Ever since my car was last modified I've experienced this phenomemon, the oil dipstick pops out and oil leaks out. Obviously there is too much pressure in the crankcase. What could be the cause? What could be the cure?
My car has extensive mods including AEM EMS, cams, cam gears, HKS intake, 3" full exhaust, fuel rail, injectors, fuel pump, FMIC and gauges.

The compression was tested and is good (150 - 140 through all cyls).
The PCV valve appears to be working fine and the crankcase ventilation plumbing appears to be OK too.

This (among others) is a vexing problem. Some of the other issues with the car have been addressed, but this one is still a stumper.

I'd appreciate any good input from people who've experienced this phenomenom and solved it.

Thanks

 

I popped my oil stick right out one day on the highway while doing a 4th gear pull to check boost, I about crapped myself thinking that I had blown a head gasket until I looked right in front of me to see that the dip stick had blown out. I now zip tie that bastard down, sure it's a little more of a pain when checking the oil but it gets the job done.

 

Thanks, I've already zip tied the dipstick down. I guess I'd like to find a more permanent solution or maybe some way to reduce the pressure in the crankcase. I'm concerned about this because I don't know how "abnormal" this is......

 

blowby??.. check your hose from your valve cover to your intake (return) where they put the oil catch can for any obstruction...

 

que?

 

Your catch can is full if you're using one.

Typically, it's installed with one port going to the valve cover breather and the other going to the intake pipe. If the catch can fills, that positive pressure has no where to go but out the dipstick, btdt on the track last month.

I vented my catchcan to atmosphere instead of plubming it back into the intake. A little smellier, but no popping dipstick.

 

Well, the compression test looks good, but I have not done a leak down test yet.....


I don't have a catch can.... For what it's worth, there is no evidence of oil in the intake pipe either...??? Since it's the HKS suction kit, it's very easy to see in there. Could something be plugging up the passage between the valve cover and the intake? I guess I could take the hose out and check it, but maybe the blockage is inside the valve cover......

 

I would definitely check on that, sounds like a good possibility if you aren't seeing any signs of oil in the intake pipe.

 

Im not sure about your compression values. I´ve checked mine and those are in the 180-190psi range (my EVO VI has 70000km). That values could tell me you have a compression leak problem, in fact the oil leak through the oil pan means compression is passing piston rings. Check blow-by and pressure in the cranckcase and compare both with another EVO to figure out how higher are those.

 

The values quoted by silverEVO8 are within range quoted in the Mits manual

 

Assuming compression test was performed properly then gases should be going to the crankcase from the valve cover (cylinder head) for any Block passage (valve cover obstruction?). Again, check blow-by and cranckcase pressure and compare both with another EVO to figure out how higher are those.

 

I have heard that this is a pretty common phenomenon on the 4G63T... If you haven't already done this, try putting a breather on the valvecover in place of the breather hose..

This is actually something that used to happen pretty frequently on my supercharged small block..

There is likely nothing wrong, what happens at high RPM is your engine builds up pressure from all the moving parts, plus the engine blowby.. what happens at high-rpm heavy load is there's more air trying to get out, than the breather hose can handle.. Its likely the hose itself is building up a bit of crud in it.. so the air will take the path of least restriction, which will be the next leakiest part of the engine, or the dipstick tube..

Put a catch can on the breather to catch the oil, and vent the catch can to the atmosphere (put a little filter on it since it also breaths in under part throttle when the engine is under vacuum and the PCV system is functioning) your problem should go away, just remember to use large enough hose and not kink it..

You can check your blowby and compression, and you could have a problem, but its unlikely.. once you start dealing with higher boost, higher RPM, and higher cylinder pressures you begin to see these phenomenon..

 

Thanks man, I've heard similar things before but we still were not sure if this is more serious problem than it appears. The vented catch can is a good solution. I wonder if you could recommend a good catch can?

 

I use the Greddy, but pretty much anything with 2 holes in it that's sealed will work.

 

Ok, i´ve seen this when setting our EVO´s to a boost pressure of 2.0 bar (28 psi)....really extensive mods. I´m not sure how much boost presure your car is running but certainly that could be happening.
As i said before i´d like to see pressure & flow values and perhaps more info about your engine setup after doing the mods you listed above...with those mods there is no clear reason for that crankcase pressure but ok that´s possible.
Please let us know how it goes?