Best way to remove exhaust manifold studs from cylinder head

[bricol]

I'd be leaving them well alone if the threads on them still do what they are supposed to do.

No point giving yourself more grief than you need to.

 

[Morrisman]

I'd be leaving them well alone if the threads on them still do what they are supposed to do.

No point giving yourself more grief than you need to.

I was thinking that, but assumed they needed to come out for machine work or face skimming.

 

[DAPPH]

ATF on its own is too thick. Try thinners, see if it mixes. Otherwise, diesel is a good one part release agent. The Acetone allows the ATF to get where it is needed before evaporating and leaving an oil film.

I think pure turpentine would also make a beneficial additive to the ATF as it creeps even in the most microscopic of cracks . Find it on line eBay or an artist shop that sells artist oil paints .

 

[minimutly]

I was thinking that, but assumed they needed to come out for machine work or face skimming.

No, unless you need to machine the manifold face (super rare event). Leave them alone.
And, re the valves - pull them all to inspect guides and seals, and lap them in.

 

[Barking Mat]

Go buy some acetone, if you really feel the need to remove them.

 

[Danez]

I'd be leaving them well alone if the threads on them still do what they are supposed to do.

No point giving yourself more grief than you need to.

the thread seems to have gone on a couple of them, suppose i could just try and run a die on them?
would save a lot of hassle

 

[Danez]

and the exhaust manifold does need to be machined flat:

although i reckon the face that's on the head might not need to be machined? i'll clean it up and check with a straight edge!

 

[Keithmac]

As everyone says, of you can salvage them with a tread chaser or die then leave well alone!.

You will be in a world of pain trying to remove a snapped one.

There's only one thing worse than a snapped stud and that's a snapped stud someone has already had a go at drilling out..

 

[Danez]

Looking closely at the studs they don't look too bad...apart from this one

there's an actual thread missing near the top so i don't think i'd be able to run a die over that....

 

[minimutly]

Looking closely at the studs they don't look too bad...apart from this one
View attachment 460007

there's an actual thread missing near the top so i don't think i'd be able to run a die over that....

Yes of course you will, or do you prefer risking having to drill it out?

 

[RichardM]

Stick a thread gauge on them to make sure they haven't stretched and use brass nuts when re-assembling.

 

[Danez]

Yes of course you will, or do you prefer risking having to drill it out?

obviously not, just thought the thread was far too gone? I'll give it a go anyway

 

[Ubique]

Stick a thread gauge on them to make sure they haven't stretched and use brass nuts when re-assembling.

Most exhaust manifold stud nuts are copper coated steel, certainly for vehicles from early 1990's onwards.

 

[RichardM]

Most exhaust manifold stud nuts are copper coated steel, certainly for vehicles from early 1990's onwards.

Brass nuts won't seize onto the studs.

 

[arther dailey]

Brass nuts won't seize onto the studs.

that s a good point , if you can get those overly long nuts like they used back in the day , brass ones ,even that odd stud might not be a problem , they were up to twice the length of "normal" nuts .

 

[Ubique]

Neither do the copper coated steel nuts. The studs corrode either side of the nut however, which is generally where the problem lies.

 

[OJCar]

if you can get those overly long nuts like they used back in the day , brass one

Imperial
https://www.wrightsautosupplies.co.uk/product/deep-manifold-brass-nuts/

Metric
https://www.spaldingfasteners.co.uk/m8-m10-brass-manifold-exhaust-stud-nuts/

 

[DAPPH]

Mostly as per Memmeddu.

But not drilling at minor thread diameter of the stud - if slightly off, the threads can be drilled away.

At that point it would be on the mill table, so easy to drill them centrally and perpendicularly. Generally a pilot hole followed by increasing sizes of left handed (anti-clockwise) drills. Sooner or later the stud will unscrew, the latest at the point of almost drilling away all the central core at one point.

The one item I rarely ever use is a stud remover screwed in anticlockwise hole in the stud. That is a good recipe for further complication!

Exhaust manifolds often require milling flat. They can (sometimes) be sorted by extra gasket thickness but the cure is better than extra gasket material.

The old " Rigid " thread extractor tool is brilliant of taking out the sleeve left by milling out damaged studs there are also drill guides in the kit to help you center over a broken stud if you y-use a battery or corded hand drill

Warning they are not cheap .

 

[DAPPH]

Looking closely at the studs they don't look too bad...apart from this one
View attachment 460007

there's an actual thread missing near the top so i don't think i'd be able to run a die over that....

Making a jig out of thick flat bar so you put it over a good stud and lock it down precisely over the broken ground flat stud helps in drilling & tapping out the old stump thread

 

[Danez]

I ordered meself a full set of studs and brass nuts before even taking the manifold off!
Might have been a bit hasty but it's why I originally wanted to take them all out but I'll now try and salvage the ones still in there