Guest Posted April 28, 2011 Share Posted April 28, 2011 Has anyone had issues with a Yanmar 3GM30F water cooling. Ever since we blew the salt water pump impeller and replaced it, i have had an intermitant lack of salt water cooling ( i removed all parts of the old impeller ) when we have this issue there is plenty of water coming out of the pump if i remove the water pipe. So the pump seems to be working fine. This problem seems worse after a hard sail this is as you know is not oftern in a Stewart 34 If i remove the pipe from the base of the water pump and blow through it i hear a bubling sound and we have water issue fixed until we sail hard again and the problem is back any ideas Kurt Ps i think i hate boats Link to post Share on other sites
Guest Posted April 28, 2011 Share Posted April 28, 2011 Sounds like you are getting an air lock on the pick up... Link to post Share on other sites
wheels 543 Posted April 28, 2011 Share Posted April 28, 2011 Kurt, were you able to account for all the little impellor parts??? It is a very good idea to try and piece the thing back together when they destruct. That way if a piece is still missing, you can then assume it maybe still in the system. What often occurs is a piece of impellor blade will continue on to the heat exchanger and get stuck there and reduce the waterflow and thus cooling. Failing that, the next important place to look is the exhaust bend. These are natoriuos for blocking up with crud. And then failing that, ensure the heat exchanger has all the little internal tubes clear. If you are getting good water flow when disconnected, then I will assume the intake side is free, but do ensure the through hull does not have fouling that could be clear of obstrcution, but then suddenly get sucked in at sometime and causing a blockage. Link to post Share on other sites
Steve Pope 243 Posted April 28, 2011 Share Posted April 28, 2011 The last time I cleaned the tube bundle in our heat exchanger I found several of the tubes had a small sea animal in them that almost took up the entire diameter of the tube. Given that the salt water entry into the system is made up of 100 odd 3mm holes the bug must get in while still quite small and manages to stay in there and grow in the tube. (it looked rather like a sea going slater) A 20% phosphoric acid / water solution will sort them and any calcium build up out with fresh water. Remove bundle and put in bucket with solution for 15 mins or so, rinse out, repeat if not satisfied. (use gloves) As wheels said you will find any pieces of impellor that got pushed through the pipes before it totally self destructed. Link to post Share on other sites
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