joepouliotsc

I have a 2007 Suburban with the 5.3. This weekend my wife was driving down the interstate and the low oil pressure alarm went off. She noticed the oil pressure was at "0". She can't recall all of the details after that, but she said the oil pressure shot back up to 60 and dropped back to 0 several times. She also said there were several thud sounds when the oil pressure was at 0 and the burb jolted. She described it as if it was about to stall.


We immediately got off of the interstate and I took the wheel (I was leading in my truck). When we stopped everything seemed normal. As I drove I noticed everything was normal until about 48 mph and the oil pressure dropped very quickly to 0. Let off the gas and it came right back up to mid 50s. If I stayed 45 or below it was like nothing at all was wrong. I did feel the "thump" twice before I figured out the 45 mph thing. It was significant.


I was traveling to a family vacation, but found a chevy dealer 10 miles away and limped to him. They're supposed to look at it tomorrow. The check engine light was obviously on. I got them to read the codes before I left. There were three codes with duplicates. One was for low oil pressure, the other was another oil pressure code. The third was for the cam position sensor. Seems out of place and I don't know what to make of that one.


Anyone experienced something like this before? I had the issue where it slowly creeped down a few months back. After reading through the forum I learned about a collapsed oil filter. An oil change with a quality filter cleared it right up. This was much more severe.


Thanks!

in2pro

Welcome to the forum...
I suspect that is a bad sending unit or a dirty filter screen, or a poor electrical connection,those seem to be the more common explanation... if the oil pump fails it usually fails and the engine is just minutes behind..
Do you use a quality oil filter and oil?
Is the oil fairly dirty when you change it?

joepouliotsc

Interesting. I replaced the original sending unit two months ago when the old one quit working. I've had no issues with the new one since. I guess that could be it...

I use Castrol and this time used an AC Delco filter. I've never noticed anything unusual when changing the oil like sludge, indications of water, or any debris.

I still don't understand the speed correlation and neither of the other two events had any mechanical events like the violent ones I've experienced this time.

in2pro

I can't say for sure but its possible the pressure drop is not the cause but an effect of something else happening.... maybe a poor battery or ground connection... the connection drops out the vehicle lunges do to the loss of power and you just happen to see the oil pressure drop to zero because the sensor lost power... just a thought...

joepouliotsc

This is a little embarrassing, but it appears the only thing wrong was a very low oil level. I've always burned a little oil and have come to believe it is normal with this make, but never as much as they say was added. I've previously relied on the low oil indication before I'd act on adding oil, but that will change immediately. Apparently I've burned over three quarts (added a quart since the oil change that I did and am very confident it was full at the change) in somewhere around 3000-4000 miles...

in2pro

No problems , maybe a little embarrassing, but a lesson learned and thanks for sharing it as it may really help someone else thanks for following up with your findings...

joepouliotsc

Looks like I might have jumped the gun on that. 20 miles down the road from the dealership almost the exact same thing started again, without the thump this time. They seem to think it's the filter on the oil pressure sender. Update to come.

Chevrolet Customer Service

Hey Joe,

Sorry to hear you had this concern during a family trip. Do you plan to have your local Chevrolet dealership look into for you again? If so, please private message me your name, VIN, phone number, and dealership name.

Erica Tiffany
Chevrolet Customer Care

joepouliotsc

So, the saga continues.


The dealership replaced the pressure sending unit which they say was "broke" and the small filter to the unit. It fixed the oil pressure indication issue.


On the 100 mile trip home I noticed the Volt meter wasn't at 12 o'clock. It was just to the left of the 14. I had the jolt experienced before. A few times but it only did it once then would go away for many miles and then would do it again. Twice I observed the meter returned to 12 o'clock but it dropped back down very soon after. It only jolted when going highway speed.


What I'm thinking...the alternator is on the way out. I'm slightly over 90k miles. The jolt is from a misfire because there isn't enough juice. The "broke" oil pressure indication acted up due to the same lack of voltage.


Thoughts? Is there something else that would cause low voltage and potential misfires? Thanks for looking.

in2pro

As suggested in post #4 you might want to check the ground cable and the ground strap from body to engine...also check the battery/alternator cable for clean snug fit