Heater (Interior) Core Matrix replacement (w/o AC !!!!!)

[745 TurboGreasel]

You know the vac pump is what sweeps the fumes form the crankcase right.

[v8volvo]

Originally Posted by 745 TurboGreasel

You know the vac pump is what sweeps the fumes form the crankcase right.

Interesting, could you expand on this a bit further? Didn't realize there was an interaction there. I've run them with the pump off for diagnosis before (rubber stoppers in the pushrod and drain holes) but never long enough to see it have any other effect.

OP: great news that that fixed it! Must be a lot easier to change the core in your setup than in the A/C-equipped cars -- sounds like it wasn't too big of a deal. Congrats that it all worked out!

[745 TurboGreasel]

the air sucked out of the vac system is blown into the crankcase, working against the CDR valve maintains some set low pressure in the case , and sweeps fumes toward the intake.

Probably there are little or no short term effects without it.

this is a newer pump, but all the passages work the same
https://www.youtube.com/watch?v=fWATwtqCEXw