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oil pump question 22 Jun 2022 10:26 #236289

  • Lang
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Wee

I think they both have similar relief valves. Number 21 on both drawings. The original beside the outlet and the 3 gear pump on top obviously via a gallery - who knows where the oil pressure is exerting its force in that one?

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oil pump question 22 Jun 2022 11:22 #236294

  • jon_d
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The pinion gear that meshes with the cam is the same part on both.
The outlet position is the same on both. (ie between the 2 RH cogs. Noting the 3 gear pump is the idlers gear. -
Suction is different. (part 31 or 31-1)

Hayseed, not to scale. Good thinking. I also tried to work out if the gears were the same height and same volume.


Here is another twist; as best as I can determine, this is the same pump. The top and bottom castings show cast pipes.
www.amazon.com/-/es/Bomba-aceite-para-Is...1-5-8L/dp/B01BE5NTTS

AHHH, I think I've worked it out. There are effectively 3 separate displacement pathways. The bottom cast pipe sort of shows a feed into the left and right gears separated by the idler.

The top casting shows shows a pipe from the high pressure release to the outlet. The diagram shows the pathways. So, I'm now thinking the volume is 1.5 x a two gear pump.

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oil pump question 22 Jun 2022 12:32 #236295

  • Lang
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Good detective work. Actually two pumps in one. Why 1,5 and not double volume?

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Last edit: by Lang.

oil pump question 22 Jun 2022 14:52 #236299

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Thanks Lang.

Because....( I think) The volume is decided by the teeth passing the external wall of the pump.

There are 3 places where the gears pass the wall vs 2 places on the 2 gear pump

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Last edit: by jon_d.

oil pump question 23 Jun 2022 10:10 #236331

  • mammoth
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So, you are going far away and want peace of mind, particularly when the family doesn't understand "adventure". First up there is no room for experimenting with internal parts that don't belong. 2nd, given that the motor is unknown drop a bearing cap - big end and main, and measure clearance with plastigauge. If it shows gap is within spec you are now confident that there is no problem there. No one has thought that the spring of the relief valve may have weakened, what does the manual say about that? Regards oil my thoughts are keep it simple - regular 15/40 with frequent changes. Next step is to check the end gap of the oil pump gears, refer to manual.
As an aside professional mechanics report problems with replacing rear crank seals that don't leak and there is a special tool to insert them correctly. I replaced mine as a matter of course (before I learnt of the issue) while doing the clutch and got it right first time.

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oil pump question 23 Jun 2022 11:09 #236333

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Found a Cummins Forum and they said, "Cummins says the minimum hot oil pressure for a 6B series is 10 psi at idle and 30 psi at rated power."

Here is the Cummins Manual. The chart at the right is pressure switch settings for engines fitted with alarms. The main chart is the actual recommended pressure. This is a shot out of the actual manual showing 5psi idle minimum not the 10psi quoted in the Cummins forum.

Just had another thought. Do Cummins make "handed" engines ie left and right rotation for boats etc. If they do maybe that 3 gear pump is required to pump the oil with the drive going in the opposite direction?

I am starting to think JD's 3 gear pump (which gives opposite direction gears) is for a Cummins with left-hand rotation. Instead of having a multi use pump you just change to left or right pump as required.
Lang


Lang, I Think you may be a Little confused..!!
Jon_d's engine is an Izusu 6BG1 & NOT a 6B Cummins

Looking at the oil pumps available for the isuzu 6BG1, there are a few types.


Back to the engine;

The engine is a Japanese import, so I don't know the history.


This is from the 6BG1 manual.
"Be who you are and say what you feel...
Because those that matter...
don't mind...
And those that mind....
don't matter." -

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oil pump question 23 Jun 2022 11:33 #236335

  • Lang
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Hayseed you are absolutely right.

All that time wasted but we now know all about Cummins 6B series engines whether we wanted to or not. I was encouraged to keep finding stuff when people positively commented on the Cummins manual screenshots leading me further down the wrong path. If I had read the first post more carefully we might have had the answer.

Anyhow I learned a bit charging around in the wrong paddock and I like to think encouraged JD to keep pondering until he came up with his beaut diagram for the CORRECT engine.
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oil pump question 23 Jun 2022 14:31 #236346

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But Lang..... I knew you were talking about the Cummins and was just interpreting your comments to how they apply to my 6BG1. All good in the end.
So many people get caught up on internet forum imperfections; it drives me crazy when the general intent to to simply help.

Mammoth; I'm not experimenting. The pump is listed in the engine parts manual. My inquiry was to understand the differences between a 2 and 3 gear pump. Thinking about it some more; the 3 gear will be good because the flow will be higher for a lower reving engine. I'm mostly driving at about 1800-1900 so the pressure should be good. 80-90 ks.
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