Tough problem with coolant leak need advice
 

I have a 2004 Toyota Camry LE 4 cylinder. There's a hole in my water pump leaking coolant like a faucet set on low. Normally I'd just pay to have it replaced but the mechanic suspects a cracked head gasket too. I don't want to pay 350 to repair a doomed engine but the mechanic can't 100% diagnose it without pressurizing the system which he can't do with the hole in the water pump.

is there any product I can apply to the exterior surface of the water pump to seal the leak long enough to do the head gasket test? And if so which would you recommend? I'm just hoping to figure out if it's worth replacing the pump or not.

thank you in advance.

Do a search on underwater epoxy which is supposed to be able to set underwater.

Or drain the coolant system and blow out the water pump hole with air and dry. Then pack hole with a paste epoxy glue.

The mechanic can also do a "block test" to check for exhaust gases in the coolant. A blown head gasket or cracked head typically results in engine exhaust gas being forced into the coolant system.

Check if your oil is milky. Mine went on a previous car and oil was milky from antifreeze.