M30 oil pump "problems" - German forum infos

[szacsi72]

Hello everyone. 

I'm not sure if any of you are reading the german forums, but for many years, a controversial topic of the M30 oil pump having a "flaw" has been floating around. I though it would be a good idea to bring it up here.

The origin of this whole idea is the german company 'PM-Tec'.
You can read more about them and their offering here:
https://www.p-m-tec.de/oelpumpenupgrade/
But in short, they state that the main issue is that the M30 oil pump SUCKS IN AIR and cavitates.

Here are two forums, if you have the time, use google translate and read trough it:
https://www.7-forum.com/forum/showthrea ... ost2453235
https://e30-talk.com/topic/114297-an-di ... ec/page/3/

I have never found a true definitive answer/solution in the end but here are some important points.
- The oil pump sucks in air, stated by PM-tec
- Multiple users state that this is false, and his bench-testing is not realistic as the return line is open to air, while in the engine, oil from the head should return here
- Some users agree with PM-tec and there are reports of his pumps actually making a difference, however still, up to this date we don't know what exactly he changes
- There is 100% a problem with the regulator and blow-off valves, but this is not a flaw, instead just wear. This wear can lead to improper seating and closing, which COULD cause the pump to suck in air trough the regulator
- One user has uploaded pictures and a drawing of his upgraded regulator valve assembly
- One user thought that the pump is suck in air trough the blow off gate and attached a steel house that goes down into the sump, so it is always emerged in oil
- Another used pointed out that a worn gerotor assembly, that does not seal properly, could cause the pump to suck in air

Here is PM-tec's youtube, where you can see his bench testing:
https://www.youtube.com/watch?v=EUcKXnYYCHw

Another youtube video:
https://www.youtube.com/watch?v=pfASyeoiNcE
Important comment: "It is a misconception that the pump draws in air. the experimental setup does not correspond to the real conditions and is therefore not meaningful at all !!"

Let me know if any of you guys have anything to say.
Right now I feel like the regulator valve can definitely affect the performance of the pump negatively from wear, but I doubt there is any real flaw in there.


 

[szacsi72]

Also this topic:

https://e30-talk.com/topic/114157-%C3%B ... 35/page/2/

[Tiit]

Interesting, but I'm sceptical. I haven't heard of many M30 failing due oiling issues ( except for the famous loose oil bar bolts). 
 

[Federico]

Let me add to your confusion: viewtopic.php?t=156750

Also, it's been mentioned here that it helps to add sealant to both halves of the pump and the shim plate sandwiched between them. IDK

[adam_poll]

I went down this rabbit hole back when I was rebuilding my M30 and have seen the effects of this on track through hard left hand turns. The back side of the pressure relief valve/piston is open to the oil pan sitting in the front left corner of the pan, if that becomes uncovered the pump starts to pull air into it and oil pressure goes down. I would not classify that as cavitation as that would happen inside the pump without any outside air being introduced to it and those bubbles would collapse as soon as they were in the pressurized oil so you'd only see it as damage to rotor/housing. I would see oil pressures on track drop from the normal 55-65 psi down to around 25-35 psi when this was happening, if it was the oil pickup in the sump running dry I think the pressure drop would be much more severe. I would imagine drag racing could see the same issue

It is not hard to replicate the problem with the pump removed, I ran mine with a drill just like in the videos you link, with the port open to air the oil is full of bubbles, as soon as it is covered or dropped down into the oil you get a solid stream of oil with no bubbles in it. 

As far as I can tell the backside of that pressure relief piston needs to be open or it would just hydrolock with oil and not open/operate. In a perfect world you would come up with a way to vent it down into the sump part of the pan or into the oil pickup to guarantee it always has oil covering it. What I did was add a small baffle to my M30B34 oil pan in that corner to help keep oil around it at hopefully all times. My pan also has a custom sump with baffles and holds approximately 9 litres of oil now

The baffle below is 20 mm tall, comes 60 mm off the front of the pan and around 65 mm off of the left side of the pan. The bosses you see in the corner of the pan are where the bracket mounts for the power steering pump. Don't mind my welding, it's mostly functional lol.