Helicoil help!

[Matty P]

I need to helicoil a couple of holes where the manifold studs pulled out on my 3S-GTE

I've bought a kit (powercoil) and know what I need to do - just wanted to ask anyone who's done it before if there are any tricks/hints for getting it right.

I'm most concerned about drilling out the old damaged thread. Is there a good way of ensuring that you drill straight and clean?

Also, if anyone can suggest if these coils are suitable for an alloy head - I would assume they are?

Thanks guys - any help much appreciated.

[ira11y]

Yes they are suitable for alloy, in fact Porsche use them on every thread in there engines i believe.

As for clean and straight, make sure you get all of the snapped off/damaged bolt out first, use ezi-outs if necessary. if its in a tight spot in the engine bay then remove that part or pull the whole engine out so you can get a cleaner finish.

Just start off gentle, if your really worried then tape a small level to the drill to keep the angles right.

[YelloRolla]

make sure that you follow the instructions. wind it only in the one direction until the top part of the coil is adequately below the surface (I like to sink them one full thread below). Break the driven bit off and don't root around with them once they are in. Re-fit your studs and enjoy the fact that it is more reliable than the aluminium thread that it replaced (like ira11y said - Porsche use them).

[Ben Wilson]

If you can get your hands on a 90 degree air drill it will probably make it a lot easier. There was no way I could have done the same job on my mr2 without one.

[o_man_ra23]

Using care Ive not had a problem with drilling in the past, if you drill slowly, the drill bit will want to follow the line of the hole anyways. Helicoiling all aluminium threads is a great investment in any performance engine.

Cheers, Owen

[toddw]

As an owner of an old Porsche as well as an AE86 race car(in process of being built) I can tell you that Porsche don't use Helicoils on their threads. If on occassion if they do pull a head stud which is not uncommon on earlier engines a Helicoil can be used but it is not the best option. The ONLY real longlasting repair is a "Timecert" which is similar but instead of just inserting just a thread it inserts a complete insert. They are not cheap but are the best. As Porsche say " there is no substitute".

[Matty P]

Thankfully I was able to get all the studs out without breaking any, so no problems with that. Also there is plenty of room to work, because I have removed the turbo, manifold and radiator - so should be able to get a drill in there OK.

I thought the drill would follow the hole OK, but someone suggested that it might 'bite' into the alloy and be hard to control - I don't want to enlarge the hole unnecessarily.

Any recommendations on a drill to use - powerful / fast / slow etc..

Cheers for the advice guys

[YelloRolla]

you can "knock the lead edges off" the drill. this is basically tipping the outer points so that they wont bite. I just nick them off with a stone and make them flat (no rake). Use WD40 as the lube and run the drill fairly fast. Remember though, you are not drilling the material out, you are only cleaning out the existing threads.

[Matty P]

Well I had mixed success with the helicoils

Attempted to fix two holes. The first one went in perfectly and is now proudly holding a nice new stud.

The second one seemed to go in fine, but when we put the stud in it was a crooked as a trade union president! Managed to get the stud out and the helicoil, but obviously the hole is f*&%ed.

Best option now I suppose is getting an oversized (~12mm) thread cut and a larger stud.? I'll leave it to the professionals this time I think (if I can find one ) Get them to check the other holes at the same time. I think you can get mobile thread repair guys?

Probably should have done that in the first place......

[30psi 4agte]

Put a time cert in it !!! like a heli coil but way better. You wont have to worry about the oversize hole as they need a big hole to start with. get a pro to do it. They are like a pipe with a thread on the out side and one on the inside they have two pins that lock thm in to place.

[Matty P]

Sounds good! If I can get a pro to come out and do it, I would do it in a flash!

[30psi 4agte]

IN adelaide there is a guy called Captain thread who does it. Check phone book under thread repair for a local repair guy

[Matty P]

The guy in Canberra is called 'Capital Thread Repairs". Did a very good job and was much cheaper than I expected.

If I had known about him, I wouldn't have bothered trying to helicoil it myself

[30psi 4agte]

How did he fix it? did he use one of them thread serts?

[Matty P]

Used the thread inserts on the ones I (unsuccessfully) tried to helicoil and just helicoiled one other hole that was stuffed.

Needed to use the inserts because the holes were too big to helicoil the ones I stuffed up.