Since I got the H2 the oil pressure was stady around 40psi .. a few months ago it came a little lower while in idle but now the gauge i showing below the first mark
The pressure goes up with the Rpm . Also it gets a little better once the engine is warm/hot .When Cold start gauge is showing a low oil pressure message for a couple seconds (current ambient temperature around 80) ... This doesnt make sense to me , a cold engine and oil is supposed to have a higher pressure . I guess?

In a hope and Against my wish I put seafom and run it for 50 miles . I notice the pressure is fluctuating more . It goes faster higher but also goes lower in idle
Will do an oil change and a mechanical pressure test to discard an issue with the oil sensor .
Next step removing the oil Pan to check whats in there

Any advise what to look at , what could be wrong etc

Thank you
Update : since I posted I was looking info and removing the oil pain seems to be a huge pain in the A$$ ... looks like the differential needs to be take it down . Could anyone clarified if this info is right

 

have you checked for any leaks under or an creamy goodness in the oil/ coolant?

i am not saying it could be that bad, but those are the first places to look. Given I also know that the placement for the oil pressure sender isnt the best place, but usually when they go out they show oil pressure to be maxed out

 

On my 08 the diff had to come out / down to get to the oil pan out.

Check with a mechanical gauge first, to verify the gauge and sender.

I've seen pic's of a small screen at the sender that can plug and cause pressure indication issues but not sure if the 06 6.0L in the hummer has this screen.

Also issues with the O-ring at the pump / pick up tube that will break and allow air at the suction of the pump that can cause issues.

being low while cold then increasing once warm is very odd

Neal

 

No leaks or mix with coolant .
i dont want to run and start replacing parts before make sure is not the sensor butbto have an idea
Is the pump located on the front ? , how hard is to replace

 

Pump is in the front behind the timing cover.

You will also have to drop the oil pan to get to the 1 bolt in the oil pickup tube.

As stated above you will have to drop the front dif, which isn't too bad, undo the bolts holding the CV axles in place, then there are 3 mounts that hold it in place.
And don't forget to unhook the vent line for the dif.

I ported my oil pump when I just replaced it, and shimmed the spring for a tad more pressure.

I have about 50 pounds of pressure cold, and then it will drop down to about 25 when hot, but my idle is like 550 RPM due to VVT.

As you stated though it goes up with RPM.

An old rule of thumb is 10 PSI for every 1000 RPM as it goes up...

I replaced my oil pressure sensor at the same time, and mine did not have a screen, at least that I could see.

 

A video showing the oil pressure gauge acting weird .
once the Rpm goes back to idle the oil pressure drop then rise again and the needle keeps a slightly movement
the pressure on this truck was always 40 psi steady in idle and 50 in Hi rpms

 

I wouldn't be too concerned with it. It could just be the spring pressure of the bypass opening up and closing.

You did drain the seafoam out right?

IIRC you are only supposed to leave it in for a short amount of time.

 

Yes seafom was in for 100 miles theb then drained
in fact it gets worse after using the seafom .
before the seafom pressure was low on the first mark but never drop below that . After seafom is going almost to 0 then back to what you see in video
also having a Low pressure code on screen , only at start . It takes about 2 sec to read any pressure

im taking the truck tomorrow to a very reputable shop for a diagnostic and possible fix .. Will post

 

Good, can't hurt to double check.

Your in a much wamer climate than me, but my gauge take a second or so for it to register as well.

I'm hoping it's just your gauge or something easy.

The oil pump job is a PITA.

Sounds like you did the seafoam correct, providing you used the correct amount.
It been a while since i've used it so I had to google it LOL

https://seafoamsales.com/how-to-add-...oil-crankcase/

 

Did you use a good oil filter? Oil filters have a built in bypass valve. Cheap ones tend to act up. Seafoam will not hurt anything, if anything it will loosen up and sludge that might be in the system. I routinely use Marvel mystery Oil into my oil changes, I've used seafoam too but like the MMO better.

Tim