Oil pump question

[MarcHogenboom]

My low oil pressure problem seems to stem from the use of a remote oilfilter and extra oilcooler. The supplier of my engine says this should be remedied by use of a high volume oilpump. From these pages I understand this is a +98 pump. Acoording to my parts suplier here in the Netherlands the pumps for '97-2000 are all the same. This means I already have a high volume pump, or do I? Can someone give me partnumbers for the low and hihvolume pumps, so that I can see what I have? This is getting convusing.

[Kennedy]

I seriously doubt the cooler or filter are the problem. If the pump was good, and the system tight, the bypass valves in the block should take care of any restriction issues.

I'd say either bad bearings, or clearances IF the pressure proves low using a mechanical type gauge.

I guess a little history on the engine would be helpful.

[MarcHogenboom]

I think the pump is good, but didn't check clearances. Just checked the relief valve. The history of the engine is: Bought from Global Engines( http://www.gm-diesel-engines.com )in 2003 as an unused engine, shipped to Europe, mounted on the Motorhome frame, where it sat during the rest of the restauration, and just started a couple of times to see if everything was working. Then 3 weeks ago the first testdrive with the low oilpressure as a result. (First time it warmed up.) I took off one of the main bearing caps and it looks good, so I wouldn't expect these to be the cause.

[JohnC]

(See my response to your other thread)

A high volume pump will help if you have added parallel flow paths to the lubrication system, like oil spray nozzles or a second turbo. Adding resistance cannot be corrected by increasing flow. that said, i think you may have some sort of plumbing problem that is forcing the oil into a path it was not intended to follow.

[MarcHogenboom]

Maybe youre right. It would help if I could see a scematic drawing of the oilflow, but I do not have a manual. Can you show me such a drawing? It would make things easier to understand.

[Kennedy]

Originally posted by Marc Hogenboom:
I think the pump is good, but didn't check clearances. Just checked the relief valve. The history of the engine is: Bought from Global Engines( http://www.gm-diesel-engines.com )in 2003 as an unused engine, shipped to Europe, mounted on the Motorhome frame, where it sat during the rest of the restauration, and just started a couple of times to see if everything was working. Then 3 weeks ago the first testdrive with the low oilpressure as a result. (First time it warmed up.) I took off one of the main bearing caps and it looks good, so I wouldn't expect these to be the cause. I would guess that the engine itself is bad IF you have verified the oil psi on a mechanical gauge. The concept of new, unused engines that have only been run on a test stand is a little far fetched to me. GEP runs their engines in a dyno cell after assembly. Those that pass are shipped. Those that fail, well draw your own conclusions...

[StephenA]

Don't mean to go off topic, but interested in your extra oil cooler. Is it plumbed in series with the original? Where is it mounted. How much does it lower oil temps?

[MarcHogenboom]

It's instead of the original, mounted 4" in front of the radiator. How much it lowers the oil temp I do no yet know, as I haven't gotten to real driving yet.

[StephenA]

Originally posted by Marc Hogenboom:
It's instead of the original, mounted 4" in front of the radiator. How much it lowers the oil temp I do no yet know, as I haven't gotten to real driving yet. Be interesting to know. 4" space infront of the radiator has got to be cooler than the 1/2" clearence on my 92. I have an extra stock oil cooler and was thinking of mounting it in tandam with the original one, but I'm not sure of placement. Seems to me that the oil should reach 212 degrees when run through the cylinder galleries or turbo, releasing water vapor if it's not cooled too much by the cooler. I wonder if there is any engine cooling advantage in lowering the oil cooler thermostat trigger point? Might be usefull to place oil temp gages at several points, so as to monitor the max & min oil temps. Seems like keeping the max at 212 or 215 might be optimum.

[tom.mcinerney]

Marc--
Since you've done much work and an investment...
Did you check oil pressure with a dedicated mechanical gage confirming readings?? On rare occassion a bad filter element can drop pressure enough to cause knocking, so try another filter element.

There is a good written description of oil flow in a post somewhere on this site. Not aware good diagram, will look.

After confirm (good plumbing)+ (bad oil press), I'd suggest renew the oil pressure regulating valve assembly between OEM filter pad and block, and new oil pump. Then you've either solved problem, or set yourself up to start a teardown?

Good luck, post progress.

[MarcHogenboom]

Yesterday I took off the main bearing caps 2 and 4, and messured the oilclearance with Plastigage. The clearances were well within the limmits stated in that awfull, unusable Haynes Diesel Engine repair manual. They messured 0.0022 and 0.0027, so this cannot be the cause of the low oilpressure. I did bring the filter plumming back to its original routing, thanks to the drawing provided by Hye. The bypassvalve in the filtermounting seems to work ok. However, the oilcooler bypass valve is kind of mysterious. Is it actuated by the pressure in the fiterhousing? In the cup plug in the filtermounting roof there is a small hole, does this actuate the bypass valve to close or open? If so, it could be an explanation for my problems, if not, I'm still in the dark.