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3800 engine

11-10-2012, 07:45 AM
Has anyone ever read a consumer report on the trouble with the plentum on the 3800 gm engine // also does the 3100 gm engine have the same problem with the plentum

11-10-2012, 12:12 PM
I'm not sure about the 3100 plenum (upper intake manifold, or UIM), but both the UIM and lower intake gaskets (LIM gaskets) fail in the 3800. There are permenant fixes for both. The best UIM is sold through ineedparts.com, and is called "Surefix". It has a metal sleeve that protects the vulnerable part.

The LIM gaskets should be replaced with aluminum-framed gaskets available through GM or Felpro (aftermarket).

11-10-2012, 12:20 PM
I ment to ask if anyone has read an article from consumer report on the problem with plentum on the 3800 gm engine if so what issue ///i have a 96 buick regal with 3100 engine & had to replace plentum on it also at 70 000 miles // thanks for ur responce

11-10-2012, 02:25 PM
I can't help you with the consumer report question. I have talked to lots of people who had problems and fixed them. Maybe consumer reports will have more information useful to you. However, the 3800 is so different from the 3100 that I don't think you can compare them. some one with more experience with the 3100 can probably help you better.

Tech II
11-10-2012, 02:35 PM
The 3800 engine had a degradation problem in the upper plenum, where the EGR tube passed through it(it would melt the plastic composite, creating a coolant leak).....this was on the series II engine, up until 2000(?), when they changed the diameter of the tube(SMALLER) and increased the opening in the plenum(LARGER).....

As far as the lower intake gaskets on the 3800, they were not as much as a problem as on the 3100 engines......generally, the lower intake gaskets had problems when engine overheated due to low coolant leaks(upper plenum, throttle body gasket, w/p, etc.)and also due to not changing coolant every 5 years....

As for the 3100/3400 engine, their main problem was the lower intake gaskets, and sometimes(once again due to overheating), headgasket problems, especially at #1 cylinder.....never had upper plenum problems.....

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