Intake manifold stud unscrewing from head

The lower studs on the right side are rusty and have been rounded off by previous owner. I've managed to get one started using Irwin extractor but the stud is actually unscrewing from the head. How bad is that?

And any suggestions how I get the other one out?

 

That’s actually good, replace the studs with new.

If you can get a 2nd nut on, tighten 2 nuts together to lock them and then undo the the inner nut, and the stud should unwind, but if the studs aren’t long enough or too chewed up, decent mole/vise/ grips should be able to get a decent bite on them to allow you to unwind them.


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Hopefully the threads in the head are all good still. The problem is the access as it's the lower, inner ones at the base of the inlet manifold. This job is taking forever.

 

If you can, depending on tools available, grind/cut the nuts off Flush with the manifold, remove the manifold, then remove the studs.

 

^ this. Good opportunity to use new studs. Just double-nut the new ones in.

I’d avoid using screw extractors, as they will 100% sure snap off.

 

I got one out cleanly:


I just can't get any purchase on the head of the last bolt

 

Have you got a long 13mm socket?

 

Yep tried that.

I think, as it's the hard-to-reach lower imner bolts on the intake, they are 12mm. So 13mm does nothing, 12mm does less and 11mm is just too small.

Tried imperial. No joy.

My Irwin nut extractor which got the one above out goes 11mm (which is too small) and then straight to 13mm which is too big. I did get 1/4 turn with the 13mm extractor initially but now it slips. I need 12mm extractor I think.

Calling it a day now. *******ed off.

 

Best penetrating lubricant I've ever used. I had the same problem with studs, used double nut method if no thread then really good quality mole grips

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I have plus gas might give it a squirt tonight. Its getting on the end of the nut that's the issue. Just no space.

 

Long nose pliers gripped with mole grips? You can get a socket that adjust to the nut with pins

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I've seen them before and I reckon it would do it just can't find any atm. Grip Tite was one brand I think. Ill keep looking. Thanks for the suggestion

 

And then try cleaning off the penetrating oil from the surface and welding a 13mm nut on top of the wreckage..if it breaks off weld another on. One pain can be that the stud is poking through a part of the cylinder head and out into air again. Where it rusts into a big lump and this wont come through.

Often though the tools like stud extractors we think we can afford are too cheap.

A pair of proper Mole grips done up really hard with the pressure of another pair of pliers or pump pliers , or even some Knipex or similar brand pump pliers may provide grip. Not cheap generic barely hardened /toughnened / wrong mix steel alloy market trader trash...

But in the end, welding with a fair amount of current to get penetration can give you bigger things to grip and twist.

 

What's the problem exactlu with the 12mm socket on the 12mm bolt?
I have a few sockets that I've ground down the outside for this sort of thing.

 

This - has a double whammy as the heat helps break the bond

 

If the nut is still there then you have a lot more options and @zedders is right about sticking with a socket, preferably a single hex one. Plusgas is great and much better than WD40 or similar. If, or when, the stud breaks then welding a nut on is the way forward as @mikedjames says. I put a washer under the nut just to protect the head or whatever it is that the stud is in - I've done loads in the blocks of the flathead Fords! Oh, and I usually put a much bigger nut on so there's a gap to get decent penetration for the weld. When I've been really desperate I've squirted that plumbers' freezing spray on the hot stud to shock it and break the corrosion bond between the stud and block or head. It's a bit expensive to do it routinely.

 

It WAS a 12mm nut but previous owner plus rust has made it a lump of XXmm in size. So 12mm socket is now too big but 11mm is too small.

Its not an issue of getting a socket in there (although that was a nice surprise when I did the left side carb and manifold. Good job I have skinny sockets to start with). The issue is that the nut is *****ed. I've tried single and 12 point and imperial.

 

3/16 BSW or 1/4 BSF are 11.3mm across the flats

 

...or file the flats down to 11mm. Done that before!

 

Rusty nuts break quite easily with a sharp chisel if you can get at it, hit it just off centre in the anti clockwise direction!