2007 Tahoe 5.3l AFM DOD delete thread

[Geotrash]

No...

The M355 is a higher volume pump for engines with AFM/VVT

The M295 is standard volume pump for engines without VVT or AFM

So you would see lower oil pressure with an M295 vs M355

There are *two* Melling oil pumps with the 355 designation. One is the 10355 (standard volume) and the other is the 10355HV (high volume). We need to know which one he installed. His engine needs a high volume pump.

 

[wsteele]

There are *two* Melling oil pumps with the 355 designation. One is the 10355 (standard volume) and the other is the 10355HV (high volume). We need to know which one he installed. His engine needs a high volume pump.

I was under the impression the high volume pump was for the AL block engines and the standard the iron block?

Not questioning your statement that he needs the high volume pump (empirical results sure would support that), just trying to get the data straight in my head. I was also under the impression a high volume pump on an iron block wouldn’t hurt anything.

 

[wsteele]

I just got off the Melling site and I think the various 355 oil pumps are for the 6.2L.

Essentially for the 5.3L 2007 model year your choice on their site is M295 or M295HV, with the HV being a higher volume pump. The high volume pump is their "high performance" line.

I can't understand the difference in the 295 and 355 figment wise as I thought all the accessories pretty much bolted right up, engine to engine.

Edit: I wonder if the issue is a 295 pickup line and a 355 O-Ring? Just guessing here.

 

[Taheezy_88]

I just got off the Melling site and I think the various 355 oil pumps are for the 6.2L.

Essentially for the 5.3L 2007 model year your choice on their site is M295 or M295HV, with the HV being a higher volume pump. The high volume pump is their "high performance" line.

I can't understand the difference in the 295 and 355 figment wise as I thought all the accessories pretty much bolted right up, engine to engine.

Edit: I wonder if the issue is a 295 pickup line and a 355 O-Ring? Just guessing here.

That's the information I was reading last night. I am going to replace the m355 with the m295hv and seat a new Oring and go from there.

I have low oil pressure only when engine is cold and after I get to 210 degrees my oil pressure stays above 40psi even at idle.

Tahoe runs great otherwise.

 

[Taheezy_88]

My invoice

 

[wsteele]

That's the information I was reading last night. I am going to replace the m355 with the m295hv and seat a new Oring and go from there.

I have low oil pressure only when engine is cold and after I get to 210 degrees my oil pressure stays above 40psi even at idle.

Tahoe runs great otherwise.

That is strange that it is low when cold and higher when hot. I don't think I have ever seen that.

FWIW, minimum acceptable oil pressures, according to my GM shop manual, are 6 psi at 1000 rpm, 18 psi at 2000 rpm and 24 psi at 4000 rpm. Personally, I wouldn't run it that low and would be looking to fix it, but that is what the book says.

 

[wsteele]

That's the information I was reading last night. I am going to replace the m355 with the m295hv and seat a new Oring and go from there.

I have low oil pressure only when engine is cold and after I get to 210 degrees my oil pressure stays above 40psi even at idle.

Tahoe runs great otherwise.

I also saw an offering that is both high pressure and high volume (I think it is 10296), I couldn't find that this last search though, might be old nomenclature.

 

[Taheezy_88]

That is strange that it is low when cold and higher when hot. I don't think I have ever seen that.

FWIW, minimum acceptable oil pressures, according to my GM shop manual, are 6 psi at 1000 rpm, 18 psi at 2000 rpm and 24 psi at 4000 rpm. Personally, I wouldn't run it that low and would be looking to fix it, but that is what the book says.

When starting it, the pressure will shoot up to 40-60 psi and slowly drop down to zero then I get the low oil pressure warning light. After driving around for a couple minutes the pressure stabilizes above 40psi.

 

[wsteele]

When starting it, the pressure will shoot up to 40-60 psi and slowly drop down to zero then I get the low oil pressure warning light. After driving around for a couple minutes the pressure stabilizes above 40psi.

Very strange, I wish I could be more help. It would be interesting to know if the 6.2L pickup tube is a different diameter than the 5.3L.

Edit, on Rock Auto's site, they list the same Melling pickup tube for both the 5.3L and 6.2L, so it doesn't appear the O-Ring is the issue.

 

[Taheezy_88]

Very strange, I wish I could be more help. It would be interesting to know if the 6.2L pickup tube is a different diameter than the 5.3L.

Edit, on Rock Auto's site, they list the same Melling pickup tube for both the 5.3L and 6.2L, so it doesn't appear the O-Ring is the issue.

