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Q: Went to check my oil, oil cap was broken, threaded plastic was still intact, looked like top blew off.

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I went to check my oil because there was a faint puddle in my garage, opened the hood saw the oil cap had blew its top, literally. It was never loose because the threaded part was still threaded in the motor. I took off the wheel, because that is how you access the filter. It was maybe a bit loose because I could turn it a tiny bit more to the right. There was oil all around the steering dust boot and control arm. Would a loose oil filter cause a pressure issue and blow the oil cap? Or cause other gasket problems? I noticed a bit of oil around the valve cover gasket. I checked the oil, it was maybe a half of a quart low. What could cause the oil cap to blow of?

My car has 85000 miles.

A: Hi, thanks for writing in. Excess crankcase...

Hi, thanks for writing in. Excess crankcase pressure is the likely source of this problem. If one or more of your crankcase ventilation components (i.e. PCV valve, oil breather/separator, or other crankcase ventilation device) are clogged up or inoperative, then crankcase pressure will build, forcing the dipstick out, and can force oil out of the rear main crankshaft seal, which could be where the oil around the steering boot and control arm came from. I would recommend having an expert from YourMechanic come to your home or office to confirm a diagnosis on the leak and make or suggest the necessary repairs or replacements.

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