Man, I can't believe this new Marine headgasket (stock thickness) was installed a month ago and now I have a coolant leak on the ARP head stud/bolt that is the one all the way back next to #6, the one outside--passanger side. (not under the valve cover) What did we do wrong???


Tom

 

Don't those all get thread-sealer on the block-end threads?

 

Nope no thread locker, just a bit of oil since they are torque to yield.Any chance the head is warped ?

 

Studs are to be locked in the block - the oil is for the nuts and washers on the head-end, to reduce friction during the compression procedure.

Titen 'em nuts down, billy-bob - pull, boy, pull!

 

All I know is that this sucks. The heads were not shaved. It measured better than spec's, so we just went ahead and put the new gasket on it.

 

No indication the threads require sealant, so here's an easy check -

Remove the nut and washer, then install two nuts and lock them together - you can use lock-tite if the stud is stuck - then remove the stud.

Should be no coolant gushing from the hole - pressure up the radiator with a hand pump, still should be no coolant from the hole.

What you're looking for is a leak from the cylinder block water jacket, into the threaded head-bolt hole - which a coat of loc-tite thread sealer on the lower stud threads may fix.

When using studs, they should be loc-tited into the block, such that the twisting of the torquing force results in stretching the stud, and not forcing the stud to turn further into the block.

The stud then imparts linear tension force into the block threads, and not twisting shearing force - much easier to achieve the proper stretch-to-yield torque thru the oiled nut\washer interface if the stud is not also turning in the block threads.

Anyway, check the source of the leak B4 you pull the head - might save you a bunch of time and effort.

 

they are usually chromoly studs WHICH DONT STRETCH, thats basically the whole reason for studs and i have never ever heard of anyone putting lock tite on studs. i have ARP studs and the instrucs say NO NO NO NO NO locktite, just my .2$

 

You dont loc tite them in because you thread them all the way down then back the off a quarter to half turn for expansion purposes. And the stud itself does not move if you hold it in place with an allen then finger tighten the stud down all the way and then torque it. At least all of mine havent moved by doing it this way.

 

Thanks for the input, folks.

Correction, then - always follow the manufacturer's explicit instructions intended to PREVENT TURNING THE STUD while applying compression torque to the nut.

You absolutely do not want the longer-than-stock stud to thread deeper into the hole such that the applied torque cracks the cylinder block.

Minimal damage is a coolant leak around the stud - you can well imagine worst-case damage.

Cylinder head and main cap studs aren't usually of tty type material, as they are designed to include multiple reuse - very practical where the head or other assembly may require removal several times during a motorsport season.

However, some oem studs, required by the mechanical constraints of a designed application, are tty and must be replaced to ensure integrity of the assembly - piston-rod cap studs come to mind.

So - always follow each manufacturer's installation instructions for best results.

The test I suggested is to determine a direct leak from the water jacket, or a head gasket leak.

A simple water-jacket leak may be corrected with thread-sealer - a head-gasket leak can result from insufficient torque on that particular fastener.

 

Some castings in the block leaves the coolant port close to the thread bore. Remove the stud and put some thread sealant on it and reinstall. Sometimes in the utmost extreme cases you have to use a little iron tite block sealant.

 

Ponci- Can that be done w/o pulling the head?

 

Iron tite pours in you cooling system. You can also pull out 1 stud at a time and install sealant on the threads. Make sure you torque the stud before going to the next stud.