Threads stripped...suggestions?

[OaklandSpider]

So...after finally figuring out the timing issue which kept her on the sidelines, she seems to be running just fine. The oil leaking from the numbers 1 & 4 bolts on the exhaust manifold were the next task. Oil leaking and burning up on the engine block and beyond...As per the suggestions seen on the board, I got some high temp thread sealant, pasted it on the threads, and sunk them back into place. The leak seemed to get worse. I backed them out again and noticed that I pulled out a large section (if not all) of the heli-coil the PO (I'm guessing) had installed. Now the bolts sink in, but won't grip. I can turn them freely, and they won't seat. So the questions are:
1. Has this happened to anyone else out there?
2. Can I bore out the remaining heli-coil and re-do it? (It didn't really seem to work in the first place, oil leaking and burning up on the engine before...hence the attempt to seal the threads)
3. What is the exact size of the bolts involved?
4. Has anyone used the Time-Sert brand of thread insert? It looks superior to the heli-coil, although I've never used either.
5. Any other suggestions you might have would be helpful.
Thanks in advance,
Peter

[engineerted]

Peter, I have used this type to repair cam box threads http://www.mcmaster.com/#metric-fine-th ... ts/=28omsp
They are a good replacement for pulled out helicoils.

Time-serts cost too much and are harder to find in the right size, McMaser Carr, order today here tomorrow.

Ted

[mbouse]

the boyz in the die shop prefer the thread locking kind. yup! expensive. i have a couple i am getting ready to use for the cam cover bolt threads that are about to give out in the '78

[OaklandSpider]

Ted/Mike...
thanks for the quick replies.
Mike...I'm a bit confused, is yours a vote for the Time-Sert or McMaster variety?
Also, any ideas on the size of the bolt?

[So Cal Mark]

8mm x 1.25

[mbouse]

sorry to confuse. i've not used the time-sert, but it looks better than a heli-coil. McMaster Carr offers several varieties of thread replacement inserts, and deal in volumes that generally are really competative; however the locking thread variety on the page ted suggested are about $11.00 per insert, without buying all the special tools.

expense is a relative thing. i'd go for the one that you think gives you the best one-time application. to me, doing something a second time is more expensive than buying the RIGHT part for the job. as you know, heli-coils have a limited life.

sorry, i dunn have those specs memorized. you'll have to ping someone else for the thread size.

[OaklandSpider]

Mark/Mike...
Thanks for the info...I'm hoping that this will take care of the leak and low oil pressure readings I'm getting.
Any other advice before I make an order?
Peter

[ventura ace]

Peter, try to find out what the OD was for the previous helicoil repair, and make sure that your new repair is a larger diameter. If your new helicoil/timesert/etc. insert is the same diameter as the previous repair, it will likely rip out again. The inner diameter of the insert should be for 8mm studs to match the other studs and to match the mounting hole in your exhaust manifold, though I’m guessing you could go up to the next size and drill the exhaust manifold hole larger if you had to.

It is very important for the pilot hole and insert to be perpendicular to the face of the head. If there is any doubt that you can keep it perpendicular, you may want to consider pulling the head and taking it to a shop, or towing the car to a shop if you trust their ability to make a perpendicular repair with it in the car.

A

[So Cal Mark]

fixing that leak won't help low oil pressure unless the engine is out of oil

[majicwrench]

Just wanted to make sure, are you sure what came out was really part of a helicoil, and not just the aluminum threads?? Have never had a Helicoinl come out if it was put in correctly. If indeed it came out, and the threads that the Helicoil bite into are OK, I would get another Helicoil with the installation kit ( any good parts store has em, cheap) and install a new insert, with threadlocker. An 8X1.25 bolt takes very little torque, be nice to it.
Maybe a picture of what came out with bolt??
Keith

[engineerted]

No need for the $12 ones, those are Stainless steel, get the $2 ones and no need for the install tool all that does push in the locing pin. You can do that yourself will a small hammer when installing in Aluminum.

Ted

[majicwrench]

I'll respectfully disagree with Ted. The tool helps you get the insert in without goofing it up, it does not break off the tab part of the insert. Yes it is possibly to get the insert in without the special tool, yes, it is much easier to do WITH the specail tool. Buy the tool, make life simple.
Keith

[ventura ace]

Back to the original problem of leaking oil around the exhaust manifold studs . . . and a related question:

These studs are anchored to a through-hole in the cylinder head that is open to internal splashing and pooling oil. We normally seal off the studs by a combination of sealant and shouldering the non-threaded stud portion against the cylinder head. If helicoils are used (or other types of threaded inserts), how do we make sure that they don’t leak?? With a helicoil, the stud no longer shoulders up against the cylinder head, but shoulders up on the top of the helicoil. It seems that the oil would tend to leak along the spirol wire of the helicoil. Perhaps the helicoil could be sealed with Teflon paste or other suitable sealant??? I would think that other inserts, like Timecerts, would be easier to seal, since they are solid. Has anybody out there been successful in sealing these particular studs from leaking, when helicoils are used?

Alvon

[majicwrench]

I can't speak for the particular studs in Fiat heads, as all mine are O.E., ( and don't leak) but as for as helicoil inserts, I generally use a locknut product of some sort when I install them, and would not worry bout them leaking. Have no knowledge of other type thread repairs.
Keith

[OaklandSpider]

Wow...okay...I don't feel much closer to answering the question at hand.
majic: I'll look for the piece that came out with the bolt, and post pics if I can find it. It was soft, maleable, and fit perfectly in with the threads of the bolt. At first, it looked liked some sort of gray grease on the thread bolts, and after trying to clean it off, I realized what it was. With a paper towel, I gripped the bolt, spun it, and backed the Heli-coil/aliminum threading right off the bolt. It came off in one perfect piece. Same with the #4 bolt...Did putting the thread sealant on bust the coil?????
socal: Why wouldn't this help with the low oil pressure problem? The leak was minor before...much worse now, with more smoke, and the oil pressure light was never giving me such a low reading before. Nothing else was touched on the car aside from the #1 & 4 bolts and the ignition system...Am I wrong to assume that a visibly larger oil leak will not affect oil pressure?
How about if we do it this way:
I'll put it to a vote:
Heli-coil
or
Time-sert
or
A yet to be named third party
Again, any and all comments/experiences welcome...
Peter