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ARP head studs - oil leak


Go to solution Solved by Cabbage Fumes,

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First I thought that dist. bracket/leg/thingie gasket had given up. So I changed the gasket and the thingie just to be sure. No avail.

 

Last two head bolts, in this case arp head studs, that are not under valve cover. The upper one lh side leaks oil from thread (after the nut) enough to require action. So how do I fix this? 

2002 -73 M2, 2002 -71 forced induction. bnr32 -91

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Posted (edited)

Take some Dirko and after making sure the area where the washer will sit on the head is very clean, smear some Dirko with your fingertip around the stud, pushing a little into the space between the stud and hole. Put the washer over the stud. Take more Dirko and run some into the threads of the stud nut. Torque. Wipe excess with a paper towel for cleanliness points. Wont leak.

 

IMG_0544.JPG

Edited by Cabbage Fumes
Added no leakie photo
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I have found that using the stock BMW head bolt washers works better than the ARP washers.  This is a very common problem with using the ARP studs.  What did you torque the studs to?  The ARP recommended torque is so high it crushes the head around the rocker arm shafts.  It also deforms the aluminum under the washers and that is part of the sealing problem.  

1970 1602 (purchased 12/1974)

1974 2002 Turbo

1988 M5

1986 Euro 325iC

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Just now, Preyupy said:

  It also deforms the aluminum under the washers and that is part of the sealing problem.  

True, but the actual reason for it leaking there is that the OEM bolts are shouldered, ARP are not. That shoulder is needed because there is oil pressure in that head hole and pushes past the ARP stud and up/out through the threads.

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Agree to use a sealant such as gasket maker down in the hole under the washer-NOTE of caution do not get it on the threads above the washer. You may never get the nut off the stud bolt.  

 

 

But what do I know

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As long as it isn't a hardening sealant, any silicone/RTV sealant will allow the nut to be removed relatively easily. That nut usually brings the stud with it when disassembling. It's just a matter of walking it over to the vise to hold the stud while you spin the nut off.

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Quote

 the actual reason for it leaking there is that

there's no seal beyond the 'crush washer' that the aluminum head itself provides.

 

Stock head bolts do this, too, but not up through the threads.

The stock washers are better, I agree.   But sometimes it just leaks no matter what.

With the torque angle angle method, a smear of oil- resistant RTV works well.

 

t

 

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Ok so I shoved tiny o-ring in stud cavity and smeared some Loctite SI 5910 to finish it off. Looks like it's holding.

 

Thank You fellas.

  • Like 1

2002 -73 M2, 2002 -71 forced induction. bnr32 -91

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