Water Pumps & Thermostats

[LLove]

Roger, more food for thought.
The 1/8 inch, or larger if needed, "bleed hole" works well with high rpm engines when the OEM bypass hoses aren't enough. So the hole should work in the same way as a bypass hose if sized correctly. The thermostat also works as a restrictor to the water flow, without one the water can be forced out thru the radiator cap, given the right set of curcumstances.Of course without a thermostat you still have a thermosiphon system with or without the flow provided by the pump. And you are 100 percent correct re: horsepower is lost when compressing/pushing water, or any other load put upon the engine. Case in example... Pulled out and started to pass some cars following a slow truck, at around 5,000 rpm the radiator cap lost the war of holding the pressure at 12lbs, as the water blew out and the waterpump was relieved of it's job, it felt as thou I had gained a Nitrous Oxide boost of power. The real problem was scale build-up in the radiator.
One may try turning a water pump slower to offset the running too cold problems, and gain some of the horsepower back if it's a belt driven pump. On engines subjected to high rpm useage slowing down or even removing a couple of the fins of the waterpump is needed to allow the coolant a chance to assorb the heat better- because the flow was too fast to do so. Remember people... the coolant in the cooling system is only 70 percent of the whole cooling system. Oil = 20percent and the air flow around the engine is the last 10 percent.

 

[Egon]

Roger:

A centrifugal Pump imparts velocity to fluid it is working with. When the pump is working against a closed discharge the power demand will drop way off. The most power is required when the flow through the pump is at maximum.

Egon

 

[Soundguy]

I don't blame you, If I had found the parts at a good deal I would have bought them as well.

Chris

 

[allenp]

Roger Scotty - Thanks for the info. I have already drilled a couple of 1/8" holes in the thermostat for the reasons you mentioned and will try it out in a week or two. Will post the results once I get a little more run time without a thermostat. One thing for sure, the engine runs MUCH cooler than before, however, the grass is just starting to grow so I really haven't given it a workout...yet.

 

[tmar04]

has anyone ever installed a thermostat in the cooling system, inline or whatever, on any of the water pump YM model of Yanmars. I am just trying to get the coolant/engine temperature up to a consistent high of 180 degrees or so, to eliminate the 'wetstacking' that happens at cool operating temps. Maybe someone else has a better idea. I have been placing piece of cardboard to cover 2/3 of radiator till temp up to 190, then remove it. little bit of hassle. thanks to all.

 

[larso1]

I was going to do this on my Iseki, if I ever found the right external T-stat housing. I bought a couple of motorcycle T-stats w/ housings (see attached) on E-bay for real cheap and thought the lower one in the photo might work best. But the hose connection sizes are just too small. I would worry about flow restriction. So I just dropped the idea since I really don't use my tractor that much.

Bill