The Stovebolt Site Forums The Shop Area Engine Shop varying oil level

I have a 1955 235 in a 1946 pickup c/w a typical bypass oil filter. Often, not always, oil will show 1/2 to 3/4 quart low on dipstick. After next drive it is back showing at the full oil level. Any ideas as to where oil might be being held up periodically?

How much oil do you put in the engine when you change the oil?

If the manual says 5 qts, put in 5 qts and then add a 6th quart in the filter.

When it shows low on the dipstick, have you ever taken the top off the oil filter canister to see what was in there?

Either way. The dipstick should read full in the oil pan when the engine is cold and the oil filter should be full.

It looks like the oil filter, when the engine is off, sometimes drains back to the engine, other times it does not drain to engine. There is a small hole in the center tube of the filter cannister, near the top of the filter, to allow oil that has passed through the filter to enter the tube and drain to the engine. I don't see a hole low on the tube but this morning the oil level in the cannister was near the bottom of the filter. A few days ago the cannister was near full. Both checks were with a cold engine after sitting overnight. A few days ago the dipstick showed oil down about 3/4 of a quart (cannister full) and today it was overfull by 1/4 quart (cannister near empty). looks like I will need to remove the cannister, clean it and check for a leak point into the center tube near the base.

The 1/16 inch diameter flow control orfice is at about the level of the input fitting on the side of the filter housing, a couple of inches below the top. If the canister is draining below that level, you've probably got a hole rusted into the standpipe near the bottom. That will also cause a loss of oil flow to the engine if the hole is big enough. Try removing the filter canister, clean it up, and fill it with a lightweight solvent like mineral spirits or Diesel fuel to look for the leak. It should not drain below the level of the flow control hole.
Jerry

Do these type of oil filters do much good? I don't have room for one on my COE, I just change the oil quite often.

It depends on the filter element you use. There's no law that says it's got to mount on the intake manifold- - - -with longer flex hoses made up by a hydraulic shop, the canister can be mounted anywhere there's room for it- - - -just avoid contact with hot exhaust system parts or places the hoses can get chafed from vibration. I like to use "single braid" hydraulic hose with a 3K PSI pressure rating for custom filter canister placement.
Jerry

Yes.

They filter about 87% of the oil compared to the spin-on type filter which filters about 92% of the oil.

Not much difference to worry about , in my opinion. As you said, you change the oil frequently as most everybody does with old cars.

I got the above information from an article in Auto Restorer magazine a long time ago.

The mystery goes on. Removed the cannister from the motor, cleaned it up & could not visually find a leak below the 1/16 diameter flow control orifice at the inlet level.

I then filled the cannister with acetone and let it sit for awhile - no observed leakage into the middle tube or out the bottom connection. Put on the top and, with acetone still in the cannister, tightened the top bolt to see if this would induce a leak but again no leak.

I know you'll check the lines when its out but it's worth looking them over for clogs or leaks. Blow some air through them.