be a huge mess..! My 2000 Camaro V6 has a metal intake. Is that in place of the composite, or is the metal covering up the composite which is hidden under the metal unit..? Am I in the clear, or do I have a whole different set of problems..?

Also, it appears that the EGR is mounted on the left front of the motor, just behind the Power Steering Reservoir. Is that correct..?

Hey, I'll buy the manual when I complete the purchase in the next few days...deal is not yet done.

 

I think all 3,8L in the F-Body have the same intake (metal).....
The EGR crap is on the driver side of the motor just behind the power steering reservoir, thats right!

 

this is the Bonneville intake..... total different to our F-Body Intake!