I own a 74 Comet / slant 6. It seems like there is a lot of pressure in the engine - blowing oil out through the dipstick and blowing oil into the air filter as well. Any thoughts or ideas why it's doing that? Mark
When an engine gets alot of miles on it, combustion pressure starts leaking past the rings into the crankcase. Its called blowby, and thats most likely whats causing the symptom you describe. A bad PCV valve could cause some blowby to be apperent, but usualy not as much as you describe. You can either A- rebuild or replace the engine or B-live with it as is Oh, BTW, these ford motors are just straight sixes. The slant six is a Mopar motor. Now i'm a Mopar guy at heart (Shh... don't tell anyone) but most ford guys (and most mopar guys too, for that matter) get a little testy when you confuse the two. As you have guessed, this board is pretty much filled with ford guys.
Your PCV valve is either removed or not functioning correctly. My 250 has 247,000 miles on it and dose not have that problem as long as the PCV valve is connected.
Replace the PCV valve and hose, run a leak-down test or a wet/dry compression test. If the compression is good and the cylinders seal withing 10% (high to low) then you know what the shape of the top end is. If the oil pressure is good too then the engine's condition will tell you how far away the next rebuild is. Use that information to plan the next step.
Trust Paul's opinion. I had the same problem on a 300 in a Ford truck and it was caused by blow-by. It was just worn out. I rebuilt it - no probs since.
PCV is a cheap test and usually shows some improvement even if the rings are worn. Likely with the age, it needs to be rebuilt. Keep oil in it and as long as it doesn't foul the plugs, you can keep going. The less you push the engine, the less it blows oil. Mine will blow the dipstick out of the tube at wide open throttle.
PCV Valve replaced Thanks for all the ideas. I was told the compression test was 120 on all 6 cylinders when I bought the vehicle. But then again, who knows if that was true. I replaced the PCV valve yesterday and plugged up any open vaccum leaks as well. The car is completely out of tune... so maybe I should just have the shop do a new compression test as well. I bought a triple gauge kit... but am figuring out how to install it now. It's not the electric one... but a mechanical one so figuring out where to put it in the engine and radiator is quite interesting.
Might be a timing issue too. Higher timing will make an engine blow oil worse if the problem already exists. My 200 had 120psi across all six, didn't blow oil too bad, but leaked between the head and the block. My dad argued with me that it couldn't. After I pressure washed the engine and ran it a bit, I proved my point. Not a drop anywhere else, just leaking oil out of the headgasket. I don't know the sixes well enough to tell you where to put the temp sensor, someone here can definately help. I was still green when I was running the six, I assisted in most work back then rather than tackle it myself.
Mine has been relatively well taken care of (besides the part where it sat in a wheat field for 13 years with three seized valves), however, with that kind of mileage, I don't think the rings could get much worse. There is so much blow by, that it blows out around the oil fill cap and dipstick... it's losing about 2 1/2 quarts of oil between oil changes now. There still is no visible smoke coming out of the exaust though. I'm afraid to check the compression or leak down.
