I have 223k on my 06 hummer h3. Recently replaced the cylinder head due to a burnt exhaust valve
After replacing it I started getting a low oil pressure light. I assumed that at 223k it was probably my oil pump going out. I replaced it along with my oil pressure switch and i changed my oil and filter. However I still get the low oil pressure light even now and then once the engine is warm.

I use castrol gtx high milage 5w-30.

Any ideas why and what to do to fix it?

 

remember, new head on 223k engine, bottom end is high mileage.
i suggested a low mile used engine.
all bearings are well worn??
you dont want to pull it for bottom end rebuild, a used motor will /would have saved much time effort and money. sorry

 

I understand that the "correct" thing to do it replace the motor. If I am going to do that I am NOT going to drop a used one in and I don't have the funds right now for a brand new motor. I want to know what I can do for this motor to help with the low oil pressure at idle.

Will running some 5w40 or maybe 10w30 help (I don't know which number needs to be raised) or will that cause more problems? I know it's not running dry cause its not making any noise when the low alarm is going off. I just want to raise the oil pressure so the alarm doesn't sound.

 

At 223k it needs an overhaul, not a band aid. You already had the head off, pulling the bottom end would not have been much more effort or cost.

 

After changing the oil again it seems to be getting better and I haven't had the light come on in a couple of days.

However I have what seems to me to be an excessive amount of vacuum at the oil fill cap while the engine is running. Is it normal to have vacuum at the oil fill cap when the engine is running on these motors?

 

I had low oil pressure on start-up that went away after the engine warmed up. The oil pressure gauge rarely got to 40 lbs. unless I was at highway speed for a while.


I thought that it was the oil pump going out, but read somewhere that it could be caused by the aging O-rings on the oil pick-up.


Replaced the O-rings on the pick-up and that did the trick. No more "Low Oil Pressure" warning on start up and it jumps top 40 lbs. at an idle. Oil pressure up to 60 lbs. at highway speeds. Hasn't been up there in years.


Apparently when the O-rings get older (I'm at 190K miles) they get hard and shrink just a bit causing loss of suction. The new O-rings sealed the pick-up and the oil
pressure is back to normal.


Unfortunately, you have to remove the oil pan to get to the O-rings and that requires
dropping the front differential. It's a big job.