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Low oil pressure / stop engine warning

83K views 33 replies 25 participants last post by  Ravalli Surfer 
#1 ·
This morning about a mile from my house the low oil pressure / stop engine warning came on. I pulled over and stopped the engine. I restarted it and the warning remained. I returned home and swapped vehicles. I am close to due for an oil change but I know I am not leaking oil. There is no evidence of oil on the garage floor. I will check my oil level when I get home just in case. What might be causing this problem?
 
#2 ·
Nobody knows what is causing that problem. I've had it occur on my truck many times over the past 18 months or so. Seems to happen randomly but usually in stop and go traffic (for me, it may be different for others). I've always been up on maintenance so no issue there. I did change the oil pressure sending unit/sensor about 45 days ago thinking that may have gone bad but the day after I changed it my wife was driving the truck and the warning light came on three times while driving. It hasn't happened since which is interesting, well, not really but it adds to the confusion. Many people have posted the exact same issue here and nobody has found a cure. At least they haven't posted a cure.

If you discover anything leading to the cause of this issue please post your findings. There are many of us here that would like to determine the cause.
 
#3 ·
I know this thread is 1 year old (to the day) but I just experienced the same issue.
Low oil pressure warning followed by "shut off engine" in the Display

After reading up on the issue I tried the following
-cleaned the throttle body
-inspected all vacuum connections

The throttle body was pretty clean but had some soot around the butterfly and I cleaned that off.
I put zip straps on all the vacuum connectors to tighten up the connections.

So far, I have gone 2 days without the low pressure warning.

total cost:
45 minutes of my time
.50 worth of TB cleaner
.75 worth of zip straps
 
#4 ·
I've read on there that someone cleaned the little filter located above the oil pressure sending unit. When I changed my sending unit I didn't look to see if there was a filter so I don't know this first hand. Another individual on this site posted that he was going to flush his oil figuring that there is some crap build up that is causing this issue. The flush he was doing drained the oil and then partially filled it with kerosene (but didn't start the engine). Drained that and then flushed some new oil through to remove the kerosene, drained that and then filled it new oil. I never read an update to that posting so I'm not sure it worked or not. Another person said they cleaned the CPAS and said that solved the issue. The good thing to these "fixes" is that none of them cost very much. They may not work but at least they don't do any harm either.

Good luck with finding the problem. It baffled me for years and I never found a solution.
 
#5 ·
Oil pressure low warning at cold start

Since having the front differential in my 97z 5.3 engine which necessitated removing the oil pan, at every cold start the display reads oil pressure low for a few seconds. Oil pressure gauge goes to normal and pressure is fine during all driving conditions. Lots of engine problems including two rebuilds due to the AFM system in my opinion. Any thoughts on whether something could have been disturbed during the repair? It's making me crazy!
 
#29 ·
Oil pressure low warning at cold start

Since having the front differential in my 97z 5.3 engine which necessitated removing the oil pan, at every cold start the display reads oil pressure low for a few seconds. Oil pressure gauge goes to normal and pressure is fine during all driving conditions. Lots of engine problems including two rebuilds due to the AFM system in my opinion. Any thoughts on whether something could have been disturbed during the repair? It's making me crazy!
Oil pressure low warning at cold start

Does it to hurt to continue to drive like thothos when the oil pressure ddrops when you come to a stop but goes back to normal when your driving??
 
#6 ·
So I've had a few LS powered vehicles this Trailblazer has the 5300 its an 07 EXT 2wd. I picked it up very cheap because of the loud knocking noise. I was thinking it was a lifter issue until I pulled the pan off. I've been scouring the site for info tons of good stuff found the TSB listing the oil pump pickup tube o-ring failure. the previous owner had just had this thing serviced by Jiffy Lube who put four and a half quarts in the system. Subsequently the motor started knocking very loud he shut it off and traded it to me. as it seems all of the rod bearings are fairly scarffed yet the mains are perfect. #5/6 rod bearings were sitting in the pan. Trust me I know what you guys are going to say but I have check these every which way the crank and rods are perfect still. I have never seen an engine throw bearings and be a simple refresh to repair. They are still in spec. The cause was a bad o ring at the oil pump pick up tube (there is a tsb listed)-(but not listed here?) So I went to my dealer and pucked up new o-ring and standard bearings they are saying I need to run 7 to 7 1/4 quarts of oil (another tsb) and fix the o-ring and I'm golden. So maby you guys should check the O-ring and add oil. This problem also explains the missing oil conundrum people seem to be facing with these trucks? if the o-ring is bad as it sucks air and oil through the high pressure oil pump it will vaporize the oil causing it to go up through the engine through the PCV system
This scenario would also cause a low oil pressure condition even if when you stop and
check your oil it shows full on the stick. Hi I'm new here and this is my first post lol.

