Re: 25/35 impeller housing know-how

[DAN ANDERSON]

That SS baffle plate is not going to rust through. I have never seen one burn through either. It is actually pretty thick, but it warps and pulls away from the gaskets. You will know when you see a warped one. This causes the exhaust pulses to enter the water flow and it overcomes the pumping action of the pump. It is not enough that it burns up the pump, but it keeps the powerhead from getting enough water to cool properly. I do agree something else happens first! Someone will go in and put in an impeller, but that will not cure the whole problem. The water pump is fairly complicated in it construction and assembly. As Don said the shift shaft running thru the middle of it doesn’t help. These little motors have been prone to overheat since the beginning. I don’t know of any motor OMC engine ever made that has a fiberous washer between the ignition coil and the head. It’s because this motor has an overheat history and will get hot enough to melt the coils off the engine! That’s hot. This motor is also a Siamese cylinder motor. It has no full water passage between the cylinder. If gotten hot enough the cylinder sleeves will separate from the aluminum casting. If that happens you need to go looking for another block. That cylinder will not cool properly from that point on.

Dan in TN