Oil pump low pressure, prime oil pump

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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dpcd67
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Re: Oil pump low pressure, prime oil pump

Post by dpcd67 » Sat Jun 11, 2016 5:01 pm

We do use both systems and neither is hard to learn; of course, all of us grew up using feet, gallons, and pounds. . If you work on vehicles made with English bolts, you need to use that. If you are working on a modern car made with metric bolts, you need to use that system. But no one is going to mandate a change to Metric; it would cost too much. Each product will gravitate to it on it's own, which will take another 100 years. Anyway, all the TMs are in English, the jeep was made under the English system, so changing all the dimensions to metric is futile.
BTW, it is illegal in this state to post speed limits only in the Metric System. Who came up with that law?
U. S. Army 28 years.
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MB1943EB
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Re: Oil pump low pressure, prime oil pump

Post by MB1943EB » Mon Jun 13, 2016 4:32 am

Nice discussion on metric/imperial. Looks like I must have hit into a beeyard with a stick, as we'd say in my native language. Please excuse my funny English.
As long as we remain tolerant and keep a good sense of humour, then we're fine. Let's appreciate both systems, imperial + metric. They both have their advantages + disandvantages. Fact is: MB/GPW = imperial, so I adjust to it, no problem for me. I can live with that. When in Rome, do as the Romans do. Not all people in this world adjust when they should do.

Back to the actual subject. Ben, John, I had promised to give you a feedback: the new pump is a rotor pump ("Eaton pump"), modern style, very common, with internal rotor with 4 teeth, external rotor 5 teeth. No picture here, as this pump can easily be looked up in the web.

Clearance between cap + internal rotor face = set to 0.05mm (0.00196850393701", for my imperial friends...) by manufacturer. As there was no gasket supplied with the pump, I initially had put on one of my gaskets, about 0.5mm thick (0.02"). That was the reason for why pump could not build up enough pressure. I had made a mistake, should have used my brain prior to using my metric/inch tools. Solution: no gasket, just a very thin layer of liquid sealant (Loctite or similar) on the outer regions, NOT close to the outer rotor though. After that, clearance is still 0.05mm = perfect. I cannot say if cap + housing would seal without any liquid sealant; cap's surface = appears to be lapped.

Priming oil pump: if you look at the oil pump from the cap's side, then turn it clockwise and at the same time feed oil into the left hole, that's the intake (feeding / suction) hole. After a few turns, you will find oil coming out of the right hole - that's the pressure side. When you think the pump is well filled, stop feeding oil and wipe away excess oil. My experience: priming like this is sufficient, no dry run occurred, pressure was present right from starting the engine. Nevertheless, you can make a few clockwise turns with the crank handle.
Recommendation: do not put any special silicone between pump's flange side and engine block. Reason: messy, and if applied too much it will squeeze into the intake / pressure holes - no good. The flange gasket supplied with the new pump looks silverish, and it has enough flexibility to do a good sealing job.

New pump runs very nice :mrgreen: . 3-4 drops of oil at the beginning, but no additional tightening of the screws was necessary. Tight and 100% dry now.
Do not play with the shims that regulate the pressure relief valve, there is just no need for that, it's all set by the manufacturer. When cold, pump's max. pressure goes up to 58psi at higher revs than idle. When hot, idle is at 15psi (wonderful!), and at about 50 at higher revs. Plunger of the pressure relief valve opens at about 60psi (dashboard gauge reading) - fine!

Once one has understood the basic ideas of the engineers who have developed this pump, things become clear. I hope that all this information is of use for the Jeep community. By the way: from days ago on, I've had several good laughs when I worked with my imperial wrenches. I value them, as they remind me of the fact that there are many ways to Rome. Not only one.

I send metric & imperial greetings from "ancient Europe".
Eckhard
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'I've gone out to look for me. If I should get back before I return, please hold me until I get here.'
(Col. W. Klink, Stalag 13)

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