Hi there,
I tried searching the archives for "PCV" and "Flame Trap," for the 1993-1997 850s, but did not see a definitive answer for servicing the PCV/flame trap.
Aside form the mileage (two 850s; one at 85,000, the other at 76,000) and use (no hard use), if we want the 850s to go another 20 years should the PCV/flame trap be serviced no matter what?
I understand it's a fairly expensive, time-consuming procedure, and not always necessary, but the key is that there's no definite way to tell if it's necessary.
What I don't want is a blown seal anywhere. We have done the glove-over-the-filler cap test (no pressure one way or the other), and there's no smoke from the dipstick.
Do you think it makes sense to just do the service?
Thanks!

If they are not turbos, remove the plastic screen from the flame trap and toss it in the garbage. Switch to synthetic oil. Pick a car to drive, then drive it for at least 30-45 minutes to get the engine oil hot before you park it again.

If you have a turbo, look for PTC cleaning.

Part of the PVC R&R involves the hoses which get old and crack, allowing air into the vacuum system. Lack of vacuum will change the engine performance. A plugged vacuum line, PTC, or engine block passage will cause seals to pop very fast.
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Keeping it running is better than buying new

Hi Ken,

The 850 engines don't like dino-oil, and you'll do better running
full synthetic oil that is less likely to plug up the engine with
hard crusty crap.

I use the 5-30 Full Synthetic in the 5 QT jugs from Wally World with good luck here. They price it much cheaper than the auto parts stores.

Bill

You should probably service the flame trap. As mentioned, it is pretty easy. I threw out the flame trap screen on both my 850 and 240 years ago and never had any negative repercussions. In fact, I believe that Volvo got rid of the flame trap screen altogether because of its tendency to clog the system. Think this occurred when the S70/V70 models were introduced in 1998. I suggest just cleaning and or replacing any related hoses depending upon the particular hose's condition and tossing the screen.

Doesn't sound like you need to service the PVC system. Since the glove didn't inflate, then you are probably okay for awhile. These cars generally seem to need the PCV overhaul somewhere around 125-175k.

The flame trap is just a plastic disc with holes in it that can get gummed up. It is easy to find if you know where to look, I purchased a Haynes manual.

I think that that manual if worth its cost.

The PCV system is somewhat more difficult to service, and will cause troubles eventually. Hopefully Klaus will chime in - I think that there is a nipple that actually has to be drilled out if it clogs badly enough.

Have you tried youtube? How about Volvospeed?