LPOP upgrade
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LPOP upgrade
I was doing some work on my 01 350 w 290k and counting and after putting the engine back in had trouble building oil pressure. After several attemps to start and could not get oil pressure decided to change LPOP. At NAPA their replacement oil pump for the 7.3 is a 10 tooth design versus the 14 tooth OEM model, which is for more oil volume, comes with new seal, housing and gasket about a 130.00. I haven't hooked up a oil pressure gauge but the idiot gauge in the truck shows a significant increase. Its not too bad of a job to change while in the truck either. Has anybody else done this upgrade???
Post Fiend
Joined: Jul 2005
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From: 21791
There is only a real problem with a oil pressure issue when you have a dual HPOP setup, where there is two pumps flowing 100% all the time, and the LPOP has trouble keeping the HPO reservoir full (Most add a second line to it)and some get a oil pressure issue when at idle, hot.
Lead Driver
Joined: Oct 2004
Posts: 7,413
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From: Columbia, MO
I was doing some work on my 01 350 w 290k and counting and after putting the engine back in had trouble building oil pressure. After several attemps to start and could not get oil pressure decided to change LPOP. At NAPA their replacement oil pump for the 7.3 is a 10 tooth design versus the 14 tooth OEM model, which is for more oil volume, comes with new seal, housing and gasket about a 130.00. I haven't hooked up a oil pressure gauge but the idiot gauge in the truck shows a significant increase. Its not too bad of a job to change while in the truck either. Has anybody else done this upgrade???
Also, have you done something to alter your oil pressure gauge? The stock gauge is hooked to a switch, rather than an actual sending unit, and that switch gives an all or nothing signal at 7 psi. I'm curious as to how the dash gauge showed a difference.
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From: Paramount, Ca
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Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
That sounds very similar in design to the Melling pump that ITP sells, except the Melling is about half that cost. Here's the Melling pump to see if it's similar to the one you have: Low Pressure Oil Pump Was the new replacement the same dept at the stock pump, or were the gears about half as wide/deep?
Also, have you done something to alter your oil pressure gauge? The stock gauge is hooked to a switch, rather than an actual sending unit, and that switch gives an all or nothing signal at 7 psi. I'm curious as to how the dash gauge showed a difference.
Also, have you done something to alter your oil pressure gauge? The stock gauge is hooked to a switch, rather than an actual sending unit, and that switch gives an all or nothing signal at 7 psi. I'm curious as to how the dash gauge showed a difference.
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Having a high volume oil pump is good. You can regulate the pressure back down if you have to, (overpumping lifters or blowing out crank seals), but there is nothing you can do about oil starvation from a too-small of an oil pump except put a bigger one back on later on.
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If I was in the position to have to rebuild my engine, one of the things on the list is the biggest oil pump that I could find, (within reason.)
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Lead Driver
Joined: Oct 2004
Posts: 7,413
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From: Columbia, MO
Dan, from my understanding, Melling's thickness was a specific design reason.
This is a post from Dennis, at another forum:
Edit: More Melling pump info.
This is a post from Dennis, at another forum:
From the engineer at Melling:
and
As for the low pressure lube pump, our M208, the pump was re-designed to perform better than the original pump. When we started the M208 pump project we were aware of engine oiling issues and premature wear occurring in the pump. We designed our pump in a way to improve the oil delivery to the engine. But to improve the pump we had to re-design the gerotor unit. The Melling gerotor has a 10 lobed inner versus 14 lobes on the original pump. A 10 lobed inner provides a larger pumping chamber which allowed for a 30% reduction in the thickness of the gerotor set. The reduced thickness eliminated the need for the counter bore on the inner rotor for clearance of the harmonic balancer. The Melling gerotor is symmetrical so no installation issue can occur with the balancer. Even though the Melling pump looks like it will not equal the original it is actually better than the original!
Yes, our M208 output is meant to provide the same flow as the original pump but with better oil quality since the gerotor will fill better since it is not as deep as the original.
In case anyone but me wanted to know, here is the response from Melling (questioning the flow rate of the pump):
Below 2500 rpm the flow rate is as good as or slightly better than a stock pump.
Above 2500 rpm the flow rate is increased over the stock pump.
Above 3500 rpm the flow rate is 10% more than stock.
At test rpm of 700 rpm , 7 gpm
At test rpm of 4000 rpm , 25gpm
Above 2500 rpm the flow rate is increased over the stock pump.
Above 3500 rpm the flow rate is 10% more than stock.
At test rpm of 700 rpm , 7 gpm
At test rpm of 4000 rpm , 25gpm
Fleet Owner
Joined: Jun 2004
Posts: 25,090
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From: Rio Rico, AZ.
Well, that just shows that there a lot of people that are much smarter than I am.
I never would have guessed that a thinner pump (shorter gears) would be able to pump more oil.
Makes me wonder why they didn't keep the original height and make a kick a$$ pump.
I never would have guessed that a thinner pump (shorter gears) would be able to pump more oil.
Makes me wonder why they didn't keep the original height and make a kick a$$ pump.
Lead Driver
Joined: Oct 2004
Posts: 7,413
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From: Columbia, MO
Installation issue is the other reason.
"The reduced thickness eliminated the need for the counter bore on the inner rotor for clearance of the harmonic balancer. The Melling gerotor is symmetrical so no installation issue can occur with the balancer. "
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