Oil leak out of top of filter bolt washer

It’s not uncommon for a copper washer, that’s been reused multiple times, to leak. Try the new copper washer as it came from the store. 10-15 pounds should be adequate. Make sure there are no burrs on the cap or the underside of the bolt head.
 
I can't comment on your specific question about which washers to try first but if you don't get a seal with the copper or plastic washers I suggest that you cut a washer from a piece of nitrile gasket material using the 7/16 steel washer as a pattern and put it on the bolt between a 7/16 steel washer and the filter top. Make the ID such that it's a snug, tight fit on the bolt. Moderate torque enough to stop the seepage and it should stop the leak. BTW, I purchased some stock hardware store 1/2 in and 7/16 steel flat washers last week and found the fitment to be the same as you described. In fact, the 7/16 washer was a snug fit on the 1/2 inch std thread bolt but would not fit on a 7/16 SAE fine thread bolt. If you need a hole punch try a large rifle spent casing on a block of soft wood. JMHO Stan
 
Make sure your filter cover bolt hole mating surface is clean & flat, so that the washer can seal. I have turned the cap upside down & carefully run it in circles on a sheet of fine Emory paper to make sure.

Also do the same to the underside of the filter bolt head.
 
I finally got this Cub oil filter cap to stop leaking by using the 7/16" copper washer I purchased from ACE Hardware for $2.33. Instead of the CASE/IH sourced one that leaked badly for $16! As noted earlier in this discussion, ACE Hardware evidently can't measure the holes in their washers very well. Every washer in the place marked as 7/16" actually has a hole that perfectly fits a 1/2" bolt. The washers from ACE are very flat and have no burrs or deformations on them from being punched out either. Like they were made just for this purpose. I also thank everyone for all of your suggestions as I cleaned everything carefully and polished the surfaces and checked for flatness. The whole problem was just a wrinkle in the original copper washer.
 
DonMountain said:
As noted earlier in this discussion, ACE Hardware evidently can't measure the holes in their washers very well. Every washer in the place marked as 7/16" actually has a hole that perfectly fits a 1/2" bolt.
Click to expand...
FYI, they are made that way on purpose. It's called a clearance hole.
.4375 washer 1.JPG
.4375 washer 2.JPG
 
Last edited:
I see. Thank you for this information. I came out of the structural steel and aircraft industry that wouldn't allow such sloppy clearances for their bolts and washers. I haven't checked any original washers on my Farmall, CASE/IH tractors to see what their clearances actually are. But I assume that higher grade bolts and washers have tighter clearances?
 
I went to NAPA for a copper washer on a hydraulic fitting. They didn’t have the size I needed. But could order it. The salesman told me to go to Harbor Freight and you could buy a hole box of various sizes for about the same as one of there’s. He was right I found one that worked perfectly and have more for future problems.
 
Same problem on my cub and SC and I used nylon or teflon (not sure what the material was) and that worked...I also spun the bell cover an inch at a time till everything worked and then marked it for next time. If it doesn't work, then I would get another cover.
 
You must log in or register to reply here.
Back
Top