docwyte

iTrader: (4)

So I was blowing oil through the exhaust. Figured it was because of the way I had the breather setup. I had been scavenging from the valve covers in addition to my LS6 valley cover.

So I cleaned all the oil out of the intake, put in new spark plugs and capped off the passenger valve cover vents.

Now I'm venting from the LS6 valley cover into my catch can, then to the PCV valve, then into the intake manifold.

Started the car up and I'm blowing oil through the dipstick tube.

WTF! How do I solve this?

soundengineer

iTrader: (16)

you need an engine rebuild....
you have some bad rings if you are blowing oil thru the exhaust and pushing it out the dipstick...
you are pressurizing the the crankcase....

as a best guess...you have broken a ringland

docwyte

iTrader: (4)

I was blowing oil through the exhaust, that's why I rerouted the pcv system. Compression tests both wet and dry were fine with no change between the two. Motor still makes good power on the dyno.

soundengineer

iTrader: (16)

if you are blowing oil out the exhaust...its coming from somewhere..
if you are blowing oil out the dipstick, you are pressurizing the crankcase...which means you are getting pressure from somewhere...

if you can physically see oil...then there is a more serious problem

at WOT....you dont draw any vacuum, so your PCV system doesnt do anything...it only works at part throttle

if you are pressurizing the crankcase (which causes you to blow oil out the dipstick)..you are pushing pressure past the rings.

a compression test doesnt show a problem all of the time.
you have to perform a leakdown test.

brngrhd

Leak down is the answer here

ss performance

iTrader: (17)

I blew a head gasket between the cylinder and lifter valley. Kept blowing my dipstick out several inches and oiling down that side of the engine.

Just a thought.

Good luck.

docwyte

iTrader: (4)

Seems this is a common issue, a bunch of racers on another forum I'm on are having the same problem.

We're fighting issues with venting the crankcase so we don't have blow by out the exhaust on decel, but if we cap the valve cover vents the dipstick gets blown out.

soundengineer

iTrader: (16)

blow by doesnt happen on Decelleration....
you are creating vacuum....
you create suck by.....
crankcase oils pull into the cylinder....and get blown out the exhaust...

its a problem with the rings...
either built too loose, too much ring gap, or a problem with the ringlands.


you cannot CAP OFF the vents, you will get crankcase pressure...

the PCV system is designed to remove vapors at part throttle
at WOT, it doesnt do anything... the crankcase only vents from pressure forcing it out..


you have 3 choices with the crankcase vents
1... leave the stock pcv system in place (good option)
2... use Valvecover Breathers to vent the crankcase (least effective option)
3... use a vaccum pump (or a header evac system) to vent the crankcase all the time(best option)(vacuum pump does MUCH better than a header evac system)


all 3 versions require some sort of air/oil separator...something to take the oil mist out of the air before it gets to atmosphere....(or back into the engine as the stock PCV system does.















YOU NEED TO DO A LEAK DOWN TEST









----------------------------------------------

docwyte

iTrader: (4)

I'm doing a leak down test on Tuesday. If that comes back good, I'll have to figure out someway to deal with the venting issue.

Right now I have the LS6 valley cover hooked up to my catch can, then from the catch can to the PCV valve, then into the intake manifold.

That causes the dipstick to blow out. When I had the valve cover vents hooked up to the catch can the dipstick stayed put, but I was blowing oil out the exhaust on decel.

soundengineer

iTrader: (16)

re-read what you just wrote...
and compare it to what I just said in my previous posts...

I explain why you get oil out of the exhaust or are blowing out the dipstick...
they all lead to the same reason...Rings.

the only way you can get oil into the cylinders is if it comes in from somewhere else...

nhra686

If your motor isn't hurt this will fix all of your problems and add some horsepower... http://www.gzmotorsports.com/SVPK-LS...-pump-kit.html

oldmano2z

would your PCV installed backwards cause this?? it is a one way valve. engine vaccum sucking it closed causing back pressure? just a question. something easy to look at. I know I check direction of flow just cause I don't know any better. the oldman....

docwyte

iTrader: (4)

Did the leakdown test today, results weren't good. Leakdown's were 10-15% at best. Looks like the motor is tired and needs to be rebuilt.

It was a junkyard pull that I've put 3 race seasons on, so it's just given up the ghost.

Going to add a set of ported 243's while I have everything apart.

soundengineer

iTrader: (16)

well...test results definitely dont lie....

sad to hear its hurt...but now you know the cause of your problems was ring related like I suspected


it just gives you a reason to bore or stroke it and built it better...
you can always reuse the crank if its still in good shape, might even be able to re-use rods and pistons and just get a bore cleanup with some oversized rings and fix it on the cheap.

itsslow98

iTrader: (18)

Yea if you get smoke on decel the high vacuum is likely sucking oil from the crankcase past the rings and burning it. I had that issue with my car and about 500 miles later 4 ringlangs said F U and then I had to build a new motor.

docwyte

iTrader: (4)

Yanking the motor this week and taking it to the local NASA CMC motor builder. He'll look it over and see if the cylinder walls are damaged. Said we could bore it 40 over without worrying about heat issues for track use. (I road course race the car)

So between a slight bore job and the ported heads at least it'll come back together stronger than before.

What's ironic is the entire reason I swapped in this LS is my factory Porsche turbo motor had bad leakdowns and here I am doing it all over again 3 years later. Doh!

slt200mph

iTrader: (42)

You cannot bore a LS1 block 40 over. You might be able to hone it a little and clean up the bores. But forget about boring it. Sounds like the guru your a talking to does not know much about LS1 engines.

10droped

iTrader: (1)

Yea I think 98 your only allowed .005" over and 99 and newer .01" over, thats what I was told when I had mine done.

soundengineer

iTrader: (16)

Actually... it depends on the block.
The lq9 has enough meat....recommended is only 30 over...but there's enough to do 40 over typically without issues.

slt200mph

iTrader: (42)

He posted he had a LS1 so that's what I was responding to. The LS series iron blocks can be bored just like a gen 1 and gen 2 SBC.