In my last installment, I was bemoaning my fate. I own a 1996 850 -base model- with 82000 miles and a leaking rear main seal. I posted a question inquiring about the cause of early seal failure and was told that excessive crankase pressure was a possible culprit caused by a plugged vacuum hose into the flame trap or a plugged oil trap.

After saving my pennies (many pennies) for a month or two, I had my trusted tech replace the rear mail seal to the tune of $450. He said the improved volvo main seal (more felt in the new seals at a cost of $27) was all that was necessary to "solve the problem". I said what about the vacuum line or the oil trap? He resisted and delayed as there was not a problem here. I persited and finally convinced him to replace the oil trap and the vacuum line from the vacuum tree to the flame trap. The result was the oil trap and attached hose were clear, however the vacuum line to the flame trap was plugged. This caused excessive crankase pressure and made my rear main seal leak.

Moral of the Story:
Always clean you flame trap when you change your oil and filter as I do every 3000 miles. Even if you do this you may notice oil leaking around your filler cap or your dipstick being blown out and/or your rear main seal leaks slightly, check your vacuum line from vacuum tree to the flame trap to see if it is plugged. If it is not plugged you may need to check the oil trap (under the manifold) for hose blockages or install a new oil trap. This costs more money or time in labor but is cheaper than an additional rear main seal.

Thanks for the pre-rear main seal replacement advice brickboard people. You may have saved me from doing the job again.