Okay here is the deal car starts up runs killer pressure like 50 psi at idle, warms up drops to 40 where it usually stays...Now has started to drop off slowly as the car continues to run valve terrain will get clattery eventually as pressure drops to around 15-20 lbs..Shut off the car wait like 10 seconds fire it back up and it is right back to 40 psi and starts the process all over again...I am not sure what to think about it..If you rev the motor a little when pressure starts dropping it will pick up just a bit and go right back to 40 and start falling off again..I have read like a million posts and looks like I may be getting to pull off the front cover and get back into this motor...Have to go and bring the car home tomorrow so I can start on it just wanted to get a few opinions on it far as where to start, bypass spring, new pump, I am really confused how it can do this all of a sudden

 

Well figuired I would get a few hits while this was up over night..Alot of readers and no suggestions yet..I have searched and read to the end of the archives..Even went and dug out the left over o-rings for the pickup that I had to see what was left, looks like a greenish teal, red, and a black one...I have read that a blue one is what I was suppose to have used I am wondering now its been a while..Could the incorrect color cause my problem when the engine reaches operating temp for a certain period of time???

 

im not sure man but here is a free bump!

 

Did this happen after some work was done or come on overnite? Have you slowly been losing pressure over time and now it's reached this point?

 

This is happening in a 20k mile stock short block its a 2002 5.3 ...All that has been done to the block is cam swap, ARP rodbolts...Car has only been together for like 3 weeks has always had killer pressure around 40-45 at idle drove it up to the dyno yesterday and it started acting funny on the way up the highway "pressure slowly dropping", when we got there it was doing this. Has never had a problem running up and down the street in my neighborhood. Been alot of street tuning done on my suspension so the car has seen plenty of launching and what not well before its maiden voyage yesterday..

 

Sounds like an o-ring problem. When the oil thins out, it easier for the pump to suck air in through the o-ring thats not sealing right.

 

Well my new melling 10295 showed up today...Already started tearing the front end down to get it installed, hope this fixes all my problems..It came with 2 orings a teal, and a black with a diagram that shows which oring to use with what style pickup tube..Will keep you posted on the outcome..This pump is a high pressure standard volume kinda like what came in the original Z cars back in the day. I done some research and they make 2 different model 295 pumps the standard pressure and volume is just a m295, then high pressure standard volume is a M10295, and of course everyone already knows about the m10296 high pressure and high volume.

 

My car was doing almost the same exact thing that yours is doing only my engine was completely stock . I read so many threads and articles on oil pumps until I couldn't stand it . Being that my car is a 1999 z28, I assumed my engine had one of the oil pumps that was subject to the bypass valve sticking or hanging partially open due to poor machining from the factory and causing my oil pressure to drop as the car got hotter . Well, when I installed my heads/cam , I also installed a ported SLP oil pump and new ls2 timing chain . My oil pressure now at startup is 65-70 lbs and never goes below 35 lbs at idle at full operating temperature. Even after making multiple WOT dyno pulls in 95 + heat .

 

I bet that Melling fixes it. Let us know!!

 

Well just got back up from the shop, took the oil pump off and found that I did have the right o-ring installed bright blue not a mark on it..So just for kicks I took the bypass plug out and sure enough that little bastard was stuck solid about 2/3 up in the tube it slides in. So anyways got the new melling select in there and buttoned up just the timing cover, filled with oil and started it to make sure it had pressure and I wasnt just wasting my time..Now for the good part got around 53-55 psi at around 1000 rpm...It is idling a little high due to not having the MAF or inlet temp installed right now wont idle down...So that is great I will complete intalling the rest of the components and let you guys know what kind of pressure it really holds at warm up...I am just glad it didnt junk anything out...

 

i was gonna say pressure spring. i have had them act before in the past, but never on the camaro.

 

Oil pressure didn't last long....Barely got to the end of the road and back and dropped to 20 psi and wont move imagine the damage is done..Doesn't make a sound but most likely has spun a bearing in the bottom end somewhere..So on a good note made a few calls this morning to locate me a 6.0 or 6.2 waiting on some call backs time to take all these goodies and put them on a big cube bottom end..

 

dam broa Imo b4 i got my new set up done i had the stock oil pump and dealership purchased stock gaskets after upgrading the internals my oil pressure would slowly (at the gate i drive in too my community into ) drop and that freaked me out . after i put in my new set up I droped in a proted and blueprinted ls6 pump with some nice cosmetics =Problem fixed hope this helps out
"G"