Oil pump

flatjack9

flatjack9

Well-known member
Whenever I start a new engine, I crank the engine over with the plugs out until I have oil pressure. I've done this with MCF remote filter engines also. Well I had one that would not pump. Not even out of the hose that comes out of the pan with everything else disconnected. I pulled the pan to check things and all looked well. I even modified my pump test rig to test the pump and it pumped like crazy. All back together, no flow. So I bit the bullet and started the engine and had pressure in 15 seconds. Could have saved myself a lot of grief if I had just fired it in the first place.
 
flatjack9 said:
Whenever I start a new engine, I crank the engine over with the plugs out until I have oil pressure. I've done this with MCF remote filter engines also. Well I had one that would not pump. Not even out of the hose that comes out of the pan with everything else disconnected. I pulled the pan to check things and all looked well. I even modified my pump test rig to test the pump and it pumped like crazy. All back together, no flow. So I bit the bullet and started the engine and had pressure in 15 seconds. Could have saved myself a lot of grief if I had just fired it in the first place.
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Interesting. I've always done the same method you described and it's always worked. I just put together a 1940 engine I rebuilt. This one is tight, she'll require 12 volts for the initial start.
 
Jack,

If you remember the two oil pumps I sent you to be tested about 6 months ago, the one marked "Merc pump" had exactly that problem. I could not get pressure not matter how much I cranked it (this was in an engine that had been sitting 20 years). I finally pulled it and replaced it with another that I had packed and it had oil pressure with 30 seconds of cranking. As you probably remember, that "Merc pump" checked out good for you. I think that if a pump is too clean or too dry, this problem can manifest itself. Glad you got 'er going.

(In the next couple of weeks I hope to replace the Speedway pump in my fresh built 258" engine with one I got back from you. The results should be enlightening.)

You're a braver man than I am. I contemplated just starting the engine, but just couldn't bring myself to do it; I installed a packed known good pump instead.
 
I have heard reports that the MCF system will not pump if the filter is first filled with oil at the time of a oil change?? But, I have not heard of that problem with an open hose. I do not think "packing" makes any difference with the MCF problem because the reports I have heard about were at the time of oil change when the pump was well lubed.
 
Yup, I was a little nervous, but had run out of options. I always dump some STP in the pump body. Always worked for me. The only thing I can think is that my test rig turns the cam over at about a 1000 rpm and of course the engine cranks at a lot lower rpm. i do use 12 volts.
 
Mine would not pump after draining oil and having the the engine upside down on a stand. I cracked the in line to the filter and it pumped.
This wsa 95% filter filled before installed. I think it blocked the pump.

John
 
JWL said:
I have heard reports that the MCF system will not pump if the filter is first filled with oil at the time of a oil change?? But, I have not heard of that problem with an open hose. I do not think "packing" makes any difference with the MCF problem because the reports I have heard about were at the time of oil change when the pump was well lubed.
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I have heard that too, but in 25 years with the engine in my 39, it has never happened.
 
I have also had difficulty getting oil pressure by cranking it over with my full flow system; even with 12 volts. It's worse the longer it sits after draining; but the pressure always comes up immediately after starting. The pump works quickly turned by hand in a pan of oil. I attribute it to an air lock without any other evidence.
 
One thing you could have done was to put a hose and plastic funnel on the oil line!fill the funnel with oil!then turn the engine over backwards till all the oil is sucked in ,then reconnect the hose and the pump will be full of oil.
Lawrie
 
I originally was cranking with just the bare hose open from the oil pan. Nothing. As I said, I then hooked everything up and fired the engine and had pressure in about 15 sec.
 
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