manifold advice

[Ellis Kinney]

Long story/history. Farmall M tractor, bought in 1984. When I bought the tractor the exhaust pipe was welded poorly to the manifold. Through the years I just left it alone. Three years ago I bumped a tree limb gently but it broke the weld. I worked on the threads diligently and got them to accept a new pipe nipple. I epoxied the pipe nipple in using JB Weld extreme heat for pipe dope. It has held for three years but is now loose again. I am sure the threads will still be somewhat good but not like new of course. Is there a better epoxy product that someone has knowledge of that will work under heat?

I am a welder by trade and have experience with cast iron and nickel rods. Would you just weld it back in again? I am a little worried about getting a crack in the old cast manifold.

The other option of course is to buy a new manifold. I really don't want to do that because of breaking off a manifold bolt or not getting it torqued back correctly. I am not a good mechanic.

Thanks, Ellis

 

[rustred]

first of all did you tighten it good with at least a 24 inch pipe wrench. i use a 36 once tight but got to take care not to break the manifold. if all the threads were clean and it was screwed in to most of the nipple threads it should hold. i use never seize or copper coat on the threads be it right or wrong. so with out seeing it i am not sure what's best. i would run a tap on the manifold and use another new nipple, not the thin ones but one with some meat to it. i have used some really thick ones too like schedule 80. thicker will hold up better, but u loose a bit of inside diameter.

 

[560Dennis]

I don’t think much of those muffler menders. Last about a month in best application. How about braze ? You got oxy/acetylene touch , pre heat casting area , they will crack if you don’t.
All I can say , i did a Oliver hg 42 exhaust mani fold with intake/exhaust manifold with cast iron pipe patch and braze it over the rust out hole , lasted many years , sure made it quiet again ,I like quiet Used cast iron to try to have same expansions as manifold helped

 

[DeltaSteve]

I've brazed em. Clean off the area. Grind the top of the manifold tp clean metal. Clean the internal and external threads.wire brush if nothing else.Preheat the manifold before you install the pipe.Only heat the flange around the pipe. Try to turn in the pipe if you can. Continue preheat,them apply brass.Work around till you get back to the start.You can do it right on the tractor.

 

[Bob M]

There is no epoxy product that will stand up under the extreme temperatures of an exhaust manifold (when worked hard an M manifold can achieves a dull red heat - 1,100+ degF).

Were it mine I'd try rewelding the nipple. But with it off the engine so it can be pre-heated to assure a good weld and minimize the risk of cracking.

I'd not be worried about breaking off a manifold stud (I've R&R'd many manifolds with never a problem). USUALLY the clamp nuts will turn off without difficulty. But if they are really stuck, the entire stud will unscrew out of the head then can be reinstalled "as is". Also retorquing is straightforward, even if you don't have a torque wrench.

 

[rustred]

i am sure he is talking about cracking the manifold at the pipe threads which is very possible if you are not careful with old cast. and i was always told brazing on manifolds is not ideal as when its red hot the brazing will melt.in other words its not strong. guess ELLIS knows that he is the welder.

 

[busboy]

When i change my M manifold i got it real hot then broke all the nuts loose. then let it cool and removed it. replaced all the studs and manifold ( got them from Pilot knob Restoration Inc, great people to deal with.) I also got stud remover to help in the removal of the studs.. all done in a couple of hours.