tohatsu d 50's overheating

[nautico 19]

have two d 50's on a 20' power cat center console having over heating problems at about 3800 rpm one or both engines over heat water pumps are 2 years old about 150 hrs on both, water flow out of both look good. New thermostats. Removed thermosts problem goes away time for new water pumps?

 

[TOHATSU GURU]

Re: tohatsu d 50's overheating

The thermostats have to be in place for the engine to cool as designed. You have to determine why the engines are running hot. Since you have indicated that it is happening two both engines it seems more like an application problem in conjunction with wear.

 

[nautico 19]

Re: tohatsu d 50's overheating

If I understand you right you're saying that these motors may have been too little hp for the boat and with age they have to work harder and by doing so they are over heating? The motors are 1999, the props haven't changes. The load on the boat changes the rpm the engines get hot 2 people can run 5,000 rpm no over heat 5 people over heats 4800 rpm with out thermostats. Would It help if I went down on the props, or is repowering my only option? The hull is a nautico 19' 6" cat max power 150 hp 11/2 x 13 props. Thanks for your imput.

 

[TOHATSU GURU]

Re: tohatsu d 50's overheating

No, I'm not saying they are too small for your boat. I'm thinking along the lines that they may be mounted a little too high for your boat. It's a long shot, but for both engines to have water pumps go so soon and at the same time it seems like it's something other than normal wear. You are also propped too high. You should be running at least 1 inch less in pitch.

 

[whitewater90]

Re: tohatsu d 50's overheating

Checking the water pumps would be the first step, lower pitch props would also help, WOT should be 5500 RPM or so.

 

[tashasdaddy]

Re: tohatsu d 50's overheating

with the thermostats removed, the water can move too fast thru the block to properly cool the motor also.