Water Pumps & Thermostats

allenp · Apr 1, 2002

As a winter project, I added a YM2000 water pump on my YM1700 and would like opinions on adding a thermostat in the upper radiator hose. In doing some checking, most of the grays that have a water pump do not have a thermostat. Even some of the US versions, YM195 & YM240 for example, use the same water pump and radiator but also do not have a thermostat. For this reason I would suspect that the 195 runs cooler and takes longer to warm up as compared to the 240. Same goes for some of the gray Yanmars. But on the other hand, these tractors have been around a long time so I don’t think running a little cool or hot is much of an issue.

I am not that familiar with water pump design and concerned about the pressure becoming too high until the thermostat opens. Obviously with a thermostat in the heater hose (Ford 8N for example), you do run the risk of the upper hose blowing off. In researching old postings I noticed that of users that have a water pump and automotive temperature gauge, the temperature is relatively low (120F-140F). On thermosiphon systems, the temperature is more in the range of 180-230F…and VERY sensitive to angle of travel, cleanliness of cooling system, coolant mix ratio, etc. One thing I have found out on my YM1700 is the temperature of the coolant is approximately 20F higher that measured on the automotive gauge. I would assume that this is partially due to the sensor being located in a cavity and not directly in the coolant flow.

Based on limited used since the pump was installed, the temp stays around 100 under no load conditions. Under use, the temp runs in the range of 120-150, depending on the load. Regardless of the condition, I see no white smoke while running.

Any and all comments would be appreciated.

Allen

Inspector507 · Apr 1, 2002

BTW Allen...........nice to see you here...Welcome /w3tcompact/icons/smile.gif

fasteddie · Apr 1, 2002

I always wondered why my 2202 ran so cold on the temp gauge, so when I changed the colant and decided to check the thermostat I did not find one. The housing had never been removed so I assumed the was assembled without a thermostat. The parts book shows a thermostat and I later ordered one. It made a noticible difference in how the tractor ran (sounded) when at temperature and there was never a trace of smoke under heavy load, not to mention cold weather operation.
The Yanmar thermostat is 160-165 deg and the Ford hose type of thermstat that you speek of is the same temp range

Soundguy · Apr 2, 2002

A water pump, as on (most? ) automobiles, is a centrifugal pump, and should not cause problems with a normally operating thermostat setup. I have seen electric and/or inline pump setups.. but am not familiar with those specific designs ?diaphragm pump?

Chris

""I am not that familiar with water pump design and concerned about the pressure becoming too high until the thermostat opens. ""

allenp · Apr 2, 2002

Fast Eddie - Thanks for the info, however, the YM1700 (or YM2000) doesn't have a thermostat housing so I only have 2 options - fabricate a housing or put an 8N thermostat (160 degree) in the hose. Since the pipe connections in & out of the block don't have a rib, I have a concern that the hose may slide off under pressure. Don't know this to be fact so I may experiment a little.

Soundguy - Thanks for the info on the type of pump. While I knew that it is not a positive displacment pump, I was unsure as to the type and how much pressure would build up until the thermostat opened.

Soundguy · Apr 2, 2002

I', not sure exactly what your tractor outlet ports look like.. but if they are removeable.. you could always run a bead of silver solder, or braze some brass around the nozzle to give it a positive lip. By the way.. silver solder melts at a higher temp than some other solder alloys.. but most should be fine under 300 degrees.

Chris

""Fast Eddie - Thanks for the info, however, the YM1700 (or YM2000) doesn't have a thermostat housing so I only have 2 options - fabricate a housing or put an 8N thermostat (160 degree) in the hose. Since the pipe connections in & out of the block don't have a rib, I have a concern that the hose may slide off under pressure. Don't know this to be fact so I may experiment a little.

Soundguy - Thanks for the info on the type of pump. While I knew that it is not a positive displacment pump, I was unsure as to the type and how much pressure would build up until the thermostat opened.

Anonymous Poster · Apr 2, 2002

I have a 2202D also and it has always run a little cool also.. Just barely move's the temp gage at its warmest (about a 1/8 inch movement). Is it harmfull to the engine runing that cool? It never get's in wether colder than 40 deg outside...

Soundguy · Apr 2, 2002

Keep in mind that the japaneese engineers built these tractors (* some models obviously have different options )
some without thermostats.. some without waterpumps.. etc.

One would assume that they factored this in to building them, and realized that the machines were going to run slightly different than a regular diesel.

I hope it was something they really figured out.. and did it not just for cost/save benefit.

Chris

allenp · Apr 2, 2002

Soundguy - Technically, they are removable, but I don't think I will try. Since they have been screwed in for a LONG time I don't want to run the risk of breaking the pipe connection at the block. Basically, they are straight sections of pipe that are threaded on one end. The ends that the hoses connect to have a notch across from each other as a way, I assume, to remove via a LARGE screwdriver. It is possible, as you mentioned, to tack a steel wire around the circumference to give the hose a little more bite.

The more I think about it, however, I may not do anything. If the YM195/YM240 has worked for years without a thermostat..... why mess with it. The only reason I put a pump on my 1700 was due to how I operate the tractor...and because I stumbled across the parts at a very reasonable price.

"but if they are removeable.. you could always ..."

roger_scotty · Apr 2, 2002

Allen, I told you I'd put some thought into it, and here goes... A couple of thoughts.... First of all, I don't think that a thermostat would be anything except an advantge for the engine. As far a pressure goes, I had the opportunity a couple of years ago to design and build a couple of similar centrifugal pumps and the best pressure I've ever gotten out of one was just over 35 psi. These pumps were running closer clearances at about the same velocity as a Yanmar water pump, so I doubt you will ever see that much pressure. A hose clamp will hold it.

The main problem is that you need some sort of bypass to prevent the water from heating up too much right at the rotor face before the thermostat opens. A simple solution to this is to drill about a 1/8 " hole in the face of the thermostat. This allows for some circulation to dissipate the heat. That size should be plenty to dilute the pump heat. If pressure is your worry then go to a quarter inch hole. Either one is an improvement on the existing "always open" system.

Here's an interesting puzzle: When the thermostat opens, water will begin to flow around the system. Ignoring the thermodynamic effects, does pushing this water around cost you horsepower? What about before the thermostat opens?