Leaking intake gaskets

onefastmustang · #1 (**permalink**) 04-18-2009, 12:43 PM

I keep having a problem with my intake gasket on the rear of my 351 Windsor block leaking. It only leaks with the weber manifold. if I put the Edelbrock RPM back on its fine. I have tried the cork gasket with no luck. I tried black Loctite RTV and it's leaking too. This is going to get expensive if I have to keep buying intake gaskets.

Any other ideas?

Mike

vector1 · #2 (**permalink**) 04-18-2009, 01:59 PM

i use cometic intake gaskets between the intake and manifold, and black "the right stuff" on the ends. also used indian head shellac(because i had some sitting around) around the coolant holes, no leaks as of yet.

hth

onefastmustang · #3 (**permalink**) 04-18-2009, 03:34 PM

one thing I noticed when I took the intake back off is that the bottom of the intake is very shiny and polished on the ends. Should I rough that up a bit to make the gasket "right stuff" stick better? Another thing is my intake gaskets are .070 thick.. maybe they are too thick??

vector1 · #4 (**permalink**) 04-18-2009, 04:28 PM

just make sure the ends are dry, i usually clean with alcohol before using any type rtv.

don't have any cometics to measure right now. i don't think the gaskets would be too thick.

i set the intake on dry, no gaskets, and center it to fit, then mark with marker on each end. when you install with gaskets match the marks up.

i do not like the fel pro intake gaskets with the printo seal or whatever, they tend to move around in my experience.

Dwight · #5 (**permalink**) 04-18-2009, 05:20 PM

a picture can say it better than I can.

Dwight

onefastmustang · #6 (**permalink**) 04-18-2009, 05:44 PM

Were those done with a punch?

DAVID GAGNARD · #7 (**permalink**) 04-18-2009, 08:36 PM

I've only used the cork intake gaskets once, many, many years ago.......never have since then and never will do it again......

I clean off the block surface with some brake-clean on a rag and do the same with the bottom of the intake, then trial fit the intake and mark with a felt pen the outside of the intake on the block surface, then I use RTV (I prefer the blue) or "the right stuff" (have had very good luck with both), lay down a nice thick/even bead along the inside of your line, let it "tack-off" for a few minutes and very carefully place the intake manifold straight down on the block, and begin bolting it in place, rtv/right stuff should "squish out" along the entire length, be sure not to distrub it, leave it alone.... a couple of hours later I will re-tighten the intake bolts and then if you want to you can trim (I don't) the excess with a razor blade.....I like to let it cure at least overnight before firing up the motor..........

I can't remember having one leak using this method...........

David

MaSnaka · #8 (**permalink**) 04-18-2009, 09:10 PM

I used the cork gasket on the ends. But I glued it in place with a thin coat of the black Right Stuff and let it sit over night. Also dabbed it into the corners where the intake gasket and the end gaskets meet. Then with the Right Stuff again I glued the intake down on top of the cork. Just a thick enough bead to get squeezed out. I also used brake clean for a final cleansing before applying anything. It's important to make sure the distributer lines up before anything dries in case you need to move the intake to align it.

John

Dwight · #9 (**permalink**) 04-19-2009, 06:58 AM

onefastmustang

yes, I used a punch.

I do it the same way David explained it. I let it sit for 15 minutes or more before I install the intake. Test fit the intake to see had much gap you have. When you apply the silcone make it 1/8" more than the gap. You don't want to much but enough to seal. A chuck of silcone working it way to the oil plump is not good.

I use gray silcone because it matches the intake color.

Dwight

I like a few more hours to finish installing my KC heads and cam. Plus an intake, valve covers, side pipes, fan, fuel rails, throttle body and other stuff I forgot about. It started with bad valve guides last summer and I replaced the whole top end of my motor. There has to be something wrong with me.
Long winter and now it time to drive.

zrayr · #10 (**permalink**) 04-19-2009, 07:18 AM

I glue on the cork gaskets with the yellow 3-M weather stripping & let it bond for at least an hour before continuing with the assembly, & silicone at the corners of the cork gaskets. I've never had a cork gasket blow out or leak with this procedure.

As others have pointed out, the head and intake surfaces must be "white glove" clean, and dry.

Z. Ray

sllib · #11 (**permalink**) 04-19-2009, 07:20 AM

Using a punch to raise "teeth" on metal is called stipling. Gunsmiths do it on pistols to provide a non-slip surface. If you have problems with intake gaskets collapsing you can also stiple around the ports on the head to hold the gasket in place. Hint: a sharp nail works as good as a $tipling punch.
Bill Stradtner

Rwillia4 · #12 (**permalink**) 04-19-2009, 09:40 AM

How much room is there between the two metal surfaces? On mine there was 3/16" of space so I used a metal spacer to make the distance smaller so the gasket would not bulge out.

onefastmustang · #13 (**permalink**) 04-19-2009, 09:34 PM

Quote:

Originally Posted by Rwillia4

How much room is there between the two metal surfaces? On mine there was 3/16" of space so I used a metal spacer to make the distance smaller so the gasket would not bulge out.

I think that is part of my problem. I think there is more space between the intake and the top of the block than the cork allows.

So far I have tried

Cork alone - failed
Right stuff 1 minute - Failed - blew out and oil seeped past the top of it.
cork and right stuff (sat over night) - Oil seeped out past the top of the right stuff.

Looking for more suggestions or someone that would like to make a lot of money off me to make this go away..

vector1 · #14 (**permalink**) 04-20-2009, 06:30 AM

i prob have 1/4 to 3/16 gap between manifold and block, used the right stuff and no leaks.

how is your crankcase ventilation?

with correct prep and letting it sit overnight, and large enough bead, i don't see how you could go wrong.

onefastmustang · #15 (**permalink**) 04-20-2009, 08:24 AM

I currently don't have a PCV valve... should I put one in???

Got the Bug · #16 (**permalink**) 04-20-2009, 08:35 AM

Quote:

Originally Posted by onefastmustang

I currently don't have a PCV valve... should I put one in???

It would be a good idea. A PCV could reduce pressure and increase ventilation. There's not really any downside to having one.

Just curious. Who makes the weber manifold? Can you contact the manufacturer?

onefastmustang · #17 (**permalink**) 04-20-2009, 08:48 AM

I'm not sure who makes the manifold... I will have to contact the vendor..

I will try adding the PCV valve and see if my problem goes away.. If it does Ill beat the good side of my head..

this is my intake here..

vector1 · #18 (**permalink**) 04-20-2009, 09:18 AM

whatever setup, just make sure you are not building crankcase pressure.

Got the Bug · #19 (**permalink**) 04-20-2009, 09:19 AM

If you run a PCV with the Weber setup, where would the hose connect? I guess the Weber experts could advise.

onefastmustang · #20 (**permalink**) 04-20-2009, 12:24 PM

Piping into the runners with stainless I beleive is the way to do that. Something I don't have a problem doing.. I have been reading a bit about how PCV valves help prevent oil seepage so maybe this is the way to go.. Alternately Edelbrock makes an end seal spacer kit to close up the gap some. I wonder how thick it is. it doesn't say on their site.