L28ET oil spraying out of crank front seal under boost

[R0N]

I had a problem with oil spraying out from the front crank seal only when under boost. I just replaced the front seal and it's worst than before. This is my first crank seal I've replaced and I'm not sure if I installed it incorrectly.

 

Here's how I installed it:

 

- Cleaned out area where seal seats.

- Installed seal and made it flush outer housing. I'm not sure if I was suppose push it in all the way or making flush was correct. Also I didn't put any kind of sealant. I didn't see any old seal residue so I didn't put any one.

- Install crank pulley and bolt.

 

I didn't notice anything leaking when idling.

 

Btw I used a Nissan seal from the dealer and not from the local parts store.

[calvin280zxt]

Id hook a pressure gauge to your crankcase and go for a drive

[rossman]

Agree with calvin. It sounds like is excessive pressure in the crankcase. Check that your PCV valve and hoses are connected properly and working. How many miles on the piston rings? Could be excessive blow-by.

Edited February 27, 2012 by rossman

[R0N]

Thanks Calvin / Ross. My motor has less then 60k on the rebuild. I don't think it's the rings but then I could be wrong. I don't get smoke out the tail pipe when I rev it hard but I do drive it hard. Just to give you an idea how much air I'm pushing. I have a ATP .57trim t04/t3 hybrid running about 14lbs going through a custom huge intercooler. Managed through Haltech E6X. Besides the injectors engine is pretty much stock with all the emissions stuff removed.

 

I'm going to replace the PCV Valve since I'm removing it. I'm hoping to find it clogged.

 

So did I properly replaced the seal and do you recommend using rubber seal sealant? Do you think I'll to replace the seal again since the oil got through it?

[josh817]

You did it correct. No sealant is needed. I actually put antisieze on mine. Both of my L engine seals were rubber, tapped in no problem. Just get one edge started and gentle tap around the edge with a plastic mallet as it goes down slowly.

 

You could have torn it putting it in but I doubt it. They're tough suckers.

 

If it was sealing around the outer edge, which it probably was, then you need to check your front pulley too. If there was a groove cut in the pulley where the seal was contacting it then you need to get a speedy sleeve to restore the original surface. My Z pulley was tight to get in there, sealing well. The L20B I did was loose. I could slide the pulley on and off really easily. Even that, doesn't spew. The only oil that front seal should experience is that oozing from the top of the head and spraying from the tensioner. This is only really enough to cause a drip, it shouldn't spray.

 

So... for what its worth, it sounds like your PCV system is bad, if not that then your rings. I don't know how a turbo system works but last time I had a turbo on my Z, I never actually made pressure until the motor was under load. Just sitting there revving it never brought it above atmospheric pressure on the gauge and if that's the case then it would kind of mean you are somehow spraying, even though the gauge reads no positive pressure differential.... which would mean your rings and not your PCV system.

 

One easy way to check is to pull the hose from the crankcase or the valve cover, wherever it's drawing from, and rev it up. If you feel air being blown out the hose then your PCV valve or something else in the system (I don't do all the vacuum line ****) is messed up. If there isn't anything blowing from the hose but you reach down and feel near the vent on the crankcase/valve cover, and feel it blowing a lot of bypass when revved, then it's your rings.

Edited February 27, 2012 by josh817

[calvin280zxt]

Just a thought, if the check valve is bad your turbo could be boosting your crankcase

[R0N]

Much Thanks Josh! Man you just saved my a ton of time trying to figured out how to diagnose the PCV or rings. I tapped the seal the same way but used a large socket. I tapped on the large socket on the seal until it was all flush with the housing.

 

Good point Calvin, that's what I was thinking when I read your post and Ross.

[R0N]

Here's what I noticed. While engine is running I removed the hose that connects to the PCV and faint white smoke is coming out from the hose as well from the breather filter on top of the top valve cover of the engine. It's faint white smoke as well. I noticed the PCV is sucking a lot of air in. When I rev the engine air is coming out of the hose it's not strong but air is differently coming out more than it was idling. Also while reving the smoke stops coming out from the hose and the breather filter.

