Skip the auto shop - Our mechanics make house calls

Q: Oil pressure loss - 2005 Chevrolet Avalanche

asked by on

Hi, i have a 2004 Avalanche 5.3. . Truck has been idle for about 3 weeks while body was being redone. Picked it up yesterday and drove it about 10 miles when I lost oil pressure. Engine noisy. Changed out the oil filter, pressure good and engine quiet. I use synthetic oil. Drive later for about 25 miles, same issue again, engine noisy. Shut it down and called tow truck. In the meant time after about 10 minutes refired the truck, lots of oil pressure and quiet engine. Watched gauge it slowly began to drift down again so shut it off. Am I looking at sludge in the pan moving around and plugging the pickup or had the O ring on the tube hardened up and leaking from sitting.

My car has 256000 miles.
My car has an automatic transmission.

Hello - no, most likely this is the oil pressure relief valve sticking in the "open" position when the pressure comes up. It may then release after sitting a bit, or when you next hit the starter. The early 4.8/5.3 engines had some problems with this valve - scary! You might pull the valve, and using an oil gallery brush and some solvent, scrub the passage out. An engine sludge cleaner treatment MAY help as well - Seafoam is a popular choice, but there are others.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Oil pressure loss - 2005 Chevrolet Avalanche

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Why am I getting rich codes in my 2012 Chevrolet Silverado

Claimed by Robert Tomashek

Q: The cable for my hood release broke on the end that's connected under the hood.

There are small bolts on the deck where the hood bumpers are located at. Remove those bolts and bolts that are on the inside of the grill and the front grill will come off. The hole grill and lights assembly...

Q: I have a 2002 chevy avalanche z71 it won't move forward in any gear,but it will move in reverse

Check to see if any diagnostic trouble codes have been stored in both the PCM and TCM. Check the fuses in the circuits that power the transmission controls. Occasionally, a short in a sensor such as an oxygen sensor will...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...