Oil Pump Dyno

[Heo]

A problem i had noticed on all Mellings pumps, The bottomplate is all to soft,just a piece of mild steel......................When we still had the bolt factory here in town i made new bottom plates  and let them heat treat and flatgrind the bottom plates, problem solved.

      Note that different applications may be of a steel stamping while others may be of a casting.  We hand lap to aid in squaring and establishing flat the bottom of the pump bodies and the cover plates, along with the rotor & scroll.  We have in some applications had the plates nitrited to reduce the galling (but our local heat-treating establishment has closed-up!     ) and yes as stated have previously doubled them up with say a non-treated backup (now you have to surface the first plate on both sides!) and longer bolts (check pan clearance!)  But this was mostly for the endurance engines or when one is requiring an increased pressure (100 P.S.I.+) application.  I never established, that at standard pressures, for fact that the covers were bowing significantly, as on observations perhaps the most one was accomplishing was perhaps reducing the oil seepage rate, but we were trying to "cover" all the bases so to speak, and I agree in that that thin little plate sure doesn't look to impressive.       

     Scott.

     

This is A LOT of wear!  That gouge is about 0.012" deep.  The rotor is also noticeably loose in its bore compared to the M-57B pump I just tested.  At first I thought it was squareness of the pump bottom surface relative to the input shaft bore, but I was checking relative to a wonky bore.  Clearly this pump is toast.  You can move the inner rotor back and forth against the outer rotor, which explains the funny noises I heard.  Have to figure out why...

     I believe you mentioned that you "dead-headed" pump in testing - that will do what your looking at, for sure!   

     

............is it, remotely, possible that the witness marks you see on the HV cover plate might be evidence of plate deflection vs. questionable machining?

     I believe although all fault often cannot be placed on a singular door step, and there maybe "some" defection in the plate, thou we have witnessed no significant change in this wear pattern with heavier covers, and since this wear pattern is (in my experience) most always most appreciable on the high pressure side in rotation of the rotor & scroll to me this indicating that as the rotor & scroll is attempting to force oil upward the same force is attempting to drive them out the bottom, and since there is clearance about the cicumference of the scroll and the locating shaft of the rotor coupled to an end-thrust in both to the housing and cover, these are allowed to cock in their relationships in reaction to the load.     

     Also the 385 series engine is another application where the rotor shaft extends in to the cover.     

     Scott.

     

When i say to soft metal in the cover i don't talk about it bowing of the pressure but to soft so
the rotor galling the cover. The reason i used to make a thicker cover was to minimice the warpage
from heat treating. I don't know the terminology in English, but you "carb" the surface to get a really
hard surface then grind it therefor you cant have much warpage because the hardness just go so deep

[Heo]

Would a spur gear pump work any better?

It is the quality on the pump thats wrong not the type
i have opened Mercedes pumps that had 450000 miles
under the belt and not a scratch on the endcover

[WConley]

http://fepower.net/simplemachinesforum/index.php?topic=3977.msg42219#msg42219

Scroll down to se my new pump not installed yet and already scored and not
machined in a right angle.

Yes Heo - That is what the new M-57B standard volume pump looks like after five minutes of run time.  To me that is normal and good.  No machined groove!

[Blueoval77]

You can hand lap and square up and enlarge and smooth all you want , that rotor is still going to have an unsupported side load that is just made worse by its own design. It is indeed its own worse enemy . Having 4 lobes you are going to get that pop pop pop pop over and over pushing away from the load and cocking the shaft and rotor at a frequency which I am gonna say will help with cavitation.
The fix here seems simple if the dimms on the pumps are consistent . Say does one cover plate bolt onto 10 other pumps with no alignment issues . There is really no register for that cover and that is an issue in itself . From just some quick measurements it looks like the rotor shaft should be lengthened to around 3" giving it 3/4" sticking out the bottom of the rotor to then plug into a bushing or bearing in the 3/4" cover . Of course it would only need to be 3/4 in the area of the shaft and the rest could be milled off leaving a protrusion in the exterior of the cover.
Im just thinking out loud here as I gather up scrap . The rotor shouldnt be coming in contact with the cover at all and the cover material shouldnt matter as long as it doesnt bow.

