Loctiting Head studs

Trev · Post by **Trev** » Wed Jun 22, 2005 11:22 pm

Does anyone Loctite head studs into the block

The reason im asking is as follows

The strength is obtained by the thread of the head stud making a contact onto the thread in the block.

This actual thread contact patch isnt (in most cases) very much.

I was thinking that using a low strength Loctite on the block side of the head studs could only improve this contact patch as loctite is designed to fill the voids in the thread.

I dont use the stuff and have never had a problem anyway but was just wondering if anyone else out there does.

Trev

Post by **ClassKing** » Thu Jun 23, 2005 1:12 am

I don't recc. it. Proper lube to give the proper co-effiecnt of friction for torquing is needed. You're supposed to have proper thread engagemnt anyway. One of the "tricks", we were taught at Chaffey, (RE: common sense) is to make sure the studs are not tightened into the holes. Run them in til they stop, then back them out a hair so the end of the thread doesn't cock the stud in the hole. A free, straighter alignment will occur by doing this way. When you've achieved proper stretch with normal good contact, I can't see loctight being any advantage.

My .02 cents.

idunno · Post by **idunno** » Thu Jun 23, 2005 8:43 am

If you locktite them they will leak (if the bolt holes go into water). If the bolt holes go into water use a teflon sealer you can brush on and if they do not go into water just put a small amount of 30 wt. oil on them.Like stated earlier do not torque the stud into the block, simply run them in finger tight.

k-star · Post by **k-star** » Thu Jun 23, 2005 9:42 am

Are you by any chance talking about the #592 pst loctite????

Loctite 592 PST locks and seals threaded fittings. Resists leakage, vibration loosening, moisture, hydraulic fluids, and diesel fuels. Lubricates threads for easy assembly and disassembly. Won't shred or wear like teflon tape. Parts may be repositioned up to 24 hours after application. Works to 400 degrees F. Suggested applications: Head bolts into through holes, oil psi sending units and sensors, oil and coolant lines, fuel fittings, rear axle fill plug, brake and power steering fittings.

Keith

Post by **ClassKing** » Thu Jun 23, 2005 12:01 pm

"Can be repositioned after 24 hours? I'm not a chemist but that statement raises a big doubt in my mind. When I use Loctite (generally Red,) I don't want to know it can be loose enough to move later. Now occasionaly I'll use Blue for studs into the valve cover holes that are open to the intake port, knowing that later someone may want to remove them.

Loctite = sealer/fastener - But a lubricant? I don't see it giving the same frictional co-efficient of ARP moly lube.

Trev · Post by **Trev** » Thu Jun 23, 2005 12:45 pm

Guys I think you all may have the reason Im talking about this a bit cocked up. Im not asking to use loctite as a sealer for head bolts or studs that go into water jackets, not talking about super locking it in place.

Im simply asking, does anyone use the loctites such as the 592 series for head studs.

The reason i ask this is if you screw in a head stud with oil on it into a blind hole u do get some movement of the stud as the threads do not make a perfect contact everywhere.

I (from my own interest after attendting a loctite course) tried some loctite on a head stud and the head stud was a much better fit into the head. No it wasnt used as a super locker or a sealer. Just used to see if it did what the Loctite engineers said it would on the course i attented.

If you cut a bolt with a nut screwed onto it down the middle you will clearly see that it really has stuff all contact patches on the nut to the bolt.

You can all do this, then get some cheap loctite and apply it to the same type of nut and bolt and let cure then cut again and its amazing to see that the loctite has filled all those voids. Now the engineers tell me that this will give a greater and much evener load to the stud in the block.

Guys please dont take it the wrong way, Im just looking to see if anyone has ever tried this and if so did they think it worked, because technically it should work extremly well.

If i install studs i have always applied GM sealer if they go into water jackets and ARP lube if they are blind, then unscrew one and a half turns out from bottom then torque the nuts as per reccomendation from ARP.
Even the last installation instructions i recieved in the ARP head stud kist stated they can be loctited in place

Trev

airflowdevelop · Post by **airflowdevelop** » Thu Jun 23, 2005 2:10 pm

yes,,,yes,,,and yes.

I use the 592 when using studs (not too much use anymore, unless the customer is pulling the heads like mad). I run the stud until it bottoms, back it off 1/16 of a turn, and place a mark perpindicular to the direction of the motor, with a red sharpie (if you are using moly lube, red works the best) so I can make sure that the stud does not move when torqueing. You have to make sure that you get up on the stud, and start the stretch process, without catching any burrs or dirt. If not you will bottom the studs out. I let the studs sit with loctite in place for atleast a day prior to installing. ARP also resells this same sealer (can't think of part #).

Thanks
Dennis

airflowdevelop · Post by **airflowdevelop** » Thu Jun 23, 2005 2:12 pm

and the not too much references, was for the studs, not the loctite.

head gasket and bolt technology has come a LONG way in the last few years...

Trev · Post by **Trev** » Fri Jun 24, 2005 4:15 am

Thanks for the reply Dennis

Yes im not real super smart on engines but I do know a little about engineering plus Im always open to ideas and thoughts.

Using the loctite on the studs technically has to provide you with a much greater joining of the stud to the thread.

Cheers Dennis
Trev

OldSStroker · Post by **OldSStroker** » Fri Jun 24, 2005 9:10 am

Trev wrote:Thanks for the reply Dennis

Yes im not real super smart on engines but I do know a little about engineering plus Im always open to ideas and thoughts.

Using the loctite on the studs technically has to provide you with a much greater joining of the stud to the thread.

Cheers Dennis
Trev

Another look at threads:

The installed and torqued stud (or bolt) is trying to pull the threads out of the block. This is resisted by the metal-to-metal contact of the male threads on the stud against the female threads in the hole all in the same direction--the direction of the load. The block and stud metal deforms (elastically, we hope). Unless the threadlocker has the compressive strength of the iron block, which I doubt, it will not carry the load applied by the stud/bolt; it will be squeezed out from the contact area into the voids at the other side of the thread which is not really transmitting any load. The void or space there can be filled by the thread locker.

The product will help lock the thread (keep it from backing out) if this is a problem, which it shouldn't be in a head stud/bolt application, but unless it has the strength of the iron/steel, it isn't going to carry much load.

What am I missing here?

airflowdevelop · Post by **airflowdevelop** » Fri Jun 24, 2005 4:36 pm

The pupose of the sealer is to stop the bolt from bottoming in the block...that is it.

the compressive load of the sealer is not important... that is not it's job.

This also is the recommended method of installation by ARP, and seems to be widely used, although most guys that are doing "full tilt killer" work have gone back to the use of bolts... in this day and age, studs are for valve covers, unless like I said, you are pulling the heads off like mad.

Dennis

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