slammin86

iTrader: (4)

some background here.

Motor is a ls1 bored over with a cam and some forged stuff. Rings are gapped for nitrous. Car has a ported ls6 oil pump on it. Motor currently has 1400 miles on it. I am also on the stock pcv system with the walmart catchcan setup. Now on to the issue.

2 weeks ago I decided to take the car to the track. At this point the motor had about 1100 miles on it. The car has been on the dyno also at this point. Before I went to the track I changed the oil (valvoline 5w30 oil) (this was the third oil change on the car)

Anyway, I head to the track. I make my first run (an all motor run) and at the once I let off the gas at the end the car pops the dipstick out and shoots oil under the hood. Since I had just changed the oil I did not think a lot about this. I partially blew it off thinking that maybe I did not push the dipstick in all the way or something. I put the dipstick back in and wiped up the oil and went on.

I let the car cool off then make another run. This time the dipstick doesn't pop out so I think ok things are fine.

I make another run, this time adding in a small nitrous shot. Dipstick stays in.

I make another nitrous run, dipstick fine.

And another nitrous run dipstick fine.

And another run. This time the dipstick pops again. This run was on the nitrous also.

At this point I think WTF. I let her cool off and clean up the mess. At this point I decide to make another motor run to verify things are fine. On this motor run I trap about 1.5 MPH faster than the first motor run so I know things are fine.

I call it a night and go home. The next day I pull the plugs out (all of them look fine...little signs of rich, but not too bad). I do a compression test. All numbers between 170 and 180, so no problems here. I go ahead and put new spark plugs in and don't think a lot about it.

I tell myself I will get a few more miles on it and see what happens. And hold off on the nitrous till 3000 miles or so on the nitrous.

Well fast forward to yesterday. While doing some tuning on my car the dipstick pops out again. At this point I was at about 6000 rpm or so in second gear when it happened. I was not full throttle either, this was a part throttle situation.

At this point I am starting to get worried. I have read about a lot of people having this problem with ls1 motors, and they say excessive crankcase pressure for one reason or another. Many recommend putting a breather filter in place of the oil cap, and a small filter on the back side of the drivers side valve cover.

Anyone have any ideas? Should I just go with a vented system and call it a day? Is the motor damaged?

One other thing to add. With the motor running I have taken off the oil fill cap and put my hand over the hole. When I do this I do not feel any pressure coming out. From what I read pressure would be a sign of blow by.
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Chronicle

iTrader: (7)

You need think with your dipstick, Jimmy! (Sorry, couldn't resist.)

Have you tried using different grades of oil in your car? It definitely sounds like a pressure issue.

slammin86

iTrader: (4)

Nope, at this point it doesn't really have a lot of miles on it. I plan to switch it to synthetic at about 3000 miles.

ahartz28

iTrader: (9)

it sounds like you have excessive crackcase pressure, do you have hte pcv sys setup or a can?

Speed Density

iTrader: (38)

Sounds like blowby.

Get a compression tester on the car and check your holes for good psi. Same thing happend to me when my #7 ringlands on the piston decided to disinegrate and I was shooting the dipstick across the engine bay.

02SLOMARO

iTrader: (15)

you are using nitrous. how much? what gap did you set your rings at? i know from other sbc engine experiences that when you gap your rings at say 22-23 thousandths for the nitrous, it tends to build up crankcase pressure and cause blow by whenever running just on motor or under a load. whenever you put the juice to it, it tightens everything up. on your last pass on the squeeze was your bottle at full pressure, did you get the full hit. if not, that could explain the blow by/pressure build up again. i would try getting a moroso crank case ventilation system and running the vent through the header collector area as a scavenging type system.

studderin

iTrader: (28)

compression test time

slammin86

iTrader: (4)

Guys, in my first post I posted that I have already done a compression test. I also posted the numbers there.

DaddySS

If the dipstick is popping you've got too much pressure for the vacuum and breathing you're providing (obvious I know). The breather is from the front of the throttle body and the vacuum is from the PCV. Make sure the breather is clear and working, make sure the PCV is pulling vacuum (pull the hose between the PCV and the valve cover and make sure you have vacuum). If both of those are working, then do a leak down test - I would guess you have too much blow by past the rings.

disc0monkey

iTrader: (10)

first thing i would do it get rid of the walmart catch can, then see what happens

PREDATOR-Z

Too much crankcase pressure.
Check PCV routing (Has to be correctly routed)
Check if PCV valve working
I would not use a driver side back breather, those leak like ***** once saturated after a few launches.

Could you describe step by step your PCV routing and some pics will help as well.

slammin86

iTrader: (4)

Here are a few pics.





I don't think my 04GTO has an actual pcv valve does it? I thought it was built into the manifold.

PREDATOR-Z

I believe that it does have one like the LS6 setup (04 GTO owners could chime in).
But from the pic that is what it looks like.
Valley cover nipple to catch can
Catch can to PCV valve
PCV valve into intake

I have worked on Holden/Luminas (Chevy GTO) and different years have different setups, so I'm not sure about a 04 GTO.
But in 04 the intake is just a LS6 one and does not have PCV built in (at least never heard of it yet).

slammin86

iTrader: (4)

So where would my pcv valve be?

PREDATOR-Z

In stock setup it comes out the nipple as a tube into a U bend and then a rubber like plug. Plugs right into intake.
Perhaps you discarded it thinking it was a tube or hose? Who did the catch can install?

Here is a pic of it:Black hose/tube/valve plug

ms4z28

I think your right... It is a thick rubber hose one end has like a little metal pipe coming out one end and a big opening on the other that plugged in to the intake manifold that your PVC hoses plug into.

slammin86

iTrader: (4)

I put the catch can on when I put the motor back in.

I bought this car brand new, and it never had a PCV valve on it. 04 GTO's must not have them.

WTF.

SweetS10V8

iTrader: (4)

You need to do a leak down test, not a compression test.

Eric Fischer

iTrader: (8)

Curious if you ever found a solution to your blow by problem?

slammin86

iTrader: (4)

It seems to have stopped. Maybe the rings had not fully seated. Something happened...idk. I'm not complaining. LOL.