Hello All,

I have a 2005 Bonneville in really nice condition. However I bought it with a seized engine. The car has the 3.8L engine with the vin code "K".

I have a 2004 Grand Prix (rust bucket parts car) with the 3.8L engine but it has the vin code "2". I have both the engine and trans combo.

My research in interchange says that the engines are not compatible, but I have found most times this just means not a direct swap. I believe also from my research that the intakes are different on the two engines.

However that is where my research has stalled... I could not find any where that someone has done or attempted this swap.

I would appreciate all your input and what problems/concerns one would run into. I found most of the time that the reference to the two engines were often the same that is the engines would be classed together.

Thank you in advance for any help and thoughts on the swap.

I was told that I couldn't swap an Olds Achieva engine in my Grand Am. The only thing that I had to swap over was the power steering pump. The Block and heads are going to be identical, the intake manifold should be identical, the upper plenum should be identical. The only things that you may have that are different are the motor mounts ( dog bones instead of rubber puck ) It's not a direct swap, but it's a swap that can easily be done. The only faint possibility of a problem would be if a hole in the block hadn't been bored and tapped for a mounting bolt, which is extremely unlikely. Since you have both vehicles, that's all you need to do...look at what isn't the same between them, and make sure that the mounting holes are there to swap over the appropriate parts. The 3800 is a universal GM power plant across many different vehicles...a modular engine so to speak. You could likely swap in a Series 3 motor out of a 2005 Bonneville with only a few things needing to be swapped over.

The only thing that you will want to make certain of is that the flex plate is the same so that you don't have issues with the torque converter or starter..and that is highly unlikely.

When in doubt, look at the parts from both vehicles and compare on RockAuto.com

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A temporary fix does not exist. It becomes a solution until it needs to be fixed again.

https://photos.google.com/album/AF1QipOYkkevV0gKTHc_8Cstuy8yS1Qyx6SiIKeTzuHy

You can put a 3800 from a w body into a Bonneville no problem. That transmissions are what's incompatible. Just swap the Bonneville's accessories onto the new motor and you should be good to go!

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-Car Guy Carl
"Penelope" - 2003 SLE - 247k Miles
"Sydney" - 2000 Honda S2000 - 98k miles

I once had the entire 04 GP but have only the engine/trans combo left. I was hoping to perhaps swap the whole assembly into the cradle for the Bonne but perhaps I'd be better just to scrap the bonne too... either way I appreciate the responses and am thankful for the ideas.