Stripped thread in the head.

[sergei]

I'm in process of installing CT20b on my ST165, One of problems is that the thread in the head for exhaust manifold stud is completely stripped, you can actually pull the stud out with the fingers (that explains my chronic exhaust leak in that area).
Question is: what is the proper way of fixing that (without taking the head off and filling the hole with new alloy)?


Thank You.

[Lloyd]

Drill and helicoil it would be the easiest way. Good thing with that engine is that you can get a drill in because that face of the head is facing upwards

[evil_si]

yup as hrt has said HELICOIL.

basically you drill out the hole, retap it and screw in a 'helicoil'
the inside of the helicoil now becomes the threaded bolt hole

kits are available but not cheap, best to go see an engineering shop or engine reconditioner and see if they can help

[sergei]

Allright, so it is ok to helicoil exhaust stud, as some time ago fivebob was saying other wise (I think Akane had same problem as me), I cannot find old thread, but from memory it was hijacked and got nowhere....

[Dell'Orto]

Nah helicoils if done right, are easily as strong as the original thread.
When I put my CT20B on, a couple of studs stripped as I took them out. Got a old fulla from an engine reconditioners to come round one afternoon as a perky to do them, cost me $30.
I think the issue with Akane's ones was the fact he was going to a massive oversize?

[fivebob]

Allright, so it is ok to helicoil exhaust stud, as some time ago fivebob was saying other wise (I think Akane had same problem as me), I cannot find old thread, but from memory it was hijacked and got nowhere....

Was it this thread.

Anyway, I've never said that helicoils were no good for exhaust studs, quite the opposite, in fact I recommend them

[Lloyd]

Helicoil should be as strong, if not stronger, than the original thread. The kits are expensive as I needed one for my 4AGZE when the exhaust manifold was off. Most of the cost is in the tap as it can be an odd size thread made specifically to suit the coil you're putting in. Good thing is if you can find someone with a kit, the coils themselves aren't all that expensive. To give an idea, the one for the 4AGZE was about $100 for a kit with about 8 or so coils.

[sergei]

Oh, I got confused... allrite, tommorow I will go to an engineering suplier and see what they have...

[Akane]

I got the proper drill bit and the proper tap for the hecoil (recoil).

I did 2 holes in 1 go, one of them wasin't that great (sticking out like a mm or so coz i didn't dig deep enough), but there's always a 1st time.

[sergei]

Can I borrow it? Do you still live at same place?

[Akane]

I guess you could, and wtf stop stalking me!

It's only good for that brand / size of recoil (or eqvil.)

I went to hirequip to get the big fk-off angle drill (I did all this with the engine in car). There's no other drill who has a 12.8mm chuck

pm me if needed.

[sergei]

I had no patience so I have bought a recoil kit ($$$), also it is gt4, i have no problems with space for drilling grinding stuff..'
It actually worked, I was puzzled at first which way to insert helicoil, but then figured out.
now what left is to grind the factory oil cooler supply bolt so it will clear waste gate actuator...