Which Way To Tackle Broken Exhaust Manifold Stud?

[brian j 31]

Searching for the exhaust blow I find that some previous "Mechanic" has sheared off the lower stud on one of the outer ports.

 

I have removed the manifold and it was blowing badly the port with only one stud, so I don't want to re-fit it without fixing the problem. I'd rather not bodge it either.

 

I have searched on the forums and there seem to be three approaches to fixing it:

 

1. Use an angle drill and drill it in situ, then use an easy out. - Advantages: quickest, cheapest. Disadvantage: I would imagine it wouldn't be easy to drill the stud accurately so possibly I could wreck the head.

 

2. Take the head off and mount it up in a pillar drill, drill it, then use easy out. Advntage: Easier to drill it out accurately, gives opportunity to re-lap the valves etc. Disadvantage: More expensive (New HG, bolts, Cambelt, etc), need to get head skimmed before re-fitting?

 

3. Some suggest that removing the engine complete for access is easier than removing the head. Advntage: Don't need to remove head so no new parts required (the cambelt is 12months/5k miles old) Disadvantage: Need to hire engine crane. Feels like more work to me.

 

I am leaning toward no.2 but just wanted to ask opinions before going ahead because I've never taken the head off an engine before. If it helps, the car is a keeper and is staying 8v. It currently has just under 100k miles on it and I don't believe it has ever had any major engine work before.

[aCe 0]

Hello mate, this is an awkward one, but IMHO i think it would be cheaper to get a thread doctor. I mean they charge like £60 but they will do it in situ 9 times out of 10.

 

Alteratively if you do fancy giving a go:

 

Centre punch the reamaining stud

Use a very sharp drill bit on a slow rpm

use an "easy out" bit to extract the remaining

most importantly take your time

 

if you find it does go off the centre line a little don't wory it can be rectified, once all out and clean use a helicoil to retap if there is no threads, or if there is some thread use a tap and die to clean and cut it!

 

Hope that helps

[Rom 0]

Have you tried using a pin punch and hammer to tap it round to see if it will undo ? Ive ben lucky many times. Always worth a go before the next step.

 

As suggested, try calling out a specialist. Its not free like doing it yourself. But they do it for a living. And will be less time. No guarentee they will be able to do it, but surely worth a try before you take the head off / engine out.

 

Personally, if i had to do head or engine, id go engine. As less work in the long run. Engine and box come out as one.

[Rock Lobster 28]

I had this happen with an exhaust manifold stud like yours, i whipped the head off and took it down to a local machine shop and had them drill it and use easy outs. I forget exactly how much they charged but it was no more than £10 for it.

 

If you're not 100% confident like i wasn't then i think this is the safest option, just involves a bit of work on your part!

 

If worst comes to worst is there and option for fitting a heli coil in its place?

[Alfie 6]

I've never had an awful lot of luck with easyouts. Had a head stud break once, flush with the block face. Centre popped and drilled out ok, the easyout snapped and that was after I'd got the stud moving back and forth, I did have a bit of luck, I was able to remove it with mole grips,stud and all. Don't think you can drill out easyouts? so beware!

[shalmaneser 26]

I'd probably take the head off - never taken an engine out but it sounds like effort. All you'd need was a new head gasket and bolts, re-using the cambelt is fine.

 

Shouldn't need to get it skimmed either.

 

Although if it was me I'd get the head rebuilt/skimmed/etc while it was off...

[brian j 31]

Thanks guys,

 

However I may be thick but I've Googled thread doctors and thread wizards and found lots of posts of people recommending them but no-one offering the service. Has anyone got contact details for someone who does this kind of work?