intake gaskets AGAIN? geesh... how?
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 876
Likes: 0
From: Canastota Ny
intake gaskets AGAIN? geesh... how?
1st time almost instantly had bad (coolant) leaks due to crappy install. so i changed the intake gaskets (2nd time) on a stock sb 350 drove it all this summer with no probs. let it sit over winter and i go out today to see coolant leaks at front and also driver side rear bolts intake gaps.
now ive followed directions carefully with "the right stuff" in front and back china walls as well as light smear top and bottom of gasket at the water areas. i also used permatex white paste thread sealant on all the bolts. and tourqued them at 30 lbs in the order they were supposed to be.
1st time i didnt research or follow the directions well i guess (my bad) but ive been using the basic blue felpro gaskets (ms903142) from napa both times and to no avail. should i switch over to the 1256 gaskets instead? what out of all my reading am i missing and what happend to the embossed aluminum original inatke gaskets that came on these cars to begin with can i still get those at my local gm dealer? what am i missing here..... 3 times a charm?
now ive followed directions carefully with "the right stuff" in front and back china walls as well as light smear top and bottom of gasket at the water areas. i also used permatex white paste thread sealant on all the bolts. and tourqued them at 30 lbs in the order they were supposed to be.
1st time i didnt research or follow the directions well i guess (my bad) but ive been using the basic blue felpro gaskets (ms903142) from napa both times and to no avail. should i switch over to the 1256 gaskets instead? what out of all my reading am i missing and what happend to the embossed aluminum original inatke gaskets that came on these cars to begin with can i still get those at my local gm dealer? what am i missing here..... 3 times a charm?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If (either) the engine block, cylinder heads and/or intake runners have been machined/milled for some reason, the geometry of how they fit together may have been compromised. As factory new parts, stock thickness gaskets installed will result in no (or very small) gaps between any of those parts. But, if surfaces have been re-machined, gaps will be present and sealing them up will be a problem.
If this is the case, your best solution is to dry fit the parts with new gaskets in place but without being bolted. Carefully use some feeler stock to check the amount of any gaps at the valley ends or on either side at the intake runners. If significant gaps are present, you need thicker (or thinner) gaskets, as necessary, to resolve that problem. Most folks just throw silicone sealant at it. Silicone sealant and hot motor oil are not the best of "friends". Gaskets are much better at sealing those areas. Good gaskets can absorb some amount of difference in clearances, but I'm thinking less than a .010" gap on dry-fit setup.
If this is the case, your best solution is to dry fit the parts with new gaskets in place but without being bolted. Carefully use some feeler stock to check the amount of any gaps at the valley ends or on either side at the intake runners. If significant gaps are present, you need thicker (or thinner) gaskets, as necessary, to resolve that problem. Most folks just throw silicone sealant at it. Silicone sealant and hot motor oil are not the best of "friends". Gaskets are much better at sealing those areas. Good gaskets can absorb some amount of difference in clearances, but I'm thinking less than a .010" gap on dry-fit setup.
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 876
Likes: 0
From: Canastota Ny
its bone stock the original intake gaskets were in there before i changed them out the first time. now i do remember having the thermostat housing leak so im going to say thats majority of the run down i have found. ill keep an eye on it i guess.
i've heard of guys using the rtv along the lower edge of the gaskets also to avoid the mid bolt oil leaks. if there is a next time i will try the dry method with possible a high powered light through the dist. hole to see if any light shows gaps. thoughts on the 1256 gaskets anyone?
i've heard of guys using the rtv along the lower edge of the gaskets also to avoid the mid bolt oil leaks. if there is a next time i will try the dry method with possible a high powered light through the dist. hole to see if any light shows gaps. thoughts on the 1256 gaskets anyone?
