LIM gasket job on the '99, (Heads up for FEL PRO GASKETS)

[99bonnieSE]

Yep... Was time to do the LIM gaskets this weekend.... when I noticed that the overflow tank was bone dry. the tank ALWAYS had the correct amount of fluid in it. checked the radiator, was down about 5 inches. So, I went and bought me a LIM set, and a UIM gasket (money was an issue, plenum still good)




**i had to do the entire process of the LIM gasket replacement 3 times, to retrieve NO leaks. The Valley Gaskets did NOT seal, twice.
(some users may have had the same issue, i didn't search the forum for this problem, just thought i'd share my experience. Couple of people have told me the same about the valley seals.



The valley seals are molded too tall so that the intake doesn't seat flush to the heads in each of the four corners. I had called in and questioned about this issue, wondering if there were any other stories similar to mine.





In place of the valley gaskets/seals, just used a thick bead of RTV just like I did with my '96 4.3 vortec, and didn't have any leakage problems.

[The_Maniac]

Interesting experience with the Fel Pro gaskets. Over this past spring I used a set of those on my Monte when I was installing a port matching LIM. I drove the car from spring until I winterized it in October with no signs of any issues.

Since they gave so much RTV, I laid a bead on the top and bottom of the valley gasket as well as the corners. Torqued to what the shop box said and all seemed good.

I do recall when I was "dry fitting" everything to figure out how to set the intake down in one shot (without wasting or smearing the RTV all over the place), it too me a couple practice runs to get it right on the first shot.

Personally, I was surprised GM did not just use RTV to form a valley gasket (that's what you do on the 3100 v6).

[99bonnieSE]

Personally, I was surprised GM did not just use RTV to form a valley gasket (that's what you do on the 3100 v6).

See I thought the same thing, as that is what they also did on the 4.3. Since i did that, i've had no problems, and I just put together that 4.3 this past august. No issues with the bonneville either, already 60 ish miles of drive time on the LIM job. no leaks or gunk oil.

[crzydmnd72]

I just did this on my 99. I used GM gaskets and didnt seem to have any problem. I did use lots of RTV on the corners though.

[00Beast]

The issue is with the Fel-Pro gaskets, not the GM gaskets.

[crzydmnd72]

FWIW, I think my 90 just has RTV for the ends. Its been a few years since I did that one I cant remember, but its been leak free also. In a pinch, it appears a good bead of RTV works just fine. just my 2 cents