1995 Upper Intake Manifold Replacement Notes

Greetings all -

I've been checking out this forum regularly for the past few years, but up til now I haven't had much to contribute in the way of experience or questions--which I attribute to the generally foolproof and bulletproof nature of my 1995 Buick LeSabre.

Had a nagging coolant leak from the area where the UIM and LIM mate just below where the throttle body bolts to the UIM. I had a day off a few weeks ago so I figured I'd take a shot at doing the UIM replacement since it sounded like a simple procedure. Pulled the old one off, bolted the new one on, no extra nuts or bolts left over or vacuum hoses flopping around without a home: by the book. I fired it up and checked for external leaks then took it for a drive around the block.

When the engine got a little warm I noticed billows of white smoke in the rear view mirror. Fearing hydrolock or cracked engine innards if I were to keep driving, I parked it and for the next couple of weeks drove a borrowed car while I weighed my options: redo the job with some RTV on gasket surfaces and run the risk that an internal LIM leak (somehow brought on by monkeying with that general area) still exists, admit defeat and let a shop jerk around with it, or buy a new car.

This past Saturday I test drove an Xterra with the Offroad package (beautifully engineered vehicle, on the surface at least). Went back inside the dealership and played the game a little while, but those carnies weren't coming down from their ridiculous figure of $33k and I wasn't coming up from my probably equally ridiculous $25k. I walked away relieved that I got to keep my money.

Next morning I said f___ it and took the Buick for a ride. The white smoke didn't seem as thick as I remembered it, and after about five minutes of punishment the 3.8 was breathing clear. No smoke, nothing. Took it home, let it cool completely and repeated. Absolutely nothing that time. I've driven about 100 miles since then, with multiple cool down/warm up cycles, without issue. Coolant level is stable and no external leaks under the car.

My theory is that when I removed the old UIM, coolant sloshed around and got down into some crevices in the LIM, where it sat until the engine warmed up and it began to evaporate before being drawn into the combustion chambers and burned off. That morning when the smoke stopped must have been when the last residual coolant was burned off.

Can anyone comment on whether they've seen something like this before? Or is there such a thing as an intermittent internal coolant leak following UIM replacement?

Thanks.

White smoke from the exhaust is very common after completion on an UIM replacement. Nothing to be alarmed about, just some residual coolant in the exhaust & cat burning off. You should be good to go now!

Can anyone comment on whether they've seen something like this before? Or is there such a thing as an intermittent internal coolant leak following UIM replacement?


My 98 did that after the UIM change as the exhaust parts heated up enough on the second drive I took in it.

You didn't mention changing oil after the UIM replacement to purge any coolant that might have ended up in the oil instead of burning away. I hope you have done one.

Thanks for telling us about your experience.

PKG,

I sure hope your replacement UIM also had a replacement stovepipe to eliminate the cause of failure or your original. The new stovepipe is smaller diameter than the original and thus will not touch the plastic UIM (which originally caused the heat to ultimately wreck the plastic.)

Mine had lots of anti-freeze in the pockets of the aluminum LIM. The plastic isx a lousy design, and it sounds like they didn't solve it with later models. Maybe it is a revenue generator???!!!

Regards,
Jack C.

Since where talking about experiences with UIM, here is what I found.

No doubt, people are having problems with the UIM.

My Lesabre had 150,000 with the stock UIM. (bolt on the timing gear broke) it never failed.
I went into a friends shop, he was working on an UIM. He had another to do after that. I looked on the forums, the problem was all over the place! I had it one time described as, "a 100% failure rate."

My town has been described as, "a Lesabre town.' The cars are everywhere!!
Whenever I saw a person in a Lesabre, I'd ask them every chance I had. Store parking lots, anywhere.
I would ask, excuse me sir, these cars have a problem with the intakes leaking, have you ever had a problem with yours?
Some asked me more details about it. We would open the hood, look at the coolant reservoir. I think at one point I was kind of obsessing over it.

Over a period of a moth or so, I asked about 10 people about it. NONE had the problem. 10 out of 10. No one. Out of the few that I got to look at the reservoir, all had the coolant in them.

My car, and my little sample, 100% UIM's where good. No problem. Very good design (The new intake manifold greatly improved breathing, and combustion temperatures. This increases fuel mileage by a substantial margin, a very good thing).

#1. How many people go to the forums to post nothing is wrong with there car?
This is the place to go, when you have the problem. When I Looked at just this, it seems like they all have a problem.

I ask almost everyone that has a 3800. At store parking lots, etc... Almost everyone doesn't have the problem. Not sure how many millions and millions of the Series 2 motors where made, but by far, most do not have a problem with the UIM.

I think for every 3800 with the problem, there are many, many more that don't have the problem.

I ask almost everyone that has a 3800. At store parking lots, etc... Almost everyone doesn't have the problem.