Series II lower intake manifold gasket - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat
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1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-19-2004, 02:36 PM   #1
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Default Series II lower intake manifold gasket

It seems that finding an after market lower intake manifold gasket set for a Series II is really tough! It can be found if the entire intake manifold gasket set (upper and lower) it purchased. However, I already have the upper set and only need the lower gasket. I can get it from the dealership. Are the new OEM lower gaskets just as weak as the originals that came on the car? I've heard people on this board indicate that the lower intake gaskets deteriorate much like the upper intake manifold deteriorates. I don't mind going to the dealership, but if that means I'll have to change it out again in another 80,000 miles because it too deteriorated, then I'll just by the FelPro kit and shelf the extra upper intake gasket.

What do you guys know about the new OEM lower intake gaskets? Or should I just go with FelPro?
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Old 05-19-2004, 04:34 PM   #2
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Stick with AC Delco (dealer) gaskets. They're the best. Nothing at all wrong with them.
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Old 05-22-2004, 12:08 AM   #3
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Boy I'd also like some re-assurance on which lower gaskets are best. I have a picture here of three gaskets. The one on the left (red silicone beads) is the Fel-Pro (which I used). The one in the middle is the new GM, and the one on the right is the one I took out of my 1999 which had dumped all of the coolant into the oil.

(the picture is pretty large, you'll have to scroll around to see it all)
-click on the above link for the picture-

The main reason I used the Fel-Pro (-other than their good reputation on all of the Chevy V-8 applications I have used through the years) is that you will notice that the Fel-Pro set does not have those mysterious notches in the coolant ports. AND, you might notice on my failed set of stock GM gaskets, the worst failure was right there at those stupid notches.

:( "GEEEEZZ, I DON'T KNOW which are best. :( Actually, I not too sure that any of them are any good. Just think of the thousands and thousands of small block chevys out there running aftermarket aluminum manifolds, on iron heads and iron blocks, using the good old standard flat non-high-tech gaskests, AND NEVER FAILING

(somehow, I think this fancy plastic/silicone gasket idea was just another one of GM'* bad ideas, -almost as bad as putting the hot EGR pipe up through the plastic plenum)

My gosh GM !! What are you doing to your "faithful followers?"
"57 ChevyThunder"
Dark Cherry 99 Bonneville SE -her car Nice Ride.
Ivory 02 Bonneville SE -MY CAR ! "luxury with attitude"
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Old 05-22-2004, 11:23 AM   #4
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I beleive the gm gasket is as good. Also when gm does a lower intake gasket job, the improvement is installation procedures. My dad'* 98 bonnie lost these damn gasket(*) at 75000 miles , had a dealer replace that glorious plastic plenum that we all love and cherish, along with the lower intake gasets, and there is evidence of some permatex involved. I dont believe that is the case with factory procedure. Anyway, in my opinion, gm have always had poor sealing techniqes at the factory for years, and it involves most engines particularly the smallblock v-8.
There is a saying around here for years- " if you got a chev, and it isnt leaking oil, something is wrong with it". I beleive the design the best engines, but this is an area they have left to bottom drawer engineering for years. They did make an attempt in 88 with the v-8 "black blocks" and did indeed improve sealing of pan, rear main, and valve cover areas, but the intake was basically left the same, particularly the rear of the intake, in which you have to make your own gasket because permatex alone isnt enough. Some of the early "improved" 350s built in the canadian plant had head gasket apllications that were a joke. I read somwhere they improved the problem along about 91. Ive seen cases of heads pulled on some of these engines that looked like there were no gasket at all but a "shellac" type of crap that was brushed on. I have a 92 350 that has 250000miles on it that still have factory gaskets, but they are very thin. I believe the thin gasket was used to increase compression ratio a few tenths. any way, Im gonna quit blabbing on the subject, its caused enough greif over the years....
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