I rebuilt the head on my 260z. I drove it 100 miles and burned 2 qts of oil. I parked it and started tearing everything apart. I found a snapped head stud in the middle of the block. I couldn't get the bolt out at all so with 13 others how bad can it be?https://youtu.be/Ib9RJ3x2_Rs

Please whatever help you can give is tremendous because I don't want to redo what I just did and then also take the engine out and the pistons, rods, and bottom out to give the block to a machine shop. There is 1-2qt from the top of the coolant leaking into the oil only. Not the combustion chamber because the exhaust is fine. 

Edited August 20, 20195 yr by youztheclue

The broken bolt will have to come out. If it was recently rebuilt, that bolt shouldn't be rusted or seized into the block and you might get it out with stud extractor, with the block in situ.

 

 

Penetrating oil. Soak it down. Make a flat spot on the end of the stud and center punch it. Drill a small, 1/8" or so hole all the way through it.On second thought if this bolt goes down into the water jacket, don't drill all the way through. If the bolt hole has a bottom, drill all the way through it and fill with penetrating oil. Then use an "easy out" to remove the bolt. Make a bigger hole for the easy out. The really small easy outs can break and they are very hard to remove if you break them.

I can't help but wonder whether this situation would respond better to big heat and big torque.  As in, welding a nut onto the top of the stud and then putting a wrench on it.  IIRC, @grannyknottalked about this in another thread a couple of years ago when the topic was extracting a snapped-off manifold stud out of the cylinder head.  Something about the merits of using an oxyacetylene torch rather than a MIG? 

The difference here is that we have a large-diameter stud (bolt shank) that's seized inside a cast-iron engine block (vs. a small-diameter stud seized inside an aluminum head).  Whereas it's the galvanic action of dissimilar materials that typically creates problems with steel fasteners getting stuck in alloy castings, for a head bolt it's steel-in-iron so I would think that the causes for the locked threads would be simple air (oxygen)-generated corrosion (unless the block has a micro-crack and coolant (water) has leached into the stud threads -- but let's not talk about that).

In my (limited) experience of removing cylinder heads from high-mileage L24's, the head bolts take a lot of torque to break free and some of them really pop when they give way.  Looking at the threads after the bolts came out, they appeared 'sooty' but not really crusty-rusty.  I think that part of the problem with these head bolts getting stuck in the block is that they were installed at the factory without any lubrication so as to get accurate torque readings during tightening.

Having said all that, I will repeat another story that I wrote about previously.  In my area of the world (on the fringes of a 7-million pop. Canadian city), I discovered a contractor who provides the new-car retail industry with specialist services for extracting frozen fasteners from customer cars.  That's all he does.  He told me that there a certain model years for certain higher-end car brands where a key fastener (e.g. suspension mount) is chronically frozen, hard to get at, and often snaps off during attempted removal.   That's where he makes his money.  I hired him to get the snapped-off studs out of my Z's cylinder head (still mounted on the engine, in the car) and it was one of the best $120 I ever spent.  He came to my house, rolled a tool caddy out of his truck, sized things up, and had the job done (without using any heat) in 10 minutes tops.  Cheating?  Maybe.  Depends on your threshold for potentially-painful outcomes.  You might consider looking for a comparable specialist in your area.  The service managers at your local Benz, BMW, Audi and Volvo dealers might be able to help you find one.

I give you pretty much zero chance of success trying to use just 13 of the 14 head bolts. Especially missing one right in the middle. You've simply got to get that bolt stub out.

So you rebuilt the head and then the head bolt snapped when you were putting it back on? Did you know that the bolt had snapped then?

Edited August 20, 20195 yr by Captain Obvious
speling

The bolts only been in there for 100 miles! It should come out easily.

 I'd weld a big nut on it. 

agree with the weld a nut, you have plenty to work with, should be an easy one to weld on to. Easy out may work, but if you screw that up and snap it off it only complicates matters. Plus you really really don't want to f up the block with a drill hole that walks off and messes up the threads. No down side to the weld nut method.

Edited August 20, 20195 yr by Dave WM

6 hours ago, jonbill said:

The bolts only been in there for 100 miles! It should come out easily.

I guess I assumed that he performed the head 'rebuild' work without removing it from the block.  If not, it would indeed be hard to understand how the broken bolt wasn't spotted the first time the head was off.  Of course, there's always the possibility that it was spotted (and ignored) -- or that it was broken during re-assembly (and ignored) -- and that's why the car burned 2 quarts of oil in 100 miles.  For the time being, though. let's give youztheclue the benefit of the doubt and assume that the bolt was broken by someone else.

Okay sorry I need to clear the info up.

3 years ago bought 260z and spent 2 and half year in the garage fixing/correcting/maintenance of the car on a shoe string budget.

I had a cruise for STL Z club it made the cruise 100 miles 2 qts oil used. this is a stark contrast to the ~40 miles its driven since I've owned it.

Parked in garage and pulled everything off the block.

Everything is back together after a couple months, with one thing i know for sure is bad. butttttttttt is it what is causing my oil/coolant mixing?

Here's a little picture story, my z is in the back of the group photo the last day it drove.

Edited August 22, 20195 yr by youztheclue

so you put the head back on without fixing the broken head bolt? IF I understand that then as CO mentioned zero chance of it working right, yes oil/water leaks since clamping force is the only thing that keeps them apart.

That head bolt must be removed, otherwise you are just wasting your time.