Bryant fish Posted May 6, 2020 Share Posted May 6, 2020 Hi all ongoing saga with tohatsu mc40 has been running rough .steam coming out of exhaust relief idont know how to check correct operation of that have removed thermostat and replaced impeller .talking to mechanic he thinks maybe head gasket blown any thoughts before I take head off as gaskets $80 thanks 1 Link to comment Share on other sites More sharing options...
antonywardle Posted May 6, 2020 Share Posted May 6, 2020 compression test? Link to comment Share on other sites More sharing options...
noelm Posted May 6, 2020 Share Posted May 6, 2020 Compression test should reveal head gasket, do not leave the thermostat out, did you replace the entire water pump kit, or just the impeller? Check the spark plugs, if water is getting into the head, they will be steamed cleaned. 1 Link to comment Share on other sites More sharing options...
Bryant fish Posted May 6, 2020 Author Share Posted May 6, 2020 Checked plugs looked ok Link to comment Share on other sites More sharing options...
noelm Posted May 6, 2020 Share Posted May 6, 2020 OK, let's go way back to the start, is the motor over heating? Does it run rough all the time? Have you checked the spark? Have you cleaned the carbs completely? You need to know the basics before jumping to other possibilities. Link to comment Share on other sites More sharing options...
Bryant fish Posted May 7, 2020 Author Share Posted May 7, 2020 Pulled head off gasket blown have changed just waiting for glue to dry before testing cheers Link to comment Share on other sites More sharing options...
dmck Posted May 7, 2020 Share Posted May 7, 2020 "pulled head off.." was this after "tearing hair out" 🤣 1 Link to comment Share on other sites More sharing options...
Bryant fish Posted May 7, 2020 Author Share Posted May 7, 2020 Ha ha was actually easy expected seized bolts but no dramas 1 Link to comment Share on other sites More sharing options...
dmck Posted May 7, 2020 Share Posted May 7, 2020 3 hours ago, Bryant fish said: Ha ha was actually easy expected seized bolts but no dramas Did better than me... I snapped 2 stainless steel bolts in my Yamahaha water jacket cover..... I sold the boat "as is" and the buyer had the skills to get them out! 1 Link to comment Share on other sites More sharing options...
Bryant fish Posted May 8, 2020 Author Share Posted May 8, 2020 So being out of work tried to use gasket off a spare motor and save some coin guess what big improvement but still small amount of steam coming out.have ordered new gasket and will do it right this time i know I'm a dickhead☺ 1 Link to comment Share on other sites More sharing options...
noelm Posted May 9, 2020 Share Posted May 9, 2020 Can't use old head gaskets, didn't know you even tried, make sure the head is flat before you install the new one. 1 Link to comment Share on other sites More sharing options...
Bryant fish Posted May 12, 2020 Author Share Posted May 12, 2020 YeahSo being out of work tried to use gasket off a spare motor and save some coin guess what big improvement but still small amount of steam coming out.have ordered new gasket and will do it right this time i know I'm a dickhead☺ Link to comment Share on other sites More sharing options...
Bryant fish Posted May 12, 2020 Author Share Posted May 12, 2020 Ok so after a brain fart got new head gasket. There was some pitting on the head from saltwater so used head from old spare motor went to do that first time and tried to put thermostat housing on different from newer motor place I got gasket had older thermostat cover all good.went out today from parsley bay to target blue spots wind was terrible nothing like report crap fishing but motor run great I have a twin setup and motor I bought new never missed a beat other motor was a bargain about 5 years ago so do expect some problems 1 Link to comment Share on other sites More sharing options...
antonywardle Posted May 12, 2020 Share Posted May 12, 2020 That wind has been up for a few days now Hopefully it will ease off for the weekend Link to comment Share on other sites More sharing options...
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