2010 LC9 Low Oil Pressure fixed by oil filter

[Bethard728]

I have cut a few open and they appeared clean although I really have nothing to compare to as that was my first time opening a filter.  Just looks like a slight amount of dust looking sludge deep in the pleats.  It makes perfect sense that the filter must be plugging enough to cause an issue but maybe something is causing it to exaggerate the issue.  With everything that I have done to mine, I assume that it must be bearings.  I am willing to spend a weekend to pull it out and refresh it, but hate to do so and still have issues.  You know....looking for the easy "silver bullet".  The one thing that I have not done is to check my pressure between the pump and filter as someone suggested.  I really need to do that but I didn't have the correct adapter when I tried and I have since moved onto building a barn and a few Jeep projects.   Just to summarize, this is what I have done to mine:

AFM lifters

VLOM

Relief valve (in pan)

Oil deflector shield added

Cam retainer plate

Sending unit & screen

Oil pickup tube O-ring

Melling 10355 standard volume/high pressure oil pump (recommended by Summit)

Barbell

Pan gasket

[Grumpy Bear]

2 hours ago, Bethard728 said:

I have cut a few open and they appeared clean although I really have nothing to compare to as that was my first time opening a filter.  Just looks like a slight amount of dust looking sludge deep in the pleats.  It makes perfect sense that the filter must be plugging enough to cause an issue but maybe something is causing it to exaggerate the issue.  With everything that I have done to mine, I assume that it must be bearings.  I am willing to spend a weekend to pull it out and refresh it, but hate to do so and still have issues.  You know....looking for the easy "silver bullet".  The one thing that I have not done is to check my pressure between the pump and filter as someone suggested.  I really need to do that but I didn't have the correct adapter when I tried and I have since moved onto building a barn and a few Jeep projects.   Just to summarize, this is what I have done to mine:

AFM lifters

VLOM

Relief valve (in pan)

Oil deflector shield added

Cam retainer plate

Sending unit & screen

Oil pickup tube O-ring

Melling 10355 standard volume/high pressure oil pump (recommended by Summit)

Barbell

Pan gasket

 

If it were bearings you would know the first time it warmed up. Not 1500 miles later. Right? 

[Bethard728]

Yes, that is my though too.  That is what's so baffling to me.  I think I have replaced nearly everything relating to oil pressure outside of the non-AFM lifters and bearings.  All lifters and bores were in spec, so it seems the only thing left is bearings.  I am absolutely lost.

[Grumpy Bear]

[KAQ]

Thanks for getting back. I’m in the same boat don’t drive it a lot but it’s frustrating. I might get 200 miles or 1500. When it does drop it is highway driving. I just continue home roughly 45 minutes. Putting around stays 40 highway 50-55. Was thinking relief valve in pump but you said you changed yours. My oil pump now was changed 80k miles ago. I’m just dealing with it as well. Gonna make something up at work to test actual pressures. Thing purrs like a kitten and runs out. Defnitly strange. I have 07nbs with 220k miles.  

[customboss]

Have either of you gents tested the used oil to analyze a myriad of all the causes mentioned and some you may be missing? 
Another  primary question is how low is the “low” pressure ?

 

Apologies  if these questions have been answered already. 

[swathdiver]

That little iron block oil pump can't be helping things.  It's much smaller than the one you took out, notice the size of the gerotors?  The M365 pumps 1/3 more oil per revolution than the iron block pumps at a lower pressure because of the increased tolerances of an aluminum engine.

 

There's a guy on another forum with similar issues and I cannot explain why either of you is having this issue but both of you have the wrong pump in your motors.

[KAQ]

I got my pump from gm. My initial thought is pump. Haven’t had any issues with it for 80k miles. When I get time I’ll slap one in. Needs a pan gasket anyhow.

[Bethard728]

On 2/5/2022 at 6:33 AM, swathdiver said:

That little iron block oil pump can't be helping things.  It's much smaller than the one you took out, notice the size of the gerotors?  The M365 pumps 1/3 more oil per revolution than the iron block pumps at a lower pressure because of the increased tolerances of an aluminum engine.

 

There's a guy on another forum with similar issues and I cannot explain why either of you is having this issue but both of you have the wrong pump in your motors.

So your thought is that my factory pump wore out the first time?  And then I replaced it with the wrong pump? If so, that would be the best explanation I have heard...as everything else I have done didn't help.  I did speak with a Summit salesperson about the pump, (Although they might not know much about it) and he took my VIN number and recommended the M355 oil pump with a high pressure spring.  I also did some research and found this on the Melling sight.  This is a quote from Melling.  "Thanks for the question, 10355 is the performance version of the M365, it will have a hard coat anodized body, and a high pressure spring installed, either pump will work for your engine it is just a matter of preference."  

 

Swathdiver, please do not take this as me arguing, because I really want you to be right.  I would love to just swap out my new pump with the M365.  Have you had experience with the 365 solving issues?  And I wonder why both Melling and Summit are giving out bad recommendations?  This would for sure make sense though....why so many people can not solve this issue if they are putting the wrong pump in.

[Bethard728]

On 2/4/2022 at 8:34 PM, customboss said:

Have either of you gents tested the used oil to analyze a myriad of all the causes mentioned and some you may be missing? 
Another  primary question is how low is the “low” pressure ?

 

Apologies  if these questions have been answered already. 

