18 Evinrude water pumping problems

[twocyclemania]

H! I have a 62 Evinrude 18 with a weird cooling system problem. The motor runs great but the pumping is intermittent. I've replaced the impeller and I've tried two different (used) pump housings; both of which seem to be in decent shape. The tube from the pump to the motor does not leak. I attached a hose to the pipe(at the connection to the pump) and the flow does not seem to be obstructed. The power head has zero corrosion. It was from Minnesota and I've only used it twice in brackish water. I removed the thermostat. What happens is I get intermittent cooling flow and than it will decrease to an inadequate amount. Some times it will pick up again and than fail within 5 or 10 seconds. I've worked on many motors but I've never experienced a problem like this. The speed of the motor does not seem to have any rhyme or reason to this intermittent flow. Eventually the flow will slow down and the head will become overheated.

 

[Daviet]

Re: 18 Evinrude water pumping problems

Is this happening while the boat is in the water or are you running the engine in a barrel?

 

[twocyclemania]

Re: 18 Evinrude water pumping problems

This is while it's being run in a barrel. I have another 18 and a 15 Gale (that has no provision for a thermostat; I believe it's the same head as the mid 50's 15 that eventually became an 18) and run them in the tank and the flow from both is great.

 

[Daviet]

Re: 18 Evinrude water pumping problems

Will the lower units exchange between the 18's ? If so it would rule out a power head problem. Maybe the used pump housings are warped allowing the pump to suck air.

 

[jimdd810]

Re: 18 Evinrude water pumping problems

sometimes when running outboards in my test tank some motors output of water is less than it would be on the lake. Try running it in unobstructed water/

 

[twocyclemania]

Re: 18 Evinrude water pumping problems

Everybody! Thanks for the replies and your help. I have a feeling that my problem may be with an exhaust leak into the cooling water. Does anybody know the most likely place this could be? Do I have to remove the powerhead? I'd suspect the side exhaust cover gasket first and than possibly the head gasket (there is no water in the cylinders) or maybe where the gasket where the powerhead mounts to the lower unit or???? Anybody with similar experience and any helpful tips? Thanks!

 

[cougar1985]

Re: 18 Evinrude water pumping problems

try using a sealer on the pump housing before you put together ,i use permatex avaition sealer (looks like mollasses),has got me out of several issues just like yours.