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Engine overheating!! Help

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  • Engine overheating!! Help

    I'm having trouble with my 175 hp yamaha overheating. I have had the pump redone, thermostats replaced, but still overheats when at higher rpm's. At slower speeds you can run all day. But try to get on plane and high temp goes off pretty soon. My mech. says it must be corrosion in the powerheads, or block. Is there any way for me to flush it or does he need to open it up, and if he does have to go into the engine to clean out the corrosion how much should it cost. I know there are always extenuwaiting (sp)curcumstances, but give me your best shot. Thanks Don
    Don Flowers[br]Port Lavaca, Tx.[br]Mako 224 1985 \"Godspeed\"[br]Yamaha 175

  • #2
    How old is the engine? If your thermo and impellor have been replaced, the sensor could be bad. If your old impellor was really bad, I had chunks of it break off and get lodging in my pickup, causing blockage. Or, it could be something as simple as a salt buildup in the water jacket and you can run some 'salt away' through the engine. The forum below has been good to me for my suzuki, give these guys a shot;f=30
    [br]Michael R. Delgado[br]1972 Mako 22[br][br]1976 Mako 25[br],25[br]


    • #3
      I had the same exact problem with my 1986 Yamaha 115. Engine would run all day long until I broke 3000 rpm and temp gauge went up immediately and alarms away. Tell tale looked good but water was not getting to where it needed to.

      I had the engine looked at and replaced the pop it valve, thermostats, impeller, water pump etc.. and same issue. Since the powerhead is on for life due to corrosion, I was told to buy new engines because the dollars involved would bankrupt me to remove it and clean the blockage out.

      I am little hardheaded and decided new engines would be nice but my wife would never fund the project.

      After several months of frustration - running twin engines with the port motor never going over 3000 rpm- I found a mechanic that took some time to trouble shoot the issue and he says he blew high pressure air backwards through the system and magically the blockage came out which was years of salt build up, mud etc..

      Since then no problems - cost me $150.00 after the the other guy replaced the parts and told me the problem was fixed.

      Good luck
      1986 Mako 224 twin 1986 Yamaha 115\'s - repowered with 2005 200 Yamaha HPDI[br]