For those who have installed lower intakes - Silicone or block end gaskets?

Nutzy19 · Apr 14, 2005

3 motors Ive built have never leaked with permatex ultra black...throw those cork sh**'s away....

bluevenom867 · Apr 14, 2005

Cork is good stuff,if you got a Fel-Pro gasket,the cork end pieces are self adheasive.Just put a 1/8 bead on top of the cork and some in the corners and you will be good.

bgjohnson · Apr 14, 2005

best **** ever in the entire world is "Right Stuff Gasket Maker" that is honestly the best silicone sealant i have ever used. car companys actually squish this stuff into a mold and use the dried product for production gaskets. so put a thick bead of this stuff and you will NEVER have a problem with leaks as long as you prep surfaces right. i've also used the cork gasket but only with a gasket sealant like edlebrock gaskasinch gasket sealant.

MarSaleenMustan · Apr 15, 2005

vote goes for silicone. I learned the hardway, mine doesnt leak all that badly but it still does enough to notice, i just wash my engine bay around once a month and keeps it from building up.

5.0fox · Apr 15, 2005

i use black rtv and i let it sit for a few mins till it gets a skin on it. then you just have to be sure to lower the intake straight on and it will seal up perfect.

mpswirl · Apr 15, 2005

Ive used the cork ones, the rubber ones and silicone and i found out that silicone was the best if done right. The rubber ones fit great and dont move when putting the intake on but they did leak after a while and cork is cr*p.

TheUser · Apr 15, 2005

vristang said:
I have not used the cork gasket for a while and have had little trouble. With the new motor though I have had alot of trouble getting the rings to seat, in other words Blowby. Then to make matters worse the PCV valve was bad. Long story short the crankcase pressure was blowing out the rear lower manifold seal.
Ask yourself if there might be a reason why the gasket keeps blowing.
Does any one know where to get the rubber U-shaped gaskets? It sits down on the rails, and the upside down U-shape keeps it from sliding out of place. Found them before, can't find them now.

I stand behind the rubber end gaskets only because I tried silicone only, I tried the cork ones, I tried silicone w/ cork ones and I had problems w/ leaking all times. It could have been my prep/installation, but who really knows.

I would suggest the dowels to line the intake up. I got the rubber end seals that kinda have a "U" shape that sit over the block ends in a intake gasket kit I believe from auto-zone (I think I had to ask for the one w/ rubber ends) and I think you can get it from ford as well. I believe it's about $24-25. I think I put a little RTV on top of the rubber gaskets as well.

If you were to use the RTV only, I would let it set up for 10 min or something to kinda get set so it doesn't squish out all over the place.

Good Luck man.

04sleeper · Apr 15, 2005

For the last 15 years I have been doing the silicone on the ends. No leaks here. (RTV Blue)

I do a great job of cleaning the surfaces first with a 3M Scotch Brite gasket cleaners. Like this.

View attachment 517454
Then I clean the surface with brake cleaner and a clean rag.
I put a small dab of silicone between the center ports on each side of the thermactor holes to help hold the gasket in place, and a very small amount of sealer around the water ports, just enough spread out with my finger to fill in the imperfections in the metal. (Like Stang8URMPRT mentioned)
Then I put a thick bead for the front and rear and fill in the ends (little notch) where it meets up with the lower intake gaskets.
I set the intake on right away and do not let it tack up so it adheres to the intake and the head well then torque the bolts down right away going over the sequence about 5 times or so to make sure the intake is seated properly.

I do let it sit for 24 hours before I start it up to let it dry.
No leaks!

I also cut the gakset material out that hangs over in the water ports.

5spd GT · Apr 15, 2005

bluevenom867 said:
No,other way.
The blue (Fel-Pro gaskets, Mr.Gasket is red) stripe around the ports goes on the intake side.

I could have swore on Tmoss's website that he said put the raised side towards the head Although currently I do have my intake gasket raised side facing the intake...

5spd GT · Apr 15, 2005

The thing is, is that I installed the intake "by the book" by letting it sit for 10 minutes, using the cut off studs, letting it sit overnight, gasket material around the coolant ports, etc...and the bolts are tight (checked them two weeks ago when I tried to reset my valve cover gasket)...it just appears that the red high-temp silicone is breaking down at it's mating surface or something? Maybe because it can't take all the driving I do with it. I think the Black or Gray RTV (swaying towards the black) will be a more durable form I guess

The head area was clean because I added them at the same time...I installed the intake correctly but the leak has just shown up very slowly (and now is getting to wear you can smell the burning oil on the trans/block) over the last 3-4 months or so...I never had a leak or sign of a leak before then...

I was just wondering what is truely best to use? Black RTV or the end gaskets...I guess I'll just try the different RTV...

Ya'll guys have been great

04sleeper · Apr 15, 2005

5spd GT said:
I was just wondering what is truely best to use? Black RTV or the end gaskets...I guess I'll just try the different RTV...

