6.5 oil pressure issue.... still!

[ranchtruck]

If it is a low pressure, could it be a high volume low pressure pump? If so is that really that bad? I will try to get the casting numbers. When I rebuilt the motor the timing set said it was at least a 94 engine. Where is the Julian Date Code? thanks for all the help, I am use to dodge gas engines, this is a whole new learning curve for me. My 7.3 I just ran til the truck fell apart around it then sold the motor at 500,000+ miles.

 

[ak diesel driver]

That melling pump is for the older engines without squirters. They only made 2 different pumps the newer one just puts out more volume

 

[Paveltolz]

I agree with Will, Tag and others that your readings are fine, just different. I know the discomfort in having a higher pressure with an old motor and oil pump combo vs new. Similar my rebuild, the pressure readings are different from the old to new combination (lower) and about the same as yours. 25K or so later, the readings are the same and oil samples are good.

Was the Melling pump the same model you pulled out of the motor before rebuilding? I've got another question that would probably de-rail the thread so I'll save it for later.

Oh, and do not sell yourself short. For a "Novice" you're way ahead of this true novice (at least where diagnosing and addressing this type of issue) in that you noticed the pressure drop, caught it in time, did the research, identified the cause, made corrective actions (essentially rebuilt the motor) did the right thing and replaced the oil pump in the process, put it all back together, performed the prestart w/o glow plugs as advised by the 100lbs heads on the forum, and then, the sucker started. Big Cudo's from a real Novice.

 

[ranchtruck]

That melling pump is for the older engines without squirters. They only made 2 different pumps the newer one just puts out more volume

So what is the part number and the company that I probably need? I would like to make this thing right as I need it to last a long time. thanks for all the help.

 

[Twisted Steel Performance]

Melling oil pumps...

The difference between them....

The one you have - https://www.rockauto.com/en/moreinfo.php?pk=8310540&cc=1053302&jsn=690

The one you want - https://www.rockauto.com/en/moreinfo.php?pk=8310108&cc=1353439&jsn=602&jsn=602

Notice the difference in the pics, the one you want has a spacer in the middle, it has bigger gears inside to pump more oil....

 

[WarWagon]

That melling pump is for the older engines without squirters. They only made 2 different pumps the newer one just puts out more volume

@ranchtruck Did the engine have piston oil coolers aka oil squirts when you rebuilt it? This is mainly a diesel engine thing. This is why they are asking for the block casting numbers. Many times a truck has a newer engine because a 6.2/6.5 is a disposable engine, failed often, many times cracks made them scrap metal on teardown, and when a diesel engine has a problem it's usually catastrophic. Not all 6.5's had the piston cooling squirts as it was added for later model years production engines. So if you have a newer engine you may need the HV oil pump rather than the LV pump. Do you still have the old pump? It's possible the prior owner added a HV pump to get more miles out of a non squirt block. All bets are off.

 

[Will L.]

I have never seen a high volume oilmpump cause any issues in a non squirter block.

Does anyone have info on downfalls from it ever happening?

Yes a high volume pump creates more drag on the engine. Steals maybe 3 hp from what I could find.

 

[Neumann]

I had an aftermarket OPS form Oreilleys cause low readings. Went back to AC Delco OPS and all is fine.