l99 low oil pressure

[morepowerjoe]

Originally Posted by PlymouthBarracuda

Old topic but still I haven’t found the answer, what oil pressure should be at hot idle (Vin J) ?

Few years ago I saw somewhere on YouTube an old official video from GM, where they said that if the pressure is less than 26 PSI at idle, then this may be the cause / or consequence of improper operation of the AFM...

My 2011 SS L99 at hot idle at 250F show on gauge 15 psi, 240F = 18 psi, 230F 21 psi. Warm engine 26 psi, cruising at low speed 30 psi, cold start 50 psi. Using Range AFM disabler.

I started to use Lucas Heavy Duty Oil Stabilizer and idling pressure increased +5 psi.

///

I also replaced my oil pump to MELLING M365.
Stock oil pump was 12710304 (but 12612289 and 12710304 are the same thing).

I'm currently considering the MELLING M365HV as larger displacement pump - 20% Additional Volume Over Stock Oil Pump.
Or MELLING 10355HV - High Volume and High Pressure +10 PSI Higher Pressure

That pump #M365 is actually the wrong pump for a l99. Because at first I replaced my pump with that exact one and my oil pressure dropped like 15psi. Since the l99 has afm and vvt it needs a high volume pump like the melling 10296 or like my current pump which is a melling 10355HV. I went with the 10355HV because I wanted all the pressure at idle that I could get and that is exactly what I got. Now my hot idles pressure at around 900rpm is at around 34psi with 10W30 weight oil and I have an oil cooler too. If I was you I would use the 10296 at a minimum.

[1JEWLDSSRS]

Originally Posted by PlymouthBarracuda

Old topic but still I haven’t found the answer, what oil pressure should be at hot idle (Vin J) ?

Few years ago I saw somewhere on YouTube an old official video from GM, where they said that if the pressure is less than 26 PSI at idle, then this may be the cause / or consequence of improper operation of the AFM...

My 2011 SS L99 at hot idle at 250F show on gauge 15 psi, 240F = 18 psi, 230F 21 psi. Warm engine 26 psi, cruising at low speed 30 psi, cold start 50 psi. Using Range AFM disabler.

I started to use Lucas Heavy Duty Oil Stabilizer and idling pressure increased +5 psi.

///

I also replaced my oil pump to MELLING M365.
Stock oil pump was 12710304 (but 12612289 and 12710304 are the same thing).

I'm currently considering the MELLING M365HV as larger displacement pump - 20% Additional Volume Over Stock Oil Pump.
Or MELLING 10355HV - High Volume and High Pressure +10 PSI Higher Pressure

As stated in my earlier post, I'm running the Melling 10295 pump and this is what I'm seeing for oil pressures.

Idling warm it sits at 32-35psi and when cruising at 2000rpm it sits at about 55ish. Cold start she is at 65 or so then drops back down when the oil is up to temp. 5w30 Mobil 1.

[PlymouthBarracuda]

Originally Posted by morepowerjoe

That pump #M365 is actually the wrong pump for a l99. Because at first I replaced my pump with that exact one and my oil pressure dropped like 15psi. Since the l99 has afm and vvt it needs a high volume pump like the melling 10296 or like my current pump which is a melling 10355HV. I went with the 10355HV because I wanted all the pressure at idle that I could get and that is exactly what I got. Now my hot idles pressure at around 900rpm is at around 34psi with 10W30 weight oil and I have an oil cooler too. If I was you I would use the 10296 at a minimum.

But MELLING 10296 is for Vin W. Does it fit Vin J ?

What is your pressure with 10355HV on cold start and full throttle driving ?
Can 10355HV be cause of excess pressure?

[PlymouthBarracuda]

Originally Posted by 1JEWLDSSRS

As stated in my earlier post, I'm running the Melling 10295 pump and this is what I'm seeing for oil pressures.

Idling warm it sits at 32-35psi and when cruising at 2000rpm it sits at about 55ish. Cold start she is at 65 or so then drops back down when the oil is up to temp. 5w30 Mobil 1.

Thank you for your readings... 10295 is for Vin W. Can I install it on stock Vin J with AFM?
Did you use the Optional +25 PSI Pressure Spring that comes with it ?

[morepowerjoe]

Originally Posted by PlymouthBarracuda

But MELLING 10296 is for Vin W. Does it fit Vin J ?

What is your pressure with 10355HV on cold start and full throttle driving ?
Can 10355HV be cause of excess pressure?

Yes the 10296 will work with vin J and is what was comparable to your stock pump which was a high volume pump from the factory. That's why you have low pressure right now because the pump you put in is a standard volume pump. My cold start up with the 10355HV is around 80psi and full throttle pressure is around the same at 80psi but what you should be concerned with is mainly the idle pressure and the only way to get that up is with a higher volume pump. Like I was saying my hot idle pressure is around 34psi and another thing is that bypass pressure relief valve in the pan because without plugging that thing you probably won't get over a maximum of like 55-60psi at wot.

[1JEWLDSSRS]

Originally Posted by PlymouthBarracuda

Thank you for your readings... 10295 is for Vin W. Can I install it on stock Vin J with AFM?
Did you use the Optional +25 PSI Pressure Spring that comes with it ?

My engine was an L99 with AFM, we did the AFM delete and LS3 conversion, so yes, it will work on a VIN-J. and no, I don't believe we used the optional spring. I wasn't there when they installed the pump.

[SlowLS1]

I am currently in the same position with choosing an oil pump right now.

Converting to LS3, so it would make sense to go with the 10296. However it might be beneficial to go with the 355HV since the turbos will be pulling some volume.

So much conflicting info on this topic makes it difficult to say one or the other.

Based on Andrew's article, seems I'd probably be fine with the 10296. I am blocking the bypass in the pan also.

Here is the Article if you haven't read it.

[morepowerjoe]

Originally Posted by SlowLS1

I am currently in the same position with choosing an oil pump right now.

Converting to LS3, so it would make sense to go with the 10296. However it might be beneficial to go with the 355HV since the turbos will be pulling some volume.

So much conflicting info on this topic makes it difficult to say one or the other.

Based on Andrew's article, seems I'd probably be fine with the 10296. I am blocking the bypass in the pan also.

Here is the Article if you haven't read it.

I can only speak from experience. You know I have the l99 and when I was stock I tried the M365 I believe and my idle pressure went down to 15psi. So loaded with the wrong info again I went to the melling 10295 and my idle pressure was still at 15psi. What I didn't know was since I had the vvt it sucked up a lot of volume. Then I went to the 10355HV with the high pressure spring and bam my idle pressure was back to well over 30psi at idle sometimes with around 50psi depending on the weather with 10W30 Valvoline Racing full synthetic but I was kind of concerned because my pressure at wot was around 90psi. So then when I did the rebuild I used the 10355HV again but this time I used the spring that came in it and my wot pressure dropped to around 80psi. And this is with the Mishimoto oil cooler too. So in my opinion I think you would be ok with the 10296 since you won't have the vvt but the only thing I can't account for is the pressure drop with the turbo. If it's much then I would go ahead and use the 10355HV with the standard spring.