Engine dead at 100,000 miles.
 

The engine to my '94 Bonneville died yesterday. The car just sputtered to a stop. Mechanic said a piston rod broke or something.

What what would cause this? I'm a little pissed it happened so early. I performed regular maintenance on it.

What does a new engine cost? Is it worth replacing?

Thanks in advance.

It's probably worth replacing. Those are good cars, and the engines are usually good. That's surprising that it did something like that so early. Usually, they go 250,000 miles or so. I know that the SeriesII engines had a composite intake manifold that would crack and leak coolant in to the oil. That's obviously a bad thing. I can't remember if yours is SeriesII or not, though.

Well are you the original owner? If not the previous owned could of beat the living hell out of the car and sometimes shit just happens. The 94 bonnevilles had the series 1 engine which are really reliable. I've seen the hit about 260k and still run great and strong. For that type of car you could just look for a low mileage engine from a salvage yard and you would get down the road for cheap.

Yeah, those engines are bullet proof. Could've been a manufacturing defect, who knows? Sometimes shit just happens. You deal with it.

Yeah, it's worth replacing. A 94 Bonneville is a frickin tank, I've seen those cars be abused in ways that no car should ever have to endure and just keep going.

Bought it used at 75k, but the original owner was an old man, so I don't think he'd have driven the hell out of it.

I'm still pissed off about this. Last year it had a blown head gasket, that cost me a shit load too. It's been problematic lately.

Maybe it's been leeking fluids into the cylinder via cracked intake manifold or some other method, resulting in some nice hydrolock. I really can't see what else would cause a connecting rod to break like that.

Bingo. Two plus two just made four. Blown head gaskets are USUALLY indicative of an over heat. Obviously overheating isn't a good thing. But, usually when a H/G fails, coolant seeps in to the oil, OR oil is spewed from the engine. Here's what happens in those scenarios.

Coolant in oil - contaminates rod and crank bearings, and eventually can and will lead to engine failure, either by locking up the engine, or breaking something hard in the bottom end.

Oil loss - If it never ran dry, you might think you're alright, but low oil conditions will eventually cause the bottom end to run hot, and you'll end up spinning a bearing.

Now, the early 3.8's, up to and including the Series I, which merkurguitars has informed us you have, do tend to have oiling problems in the bottom end, which can lead to either a seized engine, or a spun bearing, which will also seize the engine, and sometimes crack a block. Had that happen once. It looked cool, but cost a lot of money!

Personally, I'd find a Series II engine, and find out what the differences are for installation, and if it's not that big of a deal, install that engine. Just find the updated intake manifold and install it first. The Series I is usually uber-reliable, so reinstalling another one of those wouldn't be a problem at all. Probably find one at a salvage yard with 100k for under $500, and then take a couple weekends to install it.

Yeah, definitely keep the car, it's too much of an investment to give up on.

Oh yeah, the dreaded plastic intake manifold.

My 97 Series II plastic intake manifold cracked and destroyed the engine. The coolant mixed with the oil and killed the big end connecting rod bearings.

The series II came out with the plastic intake manifold in 96, so our original poster doesn't have that problem.

Personally, if you could fix the car yourself, cool. But an 11 year old Bonneville isn't worth very much. (Not to be cruel, just truthfully.)

The series II has the dreaded plastic intake manifold.

The series III however switched back to aluminum (imagine that). The series III came out last model year I believe.

If you want a really nice engine, then find a series III off of a crack up.

Actually, if I understand right, the only Series III engine is the supercharged engine, or L32. The L36 is naturally aspirated, and still a "Series II" design, if I recall properly. I may be wrong on that, but I do know that the power output for the 2005 N/A 3800's is the same. What the OP may want to do is research a L67 install. That's gonna be a bolt in job, if I remember right. Those SSEi Bonneville's had them from the factory. The website to check on that stuff is www.l67swap.com if he or anyone else is interested. Quick way for him to pick up about 65HP.

Either way, I think the N/A 3800 has returned to an aluminum intake manifold design, you are correct, sir.

go to www.car-part.com and find an engine in your area, they are common and you should find one for cheap, swapping a 3.8 isn't too horrible, if you know a friend the has the tools/resource you can get back on the road for cheap :)