Fel-Pro MLS head gaskets???

[kuhio]

Just wondering if any of you guys/gals used the Felpro MLS headgaskets? Reason I'm asking is that I installed a set when I replaced my vortec heads because of a crack on the passenger side head, the cylinders were bored .040 over so I got a set spec'd at 4.100 bore with a .026 compressed thickness. Now I developed an oil leak on both heads in the rear at the intake manifold valley where the top edge of each heads meets with the intake manifold "china wall"!!! Some say the horns of the these MLS head gasket are too short and a dab of RTV is required to seal this gap. Apparently the blow-by crankcase pressure is pushing oil thru at this gap.

Pic #1....is the MLS headgasket (1142026)
Pic #2....is the Fel-Pro headgasket I replaced (7733PT-2)

If any of you had this issue with these gaskets how do you seal that gap without yanking the intake manifold off or removing the heads???

Input, Opinions?.....Thanks in advance!

[1967KaiserM715]

ok, I have no clue on why the different designs, but I would say that getting the second(the ones you replaced)design gaskets would be the answer, not RTV(no matter what works for others, it is a backyard fix that will most likely fail and drizzle again in 50% of the cases)

I know there is a similiar situation with the Jeep tornado engines, one head gasket is straight rectangular at one end, the other has triangle ears-if one did not use the latter gasket on an engine originally equipped with them they would leak

this is just my opinion

now you may be able to smear some RTV down there with a spatula(long screwdriver, whatever), without removing anything; but the surface would need to be cleaned well to even remotely work for a reasonable time

[kuhio]

Appreciate your input, Kaiser....all I know and read about is that the head and block deck surface HAS to have a specific smoothness/roughness (Ra, RMS) in order for these MLS gaskets to seal properly. The heads were milled when I had them redone but I think the block deck was not smooth enough and that also could be the source of the leak. I kind of doubt it since there is no oil passages in an sbc vortec head, or is there? The only leak if the gaskets wasn't sealing properly would be a coolant leak with all of the coolant passages. Sooooo it leads me to believe it's that smallll void at the horns of the head gasket....you can tell my wheels are spinning!!

Once again appreciate your inpu!!

[enaberif]

I put new headgaskets on my truck don't remember which but all I did to the surfaces of the heads and block was take a sharp edge and clean them up real good with acetone afterwards.

From there 1/4" bead of black rtv on china walls and up the edges to cover the edges of the head gaskets... not one drop from mine.

If you have that much blow by or crankcase pressure you have bigger issues elsewhere.

[bd]

This ^^^^^

Virtually all Gen I engines REQUIRE silicone sealer at the triple junction of the intake, head and block!  In addition, both china walls should be sealed with a 1/4" bead of high quality silicone in lieu of the cork gaskets that are supplied with most intake gasket sets.  If you skip the silicone, you are virtually guaranteed a leak.  Make sure all the metal sealing surfaces are clean of any lubricants or leftovers.  A thin smear of silicone around the coolant crossover ports of the intake gasket is also a prudent move.

I agree with enaberif.  If you are building crankcase pressure, you need to determine why and correct it or you will be plagued by leaks and oil consumption.

[kuhio]

enaberif, bd....well I kind of did a jerry rig poor mans test by forcing a slight amount of regulated air, not enough to blowout any seals of course, thru the pcv valve opening on the passenger side valve cover while taping up the other two openings on the drivers side valve cover then blow some white smoke around and near where the heads mate to the block and sure enough on the ascent of the china wall where the head meets the intake manifold is the source leak! It's so small but enough for oil to escape!! To avoid yanking the intake manifold off (last resort) think I'll shoot some carb cleaner thru the small void then squish/force some hi temp RTV, let it cure and see if it solves my leak. Of course I'll check it religiously for any leaks and if it does again then off with the intake manifold!!

Appreciate it guys!

[enaberif]

Do it right or don't do it at all. Rarely does RTV ever stick to itself well after it has cured.

Just pull the intake and do it properly and forget about ANY leaks. I know Gen I SBCs are known to be leakers and seepers but if you do things correctly the first time you shouldn't have any issues.

For example my valve covers do NOT leak and those are cheap $25/pair chrome covers. I made sure to rough the crap out of the inner flanges then clean the heads good with acetone again then when I install the covers I used felpro blues and t-bars with spreader bars.

[HAULIN IT]

Tape/plug all holes in your valve covers except one. Rig up a shop vac hose to pull a vacuum on the crankcase through the remaining one. Spray the leaking area with brake cleaner, once dry... apply the RTV, then remove the sweeper after a moment or two. The vacuum will help pull the brake cleaner into the area helping clean the oil out of the area better, also the RTV will be forced inward deep into the void. Hope This Helps, Lorne