Broken engine stud... Help please :(

[Zcat7]

Popped the engine out today to try and fix the leaking oil cooler. All was going swimmingly well until I had occasion (while retrieving a dropped washer) to brush against an engine stud and felt it rattle...

So the crux of it is that the lower rearmost stud of number 4 cylinder (l/h bank) has snapped and left the stub in the block - think worst 'place' scenario here. I have never stripped a VW engine to this degree so I'm interested to know:

a) What is the minimum I need to dismantle and what parts would I need to replace (piston rings, pushrod tubes, gaskets etc)
b) Has anyone sucessfully retrieved a broken stud from the engine case before and if so how (I've never had much luck with thread extractors but was thinking of trying to weld a small bolt or something to it if there is enough space?)
c) Is there a sinister reason that has caused the stud to break and could I have further damage to fix?
d) Should I pretend I haven't seen it and just put everything back together...

I'm optimistically hoping for good-news responses but suspect that there will be tears. Please be gentle

Neil

 

[67panel]

GET THE TISSUES OUT best one is weld a bolt to it might undo better when hot.

 

[jonboylaw]

I had several snap (exhaust studs, this is) when trying to undo the nuts.
My solution was to centre punch the remnants of the stud then progressively hand drill (with a cordless drill) the stud until I could get a tap in, then very carefully tap the heads.
You will find that they were originally taper cut so I used some thread lock to lock the new studs in. Worked a treat.

 

[Zcat7]

Thanks Jonboylaw, that sounds good.

Just spent the time since my first post clearing crap in the garage to make space for this job. Off to CoolAir tomorrow to get some parts I guess. Looking at the remaining stud, its very deep so I suspect that welding is out.

Parts wise I guess I'm looking at:

Head gasket
Cylinder=block seal
4x pushrod tubes
New stud/nut

"Specialist" tools:
Ring compressor that comes apart (though I may have one of these)
Tap (stud thread size anyone?)


Do any of the experienced engine guys out there think I should look for collateral damage? In fairness the engine was running sweet as a nut (apart from the oil leak) so I'm still hoping for the best!

Wish me luck...

 

[Zcat7]

OK so its stripped down a bit: cylinder head off and the offending barrell. Its looking like a drill and tap job but I'm worried about the swarf and the depth to go with the drill bit... Will I just burst into the case and deposit a load of crap in there? Also, does anyone know how the metal inserts are held into the aluminium; can they be replaced?

Not feeling much better at the moment...

 

[Zcat7]

Ended up welding a bit of metal to the stud and the case saver and pulled the lot out; bloody tricky as there isn't much space before you're welding it to the piston! Could only buy a complete set of studs so 15 studs to appear on Ebay shortly!

Still, all back together now; fingers crossed I'll get it back in tomorrow and see how it all pans out...

 

[jonboylaw]

Well done that man !

I am guessing they were 8mm studs. My method works fine for the exhaust studs but I would not try it on the cylinder studs.

 

[Zcat7]

Yes they were 8mm in 12mm case savers. I took your lead and threadlocked the new one in. I did try to drill the broken stud but it was having none of it so it was out with the welder.

Thanks for your replies Jon, I needed the moral support! :lol:

 

[Zcat7]

All sorted. The whole thing was a pain but it gave me a chance to tidy up a few issues. Found some strange things had been done during assembly, like the oil deflector plate under the alternator pedestal had been put on sideways (which was undoubtedly contributing to the crankcase pressures I've been experiencing) and loads of washers had been used on the oil cooler to pedestal for no apparent reason (not spacing anything), which makes me worry about how the thing was built in the first place... Anyway, it all seems to be running well and sounds much smoother to boot right through the rev range so I'm happy!