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Old 05-08-2011, 04:43 PM
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Intake Gasket Sealer - where to coat?

Okay, here we go again!

454 with Weiand tunnel ram

After 11 years of thinking there was an issue with valve guides or intake seals, removing the top half of my tunnel ram and looking down the port, I could see a very definite offset of the intake runner not lining up with the head port (vertically). Lets go along with that being caused by the head being shaved way back when and maybe in combination with a new block installed over the winter.

A trip to the machine shop and milling the intake .070 dropped the manifold down to where it lines up nicely with the head port. The angle of the head is 45 degrees, the intake is 45 degrees. When I place the intake on the engine with the gaskets taped into place, it appears to be a great fit. There is no rocking, and I have plenty of clearance for RTV (I use UltraBlack) for the end rails.

So, backing up a few steps, the original Fel-Pro ultra seal leaked oil into the head, the second one did also, and then after trying a .0120 (that made the situation far worse), I'm back to the standard gasket thickness. Plus now with the advantage of a fresh cut on the intake surface and better alignment of the ports.

Now for the age old question (s).

1. UltraBlack isn't fuel proof, but I have used it on the back side of the gasket to hold it in place. This last time, even used it around the intake ports and along the bottom but it still leaked all along the gasket edges and dumped tons of oil down the intake. I called Permatex and they want me to use Hylomar on both sides of the gasket. No problem with that. What I didn't ask was if it was okay to put it on the blue seal around the intake ports. I don't want to do this a 4th time, and I would just as soon run a bead of something around every port and surface that could possibly leak oil - even though...everything should be snug this time around.

Do I put Hylomar right on the blue ring and conversely on the reverse as well?

2. Everything I read on the Permatez site pretty much said any of the RTV's were not fuel proof. I'm sure most of their products will hold up for a few thousand miles, but I want a permanent solution. I'm not concerned about how difficult it will be to remove the manifold to swap a cam out in the future. A lot of posts talk about the Right Stuff and Motorcraft TA-31 and it seems like many of you have had success with them.

I'm a bit nervous that the Hylomar won't seal a large gap (if there is one). Seems like the other products are better as a gasket maker rather than Hylomar being a sealer for a pre-cut gasket.

So do I run Hylomar around the intake ports and then use a RTV as additional protection all along the bottom of the head or ????

I have plenty of photos I could post, but just adding these two to give you an idea of the situation.



Note how high the oil line is on the photo below. I would be very surprised by lowering the head .070 would stop a leak like this alone, but the angles were correct and verified. The bolts were not holding the head up.



Thanks for any tips. Manifold is getting installed Monday night and then it is going to sit a couple of days to make sure everything is cured before starting the engine.

Appreciate the help.

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Old 05-08-2011, 09:07 PM
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In general its a big no-no to use a flexible sealant on intake ports. The constant vibes from suction/pressure will develop a vacuum leak.

The bottom line is (and I know you don't want to hear this) is that the gaskets are supposed to be installed dry, at least on the ports. If its not sealing dry, something is wrong.

If you absolutely must use a sealant, make sure it dries non-flexible. It doesn't have to be hard, just not silicone. I think a spray adhesive might work, but any way you slice it, you're stepping away from the recommended installation procedure.
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Old 05-08-2011, 09:08 PM
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I do use a tiny skim of ultra black around the water passages though...
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Old 05-08-2011, 10:09 PM
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Curtis - couldn't agree more that a gasket should work straight out of the package. Hopefully whatever the fit issue has been taken care with the milling and a small amount of Ultra Black on the back side of the gasket to hold it in place is really all I need to get a good seal this time.

I have never had a problem with end seal leaks or the water ports - just oil leaking up into the manifold ports and in between the cylinder pairs. I should have .050-.060 clearance on the end rails after the manifold is set into place, so there shouldn't be any reason why it won't set down in the V and snug up.

Still I see the application for Hylomar on the Permatez site showing it smeared all over a head gasket to provide easy removal and be a gasket dressing. If it can hold up to full on compression, why wouldn't it work on a manifold? Something it stays it is designed to do.

http://www.permatex.com/documents/PX...0Hylomar1A.pdf

http://www.permatex.com/documents/td...tive/85249.pdf

http://www.permatex.com/products/aut...ge_Sealant.htm

I wasn't really thinking about coating both sides of the gasket, head and intake, but with the grief I have had in prior installations, it seemed like a no-brainer to at least do it around the ports - and use RTV to help seal the other areas since they are designed to be gasket makers.

