Cooling w. stops at warm engine

[cahl]

Just bought a -79 Yamaha 6hp. Cooling water coming out from housing is very poor at cold engine and when it warms up, there no water at all coming out. Becomes grey smoke instead and I don't dare to run any longer. Changed to a new impeller today - same result. <br />If it's clogged, where to start dismount?<br />Does this engine have a termostat/where?

 

[ob]

Re: Cooling w. stops at warm engine

Cahl, have you inspected or changed thermostat?

 

[im_tawd]

Re: Cooling w. stops at warm engine

Hello, If you have a thermostat that very well could be your problem. Make sure you properly aligned the water pump tubing that runs back up to the powerhead when you removed the lower unit to install the impeller. If you happened to have missed the alignment, the waterpump will just pump water into the lower unit exhaust housing. If you have a thermostat, take the thermostat out, and leave the thermostat housing off... put your motor into a test tank and start your motor and see if water comes out of the lower thermostat housing in the engine. If no water comes out, you have an water pump, or clogged tube problem. If water does come out, replace the thermostat housing top without putting the trermostat in it. Put your motor back in the tank and see if its pumping water out properly. If it doesnt pump water with the thermostat housing back together without a thermostat installed, you probably have a serious clog in the powerhead. If it starts flowing properly when you put the housing back on, then just go buy a new thermostat/gasket and you should be good to go!! Hope this helps<br /><br />Tawd

 

[Hooty]

Re: Cooling w. stops at warm engine

If you bought the engine, you're obviously wanting it to run and keep on running. <br />Invest in a shop manual.<br /><br />c/6<br /><br />Hooty

 

[cahl]

Re: Cooling w. stops at warm engine

WHERE is the thermostat located? (If it's the small housing above the spark plugs, there is no thermostat there, I have checked.)<br /><br />If there is clog in the powerhead, how to remove it?

 

[im_tawd]

Re: Cooling w. stops at warm engine

Hello Cahl, Im not exactly sure if you have or where your thermostat is. If you cant find anything obvious it might not have one. If its a clogged up powerhead its more than likely going to be a costly repair. agian, im not sure how much, but its expensive. Email me at tawd77@punkass.com - if you would like me to check into how much repairs would be. <br /><br />Tawd

 

[cahl]

Re: Cooling w. stops at warm engine

Hi Tawd,<br />Thank you for your offer to calculate repair costs, but I'm living in Sweden and you are probably not... I guess price can vary a lot.<br />On the other hand, I'm not planning to let a shop do the repairs, I have to do i myself. A problem is that stainless bolts in aluminum is not a good combination. Not if you ever want to loosen them without breaking... any tips on that?

 

[ob]

Re: Cooling w. stops at warm engine

Cahl if you think you've located where thermostat housing is and found there is no thermostat in motor , try one thing.Funnel some water into removed thermostat housing and see if it drains at lower unit near intakes or pump discharge.One other tip on running without thermostat in place .Thermostats and there internal cage components also act to keep water pressure against jackets of motor providing what is refered to as squeeze.this water squeeze acts to better transfer heat generated by friction.In some cases if thermostat as well as its components are removed water will simply chug through engine jackets and won't provide necessary squeeze for cooling.Some years ago I experienced this very thing on 81 model 60hp evinrude.I had originally removed thermostat because I got tired of replacing them every year as I operated solely in salt water.I was advised to simply cut off thermo section of assy. and replace rest of internal components to keep back pressure on water circuit.It worked.Don't know if yours is similar , but ,food for thought.Try leakdown check from thermostat housing as it may eliminate water jacket restriction as part of problem you are experiencing. Good luck.