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Dan, Road Mechanic
Category: Volvo
Satisfied Customers: 730
Experience:  21 years working with the volvo heavy equipment line.
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Volvo vnl crankcase pressure valve too high shut off truc

Resolved Question:

crankcase pressure valve too high shut off truck
Submitted: 5 years ago.
Category: Volvo
Expert:  Dan replied 5 years ago.
It is possible the sensor or wiring is bad. When the truck is running is there any oil leaking from dipstick or any pressure when removing the oil filler cap? What is the motor size?
Customer: replied 5 years ago.
ther is no oil leaking from dipstick or pressure from oil cap motor size 465
Expert:  Dan replied 5 years ago.
Okay then I would suspect a faulty sensor. I work on off road equipment but the principles should be the same. There is a code showing on your dash when this happens correct? If I was working on it I would go into the computer and shut the parameter off for that sensor to keep it going. However in your position, you would need a Volvo service tech to access that info. My thoughts are to either replace the sensor to see if the code clears or if permitting, have a Volvo tech put his laptop on the unit to see what the sensor is telling the computer and verify if the actual reading matches your present condition. This would give you an indication if the sensor is bad, or the other thing you should do is check the circuit wiring to the sensor from the computer. Now on our equipment we have updates for the software all the time that will tweak various parameters settings to prevent codes or odd symptoms that happen from poor programming design. so have a tech check to see if there are any updates first. On our end, Volvo offers two types of programs, Campaign and replacement. Campaign should be free other than the charge for the labor, replacement will charge 300-700 dollars for new software plus the labor. Since your not blowing oil out the dipstick i would imagine this is an electric issue not mechanical. Hope this answers your question. Please Advise, thanks Dan.
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Customer: replied 5 years ago.
wher wood that sensor be.
Expert:  Dan replied 5 years ago.
That sensor should be just below the oil pressure sensor on the left side of the motor sitting in the truck. You should have a computer mounted to the side of the motor and just before the plug there is two sensors, the top one is the oil pressure and the bottom one is the crankcase pressure. This sensor will set a code if it see .75 psi over atmospheric. In other words more than 15 psi. One thing to check is to make sure the engine breather tube isn't clogged and you feel air coming out while running. Not excessive amount but just a small amount of air and oil fumes. A cause of the high crankcase pressure would be piston blow-bye.

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