Heater Outlet Studs Broken (948cc Head,1960))

[whyperion]

While trying to fit new supplied studs , washers and nuts to a new base at rear of cylinder head , the nuts decided not to go down the studs (either way up) and as a result one has twisted off leaving the new stud merrily stuck in the head.

Options: (A) Remove head and get machine shop (at a price) to drill out,retap head(?) and supply/fit new proper(?) studs and nuts.
(B) Attempt to drill out (unless i can find two thin nuts to lock on and hope that stud comes out) and hope that head threads are not damaged

Is there any other option(can i araldite the outlet base onto the stud and hope that one nut and stud might hold water for now).

Is there a reliable supplier of correct sized studs and nuts?

[bmcecosse]

I don't understand your 'new base at rear of head' - please explain - or a picture maybe? Removing the head must be an extreme last measure. Is this one of the 'new' studs that has broken -or an old stud? If there is enough stud sticking up, dose it with Release oil (NOT WD40) and then try to grip it and remove it - without any drilling... DO NOT under any circumstances try to use the dreaded 'Easy Outs' !! If you have to drill it out - first cut it off flush (near as possible) with the head - mark the centre with a 'dab' and then drill v carefully and slowly, keeping the drill vertical in both planes - and starting with a very small drill, slowly increasing in size up to 3/16" Then hopefully the remaining threads will 'shell out' - and you can then run a 1/4" UNF tap down the hole. I suggest your 'one stud +araldite' idea is not going to be reliable.....

[les]

If you have to drill the new stud out, and want to keep the original size thread, preferable, Helicoils are an option. You must have really forced the nut on to have snapped the stud, obviously a wrong thread somewhere along the line. You should be able to keep the head on.

[whyperion]

Thanks, Its more that the drilling expert is some way away from the car.

The heater tap base , does not really matter if new or not (though the old casting had snapped at the stud location some years ago- car has been off road some 8 years (owing to the rather too well fitted clutch and brake pedals and master cylinder problems-these have now been fixed),the engine itself was a replacement a few years before that fitted by others)).

Borrowing a stud from a 1098cc cylinder head (where it was a perfect fit), the stud does not fit into the hole, are 948cc heads tapped to a different size? though I am worried that the nut supplied did not fit the thread of the stud.

[simmitc]

The only advantage of removing the head is to gain better access, and possibly use a pillar drill. However, if it is a new stud that has sheared, then it should come out if the remains are gripped with mole grips or similar. For it to be this much bother, the threads must have been wrong. Did you fit the studs the correct way - it's a coarse thread in the block and a fine thread for the nut. As a general rule, if something will not do up with fingers, then there is something wrong and it should not be forced. I hope that the repair goes smoothly. Araldite or similar is NOT an option.

[les]

When you finally get things ready, just make sure the stud screws into the head with no force and likewise the nut on the stud. Both should start by hand before you need tools. Oops similar comments to above.

[bmcecosse]

These studs are same size on all A series engines - and they are NOT coarse thread at one end...they are 1/4" UNF both ends. Seems yours may have been drilled for a larger (maybe Metric) size some time in the past.

[whyperion]

But the 1/4 UNF nut did not fit the supplied studs eiether .

[bmcecosse]

Then either stud or nut is wrong. They are ALL 1/4" UNF as they leave the factory!

[whyperion]

Thanks

methinks son had placed a metric nut on the studs for me to tighten

[simmitc]

These studs are same size on all A series engines - and they are NOT coarse thread at one end...they are 1/4" UNF both ends

Absolutely correct, I got carried away having just changed two sets of manifold studs which ARE different, but the heater ones are the same

[rayofleamington]

Do you know anyone who's handy with a MIG welder?? If so, it's usually a quick process to remove.*

Place a very strong weld lump onto end of stud (ONLY the stud!), add a bigger nut on top with the weld lump sitting inside the nut. Weld the nut to the previous weld and use a socket to unscrew the broken stud, which is now welded to the nut.
If the original weld to the stud was too weak, it removes itself and you start again.

When welding in the engine bay (e.g. for recovering broken studs) make sure airways are blocked up with a rag (preferably a clean rag that won't catch fire with welding spatter).


* Have recovered broken studs on bodywork and engine blocks / heads and NEVER had to drill out.

[whyperion]

thanks, in the end engineering shop did it for me, the head was off an MG of some description, but we then had problems with the engine starting , which other restorer reckoned was a valve / seat problem, so they changed the head. So it cost me to sort out something that didn't work on something that didn't work, ooh well only 3 heads left to work my way through in 2016.

[bmcecosse]

Why would it not start? There's an awful lot of nonsense comes from some of the so called 'restorers' .... Had the valves been correctly ground in and valve gaps set? I hope you kept hold of the cylinder head - is it a 940 head which was attempted to be fitted to a small bore engine??

[whyperion]

They didn't pass the head back to me, annoyingly (I might get it back later), I had done no work on it , originally being fitted with block by Castleford minors some years ago, I must have driven the car back to London but did not use it that much due to the clutch problem, which I why I expected the engine to work with no work to do on it though would have expected to get the timing and fuel set correctly, we got it firing a bit , but with difficulty and not running. I'm not going to worry as such but I don't like being defeated by things mechanical, and I want to know a clear reason why something is missing or not correct when it was functioning at a much longer time before !

[les]

I think I would have taken the head back with me, even if I had to ask for it!

[bmcecosse]

Absolutely - sounds like a load of guff to me - get the head back. And I suggest avoid the place in the future......