Broken Head stud.....

[Geronimo]

So while in the shop getting the most expensive 915 on earth.... they found a broken head stud (while doing the valves).

Easiest route to fixing this endless bane of my life? #INOWHATEPORSCHE

[Flat6pac]

Mmmm, that’s what happens when you buy outside of factory warranty...
Bruce

[boyt911sc]

Geronimo,

To replace your broken head stud/s, you will have to do a top end engine disassembly. The cam tower/cylinder head, cylinder/piston have to be removed to gain access to the 12 lower cylinder head studs. While you are there, you might as well have the cylinder heads checked. How many miles do you have on the car? To replace the broken cylinder head stud/s the shop will probably charged you at least $10K.

So this is the car you bought @ BaT? What some people don’t realize is that buying a used car specially thru BaT involves a lot of risk. Unless you are a very experience buyer, you are not saving going this route. Too many variables. This is a good example.

Tony

[Geronimo]

Yea Tony, I will admit it was an emotional buy. Now I am on the other side of the emotional ride LOL.

I had planned to do a complete rebuild at some point in the next couple years, because I wanted to learn how to and to set the engine up the way I wanted. So maybe it will be sooner now. :|

[Trackrash]

Here is your homework.

[Geronimo]

Cool, I have 3 out of the 4

[Walt Fricke]

I was able to replace an exhaust side head stud - the rear #1 as I recall - without much disassembly of the engine, though I had it out and on the stand.

The hardest part was removing the air diverter tin, which called for removing the vertical rear tin so I had access to the clips holding the tin in - and reinstalling the clip.

There was enough room for me to cut the stud near the case, leaving as much of a stub as I could. I found a piece of thin steel or stainless tubing which was a nice fit over the stud stub's OD. I welded a rod inside the piece of tubing, welded something for a wrench on the other end of the rod, inserted things through the stud hole after pulling the broken part out so the tube end slipped over the stub of stud, and welded that end of the tube to the stub. Then I backed the broken piece out. Piece of cake after that.

I'm only a goober welder with a cheap low power MIG, so my welds to the stub were too fat to pass through the holes in the cylinder and head. So I went through the usual grinding, overgrinding, rewelding, etc. This ground a bit on the case, but no harm there. The tubing I used wasn't optimum, so it twisted like a swizzler before I had the stub out - but I got it out so I could put the engine back in the car and go to a race in Texas.

Better materials and a better welder (in both senses) could avoid some of my problems. And I had some access to two sides, so to speak, of the stud down there. Studs not on ends would only have one side available. Engine tin removal might call for pulling oil return tubes? A top stud would probably require removal of the intake and engine cover, though that would still be a lot less work than pulling a cylinder if it were possible there.

Don't see why you'd have to pull the affected piston, though.

Another possibility would be to cut the offending stud stub off (with some sticking out). You might be able to weld a nut on it so you could break it loose. When finger tight, you could cut the nut off and use vice grips to turn the rest out. Or you could do the same first cut, and see if you could cut a screwdriver slot into the stub, and use a really long (maybe fabricated)screwdriver to back things out.

Again, I didn't put my mind to dealing with other than a lower outer corner stud. But like the prospect of a hanging, things can concentrate the mind.

But first pull the engine and get it on the stand - you have to do that no matter what (unless willing to run the car with a broken stud).

[Flat6pac]

Walt, with the cylinders through 2.7 the studs are visible On the 3.0 the studs are completely inside the cylinder finning and not visible.
The motor has to come apart and have the cylinder off.
Bruce

[Walt Fricke]

Bruce - I did this on a 3.0 stock 1982 motor. Where the studs were visible was between the case and the first fins. Necessity is the mother of invention.

And the broken stud was perhaps the only, or one of two or one of 4, where this could work.

Certainly an upper stud would have more work involved, and I don't know about studs not on the ends.

[boyt911sc]

An old friend of mine had a broken head studs while racing in VA more than 20 years ago. He brought his car to a local Porsche shop and was able to replace the stud with the motor installed. It took me a while to believe and understand that it was doable.

With the motor out, an emergency replacement of the stud could be done as Walt mentioned. But this method takes a lot of effort specially if the stud refused to come off easily. My friend was at the shop and it took about 4 hours to replace one (1) stud with another Dilavar. He then drove car back to Philadelphia. Had he known that he could drive the car with a single broken stud back home he would have done so.

With today’s knowledge and understanding how to replace these unwanted Dilavar head studs, engine drop and a partial engine tear down is done. I could remove the 12 Dilavar head studs today in less than an hour work compared to a day when I did my first engine tear down in the 90’s.

Tony

[Bigtoe32067]

Do it yourself and save a bundle. It's not hard even for your first time. Follow Wayne's book and if you get to a questionable part then post your dilemma on here and I'd bet you have an answer within an hour or two.
Send the heads out while they're off and for the price of the machine work and about $1500-$2000 you'll have a top end job done and the satisfaction of knowing that you did it yourself.

I'd also bet that any tool you'd need but dont have could be borrowed. Heck, I'll loan you whatever I have that you wind up needing as long as I'm not using them at the moment.

Good luck
Tony