Red Loctite?

[nike001]

Since I did my VANOS about 6 months back, I've had a stripped thread for one of the holes that are in the head. Here is a pic of the hole with the stripped threads inside:





Now, my question is.. can I use red loctite and put it on the threads of the stud and then place it in the hole? Ever since my VANOS job, I've put in and lost at least 2 studs. But they would thread in, and at some point while tightening the bolt on the end.. the whole thing would spin.

Terra said red loctite would work, but others that I've talked to said that I need to completely re-tap it and get a bigger stud. I'm iffy on that since the threads are in the HEAD of my engine, and I don't want to ruin that just yet.

[ryankokesh]

I'm no pro, and I know nothing about red loctite. That said, I'm gonna go ahead and posit that you'd need to re-tap that baby. Plus, I don't think it'd be too difficult.

[wsmeyer]

No flavor of Loctite is gong to work if the threads are stripped. I can't quite tell what that stud does from the picture, do you know what the torque spec is for it? If it's not too much you could use a Helicoil, they are available almost anywhere:

http://www.emhart.com/brands/heli-coil

If that happened to someone that was in the middle of nowhere they might smear it with JB Quick and put it back in. Depending on the torque it might not work at all, or it might last forever lol.

William.

[ryankokesh]

cool, never heard of the helicoil...

[nike001]

The stud threads into the head, and then the bolt tightens onto that, and if I copied the right specs.. the torque is 10 Nm (7 Ft-lb), so not much.

I have JB weld, think that would work?

[wsmeyer]

The stud threads into the head, and then the bolt tightens onto that, and if I copied the right specs.. the torque is 10 Nm (7 Ft-lb), so not much.

I have JB weld, think that would work?

7ft lb is not much at all for such a large nut. Or is that the torque for the stud into the head - that would make more sense and there would be another torque spec for the nut on the stud.

A tap can be used to clean out corroded or damaged threads but when you say the hole is stripped leads me to believe the threads are gone and the stud spins in the hole when you try and tighten the nut? If that's the case a tap isn't going to help at all.

Nothing wrong with trying a tap first but most of the taps you'll find at a hardware store are tapered taps. They taper to a point so they are much easier to get in straight when tapping by hand. Studs go into blind threaded holes - blind meaning they aren't open on the backside. Now picture your common tapered tap going down into the hole, when the tip of it hits the bottom it will only have completely threaded about 2/3 of the hole. What you would need is called a blind or bottoming tap, they do not taper at the tip so they will cut threads all the way to the bottom of the hole. The drawback is that without the tapered start they are very difficult to get started straight by hand. The best approach is to use a tapered tap first and then blind tap to finish off the bottom of the hole.

Drilling the hole out and tapping it for a larger stud is an extremely risky option. Studs only come in so many sizes and the next size larger won't just be a tiny bit larger, and the larger hole means thinner wall thickness for the hole. Going back to the different taps; a tapered tap is pretty easy on the material as it takes a good 10 turns to completely cut a thread, but a blind tap cuts the entire thread in 1/2 turn which puts a lot of force on the material and if the wall is too thin it will break out the side. One common way to minimize the risk is by switching from SAE to Metric or vice-versa >> 1/2" = 12.7mm so going from a 1/2" stud to a 14mm stud would only be 1.3mm larger. 12mm stud to 1/2" stud only .7mm larger.

This is also why they make threaded inserts. A threaded insert is just a coil of steel that goes into a threaded hole and then a bolt/stud can be threaded into the inside of that. The difference between the new hole and the old hole is very little, only the thickness of the coil itself. They come in a set with a drill bit that will drill out the stripped hole, a special tap to tap the hole, and an insertion tool used the install the coil. There's a picture and general description on wikipedia here:

http://en.wikipedia.org/wiki/Threaded_insert

William.

[nike001]

7ft lb is not much at all for such a large nut. Or is that the torque for the stud into the head - that would make more sense and there would be another torque spec for the nut on the stud.

I'm not sure that there is a spec listed for that on Beisans DIY. The top & left most stud is the one I'm having problems with:


The VANOS unit then goes over that and looks like this:


Then the nut that (i think) has the tq value of 7ft/lb goes over that and holds the unit on.

[zhp43867]

Are you talking about putting it on the thread to hold the bolt tight with JB Weld? It might work but I'd try to avoid it. I've used red loctite on a suspension component before- try and clean out the thread as best you can with degreaser and a Q tip or it'll have issues bonding. At least that is at some level removable (blow torch).

Have you tried a simple tap and die set? You can rent it at your local autozone.

[nike001]

No I haven't tried tap and die. To be honest, I have absolutely no clue about tapping and all of these different sets. This is something I don't know how to do and I want a 100% change of me not messing this up

[zhp43867]

The tap and die set is a kit, with clearly labeled threads of all different sizes. Based on the nut that screws on to the stud or realoem, you determine the thread pitch. A tap and die is just a really strong screw/nut with areas to capture metal shavings it creates by repairing the original thread. I used it on a seat bolt and it worked quite well.