Re: Head studs leaking coolant
 

Tim…Try Aviation PERMATEX, make sure the threads are dry...problem solved. MB.

Re: Head studs leaking coolant
 

I m just wondering why studs instead of bolts on cast heads,bolts seal 99.9 percent of the time

Re: Head studs leaking coolant
 

Engine had studs before I bought it and we replaced them with new ones as part of the freshen process. Block is fairly old (30 years approx) and compression is 13 to 1. I do recall a pile of black silicone type sealer on the old studs and some of the threads were in tender shape so we chose studs in an attempt to preserve block and apply that "more even clamping force" that studs offer. Unfortunately coolant got into the oil and now it no longer turns over smoothly. It is out of the car and partially apart,pushed to the side and my old reliable but tired 468 is back in. Just got tired of wrenching on this 496 and want to go racing before our season is over.I think block could use heli-coil inserts for most if not all the head bolt (stud) locations.

Re: Head studs leaking coolant
 

On a 454 block with a few bad threads in the head bolt holes, has anyone used recoil inserts offered by Fastenal ? Any better method ? Some head bolts spin at 30lbs torque, one is completely stripped. Thanks

Re: Head studs leaking coolant
 

Dave,
The recoil inserts are basically Helicoils. I have used them but prefer Timeserts. The only problem with the Timeserts is that they have a flange at the top and I think there are a couple of bolt holes that put them too close to the gasket sealing point for my likings.
If you get Helicoils make sure to buy some of the longer inserts. Same with the Timeserts. The ones that come in the kits are probably ok for a lot of applications but for head bolts or studs I always get the longer ones. You will probably have to order them from MSC or McMaster Carr

Not sure where you are located but Mechanics Tools and Bits is in Pa and has a nice website. He also has Helicoils and Timeserts

Hope this helps,

Re: Head studs leaking coolant
 

Thanks Bill !!

Re: Head studs leaking coolant
 

If you purchase the Timesert kit, it has an alignment tool and also a counterbore so the flange will sit flush on the deck.

http://www.timesert.com/html/inchsert.html

There is also the Keysert which does not have a flange, however, it requires a special tool to install.

https://www.fastenal.com/products/fa...eyserts%22%7C~

Re: Head studs leaking coolant
 

More great info, Thank You!

Re: Head studs leaking coolant
 

If you do not need to remove the studs to remove the heads, simply install the studs with Loctite 271 Red. They will not leak water.

To do that, clean the bolt holes and the studs to near sterile condition. Have the heads read to bolt on temporarily. Be prepared to fully install the heads and torque them to 25 ft/lb. You do not need to permanently install them, or even use head gaskets.

Quickly put 3-4 drops of Loctite 271 Red on the coarse thread end of each stud and immediately screw it into the block, installing each one in the correct location, without bottoming them out. Quickly install the head, and torque the nuts down to 25 ft/lb. Let them set overnight.

You are now ready to install the heads and finish the engine.

You can use chemical agent or a small amount of heat and a stud removal tool to remove the studs later.

Also, make sure that you are using a good quality bottoming chase tap when you clean the threads, and follow it with a stainless wire brush. Using a cheap tap, and especially a cutting tap, will ruin the bolt hole eventually.

Time-serts are indeed the ideal repair for stripped bolt holes, but properly installed Heli-coils will do the job just fine. I ran one 454 block for close to a decade that had a Heli-coil in every bolt hole on both decks. Last I saw that engine it was still running and making 900HP.

Re: Head studs leaking coolant
 

85 FT LBS on head studs on a OEM block that's alot !!!

Hopefully you block was plate honed with studs torqued that much ?? GM blocks are pretty frail compared to an aftermarket block.

If not a leak down test at TDC and 40 degrees Before or after TDC will not be good.

http://www.chevelles.com/forums/13-p...te-honing.html

Head studs are always a pain to seal and should be lock tightened in

ARP sealed works the best, Never seen Aviation sealer work on head bolts once it gets hot it solidifies.

GM seal tabs work great for leaks P/N 10-108