I have not tested the oil as I feel like it couldn't be the oil since leaving the oil in and changing only the filter "fixes" the pressure for awhile.  I get around 1000-1500 miles on each filter regardless if the oil is new or old.  The pressure is essentially zero when it happens.  The needle drops all the way down and I get a low oil pressure message.

[Bethard728]

On 2/5/2022 at 6:33 AM, swathdiver said:

That little iron block oil pump can't be helping things.  It's much smaller than the one you took out, notice the size of the gerotors?  The M365 pumps 1/3 more oil per revolution than the iron block pumps at a lower pressure because of the increased tolerances of an aluminum engine.

 

There's a guy on another forum with similar issues and I cannot explain why either of you is having this issue but both of you have the wrong pump in your motors.

I just went back and found my notes from when I was talking with Melling and Summit.  I could be wrong because they were just hand notes taken while on the phone with Summit, but it looks like I misspoke on my early posts.  I think the 10355 is 33% higher volume and standard pressure, unless you change out the spring.   If what I wrote down is correct, then I should have both higher volume and higher pressure because I changed out the spring to the highest one in the set.  

[swathdiver]

21 minutes ago, Bethard728 said:

I just went back and found my notes from when I was talking with Melling and Summit.  I could be wrong because they were just hand notes taken while on the phone with Summit, but it looks like I misspoke on my early posts.  I think the 10355 is 33% higher volume and standard pressure, unless you change out the spring.   If what I wrote down is correct, then I should have both higher volume and higher pressure because I changed out the spring to the highest one in the set.  

Check your PMs on here.  I sent over a file and an email address.

 

The M365 is the pump that delivers more volume per revolution.  The M355 runs at a higher pressure with less volume.  43 psi red spring versus 33 psi with the yellow spring.

[Bethard728]

1 hour ago, swathdiver said:

Check your PMs on here.  I sent over a file and an email address.

 

The M365 is the pump that delivers more volume per revolution.  The M355 runs at a higher pressure with less volume.  43 psi red spring versus 33 psi with the yellow spring.

I started a post, but apparently it didn't save, so I'll try it again.  First of all, thank you Swathdiver for the article!!  That's a lot of great info!  I see the size difference in the Gerotor but I am wondering if that is comparing to the OEM ironblock version?   Below is copied from Mellings website and it appears as if the 355 already has the larger gerotor in it since it states 33% increase in volume over the standard pump.  I can't find where Melling offers a M365 pump on their site, but they do offer a M355HV which says "Exclusive high volume (+20%) rotor design".  I wish I would of knew that existed before I changed mine out.  I did find the M365 on Jegs, but it stays its a standard volume, standard pressure pump.  Looks like it is used to combat cavitation at high RPMs.  This is all damn cunfusing!

 

From Melling site:

 

10355, Standard Volume, High Pressure Gen IV Oil Pump

Melling improved the standard volume GM Gen IV oil pump. To support AFM and VVT components the output of this pump is 33% more than the Gen III standard volume oil pump (Melling #10295). Design changes to the housing, cover, and components together combine to improve the performance, durability, and capability of the oil pump. It can be used in any GM Gen IV application that uses Melling’s stock replacement M355 or M365 oil pumps.

 

From JEGS site:

 

GM LS Engine Oil Pumps

The Melling M365 pump is a standard pressure, standard volume pump that is considered a suitable replacement for the factory oil pump (GM part # 12612289) and offers improved resistance against cavitation at higher RPMs. The cast aluminum housing is CNC-machined and hardcoat anodized. The cast iron cover is CNC-machined and phosphate coated. The relief valve features a screw-in valve plug. The factory LS oil pump suffers from cavitation above 6,200 RPM, which results in a drop in oil flow of nearly 1 GPM by 7,000 RPM. This cavitation can also aerate the oil, which causes drops in oil pressure and can result in oil starvation. This is why we do not recommend shifting any higher than 6,200 RPM with a stock engine. Engines that run at RPM's above 6,200 should use an upgraded Melling pump to prevent these issues.

Features:

• 33 PSI Pressure Relief Valve Spring
• 1.28 Displ (cuin/rev)
• The cast aluminum housing is CNC machined and hardcoat anodized
• The cast iron cover is CNC machined and phosphate coated. The cover also features countersunk screws for more timing cover clearance.
• The relief valve features a screw in valve plug with the optional lower stock pressure spring supplied
• Compatible with factory GM oil pickup tubes

[customboss]

2 hours ago, Bethard728 said:

I have not tested the oil as I feel like it couldn't be the oil since leaving the oil in and changing only the filter "fixes" the pressure for awhile.  I get around 1000-1500 miles on each filter regardless if the oil is new or old.  The pressure is essentially zero when it happens.  The needle drops all the way down and I get a low oil pressure message.

I’m not recommending testing the oil assuming ANY cause including engine oil. Test the oil to get an empirical look at what’s going on internally. Saves needless guessing and teardown replacing blindly. Worst case eliminates guessing. 

[Bethard728]

24 minutes ago, customboss said:

I’m not recommending testing the oil assuming ANY cause including engine oil. Test the oil to get an empirical look at what’s going on internally. Saves needless guessing and teardown replacing blindly. Worst case eliminates guessing. 

Who do you recommend?  I have never sent off an oil sample before.  Also, is there a standard test?  or what should I ask them to look for?  Thanks,