Oil Pump Prime

[Jack Ryder]

After a recent oil change, our C-85 engine lost prime on the oil pump.

We tried lifting the tail of our BC12D4-85 high up for a minute, then tried pressurizing the oil "tank" to about 15 PSI while hand-cranking the prop.

Both of these failed to do anything !

Today we will try removing the pipe-fitting from the oil-pressure-gauge to the engine, and hand-pumping oil ( supposedly ) directly into the oil pump.

Anybody out there got any better ideas ?

Thanks, Jack

[3Dreaming]

I guess you blocked off the breather when putting pressure in the oil tank? You can pull the oil temp bulb and inject oil there, or if you have a F&M oil filter adapter you can remove the oil filter and pump oil into the oil pump from there. IIRC it is the round hole not the center..

[Edwin Otha]

Lifting the tail will not work for the C series engines. Try the oil pressure tap and if it doesn't work pull off the transfer plate on the left crankcase half and pump oil into the holes. It is held on with 3, 5/16 nuts and might need a new gasket. These holes lead to the oil pump and the left hand oil galley.

[PA1195]

I had a similar issue after a new overhaul with a C-18-12 with new pump after about 10 hrs and some sitting. First removed the F&N oil filter and adapter and replaced the factory blocking plate. No improvement on the gauge after 30 seconds. The filter has a reputation of adding back pressure to the system (?).Then pumped oil into two holes (top one pump feed?) under the side plate but no improvement on the gauge. Finally flushed black crap out of the oil pressure line and filled with 5606 fluid and the oil indication returned on the gauge. So yea pump in some oil, but if the pump gears or plates are scored or worn....try straight weight 40-50 weight oil.

Gary

[Mike S]

On my a65 I squirt a couple ounces of oil behind the oil temp bulb after every oil change now, before I go to hand-propping. 5/8" wrench and a few minutes leaves no doubt the pressure will rise.

[Jack Ryder]

Thanks for these great tips !

We'll be trying some of these today.

Jack

[Edwin Otha]

The screen assembly is lower than the oil pump on the C series. I pulled an F&M filter adapter off as well. If the plane sat more than a couple weeks the pump lost its prime.
EO

[Jack Ryder]

Edwin, as you suggested, squirting the oil into the top hole behind the Transfer Plate on the left side of the Case did the job !

Thanks to all of you for your inputs !

Jack

[Hank Jarrett]

Any chance you can post a photo of which hole you are talking about? It is a hard area to see and there are lots of holes! ;-) (One of the engine drawings wold work great too.)

[Jack Ryder]

Hank - I'll post a pic on Monday

Jack

[Hank Jarrett]

POIFECT! I probably won't get out to the airport before then anyway with all this heat!

[PA1195]

Three holes in a wide horizontal-V hold on either the oil cooler, filter adapter, or without them a cover plate with internal clearance for oil passage. There's two holes vertical inside the V - the top one is from the pump, and the bottom to the gallery. The parts book Fig. 3 shows that, and in the overhaul manual the oil flow is located at the very end Fig. 47.

Gary

[at7615]

1. What oil are you using? 2. After the recent oil change did you run the engine, or wait?

[Jack Ryder]

In the C85 we are using AeroShell W100 along with Camguard Aviation.

After the oil change, we started the engine, but when there was no indication of pressure on the gauge, we shut it down.

After that we removed the top 4 spark- plugs, so that after each attempt at re-priming the pump we could easily turn over the engine !

Jack

[PA1195]

Maybe draining the oil created some suction through the pump cavity via the oil pickup tube? Just a guess. Once the oil was evacuated around the gears it takes some replacement oil to reseal them? The gears and pump cavity may be wearing and tolerances increasing?

Gary