Volvo 2001 Engine Anode holder thread

[Yara]

You have seen it so many times- a nice clean diesel engine with salt encrustation around the water pump and the engine anode.
The water pump problem I am guessing is caused by the use of paper gaskets which weep the salt water, and maybe soaking in oil or even some kind of polymer might be the fix.

The engine anode holder has to have electrical contact, and relies on being bronze in a tapered thread into a cast iron engine. My one has encrustations on the inner part of the female thread which stops the anode holder from screwing all the way in. Result -slow leak and salt encrustation. I would like to clean out the thread with a tap, but dont know what size to buy. Being a Volvo, I would expect it is metric. Anybody out there know the answer?

 

[scottie]

Could be BSP 3/8 ?
plenty of standard gaskets in use on water pump faces that don’t leak

 

[AntarcticPilot]

It is also possible for water to leak out of the water seal at the back of the pump; in my experience, this is more likely than a leak at the front cover. It's a fairly simple and cheap fix to replace the oil and water seals (they're identical); it tends to need doing every few years; more often if the pump ever runs dry! Even Volvo don't charge a fortune for them!