nonyab

Hello to all, new to forum and seeking help. Hope this does not end up a double post as have tried once already.

Here's the problem. 1991 5.0 w/125k original miles, has never used oil in past. Recently when I checked the oil after replacing the timing chain cover gasket and water pump it was 2 qts. low. No leaks. Checked intake breather and found oil in breather and filter to breather line was saturated with oil. Oil used is Mobil 1.

Have checked so far: No vacuum leaks found; Vacuum is 19 and steady;compression is, #1-200, #2=210, #3=200, #4=200, #5=190, #6=190, #7=205, #8=210; Cleaned upper intake and all PCV ports (no obstructions); Replaced PCV and hose; Cleaned valve covers and checked oil return holes; All spark plugs are clean with no evidence of oil fouling; Engine has had loss of power up a hill so I checked the CAT using vacuum at idle VS vacuum at 2000 RPM--it increased and was stable; Mileage had dropped from 18 hwy to a little over 12, increased now to about 15-16 overal; Idle RPM is high @ 900 but eventually drops to about 700; Disconnected oil breather line to breather, installed new filter, and filter became discolored after being driven once and oil fumes were noticeable in cab; No visible oil smoke under hood even with oil filler cap removed; Also, no noticeable pressure at oil filler cap even with RPM accelerated; Used 1/2 quart in less than 200 miles this past week.

Next step is to do a leak down check but am having difficulty thinking there is a problem in that area. If anyone can offer me some guidance as to possible causes I would greatly appreciate it. I hope I have provided enough information so someone can point me in the right direction or make sure I am on the right track to solve this problem. HELP and thanks a MIL. Nonyab