I'm trying to sort out a little mystery here. My new '91 245 (B230) had a rebuilt head just installed when I got it. I had to fix this water leak to be able to drive it and I'm wondering if something is missing here.

There's a hole in the head that goes into the water jacket. It is threaded, (1/8" NPT?) and sits just underneath the rearmost bolt on the #4 intake runner. I plugged it but is something else supposed to go in here? The heater hoses are hooked up right and both temp sensors are in the right place and functioning. Do you think the rebuilder removed a plug and forgot to install it?

Thanks,
--
Nineteen Volvos
445-544-122-1800-240-740
Four turbos

Thanks, everyone. Bought one $1.24 plug at NAPA today and took out the cobbled together thing that I had keeping the water in.
--
Nineteen Volvos
445-544-122-1800-240-740
Four turbos

Its a sensor position for the 740/940 but not the 240. My local rebuilder said it was a common error to forget to reinstall the plug.

Should be 1/8 NPT. Get a square head 1/8 NPT plug and install that.

My '94 945T has a freeze plug in that position, although my 1990 244 DL had a threaded plug, my '80 242GT has the thermal time switch. Sounds like your missing the plug.

Bean
--
'80 242GT 92k, '94 945T 123k

Yes, I had the same extra port. Probably just forgotten in rebuilding. Although there may have been a sensor there, there is some variability in head vs. block sensor placement sometimes.