I would feel a whole lot more comfortable with the gaskets if the blue ring really stood up off the surface and gave you the idea it would compress with torque. But these prior installs, it almost doesn't even look like they even touched the surface.

But you are right - it should mechanically work without a dressing. And just use some type of adhesive to keep the gasket in place.

I'll do another test fit tomorrow night to verify that the lower gasket is making solid contact. But the temptation sure is there to give it a little more "fill" with Hylomar since it is fuel proof.

Thanks again for the response!
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Old 05-08-2011, 10:53 PM
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I agree with RTV at the ends and water passages, just not on the ports.

Head gaskets and intake gaskets are totally different. A head gasket is hard with lots of support. An intake gasket is paper. A head gasket is also sealed with multiple large high-tensile bolts while an intake is sealed with a few 5/16" grade 5s. The clamping force of the head gasket is also spread much more evenly given the stiffness of the head casting.

I guess what I'm saying is: you can fix a headache with Tylenol, but the cause of the headache is not a lack of Tylenol in your diet. Any way you slice it, its not the proper fix. Its band-aiding some other problem.

If it were me, I would spray it with Permatex red adhesive. That will help it bond and seal, but if you need a sealer like RTV that fills a defect, the problem will just come back.
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Old 05-09-2011, 01:47 AM
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Agreed! We'll know in a few weeks if it works this time. Time to move on to other areas of the car to play with. This one is getting really old!
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Old 05-09-2011, 02:07 AM
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i see ware your going with this and the gaskets should work with a minimum of fuss. that being said i would try to get to the root problem of what is causing the gap. have you checked trueness of the intake/head mating areas? it may call for trip to the machine shop one more again. but if they are not true or warped i could see this being the problem. possibly even the angle on the intake could be bowed or warped form over torquing form years past.
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Old 05-09-2011, 02:13 AM
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sorry to double post but have you dry fit the intake and rooted around with a feeler gauge? maybe even nab some play dough form the toy isle and roll it out and cut yourself some fake gaskets and try to read the "squish" may be a pain in the rear but could verify worpage issues. a light coating of pam or sandwich play dough gasket in wax paper would make things a good deal more sturdy
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Old 05-09-2011, 02:35 AM
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TMF - thanks for the note.

I checked for both angle and warp issues. Used the tool below to get the head angle and then transferred the noted degrees to a 20" protractor to verify the angle was the same on the intake. All at 45 degrees.





The intake was then milled .070, so if it wasn't straight before, it is now. The intake now sits about an 1/8" of an inch lower in the V. Whether or not that is enough to make a difference I don't know. The transition from the intake runner to the intake port on the head is nice and smooth. Before there was a pretty severe drop between the two when sliding a straight edge down the manifold opening.

This photo below shows the result of trying a .120 gasket. It made the situation far worse than before when the manifold raised as a result of the extra thickness of the gasket.



Look how much oil has traveled up the gasket on the near side (pass). It was swallowing oil at an unbelievable rate.



With the manifold sitting lower in the V right now after the mill work, it feels really good. Still might try the play dough to see what really happens before bolting it up.

Not sure how much material was shaved off the head years ago, but I have a feeling it is key to the problem. We'll see if .070 was enough!
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Old 05-09-2011, 03:45 PM
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First, RTV doesn't belong there. A small bead around the water passages is OK, and using it to seal the china walls is fine, but you shouldn't use it on the intake ports.

Second, Hylomar is good stuff... it doesn't harden but stays thick, sticks to everything and is almost impossible to get off. I really like the stuff for hard to seal problems and for stuff that I will have to disassemble later, I've even used it in a pinch in the place of a gasket in a place that I don't believe RTV would have worked (for example, between the runners and the lower intake and plenum on a TPI manifold), but gooping up something that's leaking that shouldn't be is not the solution.

