A-65 lost prime to oil gauge

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LB 408A

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LB 408A
This is on a Luscombe 8A no starter so must hand prop. A&P says disconnect the oil line from the gauge inside the cockpit start the engine and when the oil starts coming through connect it back up to the gauge when the oil begins coming out. Told helpers needed and a mess to clean up as I probably couldn't do it alone. I thought maybe I could just disconnect the oil line from the gauge and fill it full of oil from inside the cockpit and connect it back up to the gauge and then hand prop it. Is that likely to work?
 
Some have a misconception that the line to a pressure gauge must be full of whatever fluid it is measuring. This is absolute bunk. Pressure is pressure whether transmitted by air, water or oil. Your A&P either has this misconception or he is playing a joke on you. Has he ever asked you to get a bucket of propwash?!
 
Used to have that problem on a Vagabond if it sat for awhile. For some reason, if we'd lift the tail to head level, set it back down and then start, we'd get oil pressure every time. YMMV, of course.

Jim
 
There are a couple of reasons the small Continental engines lose their prime in the oil pump. One is because of sitting too long without running, second is the oil pump gears are worn and or the alignment/clearance in the housing they're in.
By lifting the tail you are trying to get the oil in the screen to run forward and down into the pump housing. I don't recommend removing the oil press gauge line, it probably won't do any good, you need to get oil into the pump, not the gauge.

I wouldn't be doing my duty on the POA here if I didn't correct you about the C65 though.
There is no C65 designation from Continental, all 65 HP engines were A-65's, the C series didn't start until the C-75, C-85 etc.
 
Bell206 said:
Not enough info. Lost prime to what? And how do you know it lost prime?
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Lost prime to what? --- the only liquid system in the engine. (oil)

And how do you know it lost prime? --- because it doesn't have oil pressure.

A65s are noted for doing this. unfortunately the cause is the accessory housing is worn out, where the gears are held. the accessory housing can't be welded and remachined. (it is zinc alloy)
Try this, with a large squirt gun open the gauge line, and fill the oil pump cavity with 50 weight oil. usually works ?
 
Tom-D said:
Lost prime to what? --- the only liquid system in the engine. (oil)

And how do you know it lost prime? --- because it doesn't have oil pressure.

A65s are noted for doing this. unfortunately the cause is the accessory housing is worn out, where the gears are held. the accessory housing can't be welded and remachined. (it is zinc alloy)
Try this, with a large squirt gun open the gauge line, and fill the oil pump cavity with 50 weight oil. usually works ?
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My questions were to the OP. But wow. So you deduced the accessory housing is worn and determined all those other answers from the OP. So what if the oil pressure gauge is inop? :rolleyes:

FYI: since you appear to answer maintenance questions here, still waiting for your answer to a maintenance question on the other thread... or was the suspense too much for you?;)
 
I had an A-65 on my homebuilt Jodel. It did that all the time. These engines were famous for it. Much of the trouble was the metal-to-metal fit of the pump cover plate, and over a few days the oil would all seep out of the pump. I used to take the oil temp bulb out of the oil screen and pump some oil in there with a pump oiler and it would lube the pump enough to prime it. I later made a preoiler pump and permanently installed it on the engine mount and would give it a bunch of pumps before startup. It drew oil out of the tank and forced it through a check valve into the oil pressure line and would force oil all through the oil system backwards and into the pump. Worked really well.
 
There's a lot of A & C series small continental owners that would like to see the details of how you did that. Raising the tail high worked on my J-4 but that may not work for everyone.

As you know what we are trying to do is improve the ability of the oil pump to briefly pump air to reprime after a long term shutdown.
 
7 posts since I posted my original I apologize for my errors and lack of clarity. I have become overly dependent on Google and tend to be a tad sarcastic occasionally. It really is a Continental A-65 wish to claim brain fart because thinking 8A Luscombe I don't know how to edit my subject line to read A-65 lost prime to oil gauge, yet. Airplane has been sitting a couple months don't know why it drained out but figured since it's 78 years old it is likely that this has happened to others who are at this site and would know a solution maybe less messy. My A&P did give me other options but I chose not to put them into the original post to minimize clutter in the solution that you may provide.
 
