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R-2 - Dealing with slow oil leak between block and right cylinder head at rear about 4" from rear of head just above valley cover. Leaking at head gasket.

Same but slow coolant leak on left side at head gasket just below last exhaust outlet, very slow drip on starter.

Head bolt torque checked and good.. Engine rebuilt 2017, runs strong, cylinders within 7 pounds and no signs of water in oil or exhaust in coolant.

So I am thinking head gasket external seal issues. I see no cracks.

 

What do you all think, before I pull the heads and replace the gaskets.

 

Thanks, J

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Were the heads and block trued the last time it was apart?  If not do it this time.  Be sure to follow the correct sequence on torquing the heads when you install new gaskets.  

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16 hours ago, Ntenna said:

R-2 - Dealing with slow oil leak between block and right cylinder head at rear about 4" from rear of head just above valley cover. Leaking at head gasket.

Same but slow coolant leak on left side at head gasket just below last exhaust outlet, very slow drip on starter.

Head bolt torque checked and good.. Engine rebuilt 2017, runs strong, cylinders within 7 pounds and no signs of water in oil or exhaust in coolant.

So I am thinking head gasket external seal issues. I see no cracks.

 

What do you all think, before I pull the heads and replace the gaskets.

 

Thanks, J

If there's no evidence of cross-contamination, and the engine is showing equal cylinder pressures, I think it's a shame to tear it apart to address those minor leaks.

I think I'd drain down the cooling system a bit, super-clean the suspect areas, and give a good epoxy sealer a try.

If you do decide to pull the heads, and find the rebuilder used the thin 'shim type' head gaskets, give the thicker 'composite' head gaskets a try with a light coat of red Permatex on each side....these are all I ever use,...and are quite 'forgiving' to surface irregularities!....good luck....Ed:)

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Thanks Ed. That's what I used 17 years ago on our '57 Hawk building an R2 Avanti clone engine (actually a '63 Lark Daytona block, late model Paxton 6-7 pounds, AFB, cast headers). It has been dry all these years and 25,000-some miles. Looking at the gaps from the side, I'm very sure they used the thin head gaskets on this Avanti. Not my rebuild; we've all been there. Like you, I hate to pull it down, but I'm not too keen on coolant block sealer, either. The drip from the coolant leak is about once every 30 seconds cold, about every 10 seconds hot. This block was hot-tanked in 2017; I have the previous owner's invoices. If you were thinking external epoxy, that might work if it survived the exhaust manifold heat. Be interesting to know of any experiences with Barrs-leak and the like, but......

The top-side oil leak between the cylinder head and block at the rear right cylinder hits the bottom of the bell-housing after a 30-minute run. That's possibly the feed gallery to the lifters?

With good records and good numbers and no noises, I suspect it was a good shop with limited knowledge on the finer points of building Stude blown 289's.

 

Sigh

J

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Here at the shop I use ACDelco 10-108 Cooling System Sealing Tabs. GM called for them any time you opened a Cadillac cooling system. You can get them at any GM or AC Delco dealer. I haven't seen any problems with them and have been using them for 20-30 years.

https://www.amazon.com/ACDelco-10-108/dp/B0026JK8C8

Good luck,

Jim Wood

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