02blackbeauty19

iTrader: (22)

Hey guys,
I'm having a little issue with my oil pressure and I wanted to post up and see if anyone has had experience with this issue and what the fix was.

The car is a 2002 corvette with APS twins. LS1 block with stock crank, forged rods and pistons. Melling high volume oil pump, double roller timing set, etc. Using 5w-40 Rotella.

Here's the issue:
Cold start, my car has ~36-40 psi. As it gets hot, it will drop to mid-teens (14-15) and just hang out. While cruising, it will rise to 21-22 psi. This cruising is between 1k and 2k RPM. This is where the problem shows its face. Anything over 2,000 RPM, the oil pressure doesn't rise past 23 psi when hot.

I never noticed it before I replaced the batwing oil pan with the LS2 pan. I was under the impression that it was a direct swap, so I didn't check clearance for the pickup tube or anything.

The motor shows no audible signs of rod bearing issues and is very quiet, overall.

Has anyone dealt with this before?
-Bad oil pump?
-Improper clearance for pickup tube?
-O-Ring issue?
-Internal oil leak?
-Bearings?

Jimbo1367

I'd check the oring 1st

JaYZeig

iTrader: (11)

i guess i can say i was sorta having this problem also, when the engine was hot with my single turbo setup, my pressure was dropping way down from where it should be, im thinkking the oil is getting too hot and thin, thus lowered pressures..

i rerouted my exhaust away from the oil filter and it seemd to have helped my issre some...may want to look into an oil cooler and possible switching to a heavier oil?

02blackbeauty19

iTrader: (22)

My oil temps get to about 230-235* in 107-110* Texas heat, so thats not terrible.

02blackbeauty19

iTrader: (22)

I'm thinking that would be the easiest for me to check first. After a mechanical oil pressure check.

02blackbeauty19

iTrader: (22)

I guess I should also add that the oil return was previously to the passenger valve cover, but at the same time as the LS2 pan swap, I relocated it to return directly to the pan. There is a check valve in place.

I'm just trying to think of all I can that has to do with anything oil...

LS1121

iTrader: (17)

heat affects oil pressure.

02blackbeauty19

iTrader: (22)

Yeah, I know that. However, 235* isn't significant enough to cause this issue. Some guys run up to 260* without issues on the race track.

02blackbeauty19

iTrader: (22)

Any other opinions?

01ssreda4

iTrader: (96)

Considering this issue directly followed the pan swap I would lean towards the Oring because it makes the most sense. I did have an almost identical issue a long time ago on a DD 4.3 engine and it turned out the oil pump was no good....likely the bleed off valve was not functioning properly. I replaced the pump and the oil pressure went through the roof....big difference. So, those would be my 2 suggestions.

02blackbeauty19

iTrader: (22)

Yeah, it seems it followed the pan swap. However, I didn't touch the windage tray or the pickup tube, but I guess it's possible. I'm going to pull the timing cover off next week, most likely!

S10xGN

iTrader: (11)

Are you saying you never noticed having this issue at all? Are you running any type of restrictor orifice in the turbo oil feed lines? If not, you might try them and see, it almost sounds like too much oil circulating through the turbos...

02blackbeauty19

iTrader: (22)

Correct, I didn't ever notice it before. I believe if the car was idling at 12 psi hot and only rose to 22-23psi at 6k rpm, I would have noticed it. I truly seems to be new since this round of winter mods. I did quite a bit of stuff, but only a couple things relating to the oil system or motor.

1) Simple LS2 oil pan swap (didn't mess with anything but the pan)
2) Relocated the turbo return line from the valve cover to the pan.

Could it be aerating the oil causing this issue?

The turbos are journal bearing and no restrictors should be used. The turbo shop that built them said they can't have too much oil. LOL

02blackbeauty19

iTrader: (22)

I think the first thing I'll do it re-route the turbo oil return line back to the valve cover. It seems that the scavenge pump may be returning air with the oil and causing the oil to foam or something.

I think that would be the absolute easiest thing to do, first.

S10xGN

iTrader: (11)

In that case the bearings are the restriction, just like the main bearings would be. So, rule that out unless the turbos are shot (and I'd think that would be pretty obvious). Let us know if you find the answer...

02blackbeauty19

iTrader: (22)

Turbos are freshly upgraded and rebuilt. I'll keep the thread upgraded.

02blackbeauty19

iTrader: (22)

Well, I re-routed the oil return line up to the valve cover and only gained about 3psi. Now it stops rising at 26psi.

I guess I'll pull the timing cover next.

SOMbitch

iTrader: (8)

Make sure your pickup to pan clearance is correct. 1/4" to 1/2" is in the ok range.....

02blackbeauty19

iTrader: (22)

This is something my buddy and I have talked about. I really dont see how it could change when swapping from a LS1 pan to a LS2 pan. They are all interchangeable. Unless something has come loose on the pickup tube, I'd rule it out. But yes, I will check that out after the timing cover stuff gets checked. These are all things I will check before I pull the motor.

02blackbeauty19

iTrader: (22)

UPDATE:

I got the timing cover off today and didn't see anything obvious that was "wrong". The oil pump was secured well. The o-ring was perfect. The oil gallery plug was fine. I took the Melling oil pump apart and didn't see anything odd, but this is the first pump I've disassembled. The only issue I see is the timing chain is pretty lax. Here is a video of the chain and you guys can tell me what you think of the slack in the chain.

Here is the video link:
http://www.flickr.com/photos/48008900@N03/6048073964/