I we are working on my son'* 1994 Buick Regal with a 3.8 series 1 engine.
When doing a chemical test for combustion gas in the coolant, it failed. When doing a coolant pressure test it leaked coolant from the LIM and had a drip somewhere under the throttle body but we coldn;t quite tell if it was the LIM or UIM.
We took the cylinder heads to a machine shop to check them out and the owner said they had no leaks or cracks.

From everything i have read about these 3.8 engines, we should replace the plastic upper intake while we are doing this work. W could not see any signs of damage to it but given their reputation i guess we should replace it with this extensive of a repair?

So that brings me to what brand?

RA has a ACDelco and SKP. I also found a Dorman. The 94 has the EGR tube going into the UIM and from what I understand, there is supposed to be a updated UIM for these engines. None of the ones i have come across say if they are the updated version or not. According to the parts list they only fit from a 93-95 so there are not allot of choices to choose from.

Thanks
Anna

I thnk I put a Dorman in my Park Avenue, and never had an issue. There was nothing really wrong with the series 1 UIM, so I don't know there would be any real advantage choosing one over the other. Just make sure you are not getting sucked in to the talk that surrounds the series 2 engines.

When I did mine, it was the urging of the forum that replacement was likely unnecessary. I proved them wrong. Also, if there was ever a time to do some porting, it'* now.

The only reason to replace the UIM would be because it'* 25 year old plastic. It'* a good reason to, yes, but it'* not the same reasons you would replace series 2 UIMs.

I also have a Dorman # 615-180 in my Pk Ave. It comes with a new complete gasket kit. Years later all is well.
I ordered Felpro gasket for the LIM.
Here is a good how 2 about LIM replacement.https://www.gmforum.com/mechanical-1...ts-l36-297702/

Ok thanks guys! I went a head and ordered the Dorman 615-179 UIM which Dorman said fits the 1994 3.8. From what I have seen it fits the 93-95 non sc.

Good point on the 25 year old plastic...

I have learned a lot about buying used cars with this job. Before buying a used car, in addition to checking it out, a person should do a common parts search. With engineering changes every 2 or 3 years, many of the parts are not available any more. The coolant was very red and had a a lot of particles in it and we wanted to change the heater hoses but they are not available any more. I guess a person could buy several short hoses with the right bends and couple them together...

Just remember this is all series 2, which is different than the series 1 in this application.

I just checked my sons 92 regal and though there are some differences, many of the brackets and electrical connectors are in the same place. That will help getting it back together! We have still not come up with why the radiator had combustion gas in it. The machine shop said he pressure tested the heads and there were no leaks. The head gaskets were quit oily by the time we got them off.. Everything on that engine is coated in oil and all the bolts we took out were covered in oil..

Oh!!! I ordered Felpro head bolts. From the pics they appear to have thread lock on the ends. Do you know if I need to use ny other sealant on the head bolts? Some people say to use sealant if they go through a cooling passages... I also read to put some oil under the lip of the head of the bolt so it wont bind on the cylinder head while torquing them down.

Thanks
Anna