The International Cessna^® 170 Association

Hi everybody. First posting. Club member. Have 55 170B SN26936. After installing F&M oil filter adapter, I now have low oil pressure. Reads between 15-30 lbs. and varies. Any thoughts? -Tracy, Centreville, VA

Tracy,

Three quick possibilities come to mind.

1. BE sure you are using the proper oil filter, as oil filters are directional. I am using Champion CH48108 filter.

2. You could have broken loose some sludge and it has lodged in the relief valve sticking it open. The relief valve is easy to remove and check.

3. This one is expensive, oil pumps wear with time in service. The wear shows up on the end of the pump gears and the surfaces the end of these gear run against. This increase in end play allows the oil to bypass around the gears in the pump rather than build pressure. If you look at the oil circulation diagram in the Cont. O-300 overhaul manual you will note that the first stop for the oil leaving the pump is the large oil screen which is removed to install the F & M oil filter adapter, which could be causing to much back pressure on a worn pump. 50 weight oil might help this situation. If you want to rebuild the oil pump you should be abe to do it by just removing the accessory case and not tearing down the whole engine.

I have been using the F & M spin on oil filter adapter and Champion filters for several years and have had no problems and have been happy with the system.

Johneb

If you're certain the FM Enterprises oil filter adaptor is the only change you've made, and if you're certain you made the installation correctly....then I'd call them and discuss the situation with them.
http://www.fm-enterprises.com/
I'd also recommend you confirm the accuracy of your oil pressure gauge.

Thanks George and John for your ideas, you were both on the right track. We think it was dislodged carbon in the oil pressure gauge. Going to change the oil and filter and replace the gauge.