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View Full Version : DT 9.9C overheating with waterstream inconsistent



Mastrob
05-07-2011, 11:14 AM
I recently bought small boat with suzuki 9.9 oil injected. starts and runs great at first with strong water stream from discharge hole but water stops pissing after few minutes and engine overheats. I suspect a bad impeller but strangely, when hose is hooked up to motor with hose attachment the water discharge stays strong and does not overheat. When run in a barrel, water stream stops pissing?? Maybe because hose water is under pressure? I am going to look at impeller but wonder if anything else could obstruct the water flow??

Anyone had this problem? Thanks for any suggestions.

justintime
05-09-2011, 11:17 PM
i would do a thermostat and impeller and housing asap

Bassmanisme
08-07-2013, 02:49 PM
I recently bought small boat with suzuki 9.9 oil injected. starts and runs great at first with strong water stream from discharge hole but water stops pissing after few minutes and engine overheats. I suspect a bad impeller but strangely, when hose is hooked up to motor with hose attachment the water discharge stays strong and does not overheat. When run in a barrel, water stream stops pissing?? Maybe because hose water is under pressure? I am going to look at impeller but wonder if anything else could obstruct the water flow??

Anyone had this problem? Thanks for any suggestions.

I know this is an old thread but I just saw it and I may be able to help someone. I had exacly the same issue with my Suzuki DT9.9C. Checked everything, replaced impeller and thermostat, and no better results. However, I finally figured it out. When the idle speed is set too high, the exhaust comes out the center of the propeller and gets sucked into the water intake under the anti-cavitation plate. At correct idle speed most of the exhaust come out of the above water exhaust. My guess is that you are idling too high. Reduce the idle to specification. If you can't, you need carb work just like I did.