That said, that is one place that you shouldn't have a problem, something else is wrong. .050" clearance on the china walls sounds tight, I would make sure that you're not getting hung up on there, maybe drop the manifold on and make sure that you can run a .050" feeler from head to head, make sure something isn't making solid contact. If you're sure that the angles are right, well check them again, in all 4 corners. Then get a good straight edge and check the flat surfaces of both the intake surface of the head and the head surface of the intake... I know that you said it was just machined, but that doesn't mean that it was done right, something has to be wrong if you're getting the leakage that you're getting. Is the intake manifold gasket or the intake getting hung up on the un-machined area below the valve cover rails (I've seen this on some SBC heads)?

Looking at the pictures, it looks like most of it is happening in the middle, I would guess that either the intake surface of the heads isn't flat or the heads are at a slightly steeper angle than the intake.

Another thing that comes to mind is that maybe you're distorting something bolting the intake down? Are you torquing the bolts in the correct order (generally center out) and to the correct torque?
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Old 05-10-2011, 01:53 AM
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Manifold went on tonight. Before it did, I placed the manifold on the heads without the gaskets. It dropped well below the paint line I had done after the intake was milled. It's not hanging up on anything. Nice gap along the china walls. Running a screwdriver down the intake ports to feel the transition from intake to head was pretty consistent in all 8 holes.

As I looked at it all buttoned up, I am suspect of one thing - the bolt holes. Even though the manifold is sitting lower than it was, it looks like the front holes on each side might be holding the manifold up a bit. They screwed in easily, but it is something I'm going to keep in the back of my head when we pull it off in a few months to try a different cam. We'll know well before then if the gasket leaked again.

As far as the angles and the flatness of the mating parts, it's just time to find out the easy way if it worked this time - driving it.

Fortunately on my car (T Bucket) it is really a pretty quick task to pull the manifold, so if we have to do it again...aside from some frustration, it's a one night deal - plus any machining work.

Will keep you guys posted.

Thanks for the advice!
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Old 10-04-2014, 08:43 PM
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I had a similar problem years ago. I had a sbc built with an edelbrock air gap intake. The shop over torqued the intake to 35lb/ft. The intake was for a motor with vortec heads thereby a vortec intake with only requires 8-12lb/ft torque. Also, the heads were milled .30 thousandths. After the motor was running I noticed oil on the plugs. It turned out to be that the intake was sucking oil. Had the intake gasket replaced 3 times by a speed shop. Each time it leaked. First time they used thicker edelbrock gaskets - no fix - still leaked. The shop then drilled the intake and heads for center bolts like a regular sbc intake. Still leaked and di not help. I asked them to use permatex on the gaskets and the shop used home depot silicone, which they said a machine shop that builds race motors uses all the time. I explained to the speed shop that this is a street car and taken apart every two weeks like some race motors and must be reliable long term. No leak for about 300 miles then intake began leaking. silicone does not hold up to gas or oil. Third time had intake milled and shop used regular rtv on intake, not permatex. This lasted about 1,500 miles then began leaking. Again not made for fuel and oil. Fourth try I took my time and did the repair myself. removed intake cleaned head and intake with brake clean and used an edelbrock gasket. I used permatex great stuff on the top side of the front and rear walls of the motor and around the water jackets. I used permatex #2 around the intake ports, which is where the oil was going in. Permatex # 2 is oil and fuel resistant unlike many other silicones. try putting some silicone in a cup of gasoline and see what happens - it turns to jelly. Even the great stuff says right on it not fuel resistant and it does not say it is for intakes. So I used a gasket, permatex #2 on the intake ports and great stuff around the water ports and front and rear walls = problem solved! It only took 5 tries but the speed shops kept using the wrong materials. Especially with todays gas with alcohol in it the regular silcine will not hold up. Obviously the intake is warped a little etc. But it is sealed now. I also have heard thay gasgacinch also works well as a sealant with the leaky intake.
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Old 10-04-2014, 09:21 PM
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I ALWAYS use black rtv on the intake port gaskets and have NEVER had an issue. I'm not saying it's the commonly prescribed method but it does work for me. And there are very few gaskets that I'd install dry. Some head gaskets I only use dry, and some exhaust gaskets. That's about it.
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Old 10-06-2014, 10:59 AM
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On my Small block chevy's I use the right stuff gasket maker on the china walls and Indian Head on the water passages and leave the intake ports alone and use the felpro 1205 intake gaskets and I so far have not had any issues that I am aware of but I don't know how to tell exactly if my gaskets are leaking or not. Vacuum reading reads fine. Hope you get it worked out.
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