My check engine light came on last week and the code was po521 oil pressure warning. The light went out and the oil gauge was normal and it drove fine but I ordered a new pressure sensor and screen. It came back today on the highway and the engine started making a rattling noise before I could get off the road. I think maybe the oil pump failed. The dipstick says full but the noise sounds like metal on metal. It's a 97x with 123000 mile. I hope I'm wrong
I MAY HAVE KILLED THE 5.3
- Thread starter Dpitts
- Start date
The oil was 3 quarts low! I don't see any leaks underneath and it was changed 800 miles ago. I added oil and the engine sounds find but the check engine light is still on. I will inspect it further this afternoon.
Mooseman
Moderator
I'd still drain it into a clean pan and check for metal. You could also send a sample to Blackstone for analysis.
My question would be why was it so low to begin with? Burning oil or bad leak somewhere? Who changed it? If it was one of those quick lube places, I'd be putting them as the #1 suspect. Going that low in 800 miles is not normal.
My question would be why was it so low to begin with? Burning oil or bad leak somewhere? Who changed it? If it was one of those quick lube places, I'd be putting them as the #1 suspect. Going that low in 800 miles is not normal.
- Jul 22, 2015
- 2,724
I'd agree -- if you actually lost 3qt in 800mi - either the pan or the block is ventilated (e.g.; you'd readily see it leaking). The only other place it could go is past the piston rings as blow-by -- and at that rate, you would be able to see blueish smoke out of the tailpipe at idle, never mind accelleration. You'd probably smell it, too, tbh.
I'd definitely grab a sample of what you drained, if you have it. www.blackstonelabs.com will send you a free test kit via USPS, if you need one. But keep that oil in a safe place, till you get the kit.
If you don't have the old oil, run the new for 500-1000mi (longer is better). You can drain the oil, grab the sample, and reuse it, if you like.
Also... if you still have the old filter, cut it open at the seam (like slicing bologna... best analogy I can think of at the moment), remove the media, and unroll the pleats. Check for any foreign substances (metal, etc.) If you find any, clean them off with some brake cleaner and post back here. Meanwhile, we'll keep our fingers crossed that all is well with your engine. And do yourself a favor and check the oil more frequently for a bit, to see if that consumption rate continues.
I'd definitely grab a sample of what you drained, if you have it. www.blackstonelabs.com will send you a free test kit via USPS, if you need one. But keep that oil in a safe place, till you get the kit.
If you don't have the old oil, run the new for 500-1000mi (longer is better). You can drain the oil, grab the sample, and reuse it, if you like.
Also... if you still have the old filter, cut it open at the seam (like slicing bologna... best analogy I can think of at the moment), remove the media, and unroll the pleats. Check for any foreign substances (metal, etc.) If you find any, clean them off with some brake cleaner and post back here. Meanwhile, we'll keep our fingers crossed that all is well with your engine. And do yourself a favor and check the oil more frequently for a bit, to see if that consumption rate continues.
Mike534x
Member
- Apr 9, 2012
- 920
What Reprise and Mooseman have suggested!
I usually go through a quart every 500-1000 miles, pretty sure its piston rings + the bad rear main on mine. As annoying as it is, I usually check it every other fill up (usually 250-300 miles with the city driving I do).
I usually go through a quart every 500-1000 miles, pretty sure its piston rings + the bad rear main on mine. As annoying as it is, I usually check it every other fill up (usually 250-300 miles with the city driving I do).
The oil was changed as Goodyear. I will inspect it and change the oil today. Hoping it something simple as it's a good running vehicle. Thanks
When changing the oil I found the oil filter loose and leaking a little oil. However my check engine light is still on and when I turn off the engine I hear what sounds like a tire leaking somewhere near the break booster and the fuse box. it only lasts for a few seconds after the engine stops. any ideas?
Mooseman
Moderator
gmcman
Member
- Dec 12, 2011
- 4,656
Brings up a story from a ways back, obviously not the same store, but my local Goodyear nonetheless.
I was due for an oil change, mind you this is the 4.2L, and it was a very cold winter so I wanted to get some fresh oil and not do this on the ground, ambient temps were around 10 deg.
I swung by after work and pulled through the line, asked for an oil change and gave them the keys.
This was the first oil change post warranty that wasn't done by myself.
I was able to watch through the glass and all looked good. When I walked over to it after it was pulled outside, the first thing I did was check the oil.
I didn't see anything on the dipstick so I cleaned and redid the check. There was a small spot on the bottom of the dipstick.
I went inside and asked the sales clerk to come out and look. I pulled the dipstick in front of him and he had a confused look.
I said, "they do realize this takes 7 quarts right?
"7"?
I said "yeah". He said "well the oil service is up to 6 quarts, anything else is extra"
Before he could say he will have it taken care of, I quickly interjected...
"So noticing it's a quart low doesn't warrant telling me the extra quart will have a charge"? "Your tech was going to let me leave"?
He said he was going to take care of it and I knew he would, but needless to say I was totally bamboozled at the negligence.
Was the first and last time.
I was due for an oil change, mind you this is the 4.2L, and it was a very cold winter so I wanted to get some fresh oil and not do this on the ground, ambient temps were around 10 deg.
I swung by after work and pulled through the line, asked for an oil change and gave them the keys.
This was the first oil change post warranty that wasn't done by myself.
I was able to watch through the glass and all looked good. When I walked over to it after it was pulled outside, the first thing I did was check the oil.
I didn't see anything on the dipstick so I cleaned and redid the check. There was a small spot on the bottom of the dipstick.
I went inside and asked the sales clerk to come out and look. I pulled the dipstick in front of him and he had a confused look.
I said, "they do realize this takes 7 quarts right?
"7"?
I said "yeah". He said "well the oil service is up to 6 quarts, anything else is extra"
Before he could say he will have it taken care of, I quickly interjected...
"So noticing it's a quart low doesn't warrant telling me the extra quart will have a charge"? "Your tech was going to let me leave"?
He said he was going to take care of it and I knew he would, but needless to say I was totally bamboozled at the negligence.
Was the first and last time.
Mooseman
Moderator
That code I used to get on my 5.3 Saab after I did a DOD delete and put in a new oil pump, which was the wrong one. I needed a high volume pump so my pressure was a bit lower. Once the oil had some miles on it, my pressure wasn't getting past 40 PSI and it would throw that code. This is a code specifically for the DOD system as there wouldn't be enough pressure to operate it. I still had some pressure but not enough. Replaced the sensor, same thing. Once I replaced the pump with the proper HV version for DOD, it was fine.
In your case, if you didn't do anything to the pump, then it's got low oil pressure. Maybe not enough to trigger a low oil pressure warning but lower than normal. Multiple reasons that can happen including bad bearings and pump issues. What kind of pressure is your dash gauge showing? When my 5.3 started rod knocking, pressure was way down and sometimes dropped to 0.
In your case, if you didn't do anything to the pump, then it's got low oil pressure. Maybe not enough to trigger a low oil pressure warning but lower than normal. Multiple reasons that can happen including bad bearings and pump issues. What kind of pressure is your dash gauge showing? When my 5.3 started rod knocking, pressure was way down and sometimes dropped to 0.
I think my issue was the leaking filter. After the oil change and erasing the codes it is running great and the oil pressure is normal. I will keep an eye on the oil level and see if the code comes back. Now to find the source of leaking air near the break booster! Thanks for your help