Slant Six Forum :: MAJOR issues sealing Intake Manifold

What do you mean it leaks at every plane? How thick is the intake manifold flange and how thick is the exhaust manifold flange? The intake flange Must be thicker or it will never seal. The only time I have had an intake manifold to head leak is when the header flange was thicker than the intake flange.

You followed Doc's article about manifold installation, right?

Are the runners themselves leaking? As in electrowelded aluminum intake?

Got a vacuum gauge? AFR could be caused with jetting.

Quote:

Are the runners themselves leaking? As in electrowelded aluminum intake?

Got a vacuum gauge? AFR could be caused with jetting.

Not sure what AFR is. I do have a vacuum gauge set up. Starts around 18-20, but once it's hot it struggles around 15-16 and wavers a lot.

I don't think the runners are leaking. It's a Super Six intake. It's just at the flange/head where I'm seeing leakage.

Quote:

Are the runners themselves leaking? As in electrowelded aluminum intake?

Super six came in iron and electroweld (sometimes leaky) aluminum. You used the term A/F I assumed air/fuel. Vacuum is probably what you meant.

hate to say it, but you might have to pull the assembly off. if i were you, i'd take it off the head and set it on the ground. use a straight edge against the flange and see where it's warped. check the head with a straight edge too just for kicks.

take that assembly, and make sure the intake to exhaust bolts are snug. just snug, not super tight. take it to a belt sander and make the flange completely flat. no belt sander? well hell, whatever high spots you have can be ground down with a file, or sandpaper, or even an orbital sander if you're careful. get everything flush, and then buy yourself 2 felpro MS9610B1 gaskets and put them together. you want the steel side of the gasket against the head and the smoother side against the manifold. when putting the manifold on, make sure the intake to exhaust bolts are loose! first tighten the manifold to head then intake to exhaust bolts. goodluck trying to get the intake to exhaust steel shim gasket to be leak free.

start there.

Author:	63valconvert [ Sat Jul 20, 2013 12:50 pm ]
Post subject:	MAJOR issues sealing Intake Manifold
Hi, I'm wondering if anyone knows of any tricks for getting the intake to seal properly. I've run through Remflex gaskets, and now I'm on a classic Felpro gasket with Permatex Fuel Resistant gasket sealer, and NOTHING. Still leaks at EVERY plane. I am literally at my wits end here. I've torqued it to 9 ft/lbs (to give myself a little leeway to the tight side), and damned if it doesn't STILL leak. I have an A/F meter, and it idles at 19. Needless to say, the engine is ALWAYS close to pinning its Temp gauge, and it's terribly frustrating. I'm afraid to take it on the freeway, as it's so lean it gets insanely hot. Thanks!

Author:	Joshie225 [ Sat Jul 20, 2013 1:35 pm ]
Post subject:
What do you mean it leaks at every plane? How thick is the intake manifold flange and how thick is the exhaust manifold flange? The intake flange Must be thicker or it will never seal. The only time I have had an intake manifold to head leak is when the header flange was thicker than the intake flange.

Author:	DusterIdiot [ Sat Jul 20, 2013 1:54 pm ]
Post subject:	Next step...
I would agree with Josh, I also would take the mated stack to a machine shop and have them massage the mating faces so they are known to be flat. -D.Idiot

Author:	63valconvert [ Sat Jul 20, 2013 2:00 pm ]
Post subject:
Quote: What do you mean it leaks at every plane? How thick is the intake manifold flange and how thick is the exhaust manifold flange? The intake flange Must be thicker or it will never seal. The only time I have had an intake manifold to head leak is when the header flange was thicker than the intake flange. I meant that every runner in the manifold, when I spray carb cleaner on it, leaks. As in, the RPMs increase.

Author:	Reed [ Sat Jul 20, 2013 2:03 pm ]
Post subject:
You followed Doc's article about manifold installation, right?

Slant Six Forum https://www.slantsix.org/forum/

MAJOR issues sealing Intake Manifold https://www.slantsix.org/forum/viewtopic.php?t=52796	Page 1 of 2

Author:	Danarchy [ Sat Jul 20, 2013 2:06 pm ]
Post subject:
where are you located?

Author:	63valconvert [ Sat Jul 20, 2013 2:11 pm ]
Post subject:
Quote: You followed Doc's article about manifold installation, right? Yes. Relooking at the old Remflex, I can see that the Exhaust runners definitely leave a deeper groove than the intakes. I may have to do the "remove the stack" and take it to a machine shop. I'm in San Diego.

