leaking cylinder head exhaust studs

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2nd chance

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i have a stock 906 cylinder head that the exhaust studs broke in the head,drilled out the stud and installed a heilcoil and a new studs,and coolant is leaking from the stud,any idea how i can stop this leak?
 
did you put thread sealer on the threads of studs......may not fix because of it leaking past the helicoil... I would try that first use liquid pipe thread/sealer and use a fair amount.....May have to retapp threads to a bigger size and then use thread sealer..
 
The end studs go into the water jacket on small block heads so I would say tap the hole out to the next size up and use a bigger stud. You may have to drill the hole in the exhaust manifold or header one size bigger as well but it will stop the leak.

Helicoils suck!
 
This can be a problem. You need thread sealer on both the ehlicoil and the stud. I have also used a step stud and drilled/tapped the hole in the head one size bigger. All big block exhaust studs go through to the water jacket.
 
Jim Lusk said:
This can be a problem. You need thread sealer on both the ehlicoil and the stud.
Click to expand...

Agreed, sealant must be used on both the heli-coil and the stud to truly stop any leaks.

There is one other option with the engine in the car and that is to completely drain the block of coolant and remove the offending stud. Use Permatex high heat resistant sealant and apply it in the heli-coiled hole. Keep in mind that if it's wet with coolant, it'll never seal. Then apply some sealer to the stud, screw it in tight and let it sit for for 24 hours and re-assemble.

If this doesn't work nothing will, short of pulling the head and drilling the offending hole out for a larger stud.
 
thanks for the reply...will try to reseal helicoil and also reseal the exhaust stub. also was told about using pipe thread sealer to possibly help this problem. hope it does tried 2-3 different types of sealant with no luck...will let you know how I make out.
 
Permatax liquid teflon tread sealant in the squeeze tube works best, if that won't seal it you may need to remove the heli-coil and go with a larger size stud.
 
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