head studs and coolant leaks

[gofaster]

We used pipe dope on the head bolts on the old Detroit Diesels back in the '70's. That worked!

[Racerrick]

loctite 518 works better than anything I have found. I clean the studs in the hot tank , jet wash them, then brake clean the thread in the block and studs threads. I put the stud block end in dry and torque the head to final torque then pull the studs out 1 at a time, then loctite the thread, reinstall stud & torque in one pull to final torque. then move to the next one. this way they never leak and can be removed easily.

[rfoll]

We used pipe dope on the head bolts on the old Detroit Diesels back in the '70's. That worked!

The problem with many sealants on bolts is the effect on the torque wrench readings.

[roc]

We used pipe dope on the head bolts on the old Detroit Diesels back in the '70's. That worked!

The problem with many sealants on bolts is the effect on the torque wrench readings.

I wouldn't think this to be a problem considering that the nut/stud interface is properly lubricated. Wrong?

[rfoll]

My statement is for bolts only.

[roc]

My statement is for bolts only.

Got it, thanks.

[clshore]

The threaded end of a stud or bolt that goes in the block is identical, the shank is identical, the washers at the top are identical.
Only the end, with either a head or threads and nut are different.
Can someone explain what makes bolts 'magically leak free', but studs are leaky?
Makes no sense to me.

[roc]

The threaded end of a stud or bolt that goes in the block is identical, the shank is identical, the washers at the top are identical.
Only the end, with either a head or threads and nut are different.
Can someone explain what makes bolts 'magically leak free', but studs are leaky?
Makes no sense to me.

I'm all ears to learn this too.

[Dan Timberlake]

I have always used GM Sealer and have never had a problem with leaking. Threads need to be clean as already mentioned. The GM Sealer is now sold under the AC Delco banner. This stuff is made by GM for this exact purpose.

Which GM Sealer do you like?

2008 confusion - but lists 12378521
http://www.enginebuildermag.com/2008/03 ... m-engines/

A current product
http://www.gmpartsdirect.com/oe-gm/12378521

[Tuner]

loctite 518 works better than anything I have found. I clean the studs in the hot tank , jet wash them, then brake clean the thread in the block and studs threads. I put the stud block end in dry and torque the head to final torque then pull the studs out 1 at a time, then loctite the thread, reinstall stud & torque in one pull to final torque. then move to the next one. this way they never leak and can be removed easily.

I agree, Loctite 518 is excellent sealer for this (and many other applications) but why wouldn't you simply install the studs with it on the threads and leave them be? Why the R-n-R and repetitious torquing procedure?

Again, in the assembled and running engine, an ounce or two of Sodium Silicate will prevent leaks. It don't take much, actually, probably less than an ounce. A 1/4 teaspoon of the old "Solder Seal" silver powder stuff would stop a leak in a radiator tube pissing-a-stream the size of a pencil lead while you stand there and watch it do it. I want to know how it finds the hole ....... another on the bucket list of 'I want to know' things.

[MadBill]

.. I want to know how it finds the hole ....... another on the bucket list of 'I want to know' things.

It's like a beaver; finely attuned to the sound of trickling water: To the dam everyone!

[Chris1]

I assemble a lot of GM V6 engines using head studs. The head studs all open in to the cooling jacket. I have good results if I insure all threads are clean and use Loctite thread sealant.

[Zmechanic]

The threaded end of a stud or bolt that goes in the block is identical, the shank is identical, the washers at the top are identical.
Only the end, with either a head or threads and nut are different.
Can someone explain what makes bolts 'magically leak free', but studs are leaky?
Makes no sense to me.

Maybe the twisting and pulling of the threads in the bolt vs just pulling in a stud? Just a WAG..

[pdq67]

I have a quart in my closet.

pdq67

[gofaster]

rfoll wrote:
gofaster wrote:
We used pipe dope on the head bolts on the old Detroit Diesels back in the '70's. That worked!

The problem with many sealants on bolts is the effect on the torque wrench readings.

I wouldn't think this to be a problem considering that the nut/stud interface is properly lubricated. Wrong?

The use of "pipe dope" was called for in the service manual so the torque they specified would have taken that into consideration.

I just put that out there as something that might help the O.P.