Exhaust leak where pipe attaches to manififold, with pics

[wegngis]

Hey guys, I tracked down my exhaust leak to where the pipe attaches to the passenger side manifold. It was plainly obvious. I tried tightening with no luck, now I've disconnected the pipe. The pics are where I'm at now. Having never worked on this, I'm not quite sure what I have. Is this an old mangled donut ring stuck to the exhaust pipe? Does it need to come off and be replaced? I've got a shot of the manifold side as well. At the very least I'm getting new nuts and bolts for it.

 

[langester]

That's what I would say. Replace the doughnut and try it again, it should seal up. Be careful some of those old doughnuts are asbestos.

 

[blubuckaroo]

Those donut gaskets are available from any good parts store. If you have trouble finding them, try a muffler shop. They are available in steel and fiber like yours. I prefer the fiber ones. I feel they distort better to conform to any irregular surfaces you may have in the connector.
You should make a good inspection of the condition of the manifold flange for cracks, especially on the stud ears. No donut gasket will stop that leak.
Clean the connections real well with a wire brush and be sure to use anti-sieze on the studs.

 

[wegngis]

So that is an old donut on there? I guess a screwdriver will be my best friend on getting it off.

 

[66WarPony]

Those donut gaskets are available from any good parts store. If you have trouble finding them, try a muffler shop. They are available in steel and fiber like yours. I prefer the fiber ones. I feel they distort better to conform to any irregular surfaces you may have in the connector.
You should make a good inspection of the condition of the manifold flange for cracks, especially on the stud ears. No donut gasket will stop that leak.
Clean the connections real well with a wire brush and be sure to use anti-sieze on the studs.

X2 on looking at a muffler shop, but make that your first option if possible. I used to work at one, and often times we would sell little parts like that for cheaper than an auto parts store. Get a sintered metal donut, and use crimp nuts and Red Loctite. Make sure you torque them down nice and tight, and fire her up. Once she's up to temp, get a 4' foot section of rubber fuel line and stick one end to your ear and drag the other end around the joint; if you have a leak, you'll know. If you can't hear any leaks, inspect the entire surface area of the manifold with the rubber line. Sometimes cracks may not be readily apparent until the manifold has had time to heat up. Cheers :beer:

 

[wegngis]

Red Loctite? I trust you, having worked in a muffler shop, but I've read things to the effect of putting anti-seize on the bolts, so someone (me) in the future can get it back off in the future without a hand grenade.

 

[66WarPony]

Red Loctite? I trust you, having worked in a muffler shop, but I've read things to the effect of putting anti-seize on the bolts, so someone (me) in the future can get it back off in the future without a hand grenade.

At the minimum use crimp-nuts, you don't want them to back off... and it's not something you should be taking apart often anyway. Every time you take it apart, use new crimp-nuts: once you engage the crimp, removing them will make the crimp ineffective if you reinstall them.

 

[wegngis]

There were lock washers on there, that might be why it ended up working loose. I suppose Red Loctite is fine since it needs heat, and I'll have heat in great abundance down there.

 

[66WarPony]

There were lock washers on there, that might be why it ended up working loose. I suppose Red Loctite is fine since it needs heat, and I'll have heat in great abundance down there.

Lock washers don't work worth a damn down there, and will work themselves loose every time. Even double-nutting with standard nuts will back off.

 

[wegngis]

I read the specs on Loctite red, and it says it's effective to 550F. It would appear that it's not doing a lot when you're running, but perhaps keeping things together when stopped?

 

[half cab]

Lock washers don't work worth a damn down there, and will work themselves loose every time. Even double-nutting with standard nuts will back off.

This is true,lock washers ain't worth a dom at the manifold!!

 

[blubuckaroo]

There's no need for locking devices or locktite on these studs. It's a better idea to use anti-sieze.

It's not that the nuts are backing off, but that the donut gasket is settling in.

Just like header bolts, you'll need to retighten these flange bolts after a few heat cycles. After a few heat cycle tightenings, the gaskets are done settling in and won't loosen up.

Rust usually holds the nuts on after some point anyway.

The only reason I could imagine a muffler shop would do it different, is most wouldn't ask you to come back to the shop for a "scheduled" nut tightening.%)

 

[broncodriver99]

I have always used anti-sieze and the proper type lock nuts which are a one time use fastener. I would rather risk having to replace a $2 donut down the road then to have to pull a manifold to replace a stud.

New hardware is available pretty cheap. https://www.npdlink.com/store/products/bronco_stud_set_exhaust_manifold_to_pipe-107144-80521.html

 

[half cab]

a "scheduled"nut tightening.

My first wife talked about such just before unloading a 9mm!

 

[66WarPony]

There's no need for locking devices or locktite on these studs. It's a better idea to use anti-sieze.

It's not that the nuts are backing off, but that the donut gasket is settling in.

Just like header bolts, you'll need to retighten these flange bolts after a few heat cycles. After a few heat cycle tightenings, the gaskets are done settling in and won't loosen up.

Rust usually holds the nuts on after some point anyway.

The only reason I could imagine a muffler shop would do it different, is most wouldn't ask you to come back to the shop for a "scheduled" nut tightening.%)

We guaranteed the work we did at the muffler shop. If anything was wrong, the customer brought their vehicle back and we fixed it at no charge. That was rare, and it wasn't ever because a donut "settled" in. Regardless of whether the donut is sintered metal or composite, an exhaust leak will be immediately apparent if installed incorrectly. I installed my composite donut one time only, tightened the crimp-nuts, and left it be. It's not the heat cycles, but the vibration that shakes them loose. This is catalyzed with regular nuts if the exhaust system vibration insulators have little to no play.