Hello everybody, new member here from Winfield, Illinois, USA. This is my second Volvo 1800, a '71 1800E. My son and I flew one-way to Baltimore and we drove it home to Illinois. When we checked the oil prior to driving home, we found that it had been over-filled by at least a quart. I also found that the oil trap / breather had been plugged, and promptly removed the blockage. Right or wrong, we drove 700 miles and the oil level gradually dropped to about a 1/4" above max. The car ran really well, oil pressure light works but never came on with engine running, oil pressure gauge indicated good pressure range.

A few days ago, I drained the engine oil but left the filter installed until this morning. When I removed the filter just now, it did not spill more than a few drops of oil and appeared to be completely empty. I have done a lot of oil changes through the years but have never experienced this until today. The old filter was a WIX.

Could this be caused by the crankcase becoming pressurized due to the plugged breather? The oil filler cap was still connected to the intake manifold, BTW., would that prevent crankcase pressurization?

Thank you for taking the time to read this and for any advice. On a side note, I am trying to re-plumb the breather hoses correctly but am having trouble finding the correct intake end fitting. There is a nipple on the underside of the intake manifold that has a vacuum cap installed, but that is smaller than the nipple on the breather. I believe that I am missing a pcv valve, which might have a big side and smaller side?