:tiphat

burned at a relatively alarming rate compared to any other LS style or any engine with less
than 100k for that matter.
 
#7 ·
After a week at the dealer and some tests (i.e.) removing the oil filter and connecting a pressure gauge which confirmed sufficient oil pressure I picked it up and have driven it this past week with the "better" oil filter used on the high performance engines. When I park nose down on a slight incline at work the warning message is not displayed at cold start up. Each morning however after being parked in the garage which is level the message has come on all but one day. Dealer agreed to install new oil pump next week thinking that the pump could be getting tired. At 116k miles, really? I'll pay for part they will cover the labor. Stay tuned!
 
#8 ·
Well the new oil pump seems to have solved the low oil pressure warning at cold start up. How an oil pump can become worn at such low mileage is beyond belief but maybe it was taxed by the two engine rebuilds. Let's see how soon before something else fails. What I have learned on this rig is that preventive maintenance cannot counteract a poor design and poor quality parts.
 
#11 ·
Again, I know this is an older thread, but I've found out more info on this issue. A lot of people have found that this is caused by the filter under the Oil Pressure Sensor being plugged (this we mentioned above). It's a very cheap part ($5-$10) but I can only find a genuine GM part (no aftermarket). For those that have the issue, I would try this before cracking into the oil pump. I have 154,000 miles on my 05 and I'm going to put a new filter and sensor to see if my issue goes away (much like others, mine only comes on at low engine speed and sometimes after heavy braking). I'll keep people posted if they are interest.
 
#14 · (Edited)
I'm reviving this old post again because my wife's 04 Trailblazer (I6 AWD) has been lighting the oil pressure warning at cold starts. It just turned over 200k miles. I haven't replaced the oil pressure sender yet. I looked for a 'filter' for the oil pressure sender and found these, but not sure if that's what I need, nor where they go. Rockauto calls them oil filter bypass valves, but they appear to have a little filter in them. And why are there two?

Genuine GM Valve Part# 25014612

Genuine GM Valve Part# 25014006

Can anybody provide more details?
Thanks,
Joe
 
#16 ·
I have an 06 trailblazer 5.3 had it two months put about 1500 miles on it since i bought out used,
and I was driving into town and i lost all oil pressure, stopped and checked it, wasn't low on oil, started it kept oil pressure for like 10 seconds, then lost it, I have a knocking on the motor. And metal shavings in the oil! They look aluminum, the block is aluminum! Is the motor trashed or is it rebuildable?
 
#17 · (Edited)
I have an 2003 chevy tb 4wd LT and one day my son was driving it and it started knocking loud we did an oil change and put some oil treatment in after the oil change and when i took off the oil fliter it was so thick and black , we had it only month and half bought it from an dealer the engine sound good when we first got it, can someone please tell me what can i do my wife was talking about getting another engine put in
 
#18 ·
I would try oil changes every 250 to 500 miles see if it cleans out before I drop a motor in it. Don't use a motor flush I was always told. Im not a mechanic but I was told to add little trans fluid like 1/8 of a cup or less to clean up engine deposits. I would wait to see if someone else who is more engine friendly adds their option first before I do it. good luck
 
#33 ·
I would try oil changes every 250 to 500 miles see if it cleans out before I drop a motor in it. Don't use a motor flush I was always told. Im not a mechanic but I was told to add little trans fluid like 1/8 of a cup or less to clean up engine deposits. I would wait to see if someone else who is more engine friendly adds their option first before I do it. good luck
Yes Trans will clean the engine and diesel fuel will do you great. At run temp drain a gt and put a gt of Trans or diesel in your engine and run it for a couple of minutes. Drain out . You will see just how much black comes out . Put some cheap oil to level and run for 3-5 minutes drain. You will be amazed how nasty it will be. I unstuck a lot of motors with diesel and ran them for years like this.
 
#20 ·
So today, about 35 miles from home, my engine light came on and oil pressure gauge was showing low. I have a 2006 GMC Envoy Denali with a V-8. Anyway, I stopped as soon as I could and checked the oil level. It was fine. When I started back up, the oil pressure gauge went to normal, but a few miles up the road, the engine light started flashing. I pulled off interstate into a rest area. When I started the engine again there, it had a clicking sound and bad vibration. I have OnStar so I called them and got it towed to the local dealer. It is sitting there and I guess I’ll find out tomorrow what they say the problem is. I just bought the Envoy in July and I know it has a rebuilt engine. The vehicle has 99214 miles, but the engine significantly less. What could be wrong?
 
