need some old school input Mark 30 Electric

Hi All,

I just rebuilt a Mark 30 for a customer, motor runs like a top. It was burnt up pretty bad, replaced pistons, rings and block still a 4 port block. rebuilt the gearcase new seals, water pump etc. where i am baffled is it takes forever and some rpm to get water from the telltale and then when in gear and I start putting some R's on it. Then it will stop pumping and start steaming. This is using the stock telltale, I did drill a hole in the top of the block and can get water there as well but same situation as soon as I put rpm on it it steams, I have never had one do this. it has a BU style Mark 30 2 blade prop on it and it is a sierra impeller. I wish I had an old school merc pump to try as the blades on this sierra impeller feel really soft.

Thanks,

Dave

2 Sierra Impellers are Junk, I took a 10 automatic impeller (Merc old school stiff as a board NOS) filed the keyway round installed it and the motor pumps water like a bear.

This impeller was probably chinese made counterfeit junk. Like the previous reply, take a OEM (factory brand) impeller of any kind and cut it down, then bore or sleeve it and key it to work. You'll know you have good quality rubber then.