SOLVED: Can't get 440-3 exhaust manifold to seal.

[vincewarde]

We are finishing up some work on our m600 Tiffin's 440-3 and we are having a weird problem.  We can't get the manifolds to seal.  Yes, we had them both surfaced.  We tightened them down well - although we didn't have a torque wrench.  Once we fired it up, both sides started leaking and when we checked all the nuts and bolts were loose.   i??


We talked to the machinist and he suggested that we try it without a gasket and with a good  torque wrench - so that is next on the agenda.  I just wondered if anyone else has had this problem?  Is the gasket for a 440-3 different than a normal late 1970s 440-3?


Any ideas folks?

[Oz]

Do NOT torque the manifolds down without a gasket and using a torque wrench.  You stand a very good chance of snapping the bolts by doing so.  Without torquing the bolts to begin with, it certainly doesn't take much for them to come loose.  Just like needing to re-torque them after running the motor a bit - as needs to be done with intake manifold bolts, oil pans... etc.  Especially if your motor mounts are dried up and hardened.

Perhaps the manifolds were machined but, that doesn't mean anything as to the evenness of the block surface and 440 gaskets are notoriously below par besides.  Even a slight weakness in the gasket between the mating surfaces, under such pressure as is put out by the exhaust pressure is going to cause a leak

One - message search "copper manifold gasket".  Those are what you really want.

[DaveVA78Chieftain]

Be aware that 440-3 exhaust manifold bolts only get torqued to 20ft lbs.  It is real easy to over tighten them.
Be sure to use anti-seize compound.
Make sure you tighten inner to outer bolts.
Tighten then run engine to temp, cool down, retighten.
Repeat a few times.
I also found the Percy's Aluminum Header Gaskets (p/N 66036) to work well with stock manifolds.
http://www.autozone.com/autozone/parts/Percy-s-Header-Gasket-Performance/_/N-a0410Z1z13dnm?itemIdentifier=467583_0_0_

Dave

[cosmic]

I agree with everything said above. chances are the block is not true. on my passenger side i had the same problem. i used 2 gaskets on that side. 4 years later still great. first 3 or 4 times running i re- tightened them each time and they went a little tighter. problem solved.
Oh and my manifold was used and not machined on the passenger side..

[vincewarde]

We got a torque wrench for the appropriate range, pulled them, cleaned both surfaces and torqued to 30  foot pounds with no gasket.   We ran it for a few minutes and saw no leaks. 

The torque spec for this engine is hard to nail down.  I have a copy of the original service manual for this chassis - it says 25 ft lbs right and 50 ft lbs left.  Dave says 20 ft lbs and my machinist says 30 ft lbs.  We went with the machinist's advice.

We shall see if this works, if not, we will try a high quality gasket.

Thanks all!

[DaveVA78Chieftain]

For reference, the Dodge Motorhome Service manual says:

Exhaust Manifold to head - 20 ft lbs

Exhaust pipe to header manifold flange (right Side) - 25 ft lbs
Exhaust pipe to header manifold flange (left Side) - 50 ft lbs

The reason the left pipe is different from the right pipe is the left side uses a gasket and the right does not.

Dave

[vincewarde]

Thanks - I misread the manual!

[vincewarde]

Be aware that 440-3 exhaust manifold bolts only get torqued to 20ft lbs.  It is real easy to over tighten them.
Be sure to use anti-seize compound.
Make sure you tighten inner to outer bolts.
Tighten then run engine to temp, cool down, retighten.
Repeat a few times.
I also found the Percy's Aluminum Header Gaskets (p/N 66036) to work well with stock manifolds.
http://www.autozone.com/autozone/parts/Percy-s-Header-Gasket-Performance/_/N-a0410Z1z13dnm?itemIdentifier=467583_0_0_

Dave

OK, we developed a leak on the left side and - sure enough - the bolts had backed out again!  These bolts were torqued to 30ft lbs after being surfaced in a machine shop that does a lot of work on Mopar V8s.  They advised 30ft lbs.   We cannot figure out why these bolts are backing out.  I have put on lots of manifolds over the years and I have never had a problem like this before.

We have ordered the Aluminum gaskets from the local Auto Zone, but if the bolts keep backing out, I don't think it will do any good.  Any ideas?

[LJ-TJ]

Have you tried lock washers or maybe just new bolts? i??

[vincewarde]

Have you tried lock washers or maybe just new bolts? i??

Yeah, I will see our machinist today and I was thinking of something like that.  I'll ask him.  Who knows if these bolt are the right ones......

