Ok, my best friend's neighbor is quite an old guy and I'm trying to help him out a bit. He has a early-2000s model Buick LeSabre FWD with the 3800 V6. The car is 1-owner, has 130k miles, and has been serviced regularly since it was bought. The oil has been recently changed, clear as a bell.

He replaced the battery (obviously thinking the battery wasn't powerful turning the starter) and tried to start it, but all that happens is a loud slam and the crank doesn't turn. Voltage drops from 13.3 to 8.2 when the starter is engaged.


I had to leave before I could check, but I'm suspecting the timing is off, but I still think the engine should cycle in that scenario. I still have not ruled out the possibility of s broken or bent valve.

My question is whether the GM 3800 engines interference-style? Meaning that the intake valves enter the same space that the pistons normally occupy on other cycles? I want to explore all possibilities before I determine whether a crank bearing went out.

 

They aren't interference engines.
First thing you should do is take the belt off and see if it starts. I have seen a seized alternator do this exact same thing. Come to think of it, I believe it was on the same motor as well

 

Ok thanks Shawn. I'll check it out when I go over there tomorrow. The guy is in the hospital today (minor surgery), so I can't get the key.

 

That engine is famous for upper intake failure causing the cylinder to flood with coolant remove the spark plugs and see if it cranks. If it does you need to replace the upper intake (not just the gaskets) the new updated intake comes with a smaller out side diameter EGR tube that you must replace or it will fail again. The original Egr pipe would touch the inside of the intake and cause it to warp. It is just a little 2" piece of pipe inside the intake just behind the t-body

 

My friend took the belt off this evening and ruled out the possibility of a seized alternator.
I'll pull the plugs on it tomorrow and see if there is any fluid on the cylinders.

 

What happened with this car?

 

My buddy just went back to Dyess last weekend and yesterday was the only day I have been able to work on it in the past 2 weeks.

I did get the cylinder heads off and theres no valve damage or timing problem. The timing cover is off and everything seems to be lined up correctly.
I think thats enough to say that a crankshaft bearing is suspect.

 

Update....
The crankshaft bearings are toast.