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View Full Version : Iol Leak from the top of the dip stick .. On a SuperCharged YJ


The Bear
07-05-2001, 09:17 PM
Ok . I have a technical problem. This is the situation.
94 YJ 41000 miles
4.0 5- speed
Conservitvly Supercharged 3 to 4 pounds boost
By-Pass valve installed
Bi-Pass valve hose Diamiter ½ inch
1-Way valves installed to block boost to Fuel Reg., M.A.P.sensor
and C.C.V. Ventilation system orifice. Thease 1-way valves are set up so
when going from boost to vacuum they also bleed to
barometric pressure. So no residual Boost or vacuum is held with in the
sensor/valve circuit .
The large C.C.V. hosr from the front of the valve cover is open to
barometric pressure With a small filter on it .
At cruise speed I am pulling 3 to 5 HGs of vacuum.
At idle 15 HGs.
Engine runs great Lots of power – no missing. Stronge running engine .
All sensors are new. New Plugs, Wires, Didstributer Halo effect switch.
I just had the rear main seal replaced
Open Exhaust no restrictions except muffler.
The Problem I am having is it seems the charger boost is making
it into the crankcase. Oil is leaking
from around my dip stick tube .Leaking from the top where the
dip stick goes in. If the large hose from the valve cover is
open,and the orifice hose is blocked from boost.
how can a pressure be present in the oil pan . One of the
Technitions I talk to says we have to find a way to vent that crankcase.
how can I do it . The large hose from the valve cover was hooked to the
old air filter housing, Thus allways creating a vacuum state in the valve
cover . First of all I font want that engine blow by and oil being
sucked through my supercharger . And getting all the plumbing sooty
and oiley. Why is pressure presant and how can I fix this problem . I plan on removing the filter off the large hose to see if it helps. Any one run across this problem befor???
Any sugjestions ????

Bear

PlasticSpork
07-05-2001, 09:35 PM
Bear,
I have a turbo car (yep, I said car) and it had the same thing, I took it into the dealer they said it was common problem and sold me a replacement o-ring for my dipstick. (The old one was missing). The mechanic told me the pressure in the combustion chamber at the bottom of the stroke (normally would be a vacuum) leaks past the rings and gets into the crankcase. Mine dribbled with the crank case vent in place; yours must be a mess.

Just what I was told.
Bryan

The Bear
07-05-2001, 09:41 PM
Its not too bad . The problem I cant figure out is if its all open to barometric pressure . How can I have positive pressure ..
and my motor is not that old and is light on miles . Maby a leak down test and compression are in order ...

PlasticSpork
07-06-2001, 03:02 AM
Bear,
Compression/leakdown tests are always good, I think it's more of matter of volume, the size of the vents compared to the combined size of all of your rings plus the PSI. I mean normally aspirated motors have vents also. It has nothing to do with miles or wear, brand new, force feed motors have the same problems.

Bryan


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94 YJ 4.0 5spd Green very stock... hay just got it.