If the boat has a hot water tank, and it is heated with a bypass from the engine, too much water going through the bypass would mean less water cooling the engine. There should be a valve controlling the amount of hot water going to the water heater.
Alan Bergen 35 Mk III Thirsty Rose City YC Portland, OR On Mon, Jun 19, 2017 at 4:49 PM, Joel Aronson via CnC-List < cnc-list@cnc-list.com> wrote: > Thanks! > > On Mon, Jun 19, 2017 at 6:26 PM Dreuge via CnC-List <cnc-list@cnc-list.com> > wrote: > >> Joel, >> >> I have had some experience with a Yanmar 2QM15 which was in my old C&C 29 >> mk1. The 2QM15 manual states that at 2000RPM, the raw water pump should >> deliver 400 l/hr (which is about 1.75 US Gallons/minute). It should be >> easy to bypass the raw water just before it enters the mixing elbow and >> measure the flow rate. If the flow rate is fine, then the problem may be a >> clogged mixing elbow or even a bad thermostat(see comment below). If the >> flow rate is low, then check for free flow of the input line to the water >> pump. That is, with engine off, disconnect input hose from pump, lift the >> end above the waterline, open seacock, and lower hose into a bucket to let >> the water flow in. >> >> If the input flow rate & pump impeller are fine whereas the engine output >> flow is low, then you can look into pickling the engine as suggested. But >> to be honest, pickling the engine with vinegar works well for yearly >> maintenance, but likely won’t remove serious engine scale. If you suspect >> a serious scale problem, then use something like Barnacle Buster. It is >> best to set up a circulation loop: put 1 gallon BB in a 5gal bucket, use a >> cheap Walmart-like bilge pump to pump the BB into the engine (after raw >> water pump), take a hose from the engine output back to the bucket, and the >> let it run run run. >> >> Note that a bad thermostat can cause the engine to overheat. These can >> be easily removed and tested. DO NOT run the engine without a thermostat as >> the thermostat not only allows engine water to flow when open, it also >> closes the raw water engine bypass as it opens. >> >> Also, be sure that the engine is actually over heating. I once spent >> some time tracking down an overheating alarm problem when in the end it was >> a bad temperature sender unit. >> >> Scale can be a real problem. Here is a link to Sailnet post I wrote some >> time back regarding rebuilding a 2QM15. >> >> http://www.sailnet.com/forums/gear-maintenance/90991-yanmar- >> 2qm15-rebuild.html >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.sailnet.com_forums_gear-2Dmaintenance_90991-2Dyanmar-2D2qm15-2Drebuild.html&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=9w3G7Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m=dGXntbdoKRhHMwsqraCYve_LWUhS1EGEFnlHb3ORqEY&s=jso2tREVwgVdD2Aapb_DBeh-klEbeoep4E65QZA2KJ0&e=> >> >> >> Here is a direct link to photos. It was amazing how much scale was in >> the engine. Ssee photos 12 &13 which shows the inside of the block after >> removing the cylinder sleeves. It a big pile of crud. >> >> https://www.flickr.com/photos/dreuge/sets/72157631067396554/ >> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.flickr.com_photos_dreuge_sets_72157631067396554_&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=9w3G7Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m=dGXntbdoKRhHMwsqraCYve_LWUhS1EGEFnlHb3ORqEY&s=1Z5J9osZemoelXpeaakxf3RgaFiCsYnXhWzdpQOOgus&e=> >> >> >> >> >> >> >> >> - >> Paul E. >> 1981 C&C 38 Landfall >> S/V Johanna Rose >> >> http://svjohannarose.blogspot.com/ >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__svjohannarose.blogspot.com_&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=9w3G7Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m=dGXntbdoKRhHMwsqraCYve_LWUhS1EGEFnlHb3ORqEY&s=788cuuEl2UQD_PdnLNg1WLRsUKqSlvetg51Y4E77KpE&e=> >> >> >> >> >> On Jun 19, 2017, at 11:24 AM, cnc-list-requ...@cnc-list.com wrote: >> >> From: CnC-List [mailto:cnc-list-boun...@cnc-list.com >> <cnc-list-boun...@cnc-list.com>] On Behalf Of Joel Aronson via CnC-List >> Sent: Monday, June 19, 2017 8:25 AM >> To: cnc-list@cnc-list.com >> Cc: Joel Aronson <joel.aron...@gmail.com> >> Subject: Stus-List 2GM15 salt water cooled engine overheating >> >> All, >> >> The J30 I race on is overheating. It's not the impeller. The engine is >> 35 years old and salt water cooled. I pulled the hose off the elbow and >> blew into it. There did not seem to be any restriction. (Does that mean >> anything?). What's next? Thermostat? Clean heat exchanger? Elbow? >> >> Thanks. >> >> Joel >> -- >> Joel >> 301 541 8551 >> >> _______________________________________________ >> >> This list is supported by the generous donations of our members. If you >> wish to make a contribution to offset our costs, please go to: >> https://www.paypal.me/stumurray >> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.paypal.me_stumurray&d=DwMFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=9w3G7Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m=dGXntbdoKRhHMwsqraCYve_LWUhS1EGEFnlHb3ORqEY&s=8Pa5HjkiPRfW132YA4TUpgPTdxqgxUmJr59wjPQDC-Q&e=> >> >> All Contributions are greatly appreciated! >> > -- > Joel > 301 541 8551 > > _______________________________________________ > > This list is supported by the generous donations of our members. If you > wish to make a contribution to offset our costs, please go to: > https://urldefense.proofpoint.com/v2/url?u=https-3A__www. > paypal.me_stumurray&d=DwICAg&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN > 0H8p7CSfnc_gI&r=9w3G7Cf8YfQnrjmtuNxwDJYr3JMv9f1pAfgAJ9xXYQQ&m= > dGXntbdoKRhHMwsqraCYve_LWUhS1EGEFnlHb3ORqEY&s= > 8Pa5HjkiPRfW132YA4TUpgPTdxqgxUmJr59wjPQDC-Q&e= > > All Contributions are greatly appreciated! > > -- Alan Bergen 35 Mk III Thirsty Rose City YC Portland, OR
_______________________________________________ This list is supported by the generous donations of our members. If you wish to make a contribution to offset our costs, please go to: https://www.paypal.me/stumurray All Contributions are greatly appreciated!
