LML oil pump conversion info....

[malibu795]

Mellings pump gears are taller and little bigger diameter than OEM

Aluminum has to be thick to yield same strength as steel.. making the pump out of cast iron means you can thin the walls out without sacrificing wall strength thus increasing ports for bigger gears and flow.

If orfice remains the same and flow is increase.. direct result pressure increases as well... pressure is directly corisponding to restriction.

 

[LBZ]

Mellings pump gears are taller and little bigger diameter than OEM

Aluminum has to be thick to yield same strength as steel.. making the pump out of cast iron means you can thin the walls out without sacrificing wall strength thus increasing ports for bigger gears and flow.

If orfice remains the same and flow is increase.. direct result pressure increases as well... pressure is directly corisponding to restriction.

He said he had it apart and everything was the same.

Sent from my D5803 using Tapatalk

 

[malibu795]

He said he had it apart and everything was the same.

Sent from my D5803 using Tapatalk

I got one of each at the house...
If they where the same the gears would be interchangeable and I wouldn't see a 15 psi increase at idle

 

[rcr1978]

The gears from the LB7 pump fit in the Melling pump no problem so riddle me that, guess my caliper reading skills must be fukd :roflmao:

 

[WVRigrat05]

That's pretty good info, I've been planning a build for when the time comes and I still scratch my head over an oil pump, I've always put a different pump in the gassers I had done, usually a high volume pump with the oil filter bypass blocked off, and never an issue, but seems like on the duramax a stock LB7/LLY pump with maybe a little stiffer return spring.

 

[malibu795]

The gears from the LB7 pump fit in the Melling pump no problem so riddle me that, guess my caliper reading skills must be fukd :roflmao:

Lmm won't nor LBZ... though drive gear is interchangeable

 

[rcr1978]

Lmm won't nor LBZ... though drive gear is interchangeable

Well wtf Lb7's have a bigger pump then the others

 

[rcr1978]

I will post up the gear sizes in the next day so we can get this strait, maybe measure your stuff if you can to Adam?

 

[malibu795]

Will do.. when I get back home... As for max psi I hit 85-90# with 32° oil temp.
IDK which is lifting internal bypass or relief valve on the block

Both OEM pumps and the melling are left hand threaded version

 

[WVRigrat05]

I will post up the gear sizes in the next day so we can get this strait, maybe measure your stuff if you can to Adam?

I noticed that my LLY carried higher pressure, as do other LB7/LLY's

My LMM only carries 38-42 cruising where the LLY was 48-55

 

[malibu795]

At what RPM Reger? I'm 60-70@2000 with worn bearings and aux oil cooler
28-32@750 idle
With a 316 pump
Main and rod bearings clearance was .0025" avg
The LBZ/LMM pumps was 45-50@2000 and low 20s at idle

 

[rcr1978]

I thought I remember hearing the LB7 lifters had a additional lube hole for the roller on the lifter and the LBZ/LMM do not so if that's the case theres a lot less internal leaks on the LBZ/LMM.

Edit: LLY lifters may also be different from LB7

 

[WVRigrat05]

At what RPM Reger? I'm 60-70@2000 with worn bearings and aux oil cooler
28-32@750 idle
With a 316 pump
Main and rod bearings clearance was .0025" avg
The LBZ/LMM pumps was 45-50@2000 and low 20s at idle

Mine won't see 50 until 2500+ RPM's.
Unless I'm reading my shit wrong.

 

[Chevy1925]

im still on my old stock pump with 213k. oil clearances were a bit more than Adams at .0026 to .0028. at 2100rpm and oil temps at 190 i see 65psi down the highway. this is still reading at the 01-02 oil pressure spot which guys seem to think reads higher than the 03-up. Idle at same temp its 25-30psi.

when oil temp starts going over 210, pressure starts dropping though. 240* at 2100rpm leaves me at 50ish psi.

 

[malibu795]

Both LBZ/LMM reads off #4 main..
My mechanical is hooked on #2
I lose 5-8# across my oil cooler

 

[malibu795]

Both LBZ/LMM reads off #4 main..
My mechanical is hooked on #2
I lose 5-8# across my oil cooler

Clarrisa...
Between pump discharge and #2 main I loose 5-8#

 

[kidturbo]

We stiffened the internal spring on a stock LLY pump that I drilled squirters on some years ago. It always read 60-70 on the Autometer and ECM pressure gauge above idle. Then I saw an LML pump, there is no comparison.

We decided to use LML pumps with LBZ med duty pans and front covers on the twin marine build. Had to shave part of the pump case down about .150, and then take a good bit off the threaded / geared input shaft. That got us inside the LBZ/LMM front covers. Upper pan needs a touch of dremel work too, but they fit

LML gears are a good bit thicker than earlier models, reason for the conflict. But the feed tube is also about 30% larger, so makes a worth while mod IMO.


P.S.. If using LML blocks, only the #4 hole has the new thread to match LML sensor. If you wanta keep your LB7/LLY/LBZ/LMM sensor, just move up a hole or two where the threads are same as all other models.

 

[kidturbo]

Here is a couple pics I found of an LML pump apart. On left LML gear, notice the longer shaft.

Also the pump clearance to front cover wasn't main reason we machined housing. Could have just notched the cover. After thinking we had it whipped, the LB7 cam gear we used hit pump on final assembly if I remember correctly. Will post a pic of housing machine area if I can find one.

 

[rcr1978]

LB7 and Melling m316

LB7 and Melling gears are the same tried both sets in each housing.
Dia 26mm
Width 13mm
Shaft 19.95mm
I have pics of them will have upload later.
Also whoever has a Melling lay a strait edge across the back and see if it's recessed across the shaft area mine is not sure if it was intended to be machined that way or mines a pos.

 

[rcr1978]

Relief valve pressures

Stock LB7 pump pops the seat at 55-56 psi
Melling 68psi
Now this is a air check and it is at the point it just cracks off the seat the releif port is not physically open much just enough to leak air, I have no idea what it would be with fluid pressure to actually be open enough to blead off a decent amount off fluid but should be close.