Ya'll guys have been great

I have always used Blue. Never tried Black.

I assume the Black would work just fine.
View attachment 517451

04sleeper · Apr 15, 2005

5spd GT said:
The thing is, is that I installed the intake "by the book" by letting it sit for 10 minutes, using the cut off studs, letting it sit overnight, gasket material around the coolant ports, etc...and the bolts are tight (checked them two weeks ago when I tried to reset my valve cover gasket)...

David, I never let it sit before putting on the intake. I like to set the intake on right away so it bonds with the intake, then let it dry. I don't let it tack up.

5spd GT · Apr 15, 2005

89sleeper said:
David, I never let it sit before putting on the intake. I like to set the intake on right away so it bonds with the intake, then let it dry. I don't let it tack up.

Yeah I just let it skim over on the top where it made a very thin film on the top so where if you touched it it wouldn't come off on your hand but if you pressed into it just a bit it would "break the bond". I figure either way in that time frame works equally well...

It just started leaking over the last 3-4 months and was fine since late August...I've put probably 8-9k on it since then...

Any tips on putting something back there to help "catch the oil" that won't catch fire Just to keep me going for another month and a half or so... I think I'm going to stick some extra silicone (if I have enough room) back there to help for a while and I'm going to try and reach back there and put some silicone on the bellhousing/block area where they mate together to help keep oil off of the clutch parts...????

04sleeper · Apr 15, 2005

5spd GT said:
Any tips on putting something back there to help "catch the oil" that won't catch fire Just to keep me going for another month and a half or so... I think I'm going to stick some extra silicone (if I have enough room) back there to help for a while and I'm going to try and reach back there and put some silicone on the bellhousing/block area where they mate together to help keep oil off of the clutch parts...????

If you can degrease the back of the block and intake then you could try to put some silicone on the rear of the intake where it meets the block. If you have enough room to get your hands down there.
Might buy you a little more time.

Daggar · Apr 15, 2005

Looking through all the posts in this thread with what's worked for different folks, it seems that the key feature is the preparation and installation more than what gasket was actually used. I suppose that if you're in a hurry and don't take the time to do it correctly then you're probably more likely to run into problems than you would using X gaskets. I got into the habbit of coating the cork gaskets largely because that sort of thing is common practice when I'm working on jets. I see that there's probably a dozen different methods here that folks have had great success with but the thing that seems to be most common is the care taken to put everything together and let it all cure up well before riding on. My preference for sealant is the black hi temp silicone that comes in what looks like a cheeze wiz can. I use that stuff for damned near everything. I see that folks are using blue RTV as well so it kinda rules out specific sealants as being the only thing that determines a good seal or not.

mackey · Apr 15, 2005

I used Felpro 1250 Gaskets I think. They go from the head to the lower intake manifold. I lined them up perfectly then I put RTV on the corners. It is a notched setup so they will not leak. I just put the RTV on for some extra protection.

DMAN302 · Apr 15, 2005

May be a dumb question, but was the intake milled..or possibly scared on the bottom side?? most likely not, but always like to consider ever option...I HATE..HATE doing lower installs and double check EVERYTHING to ensure I don't have to do it twice. 5spd it sounds like you def have the hang of the install...I hope it works for you this time..keep us posted.

5spd GT · Apr 15, 2005

89sleeper - Yeah it is going to be tight

Daggar - It isn't the install process that did it because it did absolutely fine for 6+ months and here lately it has picked up in the oil depositing department I used the blue rtv on part of the timing cover/block/oil pan mating area and it seemed to discolor and start to break down...but I'm sure it would be fine. I was just going to use the most widely used RTV that people had success with which seems to be the black I won't get to the install until I'm out of school...it wouldn't be practical right now unless it just got "not driveable"...I would have to...when I do it I want tmoss to "take" my intake and port it...

DMan302 - The only kind of "milling" I can think of is when we messed up on the very first install of the intake we took it off and used a powered light sander on the intake to take off the old gasket material dryed on to it...I don't think it hurt anything. The intake is leaking on both ends (a bit worse on the back)...not the sides...

I just remembered (which could very well be part of the problem) but we did install a different kind of gasket (it was red)...because the FEL-1250 ripped where I didn't feel comfortable using it. We went to a local machinist and foudn the best possible matching gasket to the FEL-1250 and it was very close...but how would that effect the block ends?

fordman54935 · Apr 15, 2005

The Fel-Pro intake gasket set I just put on my car included molded rubber end gaskets that are keyed onto the block and fit together with the intake -to-head gaskets. At first I was just going to lay a bead of RTV (which has worked well for me in the past) but I decided to put those rubber ends on instead. It hasn't leaked (granted, my car only has 6 miles on it since its been back together)

DMAN302 · Apr 15, 2005

Highly doubt the sanding for cleanup would cause any issue..I'm sticking with the idea that the sealant simply did not cure properly last time.

For those who have installed lower intakes - Silicone or block end gaskets?

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