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Can ARP Head studs cause an oil leak???
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Author:  SV162 [ Thu Dec 09, 2010 5:38 pm ]
Post subject:  Can ARP Head studs cause an oil leak???
I've recently installed ARP studs and now have an oil leak on the spark plug side at the head gasket line, you know, the usual place. This leak was not there before the studs were installed and 2 head gaskets later I've still got the leak. The second gasket has had sealant used with it which has slowed the leak somewhat.
It's got me stumped, the only thing that's been changed is the head bolts for the studs. Has anyone experienced anything like this before? Any info is greatly appreciated.

Cheers, Jon.
Author:  ceej [ Thu Dec 09, 2010 6:00 pm ]
Post subject: 
Haven't had any problems with mine.

I had the deck and head cut, so I know everything was true before assembly. Been off twice, and no problems so far.

CJ
Author:  Doctor Dodge [ Thu Dec 09, 2010 8:32 pm ]
Post subject: 
Did you inspect the tops of the block's threaded head bolt (stud) holes, to ensure that they have a large counter-sink / chamfer?
Sometimes the edges of the tapped hole(s) get pulled-up and that will prevent good gasket compression & sealing.
Many SL6 engines I assemble have little to no chamfer on many of the bolt holes, especially if the block has been decked.
(this photo is cropped thru the head bolt holes but you can still see some of the counter-sink)

Another thing to check is the threaded thru hole for the alturnator bracket, use a little sealer on that bolt.
DD

Image
Author:  SV162 [ Sat Dec 11, 2010 2:16 am ]
Post subject: 
Thanks Ceej and Doc. The block has been decked so maybe a lack of chamfer could be the problem.
Author:  Pierre [ Sat Dec 11, 2010 3:54 am ]
Post subject: 
Doc, just trying to picture things. The gasket lip on the outside of the lifter galleys seal the head to the block. The head bolts are a good ways back - if the bolt holes have a lip on them will they really distort the sealing lip of the gasket? I imagine this would cause compression problems too if it were that bad.

This could explain the leak I have in the same place though - machine shop chose to shave the block instead of the head since the pistons were so far down the hole.
Author:  Doc [ Mon Dec 13, 2010 10:35 am ]
Post subject: 
Head gaskets have different sealing areas and each has it's own compressed "load" designed into it.

The "fire ring" is the thickest area of the head gasket and takes the most load, to keep cylinder pressure captured.

The other zones are engineered to seal at lighter loads, based on a calculated amount of "crush" expected at the fire ring.

So you can have a situation where the fire ring can be compressed enough to seal but other area(s) do not get the pressure / load needed to effectively seal... the fire ring and pulled-up bolt areas stop the gasket compression before enough load gets out to the edge areas.

If you really want to see how well your head gasket sealing surface is 'working', get some Sensor Products test paper, that material will show you any area(s) not getting the correct amount of gasket compression.
DD
Author:  SV162 [ Wed Dec 15, 2010 4:48 pm ]
Post subject: 
Quote:
Did you inspect the tops of the block's threaded head bolt (stud) holes, to ensure that they have a large counter-sink / chamfer?
Sometimes the edges of the tapped hole(s) get pulled-up and that will prevent good gasket compression & sealing.
Many SL6 engines I assemble have little to no chamfer on many of the bolt holes, especially if the block has been decked.
I've just been thinking about this, do you think the top edges of the threads would get pulled up with the standard head bolts? Or is it the fact that the ARP studs can be torqued more which can lift the thread edge.
Author:  1974duster kev [ Wed Dec 15, 2010 7:36 pm ]
Post subject: 
I had the same leak awhile ago yet i didn't have the arp bolts. It turned out being i warped the head :)

Kev
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