90-PSI after Oil Change??

[moss6]

Changed the engine oil and filter (1,000 miles) this weekend and after startup saw the normal 0-PSI for a few seconds pressure went to 60-PSI, normal. I then did some other installs; Bed Rug and Pace Edwards bed cover; after which I went for a drive. The engine, on start up, didn't sound quite the norm for it, additional noises I haven't heard before, hard to explain just more busy sounding more whines and lower deep sounds, and the oil pressure was half way between 60 and 120 PSI as soon as I put it in gear and rolled out. I have not seen this out of this engine cold. First thought was that the factory oil was different from the Delvac 15W-40 I replaced it with, but couldn't believe the pump was making 90-PSI (a guess with the GM guage) LBZ never made over 60 cold. I assumed it would drop pretty quick as it warmed up but that was not the case, held steady half way between 60-120 even after coolant temp reached 210, so now I'm wondering if the new oil filter (bought from the dealer) is restricted. At that point I stopped to make a purchase (pecan picker-upper to rid the yard of the damned things) and after restarting pressure at 60, in gear and roll out back to 90, on the road I decide what the hell, nail it, which I did and after about 7 seconds hard acceleration the pressure suddenly dropped back to 60; what the f*#k, did it blow some restriction out!
Any ideas on this, and also this is not BS.

[Mark Rinker]

Hard to tell - factory gauges are notoriously inaccurate as to actual PSI reading - but if its varying that much from what you normally see - how expensive is it to satisfy your hunch by spinning on another filter?

I'd probably let it cool off tonight, run it tomorrow, and if its still making crazy pressure, replace the filter and see what happens next.

At least you have oil pressure! LOL

[moss6]

Hard to tell - factory gauges are notoriously inaccurate as to actual PSI reading - but if its varying that much from what you normally see - how expensive is it to satisfy your hunch by spinning on another filter?

I'd probably let it cool off tonight, run it tomorrow, and if its still making crazy pressure, replace the filter and see what happens next.

At least you have oil pressure! LOL

Mark, my concern would be that even if I put another filter on it then I still wouldn't know if something came out of the filter, went down stream and plugged up something. I don't think that there is anyway to check that out other than a complete tear down. I'm really having a hard time with deciding what to do, if something is blocked then I would think something is going to self destruct in pretty short order and likely lead to a less than desirable engine even if repaired. Another thought, not too appealing, is that GM might deny warrenty because I changed the oil and filter. This is really making me sick.

[Mark Rinker]

Relax. Most likely a problem with sender or gauge calibration.

If you are under warranty, and bought the filter from the dealership, how bad can it get?

Whats happening today...?

[moss6]

Wife said it's 60-80; had her go by the dealership and they said normal so I guess it's on them. Fingers crossed. Find it hard to believe that before the change when hot it wouldn't even get to 60 and the old LBZ ran around 30-40.

[Kennedy]

What did you use for a filter? I haven't seen if the application has changed for 2011?

[moss6]

What did you use for a filter? I haven't seen if the application has changed for 2011?

Its the same filter PF2232, and it came from the Chevy dealership. John, if you were to hazard a guess, what would you say is going on?

[moss6]

What kind of oil pressure numbers are you guys seeing on the LML after changing out the factory oil?

[SoTxPollock]

I wouldn't worry about that pressure. My old LB7 after 170,000 miles still hits about 80 psi on the gauge at start up, but backs off to 60 after normal temps are reached.
I don't know what the factory oil fill is, but your replacement oil may just flow a little differently. OF course I always run the 5W-40 instead of the 15W-40.

Having said that, if it ever pegs the gauge and keeps it there when its running at operating temperature, I'd suggest you pull over and shut it off and get it towed.
Had that happen with a friend of mine's engine one night coming back from Daytona and the oil gauge pegged and we kept driving and discussing what might be going on. We finally deceided that it had spun a cam bearing and that had closed off the oil flow hole in the block and sure enough one of Rod's started to slightly knock after about 15 minutes and it got louder and louder, finally pulled over about the time it would have blown had we kept going, got it towed to a garage and had to have some serious engine work done on it to get it back home.

I suspect you just have an engine with manufacturing tolerances on the tight end and not the loose end of the tolerance.

[moss6]

Well it's now gone pretty much back to what it was before the change, 200 miles later. After hot it will run around 45psi mid range rpm's. It's still higher cold around 80psi (60 before) but I haven't seen 90 again. Also I've been in a few other 11's now and 80 seems pretty normal. I'm sure there will never be a good explaination for the big change, but now I'm not worried about it. I will be interested to see how it will be affected when I go to my normal 5W40 Delvac synthetic at the next change.

[cowboywildbill]

Sounds pretty normal. I notice a lot higher psi on our LML than we did on the LBZ.
But I remember seeing 90 on cold day's at startup on the LBZ, it just dropped down a lot farther after it warmed up. These new trucks run more pressure, and I'm told they have a higher volume/high performance pump in them now.