Does anyone have any secrets to pulling engine studs?

You need heat, lots of it. a MAPP gas torch, heat the area at the base of the cylinder until it is very very hot before the loctite lets go. That is how it works on a Porsche aluminum case.

 

Heat and a good stud puller with a nice long bar to gently apply pressure whilst heating it. You will feel as it starts to give.

 

Not even close.

MAPP gas at least or an acetylene torch used carefully. You probably need about 300 degrees to soften the loctite.

 

MAPP gas for about 5 minutes. Or, an Oxy Acetylene Torch if you have one of those monsters.

 

Soaking in the ATF / Acetone mixture often works well.

Good heating works well, too.

If your goal is to "melt" the Loctite, apply the heat to the stud down near where it enters the case --- it will be more effective.
If your goal is to expand / loosen the fit between the stud and the case, apply the heat to the case as described.

Whichever you choose, do not do both --- heat & ATF / Acetone --- at the same time. The reason should be obvious .

 

This suggestion might not work with aluminum block and loctite. I had some frozen pipe plugs in a cast Iron block. Heated the plug cherry red and put wax to it. The wax sucked in and the plugs backed out. Nothing else worked as well. But I think heating the aluminum to break the loctite is the way to go in this case.

 

Heat, but have an infrared temp gun to monitor temps. Go no hotter then 500 degrees. If it doesn't move by then, it's machine shop time.

 

Not sure if this will work with your situation, but...

On iron Chevy heads with stud broken off, I have used an "easy out".

Screw Extractor 10Pc Easy Out (Left Handed) - Threading Tap Extractors - Amazon.com

This is a left handed drill bit.

Once it bites into the metal, the teeth on the drill bit drive into the stud and begin turning the bolt out...lefty loosey.

Used several times successfully

Go slow.

 

Been there done that a bunch. Heat wrench. Oxy/Acetylene. Not sure I'd go to 500 but 350 degrees or so for sure all around the base of the stud. Grab the stud near the bottom and progressively add force. If they really wont come out or they break off I have a machine shop that are magicians at getting them out.

If it comes to that get in touch.

 

The EZ method:

[ame]http://www.youtube.com/watch?v=8qYKMtb3Jpo[/ame]

Matt

 

broken cylinder stud repair

 

Kev,

I have used this method of stub removal many, many times on mis-set aircraft rivets, but also on many steel bolts and studs, most recently on a screw-in-a-spinning-Rivnut that holds the cowl cover (around the pollen filter) to the body of my 430. It takes a steady hand but definitely works. I will paraphrase the instructions for a 10mm-1.5 thread.

1. Cut the stud flat and close-to-flush with the top of the block. This can be done with an irregular surface, but a flat surface makes it better.

2. Center punch the stud as close to the centerline of the stud as you can get with your eyeball.

3. Start out with a (standard) drill bit that is considerably smaller than the minor diameter of the stud thread, say 4mm for our example. Use new, best-quality bits (buy several of each size). Use lots of oil, especially if the stud is fairly hard. Be careful with the smaller-sized bits: you don’t want to snap a bit off in the stud, compounding your problem. Use a good-quality hand drill motor. Make a dimple out of the center punch mark. Carefully look at the dimple and judge how far off-center it is in the stud, and in what direction. If it is off-center at, say, 6 o’clock, tilt the drill motor towards you (6 o’clock) and “steer” the center of the hole towards the center line of the stud. Once the hole is about centered, bring the drill motor to the center line of the stud and drill through the stub lodged in the block.

4. Go to the next bit in your series, in our example it would be a 5mm bit. Look at your just-drilled hole: is it centered or off? If it is still off-center, again, steer the bit in the direction you wish to go by tilting the drill motor in the opposite direction. The more off-center, the more you will have to tilt the drill motor. Also, the smaller the hole (especially the first drilling), the easier it will be steer, so make the big corrections early in the process.

5. Go up in drill bit size a little bit at a time: for our example it would be no more than 1mm at a time, maybe in just 0.5mm steps. Keep steering the bit to get your hole on-center. Ream the hole all the way to the bottom.

6. Now, where to stop? Ideally, you want to stop right at the minimum minor diameter of the thread (the inside diameter of a theoretical nut). This would be 8.376mm for the 10mm-1.5 example. But the last drill size also would depend on if your hole was still much off-center. Also, in actual practice, the last bit need not be quite 8.376. Probably 8.3mm would be the absolute max you would want to use and 8mm flat (5/16" = 0.3125, very close to 8mm = 0.314") would likely work just fine. For our example, 8.3mm is the largest bit commercially available without going too big, anyway. So, if your 7mm hole is nicely on-center, chuck up an 8mm bit and fire for effect. It is highly likely that, given the now-thinness of the stud “wall”, the heat of the process and all the vibration, the remaining stud material just may loosen at this point (or even with smaller bits, sometimes). This is precisely what happened to the threadlockered screw-in-the-rivnut in my 430 cowl cover.

7. Once the maximum hole size has been reached or the remaining stud material has loosened, the upper end of the helix embedded into the block threads can be pried out and pulled out by grasping with a pair of needle nosed pliers and moving in a circular motion while pulling away from the block.

8. Chase the block threads (properly done with a chasing tap, not a cutting tap). Clean with solvent, Q-tips and compressed air.

Notes: Be very careful with the smaller bits; lighten the force on the bit rather than snap it off. If the bit feels spongy, quit and go to a bigger bit. Always strive to center the bit. Don’t go to a bigger bit if you are at the minor diameter on one side: go ahead and try to pull the helix out.
If you have to replace the threads, I suggest you do it with a Timesert not a Helicoil. Timeserts are much stronger and reliable.

Tom
2007 F430F1 Coupé (Izzy)

 

The one shop I used had a giant oven, we'd put the block in and heat the lump up to ~375F then using pressurized nitrogen i.e. freeze off on the studs in 80% of the time they'd come out. for the other 20% off to the plasma removal guys, not cheap but guaranteed! course this is Ferrari specific as the coolant passages leak into the studs.

 

If not wanting to melt the aluminum with heat gat a Markal thermomelt stick. Turns colors when at certain temps.

Also the best stud pullers I have used look like a socket and have 3 rollers inside to act as a one way cam. They do minimal damage to threads and the rod for that matter and are quite strong. I.e. No teeth marks. 15 years ago off the tool truck they were pricey. I assume they are cheaper these days.

Good luck....

 

Does the bike still have the original valve guides also? Prolly quite ovally inside if so.

 

The 300 SLR straight 8 engines had desmodromic valve actuation. Did not know Ducatis had it, too.

 

Probably more Duc's with desmo motors than all other users of the design put together.

 

Yup.

Kev, please do try the two nut solution before you attack it with heat. Heat warps stuff, especially hardened steel studs in aluminum castings.

Matt

 

He's got broken studs, nothing for the nuts to hang on to.