Broken head stud, need help...

[mcandmar]

I'm halfway through my 5-1 exhaust manifold conversion on my CQ20V and found a head stud already broken. It has snapped about 3mm inside the head on the 5th cyl (top most stud). Has anybody got any advice as to how to get it out? I'm going shopping in the morning to see can i find any tools for the job but any BTDT's would be great.

Mark.


Two other points of possible interest,

The head already has three threaded bores on each cyl not two like a 7A should have

The stud that snapped was already cracked; the break was black and sooty not clean metal so it’s given way a long time ago.

I pulled a stud from my spare ABY head to find the same stud snapped instantly and was black and sooty also. On closer inspection the gasket was actually leaking as a result. ....bit a trend forming here...

I also noticed the ABY manifold also has a large crack after the 5th cyl where the pipe bends. May have been a result of the above though.

[audiman]

Thats right, the end cyls do pull away from the head and make the gasket blow and break the studs off. BTDT. The easiest way to do it is to remove the head. I did it by using a 90 deg. drill and drilled the centre of the broken stud and used an 'easy-out'. This took a while but worked fine. About 2 months after that the head gasket failed so it was a waste of time.

[martinjs]

I asked the same question about 6 months ago, its worth trying toms way, i did, but gave up and had to take the head off.

martin

[Greg_S]

On mine I had a stud snap and it had about 5mm protruding still which was unusual and we managed to get it off with a pair of locking adjustable pliers.

Greg

[audiman]

It does take some time and you MUST get the drill square and central or you may drill into the head itself. The stud itself wasnt that tight in the head, just broken off below the surface.

[mcandmar]

Day Two update,

This morning i found a stub extractor (reverse thread type). I managed to drill a centre hole in then broken stud using a flexable lead on a drill, the extractor tool worked in very nicely, got very stiff, and then snapped in the head

So, it just gets better, i'm going to take the head off and give it to a machine shop to sort out. There confident they can drill it out and clean up the bore in the head. Fingers crossed :-)

I didnt relise the head studs were a torx design so i have to go buy a socket in the morning, anybody know what size they are?

Thanks.

Mark.

P.S. Can i re-use the head bolts or do they have to be replaced?

I'm halfway through my 5-1 exhaust manifold conversion on my CQ20V and found a head stud already broken. It has snapped about 3mm inside the head on the 5th cyl (top most stud). Has anybody got any advice as to how to get it out? I'm going shopping in the morning to see can i find any tools for the job but any BTDT's would be great.

Mark.


Two other points of possible interest,

The head already has three threaded bores on each cyl not two like a 7A should have

The stud that snapped was already cracked; the break was black and sooty not clean metal so it’s given way a long time ago.

I pulled a stud from my spare ABY head to find the same stud snapped instantly and was black and sooty also. On closer inspection the gasket was actually leaking as a result. ....bit a trend forming here...

I also noticed the ABY manifold also has a large crack after the 5th cyl where the pipe bends. May have been a result of the above though.

[Martynf]

You have PM mark, I forgot to say the head bolts are one use only stretch bolts. Good luck with this.

[rotoryboy]

Thats right, the end cyls do pull away from the head and make the gasket blow and break the studs off. BTDT.

Mine had just done the same

Anyone know the part number for the exhaust manifold studs? as Audi can't seem to get it right (ABY)

[S2central.net]

This morning i found a stub extractor (reverse thread type). I managed to drill a centre hole in then broken stud using a flexable lead on a drill, the extractor tool worked in very nicely, got very stiff, and then snapped in the head

So, it just gets better, i'm going to take the head off and give it to a machine shop to sort out. There confident they can drill it out and clean up the bore in the head. Fingers crossed :-)

I didnt relise the head studs were a torx design so i have to go buy a socket in the morning, anybody know what size they are?

Thanks.

Mark.

P.S. Can i re-use the head bolts or do they have to be replaced?

I hate those stud extractors - thats what happens just about every time I've ever used them. I think they are manufatured by the same people who operate machine shops to ensure a steady flow of business

Good luck.

The head bolts MUST be replaced - they are a stretch bolt. When getting new ones make sure the head bolts are marked with the same tensile rating or you'll have problems torqueing the head down again.

[BaS2]

A tip, always drill the entire stud + thread out, then helicol, easy. stud extractor's work 1 out of 100, not worth the effort and if they break their high carbon steel, so nearly impossible to drill.

[Jas11n]

Mine had just done the same

Anyone know the part number for the exhaust manifold studs? as Audi can't seem to get it right (ABY)

For the ABY
N 901 889 02, M8 x 35.
16 needed for full replacement

for the ADU
N 906 486 01, M8 x 27
16 needed for full replacement.

thinking on the second set Mark, no more syncronised spanner displays

Jas

[rotoryboy]

Cheers Jas