Rusted exhaust studs

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Mar 30, 2008 | 03:37 PM

coyote81

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Rusted exhaust studs

I'll start by saying it's not the studs that connect the manifold to the block. It is the studs that connect the single pipe from the manifold to the exhaust pipe before any of the cats. I was wondering if these are really studs or just severely rusted bolts?

Thanks for any help.

Mar 30, 2008 | 03:40 PM

rob188

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From: new west b.c

i think there bolts

Mar 30, 2008 | 05:48 PM

superdutymj

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From: La Crosse, Kansas

they are studs that are threaded into the manifold and are fastened to the downpipe with two 5/8 (i think) nuts. You can bet your life that those two studs will break off. I broke mine off in the process of replacing exhaust manifold gaskets. I simply cut the studs off flush with the manifold, center punched and drilled out the stud with a 5/16 cobalt bit and tapped the holes with a 3/8 NC tap and made some studs out of 3/8 all thread. Worked well and I know if i need to take the downpipes off again it will be alot easier cuz i used anti-seize on the threads.

Mar 30, 2008 | 05:54 PM

73f100shortbed

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From: NJ

They are studs. I currently have two manifolds off of a 98 f150 at work with two broken on each side

Mar 30, 2008 | 06:57 PM

monckywrench

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If you can get a Dremel tool or small (prefer 90-degree) die grinder to the studs (pull the inner fenders for a better view) and use the fiber-reinforced cutting disks you can cut them or weaken them so they are easier to wring off.

superdutymj has the right idea on the repair and anti-seize.
The " 5/8 " bolts are 15mm, and a six point socket is what to use the bust them loose. Wear gloves to lessen the pain of punching adjacent components when they let go...

Mar 30, 2008 | 07:22 PM

coyote81

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Thanks for the advice I will probably be taking this challenge on next weekend. Until then I will live with the noise. it's nice being a millwright apprentice as i have a wide selection of tools I can bring home from work. I think this week I will spray Kroil on the two bolts each day and night. It's a penetrating lubricant.

Apr 5, 2008 | 06:54 PM

superdutymj

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From: La Crosse, Kansas

it wont help when the nuts are rusted through and so are the studs. once you get in there, you'll see the studs are rusted down to almost nothing under the nuts. I can also almost guarantee you that your exhaust leak isn't the flanges between the downpipe and the manifold, its the gaskets between the manifold and head (not block). These manifolds are very poorly cast and even more poorly machined. They are so ill-fitting that the studs on the back cylinders on each side will snap the head of the stud off and the leak will be there. Take a flashlight and make sure all 8 nuts are in place on both manifolds. You can also look for black soot marks around the flange area of the head. Putting in new gaskets won't solve your problem, the only good remedy is to either get the manifold flanges trued up, or just get some headers, new manifolds are very costly and have the same ill-fitment.