2006 GMC 5.3 Vortec - Low Oil Pressure at startup

I get a Low Oil Pressure warning at startup and can hear the lifters and rockers tapping away. It stops after about 5-10 seconds. This only happens when it's very cold. It is kept in my garage where it's 20F-30F. It has happened about 3 times this winter. It happened once last winter. I'm afraid to drive it now.

I always run Mobil 1 5w-30... and typically AC-Delco filters. It is not low on oil and I just changed oil and filter a few days ago.

I did some online research and it seems that it may need a new oil pump and pickup tube. Does this seem like what I'm going to need to have done ?

A little more history wouldn't hurt. Have you owned the truck since new? Mileage? How often do you change the oil?

Check and see if that engine has a screen in the oil pressure sender that gets plugged

Time to replace the oil pump . We found in the chev racing parts book . A pump with high volume and standard pressure pump .
278,000 miles . Oil pressure is 40psi at idle and 50psi when reved up .

Oil pump pick up O-ring is probably hard and sucking air when cold. Requires pulling the pan to replace. This is most likely, just did one a couple months ago on an '07.

The other possible problem is a porous head casting that allows small amounts of coolant into the oil after shutdown. That coolant mixes with oil and conceals as sludge in the bottom of the pan. It then shrouds the oil pickup. A quick check is if the top of the oil filter has a film of brown gunk, it has a porous head. Typically only '03-05 engines, but always possible.

You didn't mention if this is a pickup or Envoy. 2006 Trucks are Gen 3 engines, so no AFM or oil sender screen. 2006 Envoy is Gen 4 with AFM and would have a sender screen.

Worst case scenario is it has a spun cam bearing. Not common, but I've seen it happen.

Never seen an oil pump fail on these. In fact, when I put a performance cam in my 200K mile 5.3, I inspected and reused the pump. I replaced the cam bearings when I did the cam, mine runs over 40 psi on the highway hot.

These are the things I see cause this issue on the 5.3.

How many miles are on it. I find it hard to marry a high mileage engine and I don't have to anymore : )


That being said if I fell off the wagon I would want to know if the oil pump builds oil pressure off the starter on cold crank up. I would disable the ignition and fuel pump install an adapter between the oil filter and block. As soon as it started to crank I should immediately see oil pressure of at least 15 to 20 psi. If I did not I would be looking from the filter toward the oil pick up. If I did the issue is from the filter to the internals of the engine.

5.3 are a little different I have never been into one I have had the oil pans off if it gets deeper GM sales a nice reman : ) I have seen 6.0's (non DOD) have good oil pressure at the filter but none at the oil sender I passed on them life is good...

Its not a anybody's game to play it can cost you thousands to allow a inexperienced wrench to learn as he goes. He can be a well seasoned veteran that does not understand how to check a oil pumps operation and throw parts at it.

The kink in it not all will be the same its all going to be how you interbit it. Pattern failures will bit you hard... Signs signs everywhere a sign as Sprint said I want to see what the top of that oil filter looks like castech heads are not. If the oil filter mount is gummy the rest of the engine is gummy : ( I have had my belly full of gummy engines move on life's to short to mess with them...

My 2007 GMC has 125k.
V6. It's the opposite. Cold starts very
good oil pressure. After it warms up at
an idle oil press guage show about half of
normal 20 psi.

I bought it new. It's been that way since
I bought it.
I had oil changed as recommend at 3k with
5w30 valvoline by dealer while under
warranty.
Engine doesn't use oil. Runs like new.

I'm the first and last owner of cars and
truck. That's why I will only buy new now
that I'm retired because I have no plans
to rebuild engines.

I have heard that some oil filters do not have a check valve that allows oil to drain back into the pan and cause rod and lifter noise at startup. I would not think AC Delco would be one of these. Fram comes to mind.

I purchased a new 1994 Chevrolet Silverado 4/4 with the 5.7 engine. I bought the truck in late fall of 1993. I noticed right away on cold morning's when i started the engine that it would have a slight rattle. Maybe lasting for a couple seconds or so. The owners manual called for 5w30 engine oil. As a matter of fact the fill cap on the rocker cover even stated to use 5w 30 oil. I took the truck back to the dealer and told them about the rattle. Of course they did nothing so, i decided at the next oil change to go to Castrol 10w30 oil. I sold the truck with 220 thousand miles on it and never heard it rattle agin after changing to the 10w30 oil.

My 6 liter 2500 Chev has been doing that for quite some time, right when I first start it. Mine only has 79,000 on it and I have always used Mobil one. My friend has the same thing with his 08 2500 and he has over 200,000 on it with no problem. For what its worth.

i have heard so many engines do that in the cold for a couple of seconds on start up. never heard of anyone being concerned and never heard of their engine blowing up. it is just taking a bit longer for the lifters to pump up is all. to be sure put a master gauge on and check your oil pressure at start up.

I would try a Wix premium filter next time. I had that problem using Fram filters.

Thanks for the replies.

The truck has 136,400 miles. It had 109,400 when I got it.

