2007 Tahoe 5.3l AFM DOD delete thread

[Geotrash]

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

If you're going to drop the pan, you might as well replace the relief valve with a new one and do the pump at the same time. If you were deleting AFM you could plug the valve orifice. That way you can be sure you've covered all of your bases.

 

[wsteele]

Yep.

 

[Taheezy_88]

If you're going to drop the pan, you might as well replace the relief valve with a new one and do the pump at the same time. If you were deleting AFM you could plug the valve orifice. That way you can be sure you've covered all of your bases.

AFM already deleted. I'll probably just plug the pressure relief valve.

On one start up today I let the low oil pressure light come on and then revd the engine up and immediately oil pressure went above 50psi and stayed. So I wonder if your pressure relief valve theory being stuck open could be the issue.

Would leaving the M355 pump be good or no?

 

[Taheezy_88]

Found someone with similar issue

"Installed on 2007 Tahoe 5.3 Flex. Had the hard o-ring issue on the oil pump pickup which caused low oil pressure for the first 10 minutes after cold start. In my slanted driveway idle pressure would drop to just above 0. Once the oil was nice and hot the o-ring swelled up enough and oil pressure returns to normal. Very weird issue. 156k miles by the way.

Since I had to drop pan anyway to replace the o-ring I did the oil pump as well. Left in the high pressure spring. Works great! Hot idle pressure with 5w-30 at about 38lbs is very reassuring all is well. I thought I had a little lifter noise at idle. If I did I don't now, very quiet. 55lbs or so on the highway."

 

[wsteele]

Found someone with similar issue

"Installed on 2007 Tahoe 5.3 Flex. Had the hard o-ring issue on the oil pump pickup which caused low oil pressure for the first 10 minutes after cold start. In my slanted driveway idle pressure would drop to just above 0. Once the oil was nice and hot the o-ring swelled up enough and oil pressure returns to normal. Very weird issue. 156k miles by the way.

Since I had to drop pan anyway to replace the o-ring I did the oil pump as well. Left in the high pressure spring. Works great! Hot idle pressure with 5w-30 at about 38lbs is very reassuring all is well. I thought I had a little lifter noise at idle. If I did I don't now, very quiet. 55lbs or so on the highway."

I think he is talking about an old O-Ring that hardened over time? The symptoms sound similar, but you have a new O-Ring.

I know you can remove and plug the AFM Pressure relief valve successfully as Chris @iamdub did that very thing on his delete.

On leaving the pump you have, honestly, I can't imagine why it shouldn't work. On the other hand, you do have some kind of issue and dropping that pan is a pain. If it were me, I would drop back to what is called out by Melling (I probably would just buy the OP and pickup tube bundle, just to be sure, all in an attempt to be done with that oil pan and gasket, once and for all).

I do think I would go with Melling's "High Performance" option though. You can always lower the pressure relief.

 

[iamdub]

I don't see why an engine that has been AFM-deleted would need any oil pump other than what was in it or it's equivalent replacement. If the factory pump in an AFM engine is a higher-volume design than what a non-AFM engine has, then it should create higher pressures once that engine is made to be like the non-AFM variant.

First off- have you verified that you actually have odd pressures or are you relying on the oil pressure sensor and factory gauge?

Beyond verifying your actual pressures, my guess is something is leaking. Maybe a seal(s) expands when heated and seals off something in the oil circuit.

Did you plug off the AFM towers or just relying on the valley cover O-rings to seal them? It's rare, but there has been reports of the O-rings leaking. It's cheap insurance to plug them.

Since you have no AFM, there's no reason to keep the relief valve in the oil pan. Plug off the port to eliminate any doubt that it may be a leak point.

 

[Taheezy_88]

I will replace the pump with OP and get a new pickup tube with oring and also block the pressure relief valve deal.

Iamdub
No pressure test and I did not plug AFM towers which I should of done and will get to after I replace pump and pick up tube.

Thanks guys will keep posted

 

[Decker73]

I have an 08 Tahoe LTZ with a 5.3L, similar issue. Cold start I have 25-30 psi, once up to temp 40-50 psi. I was thinking maybe the sensor/screen was possibly the issue. Could this be the start of the o-ring going ? It matches symptoms a little bit.

Sent from my SM-N960U using Tapatalk

 

[Taheezy_88]

What type of plug for pressure relief valve? Could I just find a bolt that matches and plug with that?

 

[Taheezy_88]

I have an 08 Tahoe LTZ with a 5.3L, similar issue. Cold start I have 25-30 psi, once up to temp 40-50 psi. I was thinking maybe the sensor/screen was possibly the issue. Could this be the start of the o-ring going ? It matches symptoms a little bit.

Sent from my SM-N960U using Tapatalk

I would say that pressure seems about right but would let a more experienced person around here confirm that. My problem could be not related to the oring I pulled pan today and tomorrow I pull the timing cover/oil pump to inspect oring and change pump