mudtoy

Noob to the board but been spinnin' wrenches for a couple of decades. Swapped motor out of 2002 'vette into 99 Z/28. Required oil pan swap and windage tray modification to use pickup tube/oil pan from Camaro in 'vette motor. Ran great for a couple of weeks but suddenly dropped oil pressure.

No rod knock but definite valve train noise, motor is from internet supplier in Florida supposedly low mile. Internally looked clean and fresh. After grazing the forum for a few hours tonight I see a few oil pressure threads and some talk of oil pump/bypass valve failure. I am unfamiliar with this particular engine platform from a hands on experience standpoint and welcome any suggestions before I begin the obligtory snoop and poop deduction of possibilities. Thanks in advance.

Anthony Williams

iTrader: (3)

LSx engines make valvetrain noise because of the fairly aggressive cam lobes so that may be normal. Oil pressure should be constant with no fluctuations when running, mine(new 2004 LS6) runs 60 psi @ cold start, 45 psi @ hot 800 rpm idle, and will max out @ 65-70 psi 6500 rpm. Rule of thumb +10 psi for every 1000 rpm is the minimum.

Welcome to LS1 tech!

SOMbitch

iTrader: (8)

The 98-99's are the ones that really had the problems. Did you mess with the oil pickup tube or o-ring on it at all?

mudtoy

Thanks for the response, the engine didn't make any noise till the oil pressure dropped. Maybe the slightest tick but totally acceptable.

mudtoy

We transfered the pickup tube from the Camaro engine along with the oil pan and windage tray (slight modification necessary) over to the 'vette engine. We reused the o-ring (stupidly) and I'm currently looking for a source for the "puffy" green one described by others on oil pressure issue related threads.

Here's where we're at now, dropped the pan and after looking at lubrication flow chart we blew compressed air into the pressure port (rearmost) on the block and the pressure bleeds into the forward port. Not srtaight through but there's definitely some leakage in what I'm assuming is a by pass valve. Not sure how big an issue this is, primarily wanted to look at bearings to see if there was damage. Thank God they look fine. Oil was darker than I'd like with some metallic residue. Where is the most likely early oil starvation failure bound to occur? Thanks

mudtoy

Anybody have any first hand experience with aftermarket oil pumps and pro's or cons?

01ssreda4

iTrader: (96)

I have run 2 Melling pumps with good luck. The M295 is a stock replacement and the 10295 Select is their performance high pressure pump.

mudtoy

Thanks I'm thinking of throwing this in for insurance. I've been roddin old school motors for a long time but we're going to set up a carbureted version for some mud racing so the learning curve is on.

SOMbitch

iTrader: (8)

Get a GM o-ring on there CORRECTLY and let us know how things are....

raven154

iTrader: (14)

Why do they make different o-rings for the pick up? I have seen the green and the blue. What application would require a different o-ring? Or did they just update the o-ring to seal better?

mudtoy

[QUOTE=SOMbitch;14294167]Get a GM o-ring on there CORRECTLY and let us know how things are....[/QUOTE

Ordered it (small town) first thing this morning, I should have paid closer attention when my helper swapped the parts over. Especially in that area!

Experience is a hell of a teacher.

projectcam

iTrader: (12)

Sounds like you may have piched the o-ring when you installed the pickup tube in the oil pump, specially if you reused your old one (Loses its shape). When you get your new o-ring lube the **** out of it so this doesnt happen, be very careful as you will be able to see the pickup sit flush on the pump. Don't overtighten that bolt either, it strips easy.

01ssreda4

iTrader: (96)

As a piece of info, the stock gauge is inaccurate. I broke my OEM sender and replaced it with an Orielly and it will only fluctuate from about 30-50 psi. This had me worried so I checked it with a mechanical gauge. Running a Melling M295 stock replacement pump I had about 32 psi on hot idle. While giving the motor throttle in park, the oil pressure picked up about 10-15 psi per 1k rpms to reach a maximum of 70 psi at 4k or so. Any rpms above this brought no increase in pressure. The pressure was very linear with rpm increases and very predictable and consistent. All the while the factory gauge kind of did its own thing. I swapped motors and went to a 10295 Melling which is a standard flow but high pressure, and it will almost peg the same gauge at cold start up. I would hate to check this with a mechanical gauge. It appears to have oil pressure coming out of its *** The Melling 10296 is a high pressure/high volume unit BTW. Be careful as the high volume units can suck the pan dry during sustained high rpm runs.

Car is one app, truck is the other. The pick-up tubes are different sizes, thats the reason for the different thickness of o rings.