i420tom

iTrader: (11)

I have about 300 miles on my new motor. rebuilt ls1 new bearings cam 5.3 heads ect ect. Suddenly the oil pressure is about half of what it used to be at hot idle. When I took it for a drive after noticing this the oil pressure does move with RPMs untill after a few miles or so. Then the pressure just keeps dropping all the way to zero. I shut her down for a few minutes and fired her up and full oil pressure again then lower and lower as i continue to drive the second time and hot idles at 20psi. Oil is full. WTF

So what do i do now? There is a tiny tiny bit of silver metal dust graphite like in the oil and no shavings in the filter(sorry no pics) no big flakes or chuncks. I was told that isnt unusual for a new motor.

I have a new oil pump and o-ring to try out but should I? Or just start tearing apart the motor.

Also oil pressure has been verified by mechanical guage.

What should i DO??????

i420tom

iTrader: (11)

oh and it developed a leak at the back of the motor somewhere now to. I noticed that when the pressure dropped to nearly zero it was almost pouring out. But when pressure was good it didnt leak. And when i restarted it, no leak... strange!

MM98

iTrader: (13)

Check the oil pressure sensor behind the intake & make sure it isn't cracked. Could be the source of your leak & unstable pressure readings. Would also change your oil & filter.

LS1MCSS

iTrader: (18)

Try a new sending unit for the gauge first. Yours may be going bad. It wouldn't be the first time I have seen this happen.

i420tom

iTrader: (11)

it is the second new oil sender i have tried, both same readings. Could my rear cover be leaking losing oil pressure? could it be the rear oil barbell style plug?

i420tom

iTrader: (11)

So if the rear cover is leaking at the oil passage, this could in theory be both the leak ad pressure problems?????

3rdCoastPowerSports

iTrader: (5)

yes it could possibly be your problem... or you spun a bearing, that would be my quess. I had a c5 with a massive oil leak, pour a quart in run it up to temp and watch the quart pour right back out. turned out to be the rear seal, rear cover and oil pan. even with this massive leak it showed good oil pressure hot or cold. i would cut your filter open to see what you find. sounds to me like a spun bearing

Intimidator02SS

I'd suspect rear cover if what you say is true (loses pressure when it starts pissing out). Thats just common sense!! Easier to try that then it is to remove motor to disassemble. Take your time and remember there are plenty of people around to give you advice, so if you get stuck just ask for help.

redsilv

Welcome to the spun bearing club

Thats exactly what my 5.3 does
It hasnt gone to 0 yet but still barely holds 20psi at 70mph
I get alot of shavings too.

I believe mine is a cam bearing that turned a little and its eating the cam journal probabaly, because of the noise it does, on stand still acceleration and loss of power and fuel mileage

I was spinning around 4k rpm loaded with about 3000lbs of broken down shipping crates though up these mountain passes
It all was about 4000 miles ago. She is still ALIVE !!
I drive it about 80miles back and forth to work everyday

My son sure loves his new stilt club house i built out of em though

Good Luck man,
I hope its not the same as mine but it does sound familiar

gMAG

iTrader: (1)

Yes, sir!

i420tom

iTrader: (11)

OK so ill start with installing the new pump and o-ring. I will fire her up to check oil pressure. If i still have the problem then ill pull the tranny AGAIN @#$% and change the rear cover gasket and barbell thingy back there maybe do a cam sensor o-ring too. Does this sound like a straight forward plan?

01ssreda4

iTrader: (96)

He already said he verified the oil pressure with a mechanical gauge. I wonder how many of yall actually read the threads before rattling off responses.

Yes the rear covers have an oil passage crossover. It is not supposed to leak.

i420tom

iTrader: (11)

But is that oil passage part of the pressurized system?

01ssreda4

iTrader: (96)

As far as I know...

3rdCoastPowerSports

iTrader: (5)

Yes it is

Intimidator02SS

Yes! The rear plate seals the oil galley for the lifters (and ultimately top end of engine).

bayer-z28

iTrader: (14)

^ Might just be easier to pull the trans out and get to it from the back?

Intimidator02SS

Why are you replacing the pump again?

Agreed

i420tom

iTrader: (11)

Because I originally thought it was the pump or o-ring and I have them already. Should I just do the rear cover first then?

transam215

iTrader: (4)

I am new to the ls1 engine but I rebuild diesel engines and this does sound like a spun bearing or me as far as losing oil pressure from a rear seal it would have to be almost gushing out. As far as your oil pump could be clogged up from the spun bearing. This IMO is what is going on, good luck man!