Oil Pump Bench Test

E28 technical advice asked and given! Troubleshooting, modifications and more.
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ScottKendall
Posts: 65
Joined: Jul 07, 2015 10:01 PM
Location: Kentucky

Oil Pump Bench Test

Post by ScottKendall »

Hi all,
I rebuilt my oil pump over a year ago and I just got around to making a test bench for it.

With sprocket conversion for idle of 750 engine RPM reduced to oil pump RPM of about 500.
Here is a video at 320 oil pump RPM.
https://www.youtube.com/shorts/HVlDoFw7Jss

Here is a video at 700 oil pump RPM. Note that the air bubbles are gone. Other test show no bubbles above 500 RPM.
https://www.youtube.com/shorts/bPLAAH0BwrY

My question to all of you is this a good oil pump? Or an oil pump that could be improved?
Last edited by ScottKendall on Mar 07, 2023 3:49 PM, edited 1 time in total.
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Oil Pump Bench Test

Post by Mike W. »

I give you points for creativity, but I don't see it as a valid test. The pump has to be able to pump X liters, at X pressure at X RPM at X viscosity. If it will pump X liters, but only at say 2PSI instead of 20 PSI, it's a problem.

Traditionally oil pumps are judged to be good or bad by measuring the clearances, rotor to rotor, rotor to case and cover to case. It is then assumed if clearances are within spec that the pump is within design parameters and will perform as expected. Something that people have been doing some in recent years is replacing the gears inside but not the whole pump, and saving a bunch of money while doing so. It's not the same as a new pump, but it seems to work and be an improvement at a less than breathtaking price.
ScottKendall
Posts: 65
Joined: Jul 07, 2015 10:01 PM
Location: Kentucky

Re: Oil Pump Bench Test

Post by ScottKendall »

There are some additional details.
1. All clearances are to the spec. Rotor to Stator, Stator to housing, and Rotor/Stator to wall clearance.
2. In the test shown, I am well over the spec min pressure, but I have no spec for volume flow at the spec'd min and max pressures.
3. Of the info out there, most people are concerned with how much air the pump blows rather than pushing oil. See this guys vids: https://www.youtube.com/watch?v=-kgUbMHBwP4

I will attempt to make better videos in a couple of days. AND yes, I fixed the videos so people can see them.
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Oil Pump Bench Test

Post by Mike W. »

I don't think a test outside of a lab is going to be all that useful or significant. But if the clearances are good, and the engine it came out of wasn't showing oil pump problems, I'd go with it. I've run M30 oil pumps past 300K miles without issue. Sometimes taking a while for the light to go off, like 15 seconds, but once off it never came back on, which is the best test. You could throw new rotors in there if you're concerned, it would surely be better, but absent a history of problems and with good clearances, I'd run with it and not worry.
adam_poll
Posts: 206
Joined: Jul 23, 2014 8:19 PM
Location: Kitchener, Ontario, Canada

Re: Oil Pump Bench Test

Post by adam_poll »

ScottKendall wrote: Mar 07, 2023 3:57 PM There are some additional details.
1. All clearances are to the spec. Rotor to Stator, Stator to housing, and Rotor/Stator to wall clearance.
2. In the test shown, I am well over the spec min pressure, but I have no spec for volume flow at the spec'd min and max pressures.
3. Of the info out there, most people are concerned with how much air the pump blows rather than pushing oil. See this guys vids: https://www.youtube.com/watch?v=-kgUbMHBwP4

I will attempt to make better videos in a couple of days. AND yes, I fixed the videos so people can see them.
So that test shown in the video is misleading, all M30 pumps no matter their condition will ingest significant air if the port on the bottom of the pressure relief valve is open to air as it gets sucked in there. This video shows it cleary and was a bit of a revelation for me when I found it - https://www.youtube.com/watch?v=pfASyeoiNcE

In the video of your tests it looks like you had that covered, as long as you are getting good flow without bubbles in it then I'd say you are good. For my car which sees track time and has an oil cooler I went to the drive gear from an M30B35 which ups the oil pump rpm a bit to deliver more oil at idle and overcome the extra pressure drop of the cooler when it is in the circuit. You need to use the shorter 44 link chain and a few more shims under the pump to tension it properly (I made my own with some 22 gauge sheet metal which worked out around 0.7 mm). I also built a small baffle into the front left corner of the pan to make sure that port is always in oil even through high G left turns when it could be uncovered.
ScottKendall
Posts: 65
Joined: Jul 07, 2015 10:01 PM
Location: Kentucky

Re: Oil Pump Bench Test

Post by ScottKendall »

I know this is old, but I do this for others looking for answers in our past posts.

