There seems to be a real "if theres a problem with the engine, replace it" flavour arround here at the moment, Yea they are cheap, but is it any better? As a mechanic my self it hurts me to think people would put in another engine for the sake of a seal
I think this is a case of diagnose and repair, if a seal keeps blowing, there is an underlying problem that needs fixing, not always a simple task but we're not taking multiplexing faults here, were talking an oil leak from a seal.
Initially it needs cleaning up thorougly and have it running up in the air where you can see under try to ID the leak.
If you can't confirm the leak or you can confirm its the seal, its box off again, seal out and identify what has failed and why, most likely some one has hit it back in with a mallet or something and damaged it, they can be tight but also very delicate. While in there, carefully check the face of the crank end for marks that could be cutting into it, sometimes people use picks to pull them out and scratch it up. They also allow the metal bands to slip off which keeps the rubber lip pushed against the crank. If its all good, replace with a genuine item, i say genuine at this point as most are fine but we dont want to risk it for the sake of a few more £.
While the box is off, do the sump gasket and investigate further into posibility of any other leaks, if you couldnt find one anywhere else before its most likely the crank, while the box is out, its the best time to find a leak so even if it turns out it was something else, the box was comming out anyways, so no labour lost at this point. If all looks good, replace and try again, you then know new genuine seal correctly fitted with no other reasons for failure, new sump gasket and no signs of other leaks. Problem solved.
