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Hey guys, I'm looking to rebuild my Bonneville's engine, it appears to have a coolant leak coming from somewhere. I've recently replaced the thermostat and water pump, so I don't know where else it could come from, so I'm looking at tearing it down, cleaning it up, and checking it out. If it turns out to be a cracked block, I'll go with a crate engine to avoid the headache.

I'm just looking for general hints, tips, pointers, etc. Also, if there's a reason I should or shouldn't do something.

Thanks!

Not sure if this is similar to the Cadillac engines or not


BUT...I know the Cadillac 4.1 motors were KNOWN for there coolant/oil leaks etc.

Here's the quote:
"The HT4100 was prone to failure of the intake manifold gasket due to scrubbing of the bi-metal interface, aluminum oil pump failure, cam bearing displacement, weak aluminum block castings and bolts pulling the aluminum threads from the block. Reliability issues soiled the reputation of the HT4100. As a result, the V8 Oldsmobile gas engines were a popular and straightforward conversion."


You would probably be better off swapping to a 350 motor or something like that, can get more power out of it and will run forever.

Unless, you just wanted a straight stock motor....

The 82-86 Bonnevilles never came with a 4.1L engine. The 82-86 only had the Buick 3.8 V6, 305 SBC or Olds 350 Diesel.

Is it a 82 Bonneville or a 81? The 81 would be a big one based off of the Caprice/Impala/etc, and the 82 would be the smaller ones.

Bonneville92V688 wrote:The 82-86 Bonnevilles never came with a 4.1L engine. The 82-86 only had the Buick 3.8 V6, 305 SBC or Olds 350 Diesel.

Is it a 82 Bonneville or a 81? The 81 would be a big one based off of the Caprice/Impala/etc, and the 82 would be the smaller ones.

The car is all orignal, minus a back door and some aftermarket engine parts. The manufacture date printed on the front doors is 07/82, and the label under the hood says 4.1L V6.

94SilverSSEi wrote:You would probably be better off swapping to a 350 motor or something like that, can get more power out of it and will run forever.

Unless, you just wanted a straight stock motor....

Not the case, just don't really know what I'd put in it. I heard that you can fit a 305 in it if you move the motor mounts up one notch, but I haven't confirmed this. Do you know of a place I could get a crate 350 without having to take out a second mortgage?

Ahh, well then the engine is the Buick 4.1, the big brother of the 3.8. A common leak spot on the older Buick V6 is where the timing cover mounts to the block. The gasket there fails over time, causing leaks. If the leak is coming from the front, I'd look there and see.

Depending on what you plan to do with the car. I would look to the junkyard for a 350.

TONS of GM vehicles had them, and they can be found pretty cheap.

I think even a rebuild on a core motor would be cheaper than a crate engine

What trans do you have? Is the bellhousing pattern the same as a small-block?

01bonneSC wrote:What trans do you have? Is the bellhousing pattern the same as a small-block?

This is where you got me. I know nothing about the transmission. But like I said, its all original, so whatever it came with, I've got.