Hello everybody. Just found out my engine is junk in my 89 Deville. I have an engine from a 90 deville to replace it . I know these 4.5 liter engines are virtually the same except for the fuel injection systems so I'm going to swap intake manifolds. My question is which manifold gasket do I buy for the 90 engine. The 89 or 90. I checked with an auto parts store and they said the two have different part numbers. Also since I have not worked on these front wheel drive cars much, is there anything else I need to do before swapping this engine.

Thanks Bob

Hello everybody. Just found out my engine is junk in my 89 Deville. I have an engine from a 90 deville to replace it . I know these 4.5 liter engines are virtually the same except for the fuel injection systems so I'm going to swap intake manifolds. My question is which manifold gasket do I buy for the 90 engine. The 89 or 90. I checked with an auto parts store and they said the two have different part numbers. Also since I have not worked on these front wheel drive cars much, is there anything else I need to do before swapping this engine.

Thanks Bob

i don't think that you can just swap the motor it self you'll need to get a cpu from a 90 and all the wiring from a 90 and for some reason i don't think any one has done it here on the forum but i could be wrong.

I'd pull both manifolds off first and see if they have the same port sizes and locations. If the gasket #'s are different then the ports may be different.

Or, since the 89s screwed anyways, just pull it off and order a set of 90 gaskets (can't be too much) and see how different they are. You would be able to judge the port size/location and bolt hole locations, etc. with the gasket for the 90 and compare it to the 89.

Sorry to say but quite a bit was changed from 89 to 90. Some of the differences are the heads and the intake manifold. They also raised the compression ratio so the pistons could be different. The minimum you're going to have to do is change over the heads, intake manifold, TBI, and maybe the pistons.

why do you think your existing engine is no good?

Thanks for all the info. I had the engine checked out for water in the oil by a formert GM mechanic and he said there was an internal crack, probably in one of the cylinders. So I purchased a 90 deville junker with a good engine in it to replace the 89 engine. Looks like from the info I received here I may not be able to use the 90 4.5 engine. Any other info would be appreciated.

Devilleman

Probably all that's needed to fix the problem is to install a new intake manifold gasket. If there is water in the oil, this is usually due to the leaking gasket on these engines.

Probably all that's needed to fix the problem is to install a new intake manifold gasket. If there is water in the oil, this is usually due to the leaking gasket on these engines.

2nd that