[Heo]

http://fepower.net/simplemachinesforum/index.php?topic=3977.msg42219#msg42219

Scroll down to se my new pump not installed yet and already scored and not
machined in a right angle.

Yes Heo - That is what the new M-57B standard volume pump looks like after five minutes of run time.  To me that is normal and good.  No machined groove!

yes but that pump is not instaled yet only twisted by hand and scratches that snag your nail
If you take a file to the cover,  it files just like cold drawn sheetmetal. But take many oem pumpcovers
a file almost dont leave a mark on the cover or the gears/rotor.  I have a Mellings Cleveland pump
out in the shop, totaly toast. Cars total milage 50000 miles original FE freeze cracked in 74 when
Ford Put in a 400 Cleveland. Someone  put in a Melling HV pump after that and the car have
not been driven sine early 80s so give it 30000 miles and totaly toast...i shall take a file to the
gears tomorrow and se.  Had been interesting to heat treat a cover and gears and test it in the OP dyno
But since the bolt factory is gone i cant suply you with a set

[WConley]

Thanks Heo!  I actually have some tool steel and a CNC milling machine.  Could be of some use, especially as the ideas keep popping out about a pilot-supported rotor.

[Blueoval77]

Man you have a CNC machine right there . Make some really gourmet stuff and do a one piece rotor with shaft . Stick it in the lathe after and run the broach in there to get the hex and you are done. Then whip up a fat bottom plate with a bearing or bushing and you are a millionaire......   

Attached is a cover from an HV that had maybe 15 passes on it . Came out of a running CJ with good mains and rods and aside from the rear cam bearings being screwy it was fine . That cover doesnt look fine...

[WConley]

No that cover doesn’t look so hot...  As for manufacturing kits for oil pumps, I don’t see enough demand to justify the cost and time.  I make my living designing stuff.  Every time I try to make things, I end up making Home Depot greeter wages!

[Blueoval77]

LOL , thats the suffering for the greater good man......THink about how many lives you would improve !!!! 

[frnkeore]

You can hand lap and square up and enlarge and smooth all you want , that rotor is still going to have an unsupported side load that is just made worse by its own design. It is indeed its own worse enemy . Having 4 lobes you are going to get that pop pop pop pop over and over pushing away from the load and cocking the shaft and rotor at a frequency which I am gonna say will help with cavitation.I have recently worked on 3 different pumps. Aluminum 302, Melling 302 and a melling FE. Dimensionally the aluminum pump was best. The cast iron pumps, were off up to .0015 in depth, side to side. I use a depth mic and measure 4 places. Then square them up with a bench stone and make sure that they are no more than .003 end clearance. I took the alum one down to min .0015. All the covers were cast iron and I resurface them.
The fix here seems simple if the dimms on the pumps are consistent . Say does one cover plate bolt onto 10 other pumps with no alignment issues . There is really no register for that cover and that is an issue in itself . From just some quick measurements it looks like the rotor shaft should be lengthened to around 3" giving it 3/4" sticking out the bottom of the rotor to then plug into a bushing or bearing in the 3/4" cover . Of course it would only need to be 3/4 in the area of the shaft and the rest could be milled off leaving a protrusion in the exterior of the cover.
Im just thinking out loud here as I gather up scrap . The rotor shouldnt be coming in contact with the cover at all and the cover material shouldnt matter as long as it doesnt bow.

This is basically what I would also do but, I don't think the shaft would need to be longer than 1/2". Aluminum is a pretty good bearing material so, I would first let it run with .001 clearance in the cover and see how that holds up. Replace with bronze if it doesn't.

With the support you will need 2 dowel pins but, there is no room to put them in the housing. What you can do in that case, is use 5/16 shoulder bolts (1/4x20 thread), in 2 screw holes, inline with the thrust direction and use a size for size fit. Not a big expense to try it out.

[Blueoval77]

Correct and that would make the shaft 3" overall in length , its roughly 2.5" now . That is , if you were doing just a shaft instead of a one piece billet rotor.. I am hacking on a 3/4" hunk of AL right now.

[WConley]

I am hacking on a 3/4" hunk of AL right now.

Ill be curious to see what you come up with 

[SSdynosaur]

No that cover doesn’t look so hot...  As for manufacturing kits for oil pumps, I don’t see enough demand to justify the cost and time.  I make my living designing stuff.  Every time I try to make things, I end up making Home Depot greeter wages!

