Oil Pump Dyno

[WConley]

Bill -- Nice setup. I go away for the weekend and I miss posting. I have seen alot of this stuff ...

Doug - Great to hear from an expert.  Your confirmation of these issues gives me confidence during this early phase of stumbling.  I'll keep plugging away and posting what I find.  Thanks!

- Bill

[WConley]

Some of this could be made as a drop in   . I am sitting here looking at the mill. A 1/2 cover with a receiver socket in it to receive a longer stud coming out of the center of the rotor . That would solve that part of it pretty quick. Wouldnt need a longer drive shaft or anything other than whats already offered.

It may come to something like that.  I do have a couple of tricks that I want to try first 

[Heo]

The pressure distribution on the oil pump will side load the rotors - causing one sided wear.  Melling addressed the issue with some of their SBC race pumps by extending the shaft into the cover.

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...

Never had a melling pump that was square machined twist a new one by hand without oil, open it up and
you see that the rotor scratched the cover in one spot....The pic you show here is what i found in every melling
pump i opened up. In my eyes they are junk....but whats the alternativ

[pbf777]

I wonder if you could block the bypass on the stock pump, put a tap in the feed into the oil filter adapter with a pressure relief valve,

     Yep, a remote by-pass can be plumbed a number of ways defeating the requirement at the pump itself.   

.....and then cycle the bypass from that relief valve through a mini dry sump tank and back to the pan.  If that would work, it would at least reduce or eliminate the bubbles in the oil going back to the pan...

     The remote sump tank is fine, particularly in instances where the existing oil pan sump section is of questionable execution or capacity, but solely as such is perhaps excessive complication as this execution would probably involve an increased oil volume it would probably be that that lent itself to the greatest value as the cycle rate of the total oil volume would be reduced, this presenting the greater opportunity from the vapor to self purge, which is one of the intentions of the typical oil sump (pan), but still perhaps one will form "stages" of separation.

     And as stated previously, and oil reservoir that is greater in vertical dimension will do better at vapor separation as the heavier oil liquid will sink as the lighter vapors will rise, and with a greater volume of material reducing the cycle rate, as such permitting a greater time element this promoting a more thorough result; all this assuming you are drawing from the bottom of course.   

     Scott.

     

[Blueoval77]

Tried calling Titan and got a message saying they are out until after the holidays.... Sent a mail inquiring about the pump.
Now as far as this melling goes.... I guess this is just one of those things you never really think about. Or I hadnt at least , but I have one torn down here on the bench now and the design on this thing is garbage honestly. I suppose the price does indeed reflect what you are getting but from an engineering standpoint its horrible.
This unsupported end is the worst of it all and so easy to fix honestly...
Yeah so now I am ordering a 5/16 Rotary Broach , Thanks Conley , this is all your fault ya know...

[turbohunter]

Thanks Conley , this is all your fault ya know...

LOL
I can just see the suits at Melling. Our FE sales were great then all the sudden pfft! 

[Blueoval77]

Yeah im not trying to be mean , I am told that I am "Brash" on a regular basis . These things have been working for many years and doing what they do ,  But if your looking for issues you gotta start right there . There is no way in hell that thing doesnt cause cavitation just flopping around loose in there like that.... No flippin way... I mean its fairly tight in the upper sleeve that supports it but fairly tight probably turns into a sloppy mess when this thing is at full load in the upper RPM range. Just the nature of how it works will make it start bouncing...
But yeah , its all his fault....

[Royce]

Would a spur gear pump work any better?

[frnkeore]

Would a spur gear pump work any better?

I don't think so but, maybe a vane pump?

[pbf777]

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.

     

[WConley]

But yeah , its all his fault....

Glad to be of service 

Seriously, I got interested in oil pumps precisely for this reason.  The technology has stagnated - been on autopilot for decades.  Yes Frank, a vane pump will work better but they are very expensive and delicate.  Some high-end engines are using those now.

This will be interesting to see play out.  I’ve got some of my own ideas in the works.  I’m also interested to see what that rotary broach produces!

[WConley]

Scott - I did briefly dead-head the pump at low speed a couple of times, while calibrating my torque load cell. I also noticed a pretty good scar on the pump body bore, indicating something got ingested.  I’m not going to totally blame the pump design.  I may be just as much to blame!

New pump coming soon.  Then we’ll see where we are.

[WConley]

Would a spur gear pump work any better?

Royce, from what I understand spur gear pumps have significantly less capacity, especially at lower rpm.  I read that this is the reason the manufacturers have gone away from them.

[pbf777]

Would a spur gear pump work any better?

     Many feel so!  But they won't draw as well, this due to the lack of the previously discussed larger chamber pressure depressions being presented as in the Gerotor pump; and they beat and foam the oil to a greater degree also.

     But they aren't as tendent to locking when plagued with the ingestion of foreign particulate, but once such happens they will continue to self-disintegrate polluting the oil supplied with their own particulate, but if on the late lap of the 500 miler and something gives up in your engine, the pump might consume it, spit it out, and keep going a little bit longer.     

     Scott.

[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.