Jim Rosenow said:
Used to have that problem on a Vagabond if it sat for awhile. For some reason, if we'd lift the tail to head level, set it back down and then start, we'd get oil pressure every time. YMMV, of course.

Jim
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My first lessons were in a Vagabond, and the instructor would run around and raise the tail after the engine started - every time. I think the Vagabond only flew when I was taking lessons, about once a month in 1964.
 
Thanks Dan did you create a STC or just show work done on your experimental?
 
LB 408A said:
Thanks Dan did you create a STC or just show work done on your experimental?
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No STC. Just a mod. It wouldn't work for you, and I don't know of any certified manual preoiler. There are some electric ones, I think, but that just adds more weight.

The lack of oil pressure after start causes some serious rod bearing wear. I had my crank reground when the oil pressure got too low, a sign not only of a worn pump but of worn bearings. I found the front rod journal worn about .004" undersize, most of the wear on the high (pressure) side. The others were worn, but somewhat less. That front bearing is the last one to get oil after startup. I also lapped the pump cover to get the fit as close as possible. There really isn't enough contact area to use any sort of sealant, and sealant can also squeeze out into the pump and end up causing trouble in the bearing interfaces or plugging hydraulic lifter orifices.

Old airplanes are fun.

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I also made the check valve that went between the oil pressure gauge line and the preoiler. It isn't shown here. It prevented engine oil pressure backfeeding into the preoiler.

In Canada you could reregister your 8A in the Owner-Maintenance category and make this thing and install it.
 
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Set her tail on a stand when parked maybe? As yeA this is a wide spread gremlin in these old gals.
 
Huckster79 said:
Set her tail on a stand when parked maybe? As yeA this is a wide spread gremlin in these old gals.
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That would just drain out what tiny bit is left in the oil pump cavity and oil screen housing. Make things worse.
 
Bell206 said:
My questions were to the OP. But wow. So you deduced the accessory housing is worn and determined all those other answers from the OP. So what if the oil pressure gauge is inop? :rolleyes:
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That is what 50 years experience gets you, we all know there has not a accessory case built in a long time.
You disconnect the pressure gauge to induce oil into the accessory case. that is where the oil pressure pump.
Of course when you disconnect the gauge, it won't work. you will reconnect when the prime is achieved.
 
Capt. Geoffrey Thorpe said:
And, I don't understand why the gauge would need to be primed. I can see the pump loosing prime, however.

http://bowersflybaby.com/tech/fenton.html#Cant_Get_Oil_Pressure
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Harry's way has you remove the big brass nut..( pressure regulator) the other way is to induce oil directly to the pump.( thru the oil pressure system).
but you must remove the restrictor fitting on the gauge line. it is easier to get to.

remember it doesn't take a lot of oil. getting the gears wet is all you have to.
 
Dan Thomas said:
No STC. Just a mod. It wouldn't work for you, and I don't know of any certified manual preoiler. There are some electric ones, I think, but that just adds more weight.

The lack of oil pressure after start causes some serious rod bearing wear. I had my crank reground when the oil pressure got too low, a sign not only of a worn pump but of worn bearings. I found the front rod journal worn about .004" undersize, most of the wear on the high (pressure) side. The others were worn, but somewhat less. That front bearing is the last one to get oil after startup. I also lapped the pump cover to get the fit as close as possible. There really isn't enough contact area to use any sort of sealant, and sealant can also squeeze out into the pump and end up causing trouble in the bearing interfaces or plugging hydraulic lifter orifices.

Old airplanes are fun.

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I also made the check valve that went between the oil pressure gauge line and the preoiler. It isn't shown here. It prevented engine oil pressure backfeeding into the preoiler.

In Canada you could reregister your 8A in the Owner-Maintenance category and make this thing and install it.
Click to expand...
It would be nice to install a pre-oiler, but the Luscombe 8A is a certified US aircraft.

the best solution is fly more, don't allow the oil to drain down.
 