It's a Sierra 1500 SLE (extended cab 4x4 6.5 with foot box).

I bought the truck in April 2018 from Pinegare Chevrolet in Springfield, Missouri. I am the second owner. I have a list of things they serviced before I bought it which includes an Oil Pressure Sensor.

I had this exact same issue with my '03 Silverado 1500 last year. You start the truck and the oil pressure is low around 20-25 psi with no change in RPM until the engine gets hot, then the pressure will jump up to it's normal range. This is due to the o-ring on the oil pick up tube where it connects to the pump. The o-ring wears out and will allow the pump to suck air until it heats up enough to expand and allow the pump to pull oil correctly. It is only a 15 cent part, but you have to drop the oil pan and remove the pickup tube to replace.

I had this done on mine and it was an instant fix. 35,000 miles later and it is still behaving like it's supposed to. I'm sitting at 336,000 miles now. Be aware that most shops will look at you funny when you tell them you want this done. Not many will know of this and will have a hard time believing you. They all say the same that it is the lifters going bad. The lifters do go bad and is a common problem but if it is behaving the way I described it is that o-ring and not the lifters.

That's not possible on these engines. The filter is vertical and sits at the bottom of the block on the rear of engine. Oil cannot drain out of these filters due to their position.

I'd get rid of that Delco filter. I had oil pressure issues more than once with the Delco filters on my 08.

Put a Wix on it and see if anything changes. Cheap and easy enough to try.

I don't know if the 5.3 is set up the same as the 6.0 but. On my 2000 6.0, I lost the front main bearing at 98,000, and had a Jasper rebuilt put in it. Jasper said that those engine had a check valve that kept the oil from draining back, it had an aluminum seat, and would hammer out and leak, causing it to start on a dry bearing. They replace it with a stainless seat check valve. And yes, I had the same symptoms.

(quoted from post at 14:40:35 01/05/22) That's not possible on these engines. The filter is vertical and sits at the bottom of the block on the rear of engine. Oil cannot drain out of these filters due to their position.

Click to expand...

So how come the correct wix filter has an anti drain back valve??



This post was edited by DoubleO7 on 01/05/2022 at 05:21 pm.

(quoted from post at 13:38:05 01/05/22) I had this exact same issue with my '03 Silverado 1500 last year. You start the truck and the oil pressure is low around 20-25 psi with no change in RPM until the engine gets hot, then the pressure will jump up to it's normal range. This is due to the o-ring on the oil pick up tube where it connects to the pump. The o-ring wears out and will allow the pump to suck air until it heats up enough to expand and allow the pump to pull oil correctly. It is only a 15 cent part, but you have to drop the oil pan and remove the pickup tube to replace.

I had this done on mine and it was an instant fix. 35,000 miles later and it is still behaving like it's supposed to. I'm sitting at 336,000 miles now. Be aware that most shops will look at you funny when you tell them you want this done. Not many will know of this and will have a hard time believing you. They all say the same that it is the lifters going bad. The lifters do go bad and is a common problem but if it is behaving the way I described it is that o-ring and not the lifters.

Click to expand...

It's the o-ring just like he and the other guy says.

My '06 did it too...have it changed and it will fix it.

https://www.youtube.com/watch?v=KjAUj5kfPSs

Read the comments for tips. I shipped thru it till the last 3min to see the fix. : )
If he would have took a little more time he would have known if the pick up and oil pump were the issue : (

I happen to land one time he was adding heavy oil I thought what a dumb arse... By now I thought we all would know its luck if it adds a pound are two of oil pressure cold and none hot...

This post was edited by Hobo,NC on 01/05/2022 at 06:07 pm.

Had an 01 Silverado, did what yours was doing.

Cold weather start up only, it would take way too long to get oil pressure, but once it got it, it was back to normal.

It rapidly got worse, and one morning it did not get pressure, even revving the engine. I got scared and shut it down.

Pulled the pump out the front WITHOUT dropping the pan. Surgically unbolted the tube, turned the clamp around, got the new pump back in and connected without dropping the bolt!

Couldn't see anything really wrong with the pump or the oring, but that fixed it. I did change the oil and filter at the same time, could have been the filter draining back.

I read elsewhere that someone else had done that. I am really starting to think that it's the pickup tube. What you describe is exactly what is happening with mine.

The question is can it be diagnosed with out a big guess I say it can its your call. A bud did remove the pump to get to the o-ring that's all I know other than he ended up putting a engine in it.

The interesting development out of this was we both were installing a engine in one and had an issue with new aftermarket water pumps were leaking. Both were defective pumps from two different suppliers. They leaked thru the casting SHOCK. I have one in the shop now they all get OEM Water pumps along with OEM coolant hoses. OEM pumps are not that much more : )

While on the subject the heater hoses connect to the heater with plastic connectors they are just waiting to snap/break off its in your near future.

Lets say you are who you contract go after the oil pump the crank bolt is torque to yield you will need a tool to hold the flywheel. I know some just hammer it back on : ( I remove the starter install the holding tool and do as OEM suggest and charge for it... Life is good.

HO-MADE tool for a one man show.