[Froggy1936]

Exaust manifold bolts are pretty hard Also useing locktight and letting it set up . make sure you use the correct formula Summit raceing has all types and they have manifold bolt sets !  Frank

[DaveVA78Chieftain]

For reference:

Be sure to use anti-seize compound.
Make sure you tighten inner to outer bolts.
Tighten then run engine to temp, cool down, retighten.
Repeat a few times.

Is one of the most important steps with a 440-3

The bolts have to "set" and adjust to expansion and contraction.

Dave

[cosmic]

Dave.
you say that one can easily over tightened. Please explain this? the bolt is like 3/8 bolt so are you saying you can easily stretch it easily break it? . what do you mean by easily over tighten it???
Its been my experience that i can tighten a 3/8 bolt a hell of a lot more then 20 to 30 ft/lbs without coming the slightest bit close to jeopardizing a break. (On a bolt or the manifold.)
If you leave them to long after install and seize them up then yes you can easily break those bolts.

[vincewarde]

Yeah, I will see our machinist today and I was thinking of something like that.  I'll ask him.  Who knows if these bolt are the right ones......

Machinist is at a loss to explain what the problem is.  Suggested checking closely to see if we have the right bolts.  Also suggested some kind of locking bolts.....

[vincewarde]

For reference:
 
Is one of the most important steps with a 440-3

The bolts have to "set" and adjust to expansion and contraction.

Dave

I think this may be our solution.....

[DaveVA78Chieftain]

Dave.
you say that one can easily over tightened. Please explain this? the bolt is like 3/8 bolt so are you saying you can easily stretch it easily break it? . what do you mean by easily over tighten it???
Its been my experience that i can tighten a 3/8 bolt a hell of a lot more then 20 to 30 ft/lbs without coming the slightest bit close to jeopardizing a break. (On a bolt or the manifold.)
If you leave them to long after install and seize them up then yes you can easily break those bolts.

Issue is not the strength of the bolts.  Issue is expansion and contraction of both bolts and cast iron header.   It is a well known problem that if you overtighten these bolts (listed spec is 20 ft lbs) you will most likely have header sealing problems.  Only issue I have seen with the bolts themselves, is deformation (hex head degradation) due to large temp swings and rust.  Additionally, several of the bolts use "special" washers that mate up to the header flanges.  Many times these get lost along the way.  Bolt / Washer replacement kits are available however, you have to look close at the contents to ensure you get the right package for your application.   There are different 440 header "sets" available depending on what application (car, truck, etc.) the engine was used in.  Always use anti-sieze compound with these bolts.  The bolt holes go through the head into the water jacket so the bolts are exposed to water and therfore can rust.    Yes I have had to use a stud puller to extract a broken header bolt before.  Yes, a previous owner had to have a weld repair down on a header bolt hole then retapped it.  I have had header sealing problems also and had to replace all the bolts as well as use the special aluminum gaskets to solve the head to manifold seal problem.   I still have to fight getting the stupid emissions port on the rear of the right side header to seal (aftermarket replacement).  Only one bolt holding the blank on and it should have been designed with 2.  Needs to be welded closed once and for all.

Dave

[cosmic]

Thanks Dave.
I have a much better understanding as to what you were saying now.
I guess that 20 ft lbs would be a good start. then let the engine worm up and give a little pressure to each bolt, as the cast manifold when hot can twist and expand a little different then headers so to say as they are steel. then you will know that when the manifold is hot it is sealed. Just a little thing that i did to get mine to seal up once and for all. and it still took 3 or 4 times.

[vincewarde]

Additionally, several of the bolts use "special" washers that mate up to the header flanges.  Many times these get lost along the way.  Bolt / Washer replacement kits are available however, you have to look close at the contents to ensure you get the right package for your application.

I bet that is exactly what has happened in our case.

[vincewarde]

PROBLEM SOLVED:
It was indeed the lost locking washers.  We installed "Nord Locks" on all the studs, adjusted the torque per the manufacturer's recommendations and NO MORE LEAKS!!!!!!!!!!!!!!!!!!!!!


It sure is good to be done with this part of the project.

Thanks to all - I hope this helps somebody.

[Froggy1936]

I have found that the multi layer aluminum manifold/header gaskets made by Mr Gasket Available @ Summit Raceing overcome a lot of mateing problems  Frank

[Oz]

Great to hear you found the issue and that it was a simple, inexpensive fix!

As for the copper gaskets... that's a good follow-up point and we have very good discussions here on the topic, including sources.

[RoamingRobert]

So did you toque the right to 25 and the left to 50???  also did you install gaskets on both sides and if so what kind.... I have a 76 Brave with the big 440 engine and it has a exhaust leak on the right side..... about to start investing some $$$ in it ..... Thanks !!!

[tmsnyder]

That thread is 8 years old   Read it carefully and use the knowledge there to help your situation along, and post back your results!