I'm not contradicting adam_poll in anyway by explaining the following. I'm adding to info in this thread.

I got it to STOP SUCKING AIR. I was pretty sure that the port to which Adam refers was submerged in oil. I was wracking my brain and finally I said, "The air can't be cavitation because the bubbles would collapse when pressurized." It was legit air getting in somewhere. There is only one place it can in and that's the draw chamber. I put very tiny bit of make a gasket Permatex red stuff, and it ran completely bubble free.I should have filmed that one too.
adam_poll
Posts: 206
Joined: Jul 23, 2014 8:19 PM
Location: Kitchener, Ontario, Canada

Re: Oil Pump Bench Test

Post by adam_poll »

ScottKendall wrote: Jul 20, 2023 9:00 AM I got it to STOP SUCKING AIR. I was pretty sure that the port to which Adam refers was submerged in oil. I was wracking my brain and finally I said, "The air can't be cavitation because the bubbles would collapse when pressurized." It was legit air getting in somewhere. There is only one place it can in and that's the draw chamber. I put very tiny bit of make a gasket Permatex red stuff, and it ran completely bubble free.I should have filmed that one too.
Is there anyway you can post where you added the gasket maker? Was it in between the pump housings or somewhere else? I'm not having any issues but the pan will be off this coming winter and if I can make the oil pump any better I will. I'd be a bit concerned adding anything between the housings though as I wouldn't want to open up any more clearance around the rotors which would reduce the effectiveness of the pump, maybe an anaerobic sealer would be ok as it would almost all be pushed out as the bolts are tightened.

I watched a video recently where they had a coating applied to pistons to take up some extra room in the bores and they claimed to have seen good results with oil pumps as well. Basically the coating wears in leaving a perfect fit, they developed it originally for oem supercharger rotors so an oil pump rotor sounds like a perfect application. I know my housings aren't perfect though either but I doubt there is anything I can do about that without machining. https://www.line2linecoatings.com/
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Oil Pump Bench Test

Post by Mike W. »

The manuals never mention it, but I always put a thin film of Permatex #3 on the cover. Just the idea of metal on metal with no gasket makes me think it's going to leak. Dunno if it's good or bad, but it's never caused a problem.
adam_poll
Posts: 206
Joined: Jul 23, 2014 8:19 PM
Location: Kitchener, Ontario, Canada

Re: Oil Pump Bench Test

Post by adam_poll »

Mike W. wrote: Jul 20, 2023 12:37 PM The manuals never mention it, but I always put a thin film of Permatex #3 on the cover. Just the idea of metal on metal with no gasket makes me think it's going to leak. Dunno if it's good or bad, but it's never caused a problem.
That stuff has become my Frank's hot sauce for the garage, I put that shit on everything (almost). Thinking back I'm almost surprised I didn't when I reassembled the pump last time (bolts did get loktite before torqueing).
Chimi-Changa
Posts: 1601
Joined: Nov 08, 2011 11:02 PM
Location: West Bro, MA

Re: Oil Pump Bench Test

Post by Chimi-Changa »

Have my bottom end opened up, anyone know where I can find where exactly to measure my pump for wear and what the measurement spec should be? It had one shim in there already.

Thanks!
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Oil Pump Bench Test

Post by Mike W. »

Chimi-Changa wrote: Aug 04, 2023 3:27 PM Have my bottom end opened up, anyone know where I can find where exactly to measure my pump for wear and what the measurement spec should be? It had one shim in there already.

Thanks!
Technically from the E12 manual, but still M30. Don't think it changed much.

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