Tweet
My engine warning buzzer went off and I had a good stream indicating the water pump( new impeller) is pumping good pressure. Last year I changed the thermostat for this same problem. Could my thermostat be bad again or is there debri in my water jacket causing my thermostats to clog up? How do you flush out the water jacket? This engine has never been apart so the bolts are probably be hard to get out, use heat? Thanks for any suggestions.
-
-
Jim,
Make sure the pressure relief valve (aka PRV, pressure control valve, poppit valve) is not stuck open and dumping cooling water out the relief holes.
The PRV can get clogged up just like the thermostat and stick partially open. It is just a spring loaded valve that is designed to open when the pressure in the water jacket exceeds 20 psi.
You can remove it and inspect/clean.
Also, pull that thermostat and inspect it - test it by putting it in a pan of water and thermometer and heat it up - should be fully open at 140 degrees (0.120 on mine).
You can also test the thermo switch in the same manner. Monitor the contacts with an ohm meter - should close at around 180 degrees f. I have personally experienced one closing at 130 and giving me a false overheat alarm.
If all of the above check out ok, then you probably have water jackets that are clogged up with mineral deposits - you will need to pull the head and clean out - need to replace the sacrificial anodes in the head anyway if that has never been done.
All of the above procedures are explained in the Yamaha shop manual - you might want to get one - can order online at www.yamahapubs.com
Good luck [img]smile.gif[/img] ,
Ken K
Comment