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Header exhaust leaks

Will L. said:
All the regular manifolds I've done over the years went on clean and dry, and only if it leaked (way rare) did it get a gasket- but that is cast manifolds.

On the steel hummer headers, I only delt with maybe 15 installs. Most of them get the regular felpro gaskets I mentioned.

I forgot it has been 3 years already- yeah, kinda hard to push that.

Most headers do not need the ports connected, but with the design on yours, I can't see how they are not. Stainless steel (almost all types) expand massively, ESPECIALLY PIPE.

Iirc 316 is .04 factor, meaning your header is trying to expand 1/16" in length. Between that and the vibration, I can't see how rtv is viable. And you cant compare hot rods to rv. Hotrod is constantly getting checked, tweeked, things getting tightened,etc. Your rv should be like that spinning cooker- set it and forget it.

If you haven't snapped any locking retainers, and they obviously stayed tight, you just need a simple gasket. Copper gaskets are great and have there place, but idk about them here. The copper is ductile, yes. But once it flattens out, it will just keep getting malled by the vibration. Just my guess, I never used copper on a 6.5- paper always worked as long as bolts aren't coming loose. The paper can handle expansion and contraction. When the SS expands it will squish the copper more, but what about when it contracts, Won't it leak then?
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I was able to locate gaskets that might work.

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Husker6.5 said:
1) - 14). It could have been worse, Jody. It could have been raining!
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You are right, it could always be worse, but it was raining when the transmission started acting up. It was somewhere in Ohio, it was raining hard and the transmission was shifting up and down and jerking. I had no idea what was wrong. I pulled into a Home Depot parking lot to check the fluid level, which was low. It was raining so hard I couldn't see where it was leaking from. It ended up being the dip stick/fill tube was miss aligned with the torn rubber grommet. I was able to straighten it out enough to hold fluid, but didn't help the shifting issue. I had no idea that it was the melted wiring. My biggest fear was that my new transmission was ruined.
 
Could have been the middle of February at night in the cold in the middle of nowhere. Oh, wait, we already had that happen!
 
If it were Me, installing stainless steel bolts into cast. I would use some copper anti seize on the threads.
I have had stainless bolts threads gall and that is when stainless bolts break. anti seize prevents that from happening.
Use it sparingly though, You do not want to create a hydraulic lock and crack a head around the bolt hole.
 
MrMarty51 said:
If it were Me, installing stainless steel bolts into cast. I would use some copper anti seize on the threads.
I have had stainless bolts threads gall and that is when stainless bolts break. anti seize prevents that from happening.
Use it sparingly though, You do not want to create a hydraulic lock and crack a head around the bolt hole.
Click to expand...


They are nickel plated steel.
 
I sent the headers back to Peninsular's fabricator. They are going to try to fix them with thicker flanges. I'm hoping the locking header bolts will be long enough to reach through the thicker flanges and the gasket.
 
Good for Peninsular.

"If they don't, get longer ones." Says Captain Obvious.

But seriously, if you want the bolts to stay tight they need to be threaded in deep enough to get enough thread surface area to hold the load when torqued without pulling the threads out in the block. Rule of thumb is minimum depth is 1 1/2 times the fastener's diameter. That is, a 3/8" diameter bolt (regardless of the thread pitch) should thread no less than 9/16" depth (more is always better, but do not bottom out in the hole with the bolt) into the block.

Now, that brings up the thought of using studs and nuts to attach the headers. Drill the studs and use aircraft safety nuts and some stainless steel wire to safety wire the nuts once they're torqued down.
 
The locking header bolts I have are 10 mm X 25 mm. By your rule of thumb, the bolts I have would be about 5 mm too short.

header bolt.jpg
 
I don't know for sure, but they talked about .4375-.5.

I talked to the Stage 8 people and the only locking bolt they have that's 30 mm long has a 15 mm head on it, which is too big to clear the pipe. The same would be going with studs and nuts. I may have to go back to non-locking header bolts to get 30 mm ones. I don't want to have the threads pull out of the heads with too short of a bolt holding all that power and heat.
 
You can always dimple the runner to clear the bolt head or nut, it will have basically zero effect on the exhaust flow.
 
A fastener stor might have allen heads, if there`d be enough room to get an allen wrench between the main tube and the flange. The heads can be drilled, as suggested earlier, and hten safety wire run through them. They still will need to be tightened periodically, and especially after the first few hours of run time.
 
That's weird, Jody, as almost all header specific bolts I've ever used had undersized heads on them just so that the bolt head and socket would clear the primary tubes. Have you considered going with an Allen head cap screw with a lock washer?
 
Husker6.5 said:
That's weird, Jody, as almost all header specific bolts I've ever used had undersized heads on them just so that the bolt head and socket would clear the primary tubes. Have you considered going with an Allen head cap screw with a lock washer?
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I don't think the 10 mmX30 mm locking bolts with the 15 mm heads are actual header bolts. We had Allen head cap screws in the beginning and they would always loosen and/or fall out.
 
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