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Intake manifold leaks

2K views 9 replies 9 participants last post by  JohnZ 
#1 ·
Apparently I'm the worst person to install an intake manifold. Both of my cars leak from the front and back of the lifter valley. After cleaning the areas obsessively, I put a bead of RTV on the gaskets to the heads, then a good solid bead in front and behind of the lifter valley. Then I place the manifold on gently and torque to specs. Still have leaks. WTH?
 
#2 ·
yep, I know everyone says throw away those gaskets and use RTV. I was talking to guy that owns a local speed shop, he said those gaskets can be better than screwing up the RTV. Its pretty particular how its applied. He was telling me he does a thin coat on the block and a thin coat on the intake and mates the two together. I just did mine, I'm really hoping I don't get leaks. Im sure ill probably have to redo it. If it leaks I might just use the gaskets. Its definitely something that gets better with experience.
 
#4 ·
Shouldn't need any on the gasket at all, maybe just a very light skin around the water ports front and back.
A little dab under the corners of the gaskets where the gap is between the head and block.
The bead on the block ends needs to be a little under 1/4" tall and overlap onto the ends of the gaskets a little.
All bolts get thread sealer.
Intake goes on and bolts put in finger tight, leave it an hour or so, then torque down.
Ultra Black is the highest oil resistant RTV.

I've read somewhere that if you're going to use the end seals instead, it's good to take a pointed punch and ding the block ends in several places so they'll have some bite to hold them in place.

BTW, these are cake. I had to finally do the ones on my '97 4.3L this weekend. What a pain in the rear.
 
#5 ·
I've found on my old 67 427 block that it's very important to HURRY. At least the way I've done it the last few times. I'm speaking of the valley-manifold joint. After applying a thick coat of RTV to the block (very clean block) I apply another coat to the corresponding manifold surface. Then work the manifold into place and lift it after lowering. The RTV must blend together. It's probably that stuff I've been using that comes in the pressure can, but it seems to skin over quickly.
 
#6 ·
WELL BOYS! Here's my method. I use the rubber gasket but this is what I do and it works. First wash everything with brakeclean all the mating surfaces, then also wash the end rubbers with brakclean also and dry. Step:D 2 a light smear of the RIGHT STUFF GASKET MAKER on the block and a good dot at either end .Step 3 a smear on the front and rear of the intake, carefully install intake and bolt hand tight to about 5lbs torque. Step 4 wait approx. 20 / 30 minutes and follow torque pattern in 10 lb increments to 30 lbs . This seems to work pretty well with rubber ends . my favorite ones were the cork and neoprene end rail gaskets but I haven't seen them in years .The other thing is you can use just THE RIGHT STUFF GASKET MAKER by itself . I have done both with good results but prefer to use the rubbers at the ends . Alex
 
#8 ·
I like the black Form-a-Gasket. Where I've had leaks before is the corners so I always make certain to put a extra dab in each corner. I torque all the way down and then use a wet finger to make a clean line and clean up any excess. Make sure the surfaces are clean and oil free or the gasket maker will not stick well. I also wait 24 hours before starting up just to give plenty of cure time.
 
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