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Old 30-03-2018, 05:20   #16
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Re: oil pump rotor shaft material

There are many different variations, with the consistency ranging from grease to oil, but most have a molybdenum base and have some permutation of 'extreme pressure' in their description. If two moving parts contact each other in a rebuild, they get a dab between them...bearings, cam lobes, lifter faces, push rod ends, rocker arm pivots and contact points, etc. I like this one, but I think they're all pretty much the same...

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Old 30-03-2018, 08:03   #17
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Re: oil pump rotor shaft material

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Originally Posted by Wotname View Post
FWIW to others not familiar with this oil pump, it is driven by the camshaft so operates at half the engine RPM; thus the OP is probably running the oil pump somewhere between 1,000 and 1,500 RPM.
I agree that on aluminum heads, it's a very hard alloy to start with but the cam bores are oil grooved and oils is pumped through continuously and the revs are low. This is also designed obsolescence. They will have to be bored or replaced if they run dry for any length of time. Cast iron has a much more tolerance to run dry and thus last longer.

But I drift, my apologies. Your repair might give you a long life to the pump and you can always come back and make changes. keep a close eye on the oil pressure.
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Old 30-03-2018, 14:20   #18
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Re: oil pump rotor shaft material

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That the rotor shaft has the 'tang' rather than the 'slot' alleviates to some extent my concern with the strength of the bronze; if the situation were reversed, I would have expected the 'slot ears' to fail at some point...

The clearances in a trochoidal gear pump are critical for it's efficient operation, hence the concern with centering of the drive shaft hole; if the hole is too far off center in any direction, but especially in the 6 or 12 o'clock positions (in regards to maximum and minimum clearance between the drive and driven rotor), flow may be reduced or the pump may lock up.

If, when assembled, the pump spins freely with oil in it, I would err on the side of caution and not worry about any further 'finishing' of the hole.

Both of the materials are soft enough to not worry particularly about galling, especially when run in an oil bath; any minor imperfections in the hole now will polish themselves out in very short order, provided that the pump is adequately lubed on startup.

When I install oil pumps, I squirt all the moving parts with oil, then fill them with engine assembly lube. If possible, (though I don't think it is in your case), after the engine is assembled I fill it with oil and prime the engine with a long drive pin and an electric drill. There is a surprising amount of torque required to turn a primed oil pump, and I'm sure that it is multiplied commensurately when the oil is very cold...
Yea Jim, sorry I described drive wrong when you mentioned key drive & i agreed. Of course it's tang but I was wanting to rush off & drink beer so forgot to correct it. Tang thickness is about 3.5mm. Lucky Wotname posted pics. I synthetic greased rotor for install. Yes it rotates freely with oil in it I was only going to worry about the reamer if I have to bush it as per your shoulder method. Had to grease rotor a few times a week to get it to prime on start up when hole was oval & I'm hoping the re-shafting will cure that problem. It runs about 40 psi when cold & 25 when hot. I turn the engine over with the decompression lever engaged until the oil pressure come up & then drop it. This is my standard starting procedure as I have leaded bronze main bearings ( Yanmars too expensive ) & they not as tolerant as kelmet or tri-metal to dry start. Interesting what you say about it hard to turn when pumping Thanks again for your input, appreciate it.
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Old 31-03-2018, 17:38   #19
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Re: oil pump rotor shaft material

Quote:
Originally Posted by jimbunyard View Post
There are many different variations, with the consistency ranging from grease to oil, but most have a molybdenum base and have some permutation of 'extreme pressure' in their description. If two moving parts contact each other in a rebuild, they get a dab between them...bearings, cam lobes, lifter faces, push rod ends, rocker arm pivots and contact points, etc. I like this one, but I think they're all pretty much the same...

OK, thanks! One of the many products hanging on the racks as I walk past and never take a second look .

I suppose the ordinary oil and/or grease that I use sorta works OK

But nevertheless I'm sure it would be good stuff.
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Old 11-05-2018, 20:07   #20
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Re: oil pump rotor shaft material

Well as you can see from the pic, if it's there, making an oil pump rotor shaft outa bearing bronze to go in an aluminum case is a no-no. So many of you can say I told you so. LOL. Shaft tapers from 8.6mm to 7.7mm.
My machinist friend told me that the rotating part has to be the hard material but I had already made the bronze shaft & thought I was a genius Actually I had a sinking feeling when he told me that as he has been right so often.. Oil pressure dropped from 25psi hot to 12 over 35hrs approx runtime. So it proves, as many of you said, the tolerances are critical. Bronze was strong enough but way too soft.
Have made a hardened steel shaft for the meantime but may go down the bronze bush route later. Will post again if any more mods are done.
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Old 13-05-2018, 10:25   #21
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Re: oil pump rotor shaft material

At least you went in to it well informed and knew to keep a close eye on it. No worries no harm. I think you are like a lot of us, enjoy a challenge and test the norm. But I’m still saying put the bronze bushing in there this time. [emoji2]
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Old 13-05-2018, 16:19   #22
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Re: oil pump rotor shaft material

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At least you went in to it well informed and knew to keep a close eye on it. No worries no harm. I think you are like a lot of us, enjoy a challenge and test the norm. But I’m still saying put the bronze bushing in there this time. [emoji2]
Yes, I bet you will be right as my machinist friend agrees with you but I really have to try the bigger hardened steel shaft as I'm not confident in my ability to machine a 1mm wall thickness or 0.04 in bush. To make a thicker bush I'd have to cut down shaft size from original 8mm to 5mm. May have to try that but will see.
Could have changed shaft during voyage but it was a ballache with no vise.
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Old 13-05-2018, 17:02   #23
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Re: oil pump rotor shaft material

Don't take advice from me 'cause I'm no expert but my take on your oil pump is to use your new hardened steel shaft while you get kitted out or a proper fix.

Get the necessary bamboo reamers or whatever. Work out rough sizes, turn up a brass/bronze stub that fits the reworked hole in the housing, then ream the stub in the lathe, this becomes the bushing, work up a new steel shaft to suit the new bush.

Ya machinist cobber might tell you different; if so, take his advice, not mine .

Your motor is good, you have put in a lot of hours in getting right, but the oil pump is at the heart of longevity.
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Old 15-05-2018, 14:35   #24
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Re: oil pump rotor shaft material

. Fitted latest version of hardened steel rotor shaft ( no bush) yesterday after filing down coverplate mounting face to get 0.06mm ( roughly 2 thou) clearance. Bit of a bastard to do in situ but got it pretty reasonable. Oil pressure roughly the same as when bronze shaft was new. Took about 40mins to get oil reasonably hot running in gear, ( raw water cooled)38 psi cold @ idle 30 hot @ 2200 rpm . 18psi at idle when hot. Happy enuff with those readings. Factory spec is 35-50lb @ 3200 revs ( I think)
Will see now if it will self-prime & how long it lasts.
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