Lost engine oil pump prime

[Hank Jarrett]

Re: Lost engine oil pump prime

When I rebuilt the 41 the oil P line was clogged pretty bad but still passed fluid (SLOWLY when the fitting was cracked at the gauge). I REALLY didn't like that the oil line was in one piece from the back of the gauge to the engine and was a PAIN to pass through the firewall. I bought the parts for a firewall connection so I could run the line from the engine to the firewall, then the back of the firewall to the gauge. Worked GREAT! Only issue was the fitting used a larger tube size, which turned out to NOT be a problem, but a solution. The engine fitting was modified to put the plug with a small hole in (really helps if an oil line breaks so you don't pump all of your oil overboard! Plus if I remember right it is REQUIRED!) The new, larger line was run to the firewall and a new larger line was run to the gauge with an adapter at the gauge. The gauge now responds much faster and I eliminated one rubber grommet in the firewall for a through fitting that actually seals.

[PA1195]

Re: Lost engine oil pump prime

It wasn't my idea and maybe my mechanic picked it up from some old timer he worked for. He trained with one of the best (Tom Kushida - started Northland Aviation locally with Don Shultz - both former Wien Airlines mechanics) so maybe that's the source.

The other question is does the fluid in the line ever change out? We had coffee over that and I suggested we bleed it next annual and see color what comes out.

Gary

[N96337]

Re: Lost engine oil pump prime

I like the idea of the 5606 in the line!
John

[PA1195]

Re: Lost engine oil pump prime

Thanks Dave. But it still begs the question for we owners how to determine if the pump is worn beyond acceptable or why it looses prime. Direct inspection of the pump parts is probably the best. Next might be noting how quickly then engine builds oil pressure at the engine's oil pressure port Then like I as an owner only tried monitor the gauge at the other end of the pressure line. It also assumes warm oil in the engine and pressure line, and in my case a non-restricted line.

If I lack oil pressure indication on startup I now have a better idea what to do. My mechanic would have done this a while back of course. Yea I know...call them first.

Gary

Re: Lost engine oil pump prime

Well that is a happy ending Gary, glad it worked out.

Dave R

Here is "the rest of the story" from this thread I started. No indication of oil pressure in 30 seconds noted earlier this Spring. Worked slow to rise and fall off but ok when warm this summer. Just finished annual inspection and the following was done:

Confirmed via work order that the O/H shop did the pump, plate, and acc case per specs less than 100 hrs ago. All met min specs not max. Good. New parts and O/H certified parts noted.
Nothing on the oil screen indicating aluminum or ferrous metal wear. Two small pieces of carbon and a good health report.
Removed 1/8" oil line between case and gauge. Flushed with solvent. Full of 76 year old black debris and barely flowed solvent at first under pressure but then flowed lots clean.
Filled line with Mil 5606 hydraulic fluid and purged air before tightening fittings. Cold weather fix for Alaska instead of thick oil.

Now the oil pressure gauge responds quickly as I crank up the engine and falls off quick when I shut it down. Before it was a 10-15 second response for both in summer, longer in winter when the unheated cockpit is cold. Oil comes out of the case port less than 5 seconds when started. Maybe lesson learned.

Gary

[PA1195]

Re: Lost engine oil pump prime

Here is "the rest of the story" from this thread I started. No indication of oil pressure in 30 seconds noted earlier this Spring. Worked slow to rise and fall off but ok when warm this summer. Just finished annual inspection and the following was done:

Confirmed via work order that the O/H shop did the pump, plate, and acc case per specs less than 100 hrs ago. All met min specs not max. Good. New parts and O/H certified parts noted.
Nothing on the oil screen indicating aluminum or ferrous metal wear. Two small pieces of carbon and a good health report.
Removed 1/8" oil line between case and gauge. Flushed with solvent. Full of 76 year old black debris and barely flowed solvent at first under pressure but then flowed lots clean.
Filled line with Mil 5606 hydraulic fluid and purged air before tightening fittings. Cold weather fix for Alaska instead of thick oil.

Now the oil pressure gauge responds quickly as I crank up the engine and falls off quick when I shut it down. Before it was a 10-15 second response for both in summer, longer in winter when the unheated cockpit is cold. Oil comes out of the case port less than 5 seconds when started. Maybe lesson learned.

Gary

Re: Lost engine oil pump prime

Drake Air in Tulsa reworks the accessory cases (reweld and mill the oil pump cavity). It's been 10-12 years since I had one repaired. I think it was around $700 at that time. Drake Air has farmed out their marketing and sales to Quality Aircraft Accessories in Tulsa so I think you have to contact them for assistance.

That's where I sent mine in 2001 sat on shelf until last year when i used it.

But the year before I called Drake for a customers acc. case and I think they said they no longer did which matches what you said Garry.

I don't recall a reference from them for a company that did the oil cavity though, just for the shaft bores.

But then again I may have forgotten.

Dave R

[Garry Crookham]

Re: Lost engine oil pump prime

Drake Air in Tulsa reworks the accessory cases (reweld and mill the oil pump cavity). It's been 10-12 years since I had one repaired. I think it was around $700 at that time. Drake Air has farmed out their marketing and sales to Quality Aircraft Accessories in Tulsa so I think you have to contact them for assistance.

[astjp2]

Re: Lost engine oil pump prime

Don's sends it out, there is only one place that can reweld and mill the cavity and I just cant remember their name right now. If there is too much copper in the magnesium, then it cannot be repaired either. Aluminum accessory cases can be welded all day long. Tim

Re: Lost engine oil pump prime

Tim's right on the money...I've dealt with this on a few small Continentals and the cavity is more than likely worn oversize. Don's Dream Machines can weld and re-cut the cavity and fit new gears to factory minimum tolerance and the problem will go away. I wouldn't overhaul one without doing it anymore.
John

I did not know, thanks!

Dave

[PA1195]

Re: Lost engine oil pump prime

Thanks John for the perspective from your experiences.

The shop that did the work has some old timers as fixers so I'm not too concerned with this one time issue over two years of operation. It's sat before and never had a problem.

I'll monitor and report if it returns. If it does I'll get it repaired.

Gary

[N96337]

Re: Lost engine oil pump prime

Tim's right on the money...I've dealt with this on a few small Continentals and the cavity is more than likely worn oversize. Don's Dream Machines can weld and re-cut the cavity and fit new gears to factory minimum tolerance and the problem will go away. I wouldn't overhaul one without doing it anymore.
John

[PA1195]

Re: Lost engine oil pump prime

Thanks for the oil suggestion. This is the first time I've run Phillips 20W-50 versus my normal 80 or 100 Shell. It may be that once cooled the 20W-50 is slightly thinner than the straight weight oil. And it may also be the pump assy was looser than minimum spec but still within tolerance at overhaul. If the loss of prime returns then I'll go back to the straight weights I've used successfully for 43 years in many planes and re-test.

Gary

[flybikefarm]

Re: Lost engine oil pump prime

Lucas oil treatment, mine sat all winter and had oil pressure almost instantly. Not faa approved but works, if you don't want to fly with it just drain and replace oil

[PA1195]

Re: Lost engine oil pump prime

Thanks Tim. I'm not going to replace the case/pump unless it's a frequent recurring issue as the system pressure is excellent as is the engine overall. Two years since O/H and less than 100 hrs TT. This is the first time and hopefully the last. The inference above relative to the F&M adapter and filter I assume has some merit as well. There are a range of tolerances associated with the pump components and housing fits so mine may be at the upper range. But as Dave notes w/o an as-built parts tolerance sheet it's a guess as to what's there. FGE...for now.

Gary