The oring I inserted was the green one and it fitted snug enough where it didn't even feel like it had to be bolted on the pump. So I'm hesitant to blame the oring.

 

[Taheezy_88]

I'll record a video

 

[wsteele]

The oring I inserted was the green one and it fitted snug enough where it didn't even feel like it had to be bolted on the pump. So I'm hesitant to blame the oring.

On the Rock Auto site, the picture of the Melling pickup tube for the 5.3L 2007 MY with the O-ring on it, the color is red, but I don't think I would put much importance on the picture.

 

[Taheezy_88]

2:30 oil drops to almost Zero
4:30 minute mark is when the oil stabilizes.

 

[Taheezy_88]

On the Rock Auto site, the picture of the Melling pickup tube for the 5.3L 2007 MY with the O-ring on it, the color is red, but I don't think I would put much importance on the picture.

The Orings I received were black(the smaller one) and Green. Came with a diagram picture showing which one to use as it showed to different pickuptube ends.

https://www.summitracing.com/parts/mel-m355

Link of oil pump I purchased

 

[Geotrash]

The Orings I received were black(the smaller one) and Green. Came with a diagram picture showing which one to use as it showed to different pickuptube ends.

https://www.summitracing.com/parts/mel-m355

Link of oil pump I purchased

Green is the correct o-ring for a Melling pump on your engine.

About the only mechanical thing I can think of that could be causing the behavior you're describing is the pressure relief valve in the oil pan. It's a pop-off valve designed for relieving pressure spikes caused by the action of the AFM system, and could be sticking open momentarily until the pressure drops enough to let it close. Another possibility is the 'dog bone' valve at the rear of the block. Short of that, all other possibilities that come to mind are electrical.

 

[Geotrash]

I was under the impression the high volume pump was for the AL block engines and the standard the iron block?

Not questioning your statement that he needs the high volume pump (empirical results sure would support that), just trying to get the data straight in my head. I was also under the impression a high volume pump on an iron block wouldn’t hurt anything.

That's possible, but it's my understanding that all AFM engines use a high volume pump. I could be wrong on that point though.

 

[wsteele]

That's possible, but it's my understanding that all AFM engines use a high volume pump. I could be wrong on that point though.

What I had read was the iron block engines (like mine LMG - AFM), took the standard volume pump and the high volume pump was used in the AL blocks. I don't think I am wrong about that, but I also suspect that tidbit probably doesn't have any bearing on what high volume is versus normal volume in the broader LS engine arena. I think in my case, it was what GM said in their TSB regarding oil consumption problems in AFM engined cars.

Looking at Rock Auto, for my engine I think they call out the regular M295 pump as the correct "stock" pump. They do offer a "High Performance" option from Melling in the 10295 which they claim is 10% higher pressure, no mention of higher volume. Having read your AFM delete thread, I know for a fact, if I do a physical delete, I am going high volume, high pressure with what I choose.

I also wonder if the 10295 pump is just a heavier pressure relief spring, or the pump actually has tighter tolerances, etc.

 

[wsteele]

2:30 oil drops to almost Zero
4:30 minute mark is when the oil stabilizes.

Very strange behavior. On my similar engine to yours, stock LMG - AFM just turned off in SW, my oil pressure has always idled slightly above 40 psi when cold, dropping to about 30 psi when hot (temp gauge straight up on the dash). If I rev it cold, it will jump to about 55 psi and stay there with the RPMs. Once fully warmed up, it says just above 40 when RPM's are up.

 

[Geotrash]

Very strange behavior. On my similar engine to yours, stock LMG - AFM just turned off in SW, my oil pressure has always idled slightly above 40 psi when cold, dropping to about 30 psi when hot (temp gauge straight up on the dash). If I rev it cold, it will jump to about 55 psi and stay there with the RPMs. Once fully warmed up, it says just above 40 when RPM's are up.

That's the exact pressure behavior I experience in both of my Denali's now.

 

[Taheezy_88]

Green is the correct o-ring for a Melling pump on your engine.

About the only mechanical thing I can think of that could be causing the behavior you're describing is the pressure relief valve in the oil pan. It's a pop-off valve designed for relieving pressure spikes caused by the action of the AFM system, and could be sticking open momentarily until the pressure drops enough to let it close. Another possibility is the 'dog bone' valve at the rear of the block. Short of that, all other possibilities that come to mind are electrical.

I did reuse the old pressure relief valve. Would this be a good place to start or change the pump first to the M10295?

Electrical I did leave one harness unplugged that plugged to old VLOM that was for the AFM.

Would an oil pressure test be of any worth?