I've been having issues with the bolts that mount the waterpump to the block leaking when the system is up to pressure. Not at the gasket surface between the block and pump, but at the head of the bolt.

I've been using Permatex #2 and have also used a pipe thread sealer with the same leaking happening.
I'm not interested in using silicone, but there must be something out there that works.

What do you use??

 

If you are using a lock washer, you could try using a copper washer instead. Split lock washers are useless anyway. imo.

 

If it is not the gasket you probably have cracks in the metal of the block or pump letting water get through.

 

try ''arp thread sealent/lube''

 

Already tried that.....no joy

 

I'll try the copper washers, that seems like a good idea.....and if that doesn't work I'll look for cracks around the bolt holes when I'm doing some work on it this winter

Thanks guys...

 

I can't see what difference the washer is going to make as it is only providing mechanical retention of the bolt. They don't seal anything.
Have you looked at the condition of the threads on the bolt itself?
Perhaps it needs to be replaced OR the block threads are worn.
Sealant only seals so much "wiggle room".

 

A copper washer is soft and will be used as a gasket for the bolt head to seal it to the water pump. They are used all over the 2 stroke detroit diesels because gm used through holes for most all the bolts, one of the reasons they leak so much.