Oil Pump Gears

Post by **Bruce Fenstermacher** » Wed Aug 06, 2003 2:40 am

I currently have the accessory case off my engine. Don't ask why. Took the opportunity to remove and inspect the oil pump gears and housing. Gears look good except the driven gear at the drive end has some galling(small almost undetectable rings worn ing the steal) on the shaft where it passes through the cover. The cover of course has matching wear. It's not much but it's there. Oil pressure was in normal range but at idle when hot only about 10 pounds. I'm thinking the gear and cover should be replaced. Here are my questions.

1. Would it be OK to replace just the driven gear and the cover with a serviceable unit reusing the undriven gear.

2. Is it common or more exceptable to replace the gears in sets?

3. Are servicable gears available and if so where?

4. Does anybody have any they'd like to part with?

5. If I must buy new Fresno Airparts has an overhaul kit with all the parts for $392.50 is there a better deal somewhere?

The engine is at 900 since overhaul with less on a top with new cylinders so I'm looking to get another 900 before major.

Thanks

170C · Post by **170C** » Wed Aug 06, 2003 11:51 am

I will leave the technical comments to others, but will pass this on for whatever. When I overhauled my O300B in '98 one of my oil pump gears didn't pass muster. It had groves worn in an area and although working fine was rejected. That particular gear had a retail price of approx $950! With my AI's "discount" it still cost me $725. I felt & still feel I got a royal ________! Found out later a friend of mine had replaced the same gear in his engine and somehow found out it was the same part number as a pump gear in a Cummings Diesel engine. Cost him (in 1995) approx $85.00. Obviously that part was not FAA-PMA approved and am surprised his AI would have installed it, but that engine is still running great. Who knows?

Ole Pokey

Post by **Bruce Fenstermacher** » Wed Aug 06, 2003 1:46 pm

I have found a large difference in price of the parts As I said in the first post Fresno is advertising a kit consisting of 2 gears, cover and the bolts that hold it together for $392.
My discounted price through Aviall from TCM is as follows: Cover, $118, non-driven gear, $468 and the driven gear (the one I need) $1695. That's right $1695. That adds up to over $2000 for the same thing Fresno will sell for $392.
BTW If we had a 0-200 which uses the same cover and similiar gears but thinner, TCM will sell the whole kit for $325.
There must be gold in them there TCM c-145 gears

N1478D · Post by **N1478D** » Wed Aug 06, 2003 1:56 pm

Wonder if Honda, or anybody else who is working on an alternative aircraft engine knows these prices? That is exactly how the cylinder manufactures came into being and made lots of money selling their cylinders at much less than the manufacturer.

c170b53 · Post by **c170b53** » Wed Aug 06, 2003 3:45 pm

Something you may want to inspect is the aft accessory case where the gears rotate. The gears over time will tilt on their axes possibly due to unequal oil pressure and wear away the side of the case. You will notice it on one side only ( input side I'm guessing). This wear eventually increses clearances and lowers pump efficiency.