Straight eight exhaust gasket failures

[Mark_Kurth]

I'm having having a lot of trouble with exhaust manifold gaskets on both of my straight eights, failing within a few hundred miles of being installed. What's occurring is that the gaskets seem to "creep" with repeated heating and cooling cycles, until they eventually develop tears that become blow-outs. It's happened with both of my Packards ('29 626 w/ a 1-pc manifold and 23rd series 327 w/ a two-piece). The problem seems to have become more of an issue in the last few years, since I've been using reproduction fiber gaskets (purchased from a reputable vendor, Max Merritt). Since NOS gasket sets are hard to come by, I'd like to figure out how to get the repros to work and last me more than a season. I've done what would be the obvious:

• checked the manifolds for straightness and they check out fine
  
• using brass nuts on the manifold studs
  
• the manifolds are re-tightened after a few hrs. of running
  

It seems like the manifolds move slightly in relation to the block, which makes sense since they heat and cool at different rates. It's that movement though, that bunches and stretches the gaskets until they eventually tear. I don't see how they can be prevented from moving, without overtightening and risking a cracked casting. Another mechanic friend suggested a light wipe of antiseize on the gaskets might allow the movement without tearing, but that didn't improve the life of the last set.

As an experiment, I'd like to get my hands on an NOS set of the sandwiched asbestos/aluminum style, for comparison. In theory, it makes sense that the original composite gaskets might have been more resistant to tearing.

Any suggestions from the experts out there?

[Guest 39Super8]

Egge machine in Santa Fe Springs California sold me a set of gaskets that were metal clad and seemed very high quality. They have been on my car and working well for almost 3 years and a couple thousand miles so far. Another issue as strange as it may sound is to not over torque the fasteners. I believe the torque spec. is surprisingly low. The manifolds have to be able to move and not wreck the gasket.

Best of luck,

Jim

[tbirdman]

Egge machine in Santa Fe Springs California sold me a set of gaskets that were metal clad and seemed very high quality. They have been on my car and working well for almost 3 years and a couple thousand miles so far. Another issue as strange as it may sound is to not over torque the fasteners. I believe the torque spec. is surprisingly low. The manifolds have to be able to move and not wreck the gasket.

Best of luck,

Jim

I bought my metal clad ones from Olsen Welcome To Olson's Gaskets! on my 32. No problem with them. I did use a light coat of anti-seize. I also tighten them in a series of three steps i.e. lightly tighten, more, than final.

[Guest 39Super8]

I bought my metal clad ones from Olsen Welcome To Olson's Gaskets! on my 32. No problem with them. I did use a light coat of anti-seize. I also tighten them in a series of three steps i.e. lightly tighten, more, than final.

Ahh yes, I had Olsen’s manufacture exhaust gaskets for my Hall-Scott a number of years back. They worked out very well. They weren’t metal clad, but didn’t blow out. Good suggestion Ken

Jim

[Mark_Kurth]

Egge is a good source, but I called and their supply of NORS gaskets is tapped out. I've not been able to find a torque spec for the exhaust manifold nuts-- do you have one? It's not possible to get a torque wrench on most of the nuts as they're just not accessible, but it might help to know what I'm shooting for.

[Mark_Kurth]

Ken, thanks for the lead to Olsen's. I'll try giving them a call tomorrow. What was your take on the torque spec? Jim's post made me question whether I might be over-torquing the manifolds. The brass nuts won't allow you to apply too much force, as they strip-- but maybe I'm still overdoing it. For what it's worth, the repro gaskets seem to be a lot less compressable than the originals. Could that be contributing to the problem?

[Guest 39Super8]

Mark, if I remember right it was 18 on center nuts and 16 on outer outboard nuts. I believe this allows for creeping without breaking the manifold or destroying the gasket. I used the feel method for the reason you mentioned, no good access.

Ken, does that sound about right on the torque?

Jim

[Earl B.]

Try Paul Terhorst... I've gotten NOS from him for my 1932. You never know what he has....

Paul TerHorst in NE Illinois. Phone/fax: 847-949-1030 or cell: 847-558-9732.

E-mail: pterhorst@sbcglobal.net.

good luck, B

[Guest car crank]

The shop manual for 22nd to 24th series straight eight gives the torques as:

Exhaust & Intake manifold - screw - 3/8-16 25-30 Ft/Lbs.

Exhaust & Intake manifold - stud nut - 3/8-24 25-30 Ft/Lbs

[tbirdman]

As I said I just torgue them until their snugged. Go through a heating and cooling cycling and snug up anythat are loose. Then after driving the car a little bit, I check them again. I have also had the pleasure of stripping the brass nut thread, so I take it easy. More is not always better.

[Dave Mitchell]

I might have NOS for both cars. Dave Mitchell packard12s@hotmail.com

[Mark_Kurth]

Thanks all for the responses. I'll give it another shot with NOS gaskets and a little less torque on the nuts. Dave, I'll send you a pm regarding the gasket sets.

Any thoughts on the use of anti-seize or copper coat? Seems it might allow for more slip.