Excessive oil pressure
Hi all I have a C300 that came in with oil leaking from the right rear cam plug. I pushed the plug in but once I crank it the pressure pushes it back out. The customer had the PCV replaced already . oil is actually pouring out of it. Any and all help is appreciate.
good afternoon again, initially I went by what the first shop told the owner. I checked the vehicle and found that there is no vacuum at the PCV.
Obviously you have excessive crank case pressure. Measure it and find out where is coming from. very few possibilities of the cause.
In your area short trips must be common. I would find service history and check for a sludged engine. Wrong oil or many short hops without frequent oil changes can be a real issue.
Have you installed the latest version cam plug?…you may be just dealing with a failing plug? Have you check crankcase pressure to confirm it is excessive? What did you measure? Replacement of PCV…did you mean the centrifuge was replaced? See attached.
How long ago was the pcv / centrifuge replaced? I once had a new centrifuge / oil separator that was not drilled to the breather hose (manufacturer error). This caused excessive crankcase pressure during normal engine operation which would displace the oil dipstick and cause a major leak. Quick and easy to pull the hose off and make sure it is open to the centrifuge!
Hi Kenton, I have run into this on several models and the new replacement plugs are not easy to get at times. So, the next option would be to remove all the plugs, clean them really well with brake clean and then wash with soapy water to remove any film. Clean the head block holes really well just the same. Dry everything really well. From there apply a bead of Permatex Ultra Grey RTV and…
question Is the excess crankcase pressure on a normal pcv operational engine because of more blow by inherent to certain engines ? What is normal crankcase pressure and why do service manuals not shed light on the subject ?
Hi Justin, On a gas engine it is almost a moot point to discuss in everyday tech literature. Unless a PCV valve has stuck shut or the line is plugged from carbon there is no reason to check crankcase pressure. Usually, it is obvious when the dipstick keeps popping up, or the main seals are leaking along with most of the gaskets. With some diesel engines there are specs for many of them has a…
Right rear referenced to sitting in the drivers seat? That one shouldn’t have a plug. That would be bank 1 exhaust which has an oil separator with breather hose attached to it. If this is the point you’re referring to not having any vacuum, it probably won’t have much because it is attached upstream of the throttle plate. There is a hose coming from a breather labyrinth on the front of bank 2…
Right rear (Bank 1) will have a small plug on the intake and a centrifuge on the exhaust. Left rear (bank 2) will also have 2 plugs, one small (intake) and one large (exhaust) unless it has a vacuum pump option that will drive off the rear of the camshaft.