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Exhaust Manifold Stud Removal

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HealeyDave

HealeyDave

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Searched archive but found no results: what is the best way to remove the old studs from the exhaust manifold outlet flange? Mine are in there pretty good.
Thanks,
Dave
BN7 project
 
Hi Dave, If you're lucky they haven't been welded to the manifold by rusting. Try "double nuts", run one up part way, then another up to the previous nut. Tighten the nuts against each other, then with a wrench on the upper most nut try and remove the stud. First though, soak thoroughly with PB blaster or liquid wrench let sit overnight. I usually have to use a propane torch to apply heat, and most come off. If your break one off you'll have to take it to a welder to remove. The manifold near the stud has to be heated until it turns puple, not red.

Good Luck
 
Thanks. I was wondering about heat as a next try. And the double nut thing sounds much better than vise grips.
Dave
 
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As shown, I'm heating up the nut, to expand it away from the stud, breaking the rust bond. What's not shown, is that immediately after heating, I touch the end of an old (wax) candle to the exposed threads. The wax is drawn towards the heat, and wicks its way into the threads, lubricating them. At this point, the nut is easily backed off. Backing and reversing gradually, and reheating if required, until it's all the way off.

In your case, you'll want to heat the corner of the cast iron flange, to expand it away from the stud (you don't want the stud expanding making a tighter bond). Sometimes, just the act of heating and (natural) cooling is enough to break the bond. In any case, try the wax, I think you'll be surprised.

As for the Vise-Grips versus double-nuts, since you're already replacing the studs anyway, who cares? The Vise-Grips will be a lot faster, and what I'd use if I wasn't out for saving the studs.
 
Mine were rusted through, some I could remove using penetrating oil, just, but the others would not budge. With no means of providing heat, I cut them off flush to the flange and used a smaller drill to drill through the centre, You do need to get the drill vertical to the plane of the flange surface though, then try to weedle out the rest with a probe. I ended up re-tapping some.

:cheers:

Bob
 
Here's a link to the type of stud extractor that works best. I'm sure they will be easier to find in the States and they really work without damaging the studs.

https://www.cromwell.co.uk/KEN5829480K?id=TCY3hPiU

I have to say that I'd get the manifold off the car and really heat it before trying to remove and exhaust stud. It's a foul job and I wish you the best of luck.

Ash
 
I used to run an muffler shop. The only intelligent thing to use is heat. Oxy acetelene torches will provide pinpoint heat and get the flange to a dull red glow very quickly. I will do anything to avoid breaking the stud off. Drilling them out is not only timeconsuming, but you end up destroying several bits and often drill the hole off center. Heat is the only way to go. Do not spray on any lubricant like WD-40 or PB Buster. It just ignites.
 
Ok, this weekend I will heat around the flange with a torch and then apply a bit of wax and see if I can break them loose.
I see $nap-on carries the stud extractors and you can buy indivudal components - housing and threaded collet - but the housing is $62 and the collet is $27! Then, at the opposite end of the spectrum Harbor Freight has a universal gizmo for $5.99. I think I'll try heat first.
Thanks to all for the input!
Dave
BN7 project
and now an FJ-40 project!
 
The most dependable way IMO is to tack weld a nut to the studs. You can do it with oxy-acetylene but a MIG is quicker and easier. If you don't have a MIG you might consider buying one--this is a good excuse (and Christmas is coming up)--and you'll have a new hobby and you'll almost certainly need it again. They're cheaper than you might expect and you can get by with flux-cored--i.e. no gas bottle required--until you're ready to upgrade.

I broke a couple manifold-to-downpipe flange studs off and was able to MIG-weld nuts to the thread or two that were exposed. I did this in situ from under the car; without the MIG I would have had to pull the manifold.

Penetrating oil is a religious topic; everyone has a favorite. Mine is Kroil; I've seen it work small miracles.
 
nevets said:
Randy, what's that gadget you are using to apply heat?
Click to expand...
Just the COOLEST THING EVER! https://www.theinductor.com/index.php?m=5&s=0&d=3&ds=0&prod=0

Amazon sells them for about half (!) of list price. Before any "major purchase" I always check Amazon first. Looks like the price has gone up, I only paid $350.00 for mine...
https://www.amazon.com/Induction-Innovati...ef=pd_sbs_auto2

I bought the inductor immediately following heating up one of those same exhaust flange nuts under a BMW. While the owner was standing next to me. I decided then and there that I wanted another method, not an open flame, when working in front of a car's owner.

And Bob, I agree; Kroil is worth every cent they overcharge for it! I keep both the 4oz. can & aerosol close at hand. EVERY new car I get to work on goes on the hoist overnight with Kroil on all the fasteners I plan to work on the next day(s).
 
Another technique my old (ancient) mechanic father taught me is when removing a stuck fastener (nut, bold, stud) work it back-and-forth. It may seem counter-intuitive to seemingly tighten a stuck fastener, but when you're trying to remove it rust/crud can jam the threads; turning it the opposite way can loosen the jammed crud (and let the Kroil in).
 
I must say that heat is the best but when the stud is half corroded away and some of mine were, the options begin to run out.

:cheers:

Bob
 
Yeah, they can get pretty skinny. You can try welding something on to the stub, or even burning out the old one with the cutting torch. Good torch men can heat up just the stud and then burn it out without damaging the cast iron. I'm not that good.
 
Bob Hughes said:
I must say that heat is the best but when the stud is half corroded away and some of mine were, the options begin to run out.

:cheers:

Bob
Click to expand...
Dry Ice will easily shrink the stud/bolt without the possible damage that heat does. Shrinking the stud will allow penetrating fluid to flow-in easier.
 
Legal Bill said:
I used to run an muffler shop. The only intelligent thing to use is heat. Oxy acetelene torches will provide pinpoint heat and get the flange to a dull red glow very quickly. I will do anything to avoid breaking the stud off. Drilling them out is not only timeconsuming, but you end up destroying several bits and often drill the hole off center. Heat is the only way to go. Do not spray on any lubricant like WD-40 or PB Buster. It just ignites.
Click to expand...

I've never done this before, so just to confirm: I am to heat the FLANGE in the immediate area of the stud until it gives a dull red glow and then attempt to turn the stud until it comes free? I have a small oxy-acetylene torch that produces a small, narrowly focussed flame, and I am planning to use that.
thanks,
Steve
 
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