2F Exhaust Manifold Joint Leak

[Freeborn]

The facts:
1978 FJ40 with rebuilt 2f and original (afaik) intake+exhaust manifold

There's a long story behind this post, but the punchline is that I have a bunch of exhaust leaks that I need to take care of. All of the gasket-oriented ones are no big deal. But...

Has anyone ever dealt with an exhaust leak in the joint on the exhaust manifold that goes out to the end-most cylinders (1 & 6)? How does one seal up that joint?

 

[3_puppies]

there are rings inside there, similar to piston compression rings, IIRC 2 per side
they are/were servicable/replaceable

 

[Skreddy]

When you take it off for new gasket, pull the ends out and use a small brake hone or fine sandpaper and clean up the inside surface. Then on the male surface there’s a couple sealing rings, make sure they move freely and very slightly pry to expand them and they’ll seal up better when it all goes back together. Those rings get stuck collapsed and exhaust/carbon builds up on them. They also can break and leak.
Only pic I’ve got: this is the back end with an EGR block off plate.

 

[Freeborn]

OK. This is super handy info. Thank you!

What I'm reading that I might not need to pay $60 x 4 for the rings+springs in there? That would be amazing.

 

[Skreddy]

OK. This is super handy info. Thank you!

What I'm reading that I might not need to pay $60 x 4 for the rings+springs in there? That would be amazing.

Correct, I’ve pulled a handful of these apart and not personally had a broken ring yet.

 

[Freeborn]

Quick update and a question for the folks following along...

Got everything apart and ordered parts. The rings+springs are ridiculously expensive. The OEM gasket for the interface with the head isn't much better. After all that, I put a straight edge across the flanges and figured out that my exhaust manifold has a little rock to it. In talking with a machine shop it sounds like "fixing it the right way" is going to be expensive on top of the expensive parts I've ordered.

So what would you do? Does anybody have a connection to somebody that has a good manifold for sale? Headers? I have yet to hear anything super positive about headers on the 2f, but it seems like it could simplify the situation...maybe. Other solutions?

 

[charliemeyer007]

I love my headers, especially after making a fluid heat riser so I don' get carburetor ice in the fog. I did make custom stepped brass washers (to fix the thickness difference between the manifolds) and installed longer "studs" and stainless steel nuts.

 

[Freeborn]

I love my headers, especially after making a fluid heat riser so I don' get carburetor ice in the fog. I did make custom stepped brass washers (to fix the thickness difference between the manifolds) and installed longer "studs" and stainless steel nuts.

Well that's encouraging. Which headers are you running? A quick search shows JT Outfitters to be the most "cost effective" and Manafre to be the most "sophisticated". Any strong opinions?

 

[charliemeyer007]

I think my are man-a-fre. I know the gaskets are for sure. I used 2 gaskets and installed them wet. They have been on/off at least 3 times and on two different engines.

 

[bhsdriller]

Remflex gaskets are great at sealing up slight imperfections on the sealing surfaces.

 

[Skreddy]

I run remflex on everything. I have been very pleased so far. Should seal a slight warp, as said.

 

[Freeborn]

OK. $50 for Remflex seems like a reasonable experiment to run with OEM manifold. I'll give that a shot and see how the pressure test goes. Fingers crossed that it goes awesome. Thanks for the tips. Will report back.

 

[Ming89FJ62]

there are rings inside there, similar to piston compression rings, IIRC 2 per side
they are/were servicable/replaceable

 

[sggoat]

My 79 repl engine did not have any of the 'rings" etc. in the exh mani--nothing but a straight flange--I tossed that due to the excessive heat and went the header route(prob solved) used the JT Outfit headers(less expensive) but you need to get the intake/exh flanges matched(machined) so the thickness of both flanges are exact. used my last OEM gasket for this. 4 yrs ago had to pull the head again(vac was steady declining) turned out exh vlvs were gunked up(too much city traffic idling)---something to be said for the old 'shade tree mechanic' adage that "you need to blow this thing out"--ie run it hard every month--anyway, the valve regrind needed a new gasket(toyo was not avail, so used a remflex)--been running 4 yrs now with no leaks. seems to me to be a good option

 

[Freeborn]

For those that have messed with the rings in the manifold, is there a trick to getting them to seal? I put in all new rings+springs, which was shockingly expensive, and ran a quick-n-dirty pressure test with soapy water to find out both ends are leaking a decent amount.

 

[charliemeyer007]

Perhaps it will seal better once it heats up. I would consider wrapping some brass or stainless steel shim stock to make a facsimile bushing. You could heat the outside fitting with a torch and have the inner fitting in the freezer for a few hours to help get a shrink fit.

 

[South Texas 97]

On another exhaust manifold thread someone mentioned this anaerobic high temp flange sealant as a way to help seal the manifold rings to the flange.

 

[charliemeyer007]

Wood stove furnace cement might work too - should stand the heat easy enough, vibration a different story.

 

[Wadesters]

Anther question on this topic. It seems to me there are 2 rings and 1 spring per side. Is that correct? Although FSM makes it appear 2 rings and 2 springs?
@Freeborn @Ming89FJ62

 

[Freeborn]

One spring per ring. Spring goes under the ring.