Snkebait95

iTrader: (16)

I just finished my forged 6.0l H/C/I build. To make it short, theres a little drip of oil every now and then in between the rear of the engine and the transmission. Now during wide open throttle it (only sometimes) seems to puke agood amount of oil out of the passenger side right onto the passenger side header. When it happens i see more smoke on that side and the header wrap is stained. The engine has all new gaskets and i just re-did the rear main seal.

Can a oil pan gasket puke out more oil under WOT? A 6"x4" puddle accumilates after the run. When i look under the car there is oil on both sides of engine and drips out between the engine and trans right in the middle. The saturated oil isnt any higher than the starter or oil filter, but directly adjacent. When i replaced the rear main seal i even let the engine run with the trans out and didnt see any leaks once so ever.

LS6427

iTrader: (2)

Did you RTV the entire bottom shelf of the engine where the rear main seal sits...if not it will leak in the middle and on either side, right in between the engine and Trans.

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Snkebait95

iTrader: (16)

No i didnt. I did rtv the corners where the rear cover and oil pan meet. Im about to drop the oil pan because it looks like it will be very easy with my tubular k member. Anyone have any advice on the oil pan alignment while reinstalling it with the engine in the car? And put a bead of rtv on the whole back pan rail correct?

Snkebait95

iTrader: (16)

Oh and not to discredit your suggestion (i really appreciate it and just might do that when i change the gasket tonight), but when my brother and father both built theyre ls1s they only put rtv on the corners and they dont have any problems, thats why im hoping its not the rear cover gasket. I was thinking and obviously an oil pan gasket could leak more under load due to the passages that run through the side of the block intp the oil filter and what not.

Fireberg

Not sure if you are using PCV, but you may want to make sure you are not building up any pressure in the crankcase when running WOT.

Snkebait95

iTrader: (16)

Yes i am using pcv, how can i determine if i am building too much pressure?

User_name

iTrader: (7)

I just put my oil pan back in with the motor in the car. I didn't do anything special to alignment, just held it up and ran the bolts in evenly. I only put rtv on the corners not along the back of the pan. I just degreased the bottom of the car. I haven't seen any leaks so I suspect it is good, I have put about 70 miles on it since. I will recheck it tonight.

Kfen20

iTrader: (3)

If it is still leaking after tonight check your dip stick tube and make sure it's seated all the way down. Had a friend that had a gremlin oil leak and it ended up being that.

camaroz98

iTrader: (1)

mine was doing it as well but it was from the o-rings in that piece above the oil filter for got what it was called but rtv fixed it right up.

Snkebait95

iTrader: (16)

Dipstick tube is seated it was way more obvious towards the rear. ust finished up replacing the oil pan gasket and put a bead of rtv on the back rail, i figure it couldnt hurt anything? Im going to let it sit for 24hrs just beacuse thats what the back of the tube of rtv says.

1 FMF

iTrader: (1)

i think that's an often overlooked thing or improper setup doing a motor.
need a pressure gauge that has resolution and sensitivity between +/- 5 psi, such as a manifold vacuum gauge. i think the norm is not more than 2 psi from atmosphere, there are some good articles online if you google for it. you can get some ice maker 1/8 plastic tubing from hardware store for cheap, just don't let it touch anything hot or it'll melt. then find somewhere or way to access crankcase pressure while not undoing or modifying your current pcv setup. I don't think it's easy on the LS motors, no existing fitting. might be easiest to remove dipstick and insert tubing couple inches into there then seal it up well somehow.

Snkebait95

iTrader: (16)

Well i know im a little late, but for the sake of anyone that runs across this thread while trying to figure out where their leak is coming from, it ended up being the rear cover/oil pan alignment.

haulass350

iTrader: (2)

glad i found this thread i'm having the same problem, i had the dipstick problem and fixed that and thought i was good then did some WOT runs and had oil coming out pretty good from the back side like the OP said, guess i'll lift the motor and put some rtv on that rear part as well.

joecar

PCV plumbing might be broken and lets oil fall out

( when you accelerate, g-force pushes the oil that pools in the valve covers toward the rear of the valve covers where the PCV plumbing is )

Homeless2bNY

iTrader: (2)

If you are having issue when oil leak at high pressure,

did you ever look at the oil PSI sensor and top of engine,
rear of the block where the trans mates to engine, as you are describing.

and sight unseen, i believe you have a improperly installed sensor
or a failing(cracked) sensor allowing oil to push thru it.

take off the intake and inspect sensor for traces of oil.

haulass350

iTrader: (2)

if yall are talking to me the top of the engine is clean it all appears infront of the flywheel and looks like a little is on the side of the pan as well but i see no oil down the side of the block, the dipstick was leaking but i fixed that and sprayed the entire bottom end off to check for more leaks.

Homeless2bNY

iTrader: (2)

there is the little cover plate above the oil filter for optional cooler lines
that might be it then since it see pressure too.

haulass350

iTrader: (2)

yeah i looked there as well since i deleted the oil cooler and it looked fine, gotta motivate myself to lift that engine up and drop the pan and RTV the **** out of it lol.

Homeless2bNY

iTrader: (2)

yea, i was just thinking if its a fresh build.
and you may have missed some RTV spots that are important
or damaged the gasket during your install.

its possible to be coming out between block and oil pan at pressure.

lift it, drop the pan and reinstall with new gasket and good RTV where
specified by GM.

joecar

Check the rear of the valve covers and check the PCV plumbing that crosses back there.