Front crank oil seal

[Anton CH.]

My mechanic replaced it a few years ago because it was leaking, now the leak has come back-the crank nut behind the damper has bunch of oil around it. Did he install it wrong? Makes no sense why a seal would break after only two years!

[Bill R.]

the installation wasn't done quite right or that the crankshaft pulley has a groove worn in it where the seal rides, any number of possibilities. Or that the engine has been overfilled with oil and the excess crankcase pressure has damaged the seal or that your crankcase ventilation is plugged up and pressure is building in the crankcase forcing oil out the seal, however if that was the case you would most likely see a rear main seal leak also.

My mechanic replaced it a few years ago because it was leaking, now the leak has come back-the crank nut behind the damper has bunch of oil around it. Did he install it wrong? Makes no sense why a seal would break after only two years!

[Anton CH.]

Thanks Bill, sometimes I fill my engine about .2 quarts above max level, could that have blown it? I guess I'll have to check my crankcase ventilation tube as well. In your opinion, if I have it replaced by the same or different mechanic, what are the chances that its going to leak again?

[Bill R.]

.2 overfull and the changing of the seal again...there's too many variables to give you an adequate answer. This time you may want to inspect the crankshaft pulley and replace it if there's a groove worn in it. It looks like sleeve kits are available for bmw harmonic dampers but i've never installed one on a bmw so i can't say

Thanks Bill, sometimes I fill my engine about .2 quarts above max level, could that have blown it? I guess I'll have to check my crankcase ventilation tube as well. In your opinion, if I have it replaced by the same or different mechanic, what are the chances that its going to leak again?