A friend, who happens to Crew Chief for me at the races, always says, "why would I want to pay Summit $50.00 for that, when I  can make one in 8 hours?"

[pbf777]

When i say to soft metal in the cover i don't talk about it bowing of the pressure but to soft so
the rotor galling the cover. The reason i used to make a thicker cover was to minimice the warpage
from heat treating. I don't know the terminology in English, but you "carb" the surface to get a really
hard surface then grind it therefor you cant have much warpage because the hardness just go so deep

     No argument here, and having the standard production pieces nitrited worked well for us, as we didn't have to manufacture anything and I didn't have to explain why we needed ex-number of more dollars because ..........!   I would lap them flat, send them out for nitriting and then re-lap them down again when returned generally not warped excessively as long as the heat-treater individually hung them and didn't just throw them in the bottom of the basket and pile other stuff on top.   I would always double-up on the plates when incorporating the nitrited plates on pump assembly if only because of fear that the these pieces might have become to brittle (as these would be batched with other materials being treated simultaneously and being small/thin relative to much of the rest and no real metallurgy inspection I feared they might have become perhaps a little "over-cooked"!     ) and perhaps might fail (crack) if not for an additional support provided by the more malleable standard piece; which most commonly where used "take-offs" from pumps being discarded, and I always scalped them before scrapping the rest.   

     But back in the hey-day of the FE (and even currently) it had/has not been unpopular to shim the bypass springs in order to provide 110-120 lbs. of pressure, this even at times at operating temperature in competition, (you wouldn't rev. the engine on a cold start-up as the oil filter would at minimum " blow-a-gasket!      ) and I believe this was felt by some in the time to create a force factor that could actually warp the cover, this leading to an unappreciated external pump leakage loss, and an end clearance increase between the rotor & scroll and the upper housing one or both leading to a realized pressure loss; hence the previous statement by another concerning an experience with a product from Holman/Moody "in-the-day" (who may have actually established benefit, versus myself who was only following the "monkey-see-monkey-do" engineering process      ), of the practice to double-up on the covers as a cheap quick fix, and this observation leading to the fabrication later by the better financed individules of sturdier units, which I have seen in both steel and aluminum.   

      Scott.

[pbf777]

The fix here seems simple if the dimms on the pumps are consistent . Say does one cover plate bolt onto 10 other pumps with no alignment issues . There is really no register for that cover and that is an issue in itself . From just some quick measurements it looks like the rotor shaft should be lengthened to around 3" giving it 3/4" sticking out the bottom of the rotor to then plug into a bushing or bearing in the 3/4" cover . Of course it would only need to be 3/4 in the area of the shaft and the rest could be milled off leaving a protrusion in the exterior of the cover.
Im just thinking out loud here as I gather up scrap . The rotor shouldnt be coming in contact with the cover at all and the cover material shouldnt matter as long as it doesnt bow.

     The pumps have been in my experience relative consistent in that which the manufacturer feels is important, and as there is no alignment instrument for the covers beyond of limitations of the bolt holes versus the fasteners the covers swap about just fine.  On the units which due exhibit the extended shaft protrusion into the cover it is that shaft to cover relationship that locates the cover as it is manufactured, this for at least the 385 series engine applications as I'm aware.  But this is less than ideal as upon assembly of these units, one snugs the cover fasteners and then bumps it about establishing the freest turning of the rotor & scroll then torques the fasteners and rechecks the turning effort again.  Is this truly a proper endeavor in locating engineering?  Well probably better than nothing, but truly registering cover and then boring the shaft support in the cover with tooling located off the existing housing shaft bore would be better, and would also make each cover unique to each pump housing. 

      Note that although utilizing the bolt shank for alignment sounds good for something such as furniture making, if you actually measure closely, these will rarely be truly concentric with the turning thread in the hole, this at least not to the accuracy I think we are considering here anyway.       And then the question of how critical has the manufacturer been in the location of the threaded holes in the pump body, somehow I doubt their positions of relative consistency to one another in the singular example in comparison to other examples would prove overly impressive as there is no need for such a critical dimension in the manufacturers' engineering; but this again may only be an indicator if utilized of how each cover to pump body would prove unique.     

     Scott.