18hp not pumping water

[outhere99]

My 1960/61 18hp evinrude is running great, but doesn't seem to pump water. I just removed the lower unit, and pump. Everything looks ok, though. The impellar vanes look healthy, and the housing isn't cracked, etc. The pin on the shaft is there, and spins the impeller. The intake is clean. Is there sealant needed for the pump housing to the lower unit casting?

Any other ideas?

 

[Sea18Horse]

Re: 18hp not pumping water

Are you running this on the boat in the water? Or are you running it in a barrel. In either case the water needs to be high enough to completely submerg the pump itself. Not just the water intakes. Water level up to the middle of the lower mounts is a good start.

You say the impeller vanes look healthy. Do they stand straight out from the hub or are they curved but all intact? If the vanes are curved when the impeller is out of the housing and sitting in your hand then the impeller is junk. Even if the vanes are all there. When running at low speed it acts as a positive displacement pump. Meaning the vanes have to flex to follow the contours of the housing. If the vanes are curved at rest it means they've taken a set and may not be able to flex quickly enough to pump.

Make sure the grommets are good at either end of the water tube. Sometimes if the water tube is inserted off center the grommet can be folded up inside the housing and block flow.

Generally no sealer is needed on these. But it wouldn't hurt anything either. Provided it's not silicone and provided it's not glopped on in great globs. Good luck!

Cheers........................Todd

 

[outhere99]

Re: 18hp not pumping water

It's running in a large can of water.... plenty of water. The vanes have a slight 'set', but not enough to keep from pumping water. I replaced the pump after cleaning everything. I ran it again. This time I popped the thermostat cover, and got a good spout of water... guess the thermo was/is sticking. I let it run without the thermostat (cover back on), and in 30 minutes no over heating. Next is a sea trial.

Are there different temperature thermostats for these?