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I am from South Africa, new around here so pleased to meet you all !
I have a 2007 H3 3,7L adventure with 100 000 miles and see it is blowing something out the dipstick. It is not using coolant at all. I thought it might be rings so did a compression test with below results :
I also have a oil leak on my rear main crank seal so it is using oil, not sure if its burning oil however as exhaust looks ok. Not sure what is causing the pressure at the dipstick or what to check next ?
Have you checked the rubber hose on the air resonater box? Top of engine near rear.
Hi Yes, this is the one on the LHS as you look at the motor correct ? it was worn and I replaced it with a oil catch can, I can confirm it is venting into the cash can and fed back into the box which is before the throttle body (assuming this is the resonates box you speak of?)
I dont know if there are any other breathers I need to look at ?
Was it leaking before the catch can install, because you can definitely mess up Crankcase pressure when doing one wrong?
Compression below 190# is not good, but 181 is not the end of the world.
Definitely some blow-by there.
Are you sure it is oil dipstick, not trans?
#1 is the Crankcase Ventilation Hose, #2 is the big black plastic Resonator Box.
#1 is at the bottom (underneath) rear of the resonator box and connects to a port at the back of the valve cover.
Hi, yes the reason I added the oil catch can was because of the amount of oil found in the resonator so it has been a issue for a month or so since I picked this up. I may try running without the breather at all and see if its pushing out the oil dipstick. Yes 100% its the oil dipstick.
Any other suggestions as I don't know what to do next or is it a case of pulling motor and replacing pistons and rings?
Check the oil level first.
I would try removing the catch can and replacing it with the stock piece. Still have oil coming out of the dip stick? Then you have a problem.
I believe the H3 3.7 uses a crankcase ventilation system that is similar to other late model GM engines in that the system doesn't use a discreet PCV valve per se, rather an orificed tube in the valve cover that acts as a restrictor of blow-by gases. The service manual for the 3.7 describes this as a 2.5 mm orifice in the camshaft cover. The specific verbiage is:
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A crankcase ventilation system is used to consume crankcase vapors created during the combustion process instead of venting them to the atmosphere.
Fresh air is supplied through a filter to the crankcase, the crankcase mixes the fresh air with the blow-by gases and then passed through a positive crankcase ventilation (PCV) orificed tube (5) into the intake manifold (3).
The PCV orificed tube (5) restricts the flow rate of the blow-by gases using a 2.5 mm (0.098 in) orifice located in the camshaft cover tube (5). If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase ventilation fresh air tube (6) into the air cleaner resonator (1) in order to be consumed by normal combustion.
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The manual also describes a diagnosis procedure to test the system.
This sounds like it could be the reason you see oil in the resonator. I had another GM car that utilized a similar system (PCV-like valve/orifice built into the valve cover) that malfuntcioned and caused excessive pressure to build in the crankcase. The engine emitted a whistling sound which was crankcase pressure reeding through the subsequently blown front main seal - pull the dipstick and the reed-like whistling stopped. The fix was to replace the valve cover (and replace the front main seal of course).
This may be why oil is blowing by your rear seal. Just my .02, others will chime in here for sure lol
blowing out dipstick
