How common are LIM and UIM failures on 97 3800's?

[Infinitrium]

I'm looking at getting myself a 97 Grand Prix SE with the 3800. It's not a bad looking car. I've been doing some reading and saw one person say that EVERY 3800 series II will have LIM or UIM failures at some point. Really, every one of them? How do I check to see if this one's bad or good? Other than that particular, does the car have any other trouble spots I should check? I hear the transmissions are prone to trouble as well.

[hljmesa]

I have a 97 with 140,000 miles. Change tranny fluid and filter every year.
Good car. Will get another when this one wears out!!!!!!!

[richtazz]

The UIM's are a very common issue on GM vin-k 3800 engines from late-95 to early-99 (and stll prone to failure on later models too). It's due to the area around the EGR stovepipe being too thin and too close to the heat of the stovepipe. This causes the plastic UIM to deform and leak coolant either externally at the bottom of the T/Body gasket, or internally into the cylinders (usually 5 and 6 due to they're being the closest to the leaky area). There are re-engineered UIM's available both through GM and Dorman that will rectify the situation. The Dorman one comes will everything needed to change it (gaskets, new stovepipe, injector o-rings, pcv valve, etc...) and I have used them with success. If you start using coolant and having drivability problems, the UIM is most likely at fault. Don't wait to fix it either, as it can hydrolock a cylinder if it gets bad enough.

[BNaylor]

Originally Posted by Infinitrium

I hear the transmissions are prone to trouble as well.

That depends on which autotransaxle the vehicle has. Since this is a '97 SE model it will most likely have a 4T60E which IMO are less troublesome than the later models with the 4T65E version. Only the GTP had the 4T65E stock from back in 1997. Check the SPID label located on the back of the trunk lid for which tranny it has. M13=4T60E. M15=4T65E. GTP 4T65E-HD is MN7.

[jem270]

I bought mine about 2 years ago. This is what I have replaced on mine.

rear hub
purge valve
purge switch
coolant level switch
sparkplugs and wires
front brake pads

These were existing problems when I bought the car. I went ahead and had the transmission fluid exchange done when i first bought it. A lot of people say not to but I have it done to every used vehicle I buy (this is my 4th). I have been happy with the vehicle so far. (My teenager drives it so it appears to be pretty durable).

This site has been very helpful to me.

[hljmesa]

Richtazz is right!!!!!!!!!!!!!!
I have replaced the UIM on my car at about the 120,000 mile mark.
It was running rough but I primarily wanted the AC fixed. Mechanic noticed fluid leakage and bingo, found the problem that Richtazz mentioned. Once replaced it has been great.

[BNaylor]

On the flip side of the story we have well documented cases on AF concerning '95 - '98 GM cars with the normally aspirated SII 3800 L36 engine where the UIM plenum was found to be perfectly fine with no EGR stovepipe damage, however, the LIM gaskets were shot. Member was wlkjr (Wally) and it was a '97 Grand Prix GT with SII 3800 (over 300K miles). So the rule of thumb is if you have to replace the UIM and gaskets then it would be a good idea to replace the LIM gaskets with the new GM aluminum framed ones. See links below for info on new LIM gaskets and UIM data:

Aluminum Framed LIM Gasket

UIM Data

Another popular brand of aftermarket UIM plenum is the APN brand which has a smaller diameter EGR stovepipe than the Dorman.

I did a '98 Bonneville back in January and the coolant loss problem was the LIM gaskets not the UIM. UIM was perfectly fine. No EGR stovepipe damage, no coolant passage damage or UIM warpage. No coolant found above the LIM when UIM was removed or in the UIM intake passages/runners.

[Infinitrium]

What do you think of this? I asked the owner if he's ever had any coolant loss, and he told me:

"Well, About two summers the car ran really hot, I was doing alot of stopping and going around the city on a really hot day, and the coolant overflowed after I parked the car. I got it checked out and they told me it was nothing serious, just a combination of the weather and the stoping and going running the engine so hot. As for adding, I might add coolant once or twice a year, nothing too crazy. lol If you want I have a half a jug of coolant you can have, that GM dexcool stuff that you are suppsed to use."

[jem270]

The only time mine used any coolant was when the plastic tank on the side of the radiator cracked. (It was dripping on the road when I parked it). Not including that problem, 2 years of use and zero coolant loss. I did switch to the dual purpose green stuff after the first year I had it.

[Infinitrium]

So...does that thing the owner described sound bad?

[jem270]

I'm no expert but I would be wondering where the coolant is going. From what I have read on this site, it is something to worry about. Re read the posts from richtazz and bnaylor. Spend some time reading on this site and decide. If you work on your own vehicle it may not be a bad thing. At the least, I would use it as leverage for the price.

[Infinitrium]

How hard is the upper intake manifold to replace? Could it be done in a day or would it take more than that?

[hljmesa]

Originally Posted by Infinitrium

How hard is the upper intake manifold to replace? Could it be done in a day or would it take more than that?

It is easy to take off. The problem is removing everything around it.

[Infinitrium]

Heh, alright, how hard is removing everything around the upper intake? Day job?

[hljmesa]

Originally Posted by Infinitrium

Heh, alright, how hard is removing everything around the upper intake? Day job?

Morning job