LS3 crate motor leak..opinions please.

[CamaroBill]

This question is for the LS experts. I have an oil leak on the rear passenger side. I suspect it's the valve cover gasket. The engine is a crate LS376 in a 67 Camaro with less than 1000 miles, not sure why it would be leaking already but here a picture of the area. The highlights show where the oil is. I was just going to replace the valve cover gasket, but is there something else that be leaking back there?? Thank you in advance.

[Z06vette]

Its a bit hard to tell from the pic where it starts, but it looks like its wet above the valve cover. The oil pressure sending unit stock one or possibly where you installed an aftermarket sender?) can leak. Its easy to crack the factory one when installed the engine- its bumps the firewall and gets cracked. Is it running down the back of the motor or is it concentrated just around the valve cover and wire loom pictured?

[Chad-1stGen]

If it is a valve cover leak or other seal on the engine then make sure you have a good PVC system. Almost every time I hear about an LS motor seal leaking it's because too much crankcase pressure is being allowed to develop. They like to blow out rear main seals from this too.

[gnx7]

My guess is also a cracked oil pressure sending unit. Or maybe a cracked PCV line misting oil back there.

[CamaroBill]

Originally Posted by Chad-1stGen

If it is a valve cover leak or other seal on the engine then make sure you have a good PVC system. Almost every time I hear about an LS motor seal leaking it's because too much crankcase pressure is being allowed to develop. They like to blow out rear main seals from this too.

Thanks fellas, it looks like the oil sending unit is dry, I'll check for PVC next.

Originally Posted by gnx7

My guess is also a cracked oil pressure sending unit. Or maybe a cracked PCV line misting oil back there.

[CamaroBill]

Looks like it is the valve cover gasket. As for the PVC...all I can see is this hose coming from the tube in the passenger side valve cover into the air intake. Is that sufficient?

[Chad-1stGen]

Originally Posted by CamaroBill

As for the PVC...all I can see is this hose coming from the tube in the passenger side valve cover into the air intake. Is that sufficient?

No. At a minimum, leave the current low vacuum set up you have now in place but add another hose from the valley cover to the high vaccum port on the passenger side of the intake behind the throttle body. Since this is an LS3 you should also have a restricted orifice tube coming off the valley cover in the same area. As the LS3 valley cover tube is restricted it substitutes for an actual PCV valve. There isn't enough vacuum from your current setup to properly relieve crank case pressure.

The absolute best write up I've every seen about crankcase ventilation is here: http://www.shophemi.com/images/media..._ccv_bible.pdf

You want to at a minimum mimic the diagram on page 13. The document is long but if you take the time to read the whole thing you can setup your crank case ventilation properly.

EDIT: I'd also add a catch can between on the high vacuum "dirty" side between the valley cover and the high vacuum intake port. You don't really need a dual catch can setup on a NA LS3. I have a dual catch can setup on my 427" stroker LS3 which generates crazy amounts of windage and crancakse pressure and the "clean" side catch can has never had a drop of oil when I check it. The dirty side catches a lot of oil. The best bang for the buck catch can setup IMO is: http://www.saikoumichi.com/ There are other more blinged out ones available for more money if that is your thing.

[mikels]

Originally Posted by CamaroBill

Looks like it is the valve cover gasket. As for the PVC...all I can see is this hose coming from the tube in the passenger side valve cover into the air intake. Is that sufficient?

Hard to tell exactly in your picture - but do you have the coolant vent hard line capped rather than running to radiator? (right above your PCV line in pic)

If so, you will always have air pockets in cylinder heads (and hot-spots).

Dave

[CamaroBill]

Originally Posted by Chad-1stGen

No. At a minimum, leave the current low vacuum set up you have now in place but add another hose from the valley cover to the high vaccum port on the passenger side of the intake behind the throttle body. Since this is an LS3 you should also have a restricted orifice tube coming off the valley cover in the same area. As the LS3 valley cover tube is restricted it substitutes for an actual PCV valve. There isn't enough vacuum from your current setup to properly relieve crank case pressure.

The absolute best write up I've every seen about crankcase ventilation is here: http://www.shophemi.com/images/media..._ccv_bible.pdf

You want to at a minimum mimic the diagram on page 13. The document is long but if you take the time to read the whole thing you can setup your crank case ventilation properly.

EDIT: I'd also add a catch can between on the high vacuum "dirty" side between the valley cover and the high vacuum intake port. You don't really need a dual catch can setup on a NA LS3. I have a dual catch can setup on my 427" stroker LS3 which generates crazy amounts of windage and crancakse pressure and the "clean" side catch can has never had a drop of oil when I check it. The dirty side catches a lot of oil. The best bang for the buck catch can setup IMO is: http://www.saikoumichi.com/ There are other more blinged out ones available for more money if that is your thing.

Chad, thank you so much for taking the time to explain that, and the link to the "CCV bible " , a ton of good info there. I just bought this car and I'm trying to make sure it's squared away before I really push it. I dug into a little more and discovered that the tube from the valley cover is looped to the vacuum port behind the throttle body. Here is a picture.

[CamaroBill]

Originally Posted by mikels

Hard to tell exactly in your picture - but do you have the coolant vent hard line capped rather than running to radiator? (right above your PCV line in pic)

If so, you will always have air pockets in cylinder heads (and hot-spots).

Dave

Dave, as I mentioned in my last post this car is new to me and I'm trying to "fix" any deficiencies that I come across. I really appreciate you spotting that and chiming in. Yes it is capped! There's a bung in the radiator near the cap, think that's a good spot to connect that to?