Engine/Transmission (1994 - 1998) Exhaust Manifold

[mfelix]

can anybody tell me what to torque the 10mm bolts on the Exhaust Manifold ? some how the two back bolts broke off and now replacing all with new stainless steel.

 

[BFC]

My 98 manual says 32 ft lbs. (43N. m)

 

[mfelix]

thanks alot. mine is a 97. I think it will be close. thanks

 

[T. Baker]

That is because the exhaust manifold expands and contracts alot with the heat it gets. You are lucky that the ears did not break off the head wich happens. That is why ATS sells the three piece manifold with two expansion joints like all good diesels have. There seem to be a few lame desingns on our Cummins like that and the timing gear to cam slippage and the lift pump not being a gear pump like most good diesels and of course the KDP. Good thing the rest of the engine is so good!

 

[Joseph Donnelly]

Almost all stainless bolts are much lower grade and won't hold that torque--they may break on trying to tighten them that much. I recommend stock or other high grade bolts with anti-seize compound on them.

 

[mfelix]

hey joe these are ARP GRADE 8 BOLTS torque to 32 lb easy. hope they hold ok. thanks for the concern

 

[bmoeller]

I always use anti-seize when I replace exhaust manifold bolts. Have never not gotten them out later.

 

[Reddog1]

I have read repeatedly, that the ears break off the head due to the exhaust manifold expanding and contracting.



If the holes in the manifold were enlarged, would this not allow for more expansion and contraction of the manifold?



Perhaps a lower torque on the manifold bolts?



Maybe both?





Wayne

 

[T. Baker]

I was wondering the same thing. If we backed off on the torque we might start getting exhaust leaks. If it is tight enough to not leak then the bigger holes might not help because of the friction of the clamping force would not let it slide anyway. Just a few thoghts. I hope somone knows the answer. I don't have the money right now for the ATS manifold. I would like to live without it if possible.

 

[Reddog1]

The three piece manifold is not bolted at the slip joints, and is does not leak.



Does anyone know how much the stock exhaust manifold expands? I would'nt think it would be all that much.



Wayne

 

[JWRowe]

torque

mfelix

My 96 shop manual says 32 ft lbs. Must be standard on 12 valve engines.



Regards, John

 

[chrleb1]

The stock manifolds don't expand to much, just mainly shrink. The reason why they do this is because they are made out of a higher silicon cast iron. When the manifold reaches around 1150 degrees, the silicon turnes to gas and leaves the manifold, which means the cast iron will shrink to fill the spaces from the silicon. ATS came up with a good solution, create a very low silicon cast iron. Meaning no shrinkage at high temps. This is about the best way to go, rather messing with the stock manifold. The shrinkage can cause cracks in the manifold also. So that is my thoughts on that.

 

[QRTRHRS]

I could not locate the thread but I believe Evan Beck has posted that his shop torques to 40lbs. Correct me if I am wrong.

 

[T. Baker]

Well it looks like first chance I get I'm gong to oval out the last couple of holes on each side of the manifold so somthing dosen't break!

 

[Matt42]

What's the cost of the replacement 3 piece manifold?

 

[T. Baker]

$425 + shipping from PDR. Most other Cummins have mutiple piece manifolds on them. Cummins should have done this.

 

[QRTRHRS]

Been awhile since I ranted on this.

The 3 piece is a good manifold and the only game in town but... Upon reciept, check the bell fit. It should be snug enough that you need to tap it together with a rubber mallet. If it's loose and slides right in then it will spew soot all over the place. You might think over time it would seal but not!

 

[Blakers]

Originally posted by T. Baker

There seem to be a few lame desingns on our Cummins like that and the timing gear to cam slippage and the lift pump not being a gear pump like most good diesels and of course the KDP.

Ever notice who makes the lift pumps? Mine said "A-C" on the side