Crankcase Pressure
Discussion
My wife's Mini 1275 is blowing oil/vapour out of the dipstick and the breathers.
It drives nicely, pulls well and doesn't blow smoke from the exhaust so I suspect worn piston rings rather than valves.
A quick compression test gave 185 195 155 165. Some oil down the bores increased the psi by 10-15 psi on the lowest two cylinders.
Although the numbers aren't excessively low, is the variation between cylinders enough evidence to suggest worn rings are the cause of the pressurised crankcase?
It drives nicely, pulls well and doesn't blow smoke from the exhaust so I suspect worn piston rings rather than valves.
A quick compression test gave 185 195 155 165. Some oil down the bores increased the psi by 10-15 psi on the lowest two cylinders.
Although the numbers aren't excessively low, is the variation between cylinders enough evidence to suggest worn rings are the cause of the pressurised crankcase?
It could be worn rings and the best way to test is to have the engine ticking over and remove the oil filler cap. If it's rings it will 'chuff' smoke out of the rocker cover.
However, it could be a blocked breather system, although you say that it's blowing oil out of the breather. Take the head off and check for bore wear; there will be a step above the top ring.
I guess it could be a broken compression ring on one of the pistons.
However, it could be a blocked breather system, although you say that it's blowing oil out of the breather. Take the head off and check for bore wear; there will be a step above the top ring.
I guess it could be a broken compression ring on one of the pistons.
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