I have gone through 3 cam seals, on my '91 740 turbo, and it continues to leak. The only modifications to the engine have been a VX cam and about a 4 psi increase in boost. This is the only place where it leaks. How may I remedy this? I suspect too much crankcase pressure. My mechanic has suggested putting a check valve on the main crankcase hose leading to the breather box-will this work? Please help, this problem is stagnating my efforts in fixing up the car any further.