I'v replaced my intake manifold gaskets probly about 10 times since I put the new engine in and it lasts about 3 or 4 months and it starts leaking oil. I've retoqurked the bolts and tried using permatex insted of the "china wall" gaskets (Had better results using permatex) but the leak keeps comming back, also it it's not the intake 'cause I have changed the intake 3 times since I put the engine in (upgraded from stock to wiend to edrlbrock pro-flo), also I have one hedder bolt ihat keeps backing out- pass side secon from the back - thanks ahead af thme for any replys

 

btt

 

Where is it leaking from exactly ? As for the headers bolts.. use some of the same permatex you used on the "china walls". Lightly coat the threads with then torque it back in. It will never vibrate loose again.

 

Could be the oil sender or tube for the gauge.....

 

it's not the oil sender 'cause I relocated it to the front of the block, it's the rear "china wall" I'm going to change the gasket next weekend and I want to find a way to solve this problem once and for all. I'm thinking of takeing some B1/2 (sealent for aircraft fuel tanks) from the shop and using that but I'm not sure it can take engine tempatures.

 

84,

I know it's a difficult area to access, and you're probably gettting really tired of the "revolving intake" game, but trial fit the intake with only the flange gaskets in place and no bolts. Then try to measure the gap at the front and rear of the manifold to the block. You may have enough of a gap to warrant a "Wall o' China" type seal along with an RTV compound.

I've had pretty good success using RTV blue (sensor-safe, of course) Permatex Form-A-Gasket 6C in the caulk tubes. Try laying down two smaller beads side-by-side on the block (about 1/8" diameter beads). After they skin off a bit, apply one more 1/8" bead on top of the two to form a triangle of sorts. This 1/4" high triangle will usually seal pretty well unless you have a monsterous gap.

If you have a miniature model of the Grand Canyon on the ends of the intake (5/16" or more), you might want to lay down a single bead of RTV on the case, install the China Walls, then apply another bead on top of that. Allow the sealant to skin off for about ten minutes (coffee break!) before assembling the parts.

I'm not at all familiar with the "B1/2" sealant, but I'm guessing it isn't designed for a high temperature extreme as much as for a low temperature extreme. Still, if it will keep kerosene from leaking out, is would probably seal against anything. That shît will leak out of anything, but I'm sure I don't have to tell you that...

Don't overlook the distributor gasket either.

 

I clean both surfaces (intake and block) with paint thinner ( or substitute) and then apply a thin coat of RTV red Hi temp silicone to both intake and block then build up a 1/4" thick bead and while still wet, sink the manifold into it. This is the only way I have been successful in stopping the recurring leak.
Hope this helps.
Don>>>

 

YES!!! Putting a layer of RTV on the intake itself AND the block surface is the absolute final answer to the intake leak problem. Along with making absolutely certain the surfaces are clean (ie. thinner like he said - I use brake cleaner). With that method I have had zero problems with the china walls on any intake.

 

I just used the regular rubber gaskets on mine, I cleaned it, then applied some weatherstrippng adhesive to hold the gasket in place, put a dab of RTV in the corners, and it doesent leak a drop.

if only oil pans were that easy....

 

If you go with B 1/2 make sure it is 890 B 1/2 or PR 1440 B 1/2. Rest assured it will take the heat just fine. Your block reaches maybe 300 degrees F at the most, 890 will easily withstand 500.
Personally I use the Permatex Ultra Black and have never had it fail, but I NEVER use the rubber end gaskets that come in the kits.
One other thing about the B 1/2, If you apply it right, to a clean, dry block and intake, you'll pay hell trying to get it back off again if you need to. I work with this stuff daily and it is a royal pain to get off when applied correctly, especially if parts have been "glued" together with it.
If you do use it let us know how it goes.

~M~

 

I use the permatex "gold" color RTV. I put a THICK layer on the block and then put the intake on. I do not let the RTV skin. I've never had a problem for the many of times i've done this.

 

Hey, morley, I'm not sure what selaent we have, but the promoter that comes with the semkit is the brown-clear stuff, not the "smurf ****" stuff we used in tech school (man I hated shepperd AFB), by the way what is your job, I'm a fuels troop. (currently working tank farm - I hate tank farm, I want to go back to the flightline)

 

12 years U.S.A.F., flightline, 10 years A&P mechanic.
You'll find that the brown sealant isn't nearly as good as the black ones are. 890 is made by Courtalds Aerospace and the PR's are made by Proseal.

~M~