#26 ·
Low oil pressure @ cold starts

Zippy i have the same problem when my Vortec is cold the pressure drops until
I am warmed up @ 200 on the temp gauge, then the lol is fine.. so my first attack is the oil sender unit and here goes something I don’t see people say they
Do when changing the oil pressure switch is the filter underneath the oil switch,
It’s a real a %^&* to get to but when you see how thin the screen is on this small filter you can see why maybe the oil is dropping, but if i had time i’d Put a pressure gauge in 2 areas to see. If the pressure is really dropping. Some type tap some place near the oil pump or down the line before it gets to the top of the block. Well I’ve been real busy working hard but one side wants to jump in
And do it the other side is saying hell no, no matter how those guys make to that job is, when i stand in front my truck is does not look like that, i wonder how the dealer suckers do it.. no disrespect to the good dealer machanic’s..
But i am going to do the job soon..:crazy:
 
#28 ·
Low oil pressure @ cold starts

Zippy i have the same problem when my Vortec is cold the pressure drops until
I am warmed up @ 200 on the temp gauge, then the lol is fine.. so my first attack is the oil sender unit and here goes something I don’t see people say they
Do when changing the oil pressure switch is the filter underneath the oil switch,
It’s a real a %^&* to get to but when you see how thin the screen is on this small filter you can see why maybe the oil is dropping, but if i had time i’d Put a pressure gauge in 2 areas to see. If the pressure is really dropping. Some type tap some place near the oil pump or down the line before it gets to the top of the block. Well I’ve been real busy working hard but one side wants to jump in
And do it the other side is saying hell no, no matter how those guys make to that job is, when i stand in front my truck is does not look like that, i wonder how the dealer suckers do it.. no disrespect to the good dealer machanic’s..
But i am going to do the job soon..:crazy:
i just went thought that same problem ands thats what i did i remove the oil pressure switch and the filter under the sender unit, and it did work meanwhile
the oil was weak and the dumb *&^$ wouldnt warm up the truck like i asked, so now their changing the oil pump, i think the problem was the o ring on the oil pick up tube, on my truck the pressue would drop when runnuing at 500 rpms,
so i will let you know if that cures the problem. it should it makes sence when you look at the mechanical part. the pick oil tube is like a straw for the oil pump,
when the o ring thins out air is being pulled up along with the oil, when i warm up the truck @ 1500 rpms and the water temp get too 200 the oil pressure would sit around 31 lbs revvving up take it to 40 l bs, so since their replacing the o ring am telling them to replace the oil pump, seal front and rear along with the all gaskets to replace items..
 
#30 ·
Well yes the oil is not being pumped to the top of the motor. So yes if you drive with the oil pressure low the motor can lock up, it’s 2 problems the oil pump is getting weak and what makes the oil pressure drop is the O ring on the oil pump pick up tube, it flattens out and the pump is sucking air untill the oil thins out from warming up, my truck has had that problem for a year and a few months but how I keep it working @ start up I would bring the rpms up to 1500 slowly untill I saw the temp gauge sit @ 200 degrees, at that point the pressure would hold like normal, 31 idle and 41 driving, I had to this every at first start up, I don’t recommend you try that as long as I did I got lucky, but the pump just stop pumping pressure 3 weeks ago, on vortex motors the oil pump is on the crankshaft being the timing chain cover, not in the oil pan so If your doing repairs change the pump the, pick up tube O ring, added bonus since it’s already apart change both front and rear seals, it’s a big job trust me am getting it done as we speak, but if you ignore what I’ve told you and since you had everything pulled down under the front end and you don’t do that, support when the button it back up you start getting oil leaks after just putting back together, 2 things might happen you kill your self for not listening or your going to burn the truck up, trust that..it’s costing me money but the. Next time I will have an oil leak that Denali will be some else’s head ache I love that truck but 4 wheel drive crap and the transfer cases mounted to the oil pan with an axle running though the oil pan never again, hmmmmm just sitting typing theirs a way to get rid of that head ache, get rotors and spindles from a trail blazer. Next time
 
#32 · (Edited)
............ so If your doing repairs change the pump the, pick up tube O ring, added bonus since it’s already apart change both front and rear seals, it’s a big job trust me am getting it done as we speak, but if you ignore what I’ve told you and since you had everything pulled down under the front end and you don’t do that,
You CANNOT change the rear seal that way.

If --- perhaps --- you mean you can change the rear pan gasket -- then that's OK ... but the rear seal requires a tad-bit more work to access .... where a 'tad-bit' means: remove engine or remove transmission.
Ya see ---> the rear seal is wrapped around the rear of the crankshaft --- but you know that --- right?​
I don't (usually) talk through my rectum --- I've made this same repair myself ---

 
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