C-85 Oil pump loses prime experiences?

I have a C-85 w ~1550 hrs ttsn (low TT) & "fresh o'haul" but never run from 25 years ago. It is not corroded in the cylinders and it was stored in a dry climate and area. I added a F & M full flow oil filter.

I started it first time w 40 weight oil about May 25th & had a little trouble getting oil pressure. I flooded the line to the oil gage & then things seemed OK. I ran it about 30 minutes on the ground.

Now 3 months later I'm almost ready to fly it in my J-4A, but I can't get any oil pressure again. I tried to back flush it thru the oil pressure gage restrictor w 40 weight oil from an oil can, and later from a small hydraulic pump, but so far no luck on the gage. My last run was ~ 30 seconds without any sign of pressure, so I tore off the cowl & reconnected the small pump to one of the oil galleries via the 1/2" npt port in the front of the engine.
Now I get 20 psi gage indication with perhaps 1/2 gal/min leakage flow back thru the engine, pump etc of 40 weight oil - all at ~75 degF.

Q - Have any one else experienced this? If so, how much oil did it take to prime the pump via the restrictor? How long between need for repriming? The restrictor is open.

I'm thinking that I probably have it primed now, but for how long is questionable. If necessary I'm thinkiing of using a small weed sprayer to force oil thru the restrictor so that I get a known quantity of oil into the engine.

Occassionally, the C-85 on my Cub will lose its prime if everything is lined up just so and it sits for a long period. When that happens, I pick the tail up high...I use a rope around the fuselage handle and allow the nose to almost touch the ground...and hold it for a couple of minutes and pull it back down using the rope. Yes, it really has to go that tail high/nose low to work. Lower it back down and the oil pump will typically pick up its prime. Just be sure you have your prop turned horizontally before you do it. You don't want to hit the prop on the ground, even standing still.

Remove the oil filter adapter or figure which hole lines up with the upper oil hole on the adapter and pump oil into this port to flood the oil pump exit. turn the engine backwards as you get oil into the pump to back the oil through the pump into the inlet side of the system. You might want to add a little STP or Lucas oil treatment to make the oil a little "stickier".
I am not certain about the C-85 since the O-200 is different and the above works on it.
Either way the easiest way is to pump oil from the oil cooler bypass back to the pump and turn the engine backwards to pump the oil "backwards" into the engine oil path.
From CPA....

From CPA:To: Cliff The easiest way to prime the oil pump for your installation is to remove the oil filter and pumpoil into the non-threaded port of the oil filter adapter. A piece of clean hose the size of the hole is all youneed and several ounces put into the pump cavity should be all you need. With all the bottom spark plugsremoved spin the engine by hand and make sure you have an oil flow out the same port. Spin the filterback on and put the plugs back in and you should be ready to run.

If there is no filter adapter installed, remove the oil bypass plate as has been done in this picture of the oilbypass pad with the gasket still installed; feed the priming oil in the top hole..the bottom hole feeds the

left gallery and oil injected there would not get to the pump.

Quote:

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Originally Posted by nrpetersen

I have a C-85...

I started it first time w 40 weight oil about May 25th & had a little trouble getting oil pressure. I flooded the line to the oil gage & then things seemed OK.

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That always worked for me as well, C-85/C-120. Someone had installed a "T" fitting in the gauge presssure line at some point, I can only guess that perhaps that was the reason.

Are you sure the issue isn't related to adding the filter?

Thanks guys! I'm going to fill the galleries & try again since they are exposed now.

Next time it happens I'll try the nose-down method first, then try the lube thru the oil filter adapter, then try the prime thru the restrictor. I don't want to tear the cover off the engine if at all possible.

Yeah - it just might be related to the oil filter - but that could also be considered part of the second solution w a vacuum pump.

The Aeronca forum had an interesting comment from a very observant member. He noted that the side plate of the gear pump is bolted into blind tapped holes and that these holes show a slight pulling of the soft magnesium material. This spaces the side plate out a little bit unless it is relieved and is the possible source of a lot of oil pump back leakage etc. I have not seen the inside of one but I'm sure gonna look for that.

