01-01-2010 11:12 AM
Mud in the hvac box again
they will interchange with each other as both are consider to be 3800 motors or series 1 motors in some cases, and are both on center blocks. the big thing is the 3800 went through a lot of little changes between 88-95 and not so much once it became the series 2 variant. You'll want to use a vin C or L motor if you have access to look at the vins. Make sure to avoid the vin 3 from the lesabre because it was a non ballance shaft motor based on the first fwd casting. i think they stopped using the vin in 88 or 89. The 89 should use a vin C motor were as teh 94 should be a Vin L. The main issue you'll need to take in mind is that the 89 3.8 has 8.5:1 compression where as the newer engine will have 9.0:1 compression. So you'll need to be aware of this and may even need to tune the computer for this change or possibly just run a higher grade of octane fuel. one of the big differences between the 89 and 94 is that the later motor the 94 will use a one piece rear main seal, the older motor used a 2 piece rear main seal. the rear main seal change happened in 1990. Also the later motor has a boss for a knock sensor on the drivers side which the earlier motor didn't have.
Originally Posted by jsarnold
The other big change is the cam. the engine from 89 will have a cam with a flange with 3 bolt holes and a dowel to hold the gear on. were as the later cams use a single large bolt to hold the gear on.
all the other changes are basically internal ones that shouldn't effect the engine working in the vehicle. just things to remember when ordering parts. I would keep the vin number for the newer motor on hand to help with ordering parts.