Author:	Rug_Trucker [ Sat Jul 20, 2013 4:22 pm ]
Post subject:
Are the runners themselves leaking? As in electrowelded aluminum intake? Got a vacuum gauge? AFR could be caused with jetting.

Author:	63valconvert [ Sat Jul 20, 2013 6:21 pm ]
Post subject:
Quote: Are the runners themselves leaking? As in electrowelded aluminum intake? Got a vacuum gauge? AFR could be caused with jetting. Not sure what AFR is. I do have a vacuum gauge set up. Starts around 18-20, but once it's hot it struggles around 15-16 and wavers a lot. I don't think the runners are leaking. It's a Super Six intake. It's just at the flange/head where I'm seeing leakage.

Author:	ValiantBoyWonder [ Sat Jul 20, 2013 7:35 pm ]
Post subject:
hate to say it, but you might have to pull the assembly off. if i were you, i'd take it off the head and set it on the ground. use a straight edge against the flange and see where it's warped. check the head with a straight edge too just for kicks. take that assembly, and make sure the intake to exhaust bolts are snug. just snug, not super tight. take it to a belt sander and make the flange completely flat. no belt sander? well hell, whatever high spots you have can be ground down with a file, or sandpaper, or even an orbital sander if you're careful. get everything flush, and then buy yourself 2 felpro MS9610B1 gaskets and put them together. you want the steel side of the gasket against the head and the smoother side against the manifold. when putting the manifold on, make sure the intake to exhaust bolts are loose! first tighten the manifold to head then intake to exhaust bolts. goodluck trying to get the intake to exhaust steel shim gasket to be leak free. start there.

Author:	Rug_Trucker [ Sat Jul 20, 2013 8:03 pm ]
Post subject:
Quote: Quote: Are the runners themselves leaking? As in electrowelded aluminum intake? Got a vacuum gauge? AFR could be caused with jetting. Not sure what AFR is. I do have a vacuum gauge set up. Starts around 18-20, but once it's hot it struggles around 15-16 and wavers a lot. I don't think the runners are leaking. It's a Super Six intake. It's just at the flange/head where I'm seeing leakage. Super six came in iron and electroweld (sometimes leaky) aluminum. You used the term A/F I assumed air/fuel. Vacuum is probably what you meant.

Author:	63valconvert [ Sat Jul 20, 2013 8:21 pm ]
Post subject:
Quote: Quote: Quote: Are the runners themselves leaking? As in electrowelded aluminum intake? Super six came in iron and electroweld (sometimes leaky) aluminum. You used the term A/F I assumed air/fuel. Vacuum is probably what you meant. Oh no, I have BOTH a vacuum gauge and an Air Fuel Monitor. The Air Fuel is usually around 18-19, which is obviously indicative of a leak (too lean). How does one tell if one has an electrowelded intake? The weight of the intake says Iron, but I could be wrong.

Author:	63valconvert [ Sat Jul 20, 2013 8:23 pm ]
Post subject:
Quote: hate to say it, but you might have to pull the assembly off. if i were you, i'd take it off the head and set it on the ground. use a straight edge against the flange and see where it's warped. check the head with a straight edge too just for kicks. take that assembly, and make sure the intake to exhaust bolts are snug. just snug, not super tight. take it to a belt sander and make the flange completely flat. no belt sander? well hell, whatever high spots you have can be ground down with a file, or sandpaper, or even an orbital sander if you're careful. get everything flush, and then buy yourself 2 felpro MS9610B1 gaskets and put them together. you want the steel side of the gasket against the head and the smoother side against the manifold. when putting the manifold on, make sure the intake to exhaust bolts are loose! first tighten the manifold to head then intake to exhaust bolts. goodluck trying to get the intake to exhaust steel shim gasket to be leak free. start there. Thanks for the tip. A double-gasket, you say. I would have thought the Remflex would have been the same thing. It just wouldn't seal, sadly. But I am beginning to think I have some bad variances. We'll see, I guess.

Author:	DusterIdiot [ Sat Jul 20, 2013 9:11 pm ]
Post subject:	Yep...
If it's Iron, and the remflex didn't seal, it needs to get some time on the table at the machine shop or a 3' hardwood board and some sandpaper. -D.Idiot

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Author:	Rug_Trucker [ Sat Jul 20, 2013 10:33 pm ]
Post subject:
Iron is magnetic