2 out of 12 busted

[jhelgesen]

Wow am I in for some fun. Finally got time this weekend to get knee deep into the 3.0 rebuild. Got 2 out of 12 lower studs NOT broken. Most have about 1/4" sticking out. Looks like I'll be taking it into the office and put it in a milling machine to bore out the studs.

Doesn't this look like fun?



Rest of it looks good so far, the cylinders still have honing marks, cylinders aren't too dirty.

(oops, fixed the title)

[724doorE]

Damn, thats a pain... Try all the tricks before you resort to the Bridgeport. Unfortunately dissimalar metals, stress, time, and heat cause galvanic corrosion between the affected parts. Try the old visegrip and torch trick. Good luck, were they steel or dilivar?

[Doug Zielke]

Very bad luck, John.
When you have some luck, the studs break off where you can at least get a grip on them.
Good pictures though.

[ChrisBennet]

John,
What method were you using to remove them when they broke?
-Chris

[jhelgesen]

All the bottom studs were dilivars, tops are steel. Replacing all with new steel (epoxy coated).

Wasn't doing anything at all to pull them out, I just used a magnet to pull the barrel nuts out, studs were already broken (this is a used motor I bought to stuff in the 912-6)

I may make a drill jig I can bolt on the top two studs to keep the alignment on the bottom, then try a screw extractor.

[snowman]

Are you going to use TIme Serts?. IF so you might be able to just drill the old studs out. I found that if you get within 0.020 of the original bolt size the threaded portion almost falls out.

[fallonmi]

John,
I had a couple broken Dilavar head studs on my '82 case. On the studs where there was at least an inch or so left (no threads, so the Snap-on tool was of no use), I used a tool I found at Napa. It is a hardened, one-piece tool, and it was about $10. They sell another 2-piece tool that binds on the stud, but this one is just soft steel, so it didn't hold up. The tool I used is basically a nut with reverse, tapered teeth in it that bind on the stud as you back it out. I pounded the tool onto the broken stud, and then heated the case around the stud, making sure to avoid heating the stud, for 5 or so minutes. Heating partly inside of the cylinder bore helped with this. When I put some force on it, I found I could make sure I was actually removing the stud, instead of just twisting it, if I made a small mark on the stud and one on the case. It actually worked pretty well. I was able to get 10 out of 12 out with it. The other 2 were just too short. Maybe this will help you avoid drilling the case as much as possible.
-Mike

[john walker's workshop]

de-crud the stubs and tig weld nuts to them. cheap nuts just melt, so go get some grade 8 nuts. some folks say that you can't get weld to stick to dilivar, but i've extracted plenty this way. heat the case real well before trying to turn them. oxy/acet is best, but mapp gas may do it.

[jim72911t]

If you've got a milling machine, another trick to use is a left-handed drill that is the same size as the minor diameter of the thread. Centerdrill first (the drill must be exactly on center and square, so a milling machine is a must) then drill out the studs. Most of the time the stud will be weakened enough that it will come out with the drill.

I don't know if you've checked, but most shops charge much more to remove a stud if you've already tried to remove it, and have subsequently broken it, than they would charge to remove and replace the studs themselves. Machine shop time can get EXPENSIVE!

That being said, I've got a full machine shop at my disposal and I'm not going to mess with the studs/timecerts.

Good luck and let us know how it turns out.

Jim

[Tim Walsh]

Aww man john I feel for you.

[jhelgesen]

Busy night.

Got all the 12 steel upper studs out and the 4 dilivar studs that were either not broken, or had something I could get a hold of.

Next on to the 8 nubs waiting to be drilled.

[350HP930]

I am happy to report that when I took my 1987 930 motor apart after 130,000 miles that despite the engine having one broken stud before disassembly that all the studs came out with some heat, a stud removal tool and a pair of vice grips.

With the proper use of heat and a good grip on the remains of a stud I have never had a problem getting an old steel stud out of an aluminum head.

[Wayne 962]

This indeed is a huge pain. JW, you must have a magic welder, as all attempts I made at welding nuts didn't work.

Another trick for getting these out when some portions remain is to use 2 people, a propane torch, and about 4-5 visegrips clamped tightly on the shaft. Believe it or not, this worked for about 5 out of the six that were broken. The sixth? Well, that's the EDM project in 101 Projects...

-Wayne

[john walker's workshop]

TIG is the answer. MIG doesn't melt things enough. then heat the case real good, keeping slight tension on the wrench/ratchet, until you feel it give a bit. keep heating until it turns easy. no cheap nuts! grade 8 steel. dress the end of the break until all the black crust is gone, so the weld will stick. i've had pretty good luck so far, but the real short ones are tough.

[1fastredsc]

I thought my 3.0 gave me *****. At least all 12 dilvar (or whatever it's called) studs stayed intact. Surprisingly the only wierd stud was a steel one that rusted to the barrell nut and threaded out of the case (doesn't look like there was any locktite on it). GL man

[snowman]

Originally posted by Wayne at Pelican Parts
This indeed is a huge pain. JW, you must have a magic welder, as all attempts I made at welding nuts didn't work.

Another trick for getting these out when some portions remain is to use 2 people, a propane torch, and about 4-5 visegrips clamped tightly on the shaft. Believe it or not, this worked for about 5 out of the six that were broken. The sixth? Well, that's the EDM project in 101 Projects...

-Wayne

If there was any loctite on the studs, propane will not produce sufficient heat to break the bond and therefore you will have a very difficult time. Like I mentioned earlier, propane does soften up the loctite a bit, but not much.

The reason I heat the stud, not the case is I am scared to add the ammount of heat needed to break a bond, directly to the case. The case gives no advance indication that it has melted. So instead I heat the end of the bolt/stud until the end, just the end, just turns red. This is SMOKING hot, you should get smoke out of the threaded end of the bolt as the loctite burns off. I have never damaged a case this way, as the heat transfer is down the length of the bolt and outward to the case. The tip of the bolt may be dangerously hot for Aluminum but by the time the heat is dissipated to the joint it is much much less. That would be unless you continue to hold the torch to the bolt after it has just turned red on the tip. Note the tip of the bolt can be even with the case, a little more touchy but again I have done many things similar to the one 911 case, ie 912, 356 cases and others.

If you heat it to this point, you can let it cool before you try to remove the stud, in fact I would recommend it. The stud will typically just thread out, no sweat at all.

I hope the difference between this and the other heating methods is clear here. There may be a better way to recognize when the loctite bond is broken, but I am not familiar with it.

[john walker's workshop]

heating the case is how the pros do it. i've removed hundreds of them and never once heated the stud, and never melted the case either. take a deep breath, fire up the torch and just do it. once you see how easy it is, you won't be afraid anymore. oxy/acet rules.

[brandett]

Ok, if i had a oxy/acet thingy i would have used it. But you are all familiar with the swedish chef....


Head stud removal, the other way...

I wouldnt argue with jw on how to work on a p-car.