I have been .trying to get my wife's (now mine) 1995 850 NA in tip-top condition 180,000miles. We have had it since 1997, and have been very diligent about maintaining the oil and scheduled maintenance. Now that I have the car, it smells like anti-freeze and is using oil. I went over the entire cooling system...changed ALL the hoses and heater core...even did away with the junction box in the firewall and routed the hoses directly to the 'feed tubes' that mesh with the heater core. The green O-rings from FCP were crap...leaked... I went to Volvo last week, got some nice new OEM ones... a week later...leaking O-rings. They don't seal properly. AHHHHHH! (more about that later).

I changed the entire PCV system 2 years ago...when checking the flame trap last week, I accidentally pulled the hose out of the canister located under the intake manifold. There was no way for me to re-attach that hose without dismantling the car...I did that this weekend...new hoses while I was at it....ports and hoses, clean as a whistle. I put my hand under the flame trap sections (it separates to install the screen) after it has been running for some time....OIL...wet! Now, is it that it is normally a wet area and the O-ring is worn that fits in that unit? Or am I sending oil up that hose and into the flame trap? I know that I am using an unusual amount of oil (Quart every 500 miles)... Mobil One since 1997. Just got home from a 2.5 hour ride... oil is down past the mark, was in the range before the ride. No smoke upon acceleration or idle.
I got water under my mat and it smells like anti-freeze is coming from the engine cabin when I open the hood (not a speck of anti-freeze around...did a black light search tonight).
Here is a solution that I thought of for the heater core. You know the tubes that connect from the junction box to the core? Well, since I have no junction box, I was going to cut those tubes to about 3" long...Silicone them (with the O-rings) into the heater core and then attach my hoses to the tubes...NO LEAKS GUARANTEED!
I like the car...I have had a P1800, 544, 240, 740, 760, S40 (my wife's new car). I like Volvos. But I want to end my misery... I can't afford to have the head serviced...time and $$$.
If only I knew of a great mentor, diagnostician in the Long Island, New York area. I would pay for an expert consultation.

 

Sounds like you are singing the Volvo blues. Sorry for all your headaches. I have to ask, did you do a compression test and a leakdown test on the engine to see if the headgasket is good. It might not be a HG and you just have leaks somewhere else.

 

Did a compression test a few months ago...it was solid, but I didn't do one recently...I will do that this weekend...will post results.
I DO NOT know how to do a Leak Down Test. Is it difficult?