I posted a message a couple of days ago about crankcase pressure on my 87 B230. The responses bring some additional thoughts to mind. I will install a new flame trap element although the old one is not plugged. I did remove the oil seperator that flame trap sets on and its clear. Since my post the other day I have determined that the hose that runs into crankcase from oil seperator is open. I did this by plugging one flame trap hose and blowing into other. At first I could not get any air to pass through flame trap but when I loosened oil fill cap I found I could play that b230 like a Sweedish? horn!! One response spoke of excessive blow-by due to ring wear. I just bought this car so do not know any history. The odometer is stuck at 198,000. I did drive car from Houston to Denver after purchase (1000 miles) and it did'nt use any oil on that trip, although it does leak out oil fill cap. My new questions are - 1. If excessive crankcase pressure is the problem would'nt it burn some oil? 2. A few months back there was a discussion on board about oil seperators filling up with gunk and freezeing. The recommendation was made to remove oil seperator and flame trap and plumb in an old fashioned crankcase breather that vents into the atmosphere (emmisions nightmare). At the time I wondered what that plumbing job would look like. Now I can see if I left the oil seperator on car it would be as simple as some heater hose and a 90 degree elbow. Would this removal of flame trap allow good enough flow to take pressure off of crankcase if blow-by was the cause? 3. One response mentioned changing the gasket on oil filler cap. When I look at my gasket I notice a small nick that could let some oil past. I would want to make sure I did'nt have excessive pressure before installing a gasket as I could then blow -out front or back seals in motor. Don Foster and others have mentioned a homemade tool that would measure crankcase vacumn. Is the tool actually a fill cap that has been drilled and tapped to accept a vacumn gauge?? What should this vacumn reading be?? Enough of my long winded ramblings, thanks to all for response's and wishing all a good turkey day.

I've always found that the true messure of crankcass pressure was if the oil dipstick was "blown out of its tube." If it is not, I would replsce the filler cap gasket. The only other really wierd one I have run into was high crankcase pressure caused by a plugged exaust, This will not show up on a compression test from me experience but was the problem on my 88 740. Check to see if a smaller aftermarket muffler has been installed. The Volvo tend to use a large exaust, with at 2 - 2 1/2 inch OD

Good Luck

If the filler cap seal were good, even high crankcase pressure would not be causing much leakage there and you'd have plenty of leakage elsewhere. The tiny imperfections could not possibly make a difference in total pressure when you consider the gobs and gobs of gases that pass the rings normally.

Bite the bullet and replace the O-ring.

I'd check the flame arrestor/hose,too.I had some repair work done and I asked my Volvo mechanic why the valve cover gasket leaked after a new one was recently installed when I bought my '86 245.Turns out that the flame arrestor was clogged.He told me that when it clogs,pressure builds in the crankcase and it'll blow the seals and gaskets if you ignore it.The car had 175k on it at the time.No oil leaks at present.

Oops. It looks like you didn't read the guy's original note - he started off by saying his flame trap was not clogged and he could blow through the oil separator "like a Swedish horn".

Randy, You may have already checked this but I didn't see it mentioned in the other posts. There is a small vacuum line that runs from the intake manifold to the flame trap. I have had that hose get plugged solid with gunk on two of my Volvo's. There is also a nipple where the hose attaches to the manifold that has a very small orifice. This is also prone to clogging. I remove the nipple, put it in a vise and run a small drill bit through it to clean it out.

Why not do a compression test? Tester costs about $10 ~ $20 (or borrow one).

I was the person who suggested replacing the gasket on the filler cap. It doesn't have to look bad to do a poor job of perventing oil from leaking around the cap- there is a tremendous amount of oil being thrown around under the cam cover and that alone will cause leakage if the gasket is old, hard and not sealing. I can understand not wanting to blow crankcase seals (been there, done that in my early "flametrap ignorant" days). It seems you have determined that the plumbing is free flowing- have you checked to make sure the small nipples and hose from the intake manifold through to the flametrap is open? If all the passages are open then maybe you should go ahead and change the gasket.

Randy