Tom-D said:
That is what 50 years experience gets you,
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Tom-D said:
Bell should read, and learn :) some know, some bloviate.
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Ha. Well my 40 years experience taught me to ask questions first, especially when the OP was incomplete and which the OP further clarified 7 posts later. But whats funny, is that my 40 year experience tends to consistently follow those of people like Dan or Harry when it comes to correcting issues like this. As to learning vs bloviating, we're still waiting for your answer to the question in the annual thread to determine if you're bloviating there or trying to teach us something. Unless that is your 50 years experience was just on A-65s?
 
Bell206 said:
Ha. Well my 40 years experience taught me to ask questions first
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Then you should ask some who knows, my first A-65 was my J3, (1954) and I've probably rebuilt 50 of them.
have you ever seen one?
 
flyingbrit said:
Some have a misconception that the line to a pressure gauge must be full of whatever fluid it is measuring. This is absolute bunk. Pressure is pressure whether transmitted by air, water or oil. Your A&P either has this misconception or he is playing a joke on you. Has he ever asked you to get a bucket of propwash?!
Click to expand...
many cold weather operator will flush the gauge line with kerosene so the gauge will read quicker.
 
Tom-D said:
have you ever seen one?
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The 1st two engines I overhauled were A-65s. As to asking questions, I tend to ask people who are knowledgable and capable of answering all my questions like Dan or Harry would.;)
 
Tom-D said:
show them.
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Sure... but 1st show us a picture of you, in flight, in the left seat of a Connie... Or any Navy aircraft for that matter... Or answer any of the questions presented to you in the past week.:rolleyes:
 
Bell206 said:
Sure... but 1st show us a picture of you, in flight, in the left seat of a Connie... Or any Navy aircraft for that matter... Or answer any of the questions presented to you in the past week.:rolleyes:
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Ya/ like the NAVY has pictures of those.
Nothing secret about picture of A-65
 
Tom-D said:
Ya/ like the NAVY has pictures of those.
Nothing secret about picture of A-65
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Oh so your work in the Navy was "secret" now? :rolleyes:

Besides why would I have taken pictures of an obscure engine overhaul 35+ years ago? Or any other maintenance I performed? So what's your point?
 
Bell206 said:
Oh so your work in the Navy was "secret" now? :rolleyes:

Besides why would I have taken pictures of an obscure engine overhaul 35+ years ago? Or any other maintenance I performed? So what's your point?
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ever see what it takes to a picture approved of any aircraft for the NAVY.
I have 5 cruise books. want to see?

I guess you have no point, or proof you have ever done anything.
 
Tom-D said:
Harry's way has you remove the big brass nut..( pressure regulator) the other way is to induce oil directly to the pump.( thru the oil pressure system).
but you must remove the restrictor fitting on the gauge line. it is easier to get to.

remember it doesn't take a lot of oil. getting the gears wet is all you have to.
Click to expand...

here is the big brass nut Harry mentioned.

this is about a 0-200 but it is the same part number
 

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Tom-D said:
ever what it takes to a picture approved of any aircraft for the NAVY.
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I don't know but there are plenty of Naval flying pics posted on PoA with no problems.
Tom-D said:
I guess you have no point, or proof you have ever done anything.
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Proof? Got plenty of workorder and logbook entries. Also have quite a number of answered maintenance questions with references on PoA. You?
 
Bell206 said:
I don't know but there are plenty of Naval flying pics posted on PoA with no problems.

Proof? Got plenty of workorder and logbook entries. Also have quite a number of answered maintenance questions with references on PoA. You?
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Bloviation don't count.
It would more real if you count all the posts that you changed topics mid discussion.
 
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thanks Capp. After#18 looked up PO they had addtl helpful info but i wont add to this thread
 
OK, sounds like OP's problem is the oil pump losing its prime, not the gauge of which I think we agree losing prime is impossible. However this does not change the fact that the OP's A&P's advice is awful: start the engine and run it until oil is visible and making a mess in the cockpit. This would likely cause bearing wear while waiting for the pump to self prime, if it ever does.
 
Loosing prime to an A65 oil pump is common. It happens all the time in the Champ I fly. Hold the tail of the airplane in the air about 5-6 feet for 30 seconds to a minute so the oil can refill the pump start again. Works just about every time. The tail trick is as old as the A65.
 
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