Exhaust Manifold leak

[Brian1973]

I'm thankful for those that help others to learn

I have a 1991 Ranger that I replaced the 3.0 engine a few years ago... I had been and continue to be plagued with an exhaust manifold leak. Previously it just ticked.. (don't think the engine came with gaskets originally in there?)... after the engine swap (kept heads and machined the base of both heads but did NOT think to machine exhaust manifold mating surface) the problem started burning through a spark plug wire (w/swapped manifolds)... sooooo, I took original manifold on the one side that specifically had the burned plug boot and had it machined.... it evened the manifold out a bit but I feared there was still a little bit of "space" on the head's side when putting a straight edge against it... Two years later the gasket has failed again... I don't see myself pulling heads to solve this issue... would double gasketing the manifold do any better or what other suggestions??? some kind of hi temp gasket sealer in addition to gasket? Engine sounds so much nicer when not ticking but I can handle that if I have to and have put a small piece of sheet metal around the plug boot to insulate it from the escaping exhaust....

Thx! Brian

 

[adsm08]

The manifolds are probably warped. You can try double gasketing, you can also try some copper high-temp RTV.

Usually the ultimate fix for a warped and leaking exhaust manifold is to replace the bad part.

 

[Brian1973]

The manifold in question was machined flat... the head appears to be slightly warped last time I checked with a straight edge... I'm thinking maybe I can try the copper rtv in addition to the gasket as well as maybe replace the bolts to the manifold to make sure I'm getting a good torque on em...

 

[adsm08]

The bolts should be replaced every time. They get funny by getting heat cycled so often.

 

[Brian1973]

yes, that's what I was thinking... stretched and heat treated.... I've seen manuals talk about replacing head bolts but don't think they ever said anything about the exhaust bolts... makes sense to do it... THANKS... maybe that will be enough to not allow the gas to escape through a minuscule warped area.... would think the gasket would be good enough for a very slight warp... guess if that doesn't do it, I'm doubling up and trying that route... seems to me that may just create more problems... yeah, new bolts... good suggestion.... and the copper rtv for JIC! Guess I will revisit this in a year or two if that doesn't do it.

Not all bolts are made the same, should I be looking for something specific for this purpose from automotive store? don't want to be twisting off bolts to make the problem worse! or maybe just go to the dealer and make sure I get the right bolts? I guess if I just take the old bolts into the local NAPA, they can point me where I need to go, right?

 

[Chris_North]

I tried the local Advance Auto for bolts, they said they don't stock stuff like that and I would need to try a specialty automotive store. I used stainless bolts from the hardware store with nickel anti-sieze. I'm not sure if this was the right way to go or not, but I guess it's too late now...

 

[stmitch]

Header bolts from LS motors will work too. I've got a set of Stage8 locking header bolts in mine.

 

[kimcrwbr1]

You are using the proper torque pattern when bolting on the manifolds correct? Maybe changing the torque pattern to pull it in at the leak first you are posative the manifol is not cracked. My concern with putting on two gaskets is if it burns through both geasket the leak will be bigger causing a lean condition in the affected cylinders burning valves and pistons. Backpressure is what cools the valves and piston heads with fuel.

 

[Brian1973]

it started about 15 yrs ago.... so it's been a problem in the works Back then after a trip out west going up and down mountains... it ticked... no biggie... but over that time, I suspect the gasses escaping have slowly worn away at the metal at a molecular level and blew off material from both the head and the manifold... the manifold last time around was machined flat... the head side is still slightly worn I figure....

I'm now wondering if the permatex muffler and joint sealer stuff might work better than the copper rtv? Smear some on both sides of a new gasket..... I used it to seal a leak I kept getting between the cat and header pipe, and looking at it IT is rated for 2000degrees I think compared to the copper at 1000.... and the copper stays flexible too I think whereas the muffler sealer stuff hardened like rock.... ???

 

[Brian1973]

and that is my concern about two gaskets as well... it really isn't a huge uneveness with a straight edge on the head side, but obviously ENOUGH.... hopefully slapping some goo on the gasket will end this issue!

 

[Brian1973]

btw, the other side manifold is also recently having the issue as well but I have one of those flush kits for the radiator installed on the heater hose and it was leaking down onto the exhaust manifold passenger side... thereby my conclusion for that side is the leak softened the gasket when engine was off and created a similar issue... so redoing that side as well... tightened the flush cap on the heater hose.... grrrr