The oil filter adapter is intended to be used with the filter that has an anti drainback valve. Once the filter is filled ( engine pressure oil flow, running) it should not let the oil drain back to the sump via the pump. If the oil filter was not filled after installation then the oil would be able to drainback with little trouble.
Follow the instructions from CPA:
http://www.cessna120-140.org/forum/f...e_loss_all.pdf
Best of luck,

JDB.

JDB - That oil pump .pdf file is incredible! It should be part of every C-85 owners file. Thanks for pointing it out.
NRP

I had exactly the same problem with a newly overhauled C-85, As some one rightly said you have to prime the pump and I found it was easy to uscrew the filter and prime into the port in the housing that goes back to the pump. I found it was useless trying to prime by pressurising one of the oil galleries because of the non return valve in the filter which stops the oil getting to the pump. I have never been successful lifting the tail.

Ian

Actually the easiest was is to removing the oil temperature sender at the screen housing and squirt (clean) oil into the housing which is just above the oil pump. Works every time (and saves your back).

Mike

Lifting the tail requires lifting it very high to work. Just lifting to head high isn't sufficient. The air filter/box needs to almost touch the ground to work. You'll need a rope to tie to the tailwheel or fuselage handle (Cub) to hold it from going to far and to pull it back down.

I've seen this work on more than one occasion. Of course, YMMV.

Hi guys,

Tip from an old-timer......remove the oil pressure relief valve....the big bronze nut, pull spring and piston, check piston for wear, replace or polish if worn, squirt in oil, rotate prop, repeat, reassemble, start engine. That was my once a year ritual when I returned from europe to fly for the summer. No heavy lifting, no special oil can connections or other B.S..

Old & Bold, c140ace@msn.com

had same problem on new overhaul - you can overfill crankcase with oil about 8 quarts drain excess before starting and it will prime pump,had to do on erocoupe,no way to get tail high enough -found out to fix needed new accessory case,there was to much clearence on oil pump housing-new cases are available for -12,if you have -8, there is place in oklahoma that can overhaul them

Heavy lifting? What plane with a C-85 is heavy? Maybe in my 35+ years of flying Cubs and other small Continental powered airplane I didn't learn much, but I'll be flying while y'all are still gathering tools. Of course I learned the lift the tail trick from real old timers from the 30s and 40s.

I agree with Jim. The Cub's tail is so light, you'd have to be a 90 lb. weakling to find lifting it difficult. The Champ is heavier on the tail tough, but still can be lifted by a 120 lb. weakling. I had the oil pressure problem with both my Cub and Champ, both with 65 Continentals. I completely overhauled the one in the Cub with all new oil pump componenets and that cured the problem unless it sat for a couple of months. The Champ never did quit losing pressure after it had sat for even a week. I put a C-85 in the Champ and that cured the problem. I used to use an oil squirt can and squirt oil in the pump where the oil temp bulb went until an old time mechanic told me about the tail lift deal. I'm a couple of inches over 6' tall, so have never needed a rope to pull the tail back down. This method really worked everytime I used it and I didn't drool oil on the back of the engine using a squirt can. Try it, you'll like it. Make sure the prop is horizontal like someone else mentioned.

I now have oil pressure.:)

IDAH (Ian) (and some others too) had the correct analysis. Earlier I had pressurized the galleries to 20 psi oil P gage indication w a small hydraulic pump for about 1 hour. No pressure on startup.:(

I then removed the filter & pumped in a couple of oil can squirts using a 6 inch piece of 1/4 " ID beer hose, pushing it into the kidney shaped slot at least 3 inches so oil did not run out. Got oil pressure right away on reassembly.

Analysis - The anti-drainback valve on the filter prevents any flow from the gage line or even the galleries from reaching the oil pump gears.

I didn't want to remove the oil temp sensor as it looks like that has been tried a lot of times previously (different engine) by someone & a pliars/vise grip.

That must be why a few mechanics assemble new pumps with grease, rather than just oil. Better to get an initial seal. In my case, I probably flushed out the assembly grease when I first ran the engine last spring.

Thanks guys!