 

Is this bad rings or bad crank seal? or something else?

[calvin280zxt]

Compression test

[R0N]

Thanks Calvin. I'll give that a try and post my results.

[rossman]

When you say "breather filter," do you mean an aftermarket filter attached to the valve cover breather? If you have that and a PCV valve hooked to the crankcase then you are pulling unmetered air into the intake at idle.

 

If you have an NA to turbo conversion with the NA stock hose from the intake to the valve cover then you are definitely pressurizing the crankcase during boost.

Edited February 29, 2012 by rossman

[josh817]

Alright, here is what I run on my truck which has a single Weber DGV carb.

 

Although the valve cover goes to the air filter on the carb, which you don't have a carb, that's what the small filter is for. On my NA Z I ran a small filter on the crank case and the valve cover vent. This works because you are trying to PREVENT pressurizing the crank case and the pressure is allowed to escape OUT of the filters but don't do this. My motor looked nice and pretty for a few weeks and was gunked up with oil vapor. So what you want to do is suck those vapors (all that white misty smoke) into the intake. It doesn't matter where you put your little filter and where you hook a vacuum line to, if you want to filter the crankcase and vacuum to valve cover or vise versa, that's cool it works both ways. The point is that when the you have drawn all vapors from the crankcase, you start drawing in air from the other end with the filter. Filter needed so that you don't draw in dirt and stuff. Yes, you're basically creating a vacuum leak to prevent sludge and nasties.

 

On the vacuum line hook a PCV valve inline with the system. Hell, you may not even have a bad PCV valve, you may just have put it on backwards. How do you tell? Blow into one end. Can you blow into it? If yes, then the side your mouth is on should go to the vent, the other side goes to the manifold. If you can't blow into it, but you can suck air through it, then the part your mouth is on goes to the manifold. Obviously, you can see how this would allow for the manifold vacuum to draw the vapors in until you create boost and it plugs up so you don't pressurize your crankcase to 15PSI. lol And I'm sure you can see how putting it backwards would make it so that vacuum shuts the PCV valve and boost opens it, thus the same problem.

 

 

Now as per the picture, if you remove the blue line from the crankcase/valve cover (the line your PCV should be on/the one that goes to the manifold), rev up the engine. With your hand next to the vent, is it pushing a ****-ton of air? What about when you place your hand over the hose?

 

If you're pushing SOME air through the crankcase at higher RPM this is ok. Realize that if you are running 13PSI of boost through your manifold, the crankcase would have to create over 13PSI to push open that PCV BUT it won't do this because it's venting out of the little filter at this point.

 

Obviously you are creating so much blowby or your PCV valve is messed up and your turbo is pressuring the crankcase to the point where the little filter can't vent it enough so it sprays oil. Without that filter, if it was plugged, you could have blown your seals out; hopefully you haven't already because that rear seal is a pain!

 

 

However, from the sounds of things I suspect its the PCV valve unless it was doing this from day one, then maybe consider your rings.

[R0N]

Correct Ross on the aftermarket breather. I have an L28ET motor and not an NA.

 

Good explanation Josh. I didn't think about the back flow and I didn't test for that. When everyone mentioned the PCV, I just assumed everyone was talking about the PCV being clogged.

 

I've never had this problem when I got my car together a few years back until the last year this started happening.

[rossman]

Josh - To avoid confusion, your diagram should show the top and bottom sections of the engine connected.

 

Also it's worth emphasizing that that schematic is for an naturally aspirated carbureted engine. NA FI S30s have the crankcase hose attached after the throttle plate and the valve cover hose attached before the throttle plate. Turbos have a different setup or else the crankcase WILL get pressurized or the intake will suck in unmetered air (assuming stock AFM is used). I'm not sure of the stock L28ET PCV plumbing.

 

I removed the PCV system from my car. I have both the valve cover and crankcase vents hooked to a catch can mounted in the engine bay.

 

R0N - You could try removing the crankcase hose, installing a filter on it, remove the PCV valve and plug the intake hole. If oil stops spraying out the seal then you found your problem.

Edited February 29, 2012 by rossman