318 headers leaking at the flange?

[duncan999]

I got my recently acquired ‘75 Duster fired up today (had to replace the battery, battery tray, and deal with a fuel issue first) and both headers leak exhaust right at the flange. Or so it looks. Do exhaust manifold gaskets wear out? What else can cause this?

 

[Yunick13]

If an engine has been run long enough with a loose header, it could burn through the gasket, and not allow it to seal.

I'd pull the headers and make sure the flanges are straight, and clean. Then reassemble with new gaskets regardless.

 

[RustyRatRod]

Remflex gaskets.

 

[niceolddart]

The gaskets do wear out. Cheap ones don't last nearly as long as quality gaskets. Spend the money & buy good quality gaskets like RRR said, Remflex is one of them, Fel-Pro is good, Cometic MLS etc. Remember, after running the engine to get it hot, let it cool off & re-torque/tighten ALL the header bolts, at the flanges & the collectors. They will probably be loose again & that's what causes them to leak & wear out fast too. JMO

 

[Darter6]

Remember, after running the engine to get it hot, let it cool off & re-torque/tighten ALL the header bolts, at the flanges & the collectors.

You may need to do this several times. Then check periodically.

 

[Oldmanmopar]

Cut the flamge between the front tube and center tubes and between the rear tube and center tubes on each side. Give space at the cuts for expansion and contraction. also I never run gaskets at the collectors Just make sure the flanges are flush when tightening,

Recently I eliminate the flanges and do a slip fit at the collector with weld on tabs for easy removal. I do the whole exhaust like that, the only clamps are for the exhaust tips and to hold the pipes up behind the mufflers

 

[69FBCuda]

If it's leaking at the center flange bottom the headers are probably 340 spec. You either fill in the gaps at the flange bottom or as mentioned above replace the gaskets. The old gaskets will have witness marks on both faces. I'm curious to see what they look like.

 

[duncan999]

Took some photos this morning. It’s leaking right at the flange on both sides. These look like Flowtech long tube headers? I’ll try replacing the gaskets.

 

[MOPARMAGA]

I got my recently acquired ‘75 Duster fired up today (had to replace the battery, battery tray, and deal with a fuel issue first) and both headers leak exhaust right at the flange. Or so it looks. Do exhaust manifold gaskets wear out? What else can cause this?

Yes gaskets wear out, hot steel also warps.

 

[Clelan]

As was mentioned, go for the Remflex gaskets. You will be glad you did. It's immediately apparent why i say that when you look at them.
Cley

 

[Demonracer]

As OMM stated, cut the flanges between the #1 & #3, between #5 & #7, as well as between #2 & #4 and between #6 & #8. This will allow the flanges to expand and contract, lessening the chances of the gaskets burning through. I've been doing this for years and it helps quite a bit IMO.

 

[YY1]

I'll second post #6.

I've never run gaskets on any headers but I always cut the flanges.

Makes tightening all tubes an individual operation and can be fine tuned.

 

[Rocky318]

Yes as stated cut the flanges out they can pull titer to mounting on heads, and I can only say what I know from having Mopar over the years , rite now I'm running flowtech headers with all flange in between pipes removed, and here's the kicker, and think what u want, 7 years ago when I did the motor I cut gaskets from a piece of aluminum siding and run this car every day it's the only car I drive it gets numerous miles, and I have never replaced them once at this point, even have reused them without any sealant. Try it for yourself I'll be glad u did.