I'd replace the thermostat first, see if that solves anything. Also replace coolant at that time.

You could also try pulling the thermostat and see if that solves it (will run too cool, not recommended for the long haul). You can then test the existing thermostat in a pan of boiling water.

 

I agree with Pete, pull the thermostat and put in a new one. Make sure you align the vent hole up when you put it in. I doubt it would be the water pump. They kind of work and then they don't.

 

Thanks guys, should I look for the lower temp one or the current high temp one from Deere? I'm leaning towards the original lower temp one, I just need to find the parts store and number. It'll be easier when I can get to a computer.

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A Kawasaki part number for a 180 degree F / 82C thermostat that I think fits is 49054-2056. The gasket part number is 11060-2084.

I would however like to know the part number for the 160F unit when you find it as I think that the 160F 71C thermostat is best for my 1996 model year 425.

Thermostat 49054-2056 Order now for same day shipping. 365 day return policy. RepairClinic.com

 

Have you run water through the fins of the radiator? The screens don't catch all the debris.


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I hit it with the pressure washer a few weeks ago but not since this started. I'll wash it out and see what happens, thanks!

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Here is the information I was thinking of from another thread.

I have no personal experience with it but I saw on another site a guy with a 425 replaced the original tstat with Autozone part # 7203-160 which is a 160 degree tstat, supposedly it worked ok for him. Might be worth checking into.<br/>

http://www.mytractorforum.com/showthread.php?p=1521772

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Here is the information I was thinking of from another thread.

I have no personal experience with it but I saw on another site a guy with a 425 replaced the original tstat with Autozone part # 7203-160 which is a 160 degree tstat, supposedly it worked ok for him. Might be worth checking into.<br/>

445 Thermostat - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information

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I would stick with the thermostat that came out of your tractor, which is most likely a 180*. Your problem may be that your thermostat is sticking or a water pump problem, but it isn't the fact that your original thermostat is the higher temp, it's something else causing the overheating.

 

I'm trying to verify what temperature the original thermostat was. I *thought* it was a 160, I just want to replace it with the original temperature part, whether it's a 160 or 180. It'll be easier for me if it's a 180.

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OK, so according to the technical service manual on page 3-38 states the opening temperature for the thermostat in the 445 is 150 degrees and on page 3-49 it states the opening temperature is 145-150 and the fully open temperature is 176. So now I'm slightly more confused as to what the original parts temperature rating is.

 

Below is from the Stant site and the link to same is below as well.

As I interpret both the JD and Stant material, the 445 engine has a nominal 160F / 71C thermostat or something even perhaps closer to 150F / 65C.

Stant

How does a thermostat work?

"Usually located within a metal or plastic housing where the upper radiator hose connects to the engine, most of today’s thermostats utilize the "reverse poppet" design, which opens against the flow of the coolant. Thermostats have a wax filled copper housing or cup called a "heat motor" that pushes the thermostat open against spring pressure.

As the engine's coolant warms up, the increase in heat causes the wax to melt and expand. The wax pushes against a piston inside a rubber boot. This forces the piston outward to open the thermostat. Within 3 or 4 degrees F. of the thermostat preset/rated temperature which is usually marked on the thermostat, the thermostat begins to unseat so coolant can start to circulate between the engine and radiator. It continues to open until engine cooling requirements are satisfied. It is fully open about 15-20 degrees above its rated temperature. If the temperature of the circulating coolant begins to drop, the wax element contracts, allowing spring tension to close the thermostat, thus decreasing coolant flow through the radiator. "

 

http://www.mytractorforum.com/12-john-deere-forum/223750-first-time-blowing-425-47-2-stage.html This is from my experience with a different thermostat. Put the same thermostat back in that is in it now. It will be marked on the thermostat housing in Celceius what it is. Read the whole post.

 

Well, it was simpler than I thought. I finally had a chance to look at it cool and the coolant was low. Once I topped it off everything was back to normal.

I suspect the dealer I bought if from never actually checked it prior to my purchase. The reservoir tank showed the coolant in the normal range and seems to contain an amber-yellow coolant and the radiator when topped off has green coolant. Good thing I am planning on the 1000 hour service this fall, it'll get flushed and filled then. I won't rant about the dealer, I've already done that in another thread.

 

I would recommend pulling and possibly replacing the rubber hose that goes from the overflow to the radiator cap area. On mine, the bottom 3 inches or so was packed with crud from the bottom of the tank. It had been sitting a couple of years before I got it, and that obviously didn't do it any good. I cleared out the hose with the air compressor, and that fixed my overheating problem right away!

 

Good idea! I'll do that too, better safe than sorry.

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I have to argue the flow part. I've seen engines overheat like nothing with no thermostat, and run fine with the guts of a bad thermostat cut out, and the restricted disk put back in.

I've never heard of a colder thermostat running an engine hotter, though.

 

The cooling system is designed for the max flow through the thermostat when fully opened. If the thermostat is removed, the opening is larger and the flow is proportionally greater resulting in less dwell time for cooling as the coolant passes through the rad and back into the engine. The coolant exiting the rad is at a higher temperature than the design calls for with the result that the engine temperature climbs.

 

To set the record straight, I am not a thermodynamic engineer, or an engineer of any discipline. I am a civil engineering technician graduate who spent his working career as an industrial maintenance mechanical technician. During those two phases of my life (school and work), and also since retiring, I have gleaned many tidbits of information from conversations, reading, and experimenting. I can't remember a persons name 30 seconds after being introduced, but I can recall most of these tidbits from as much as 60 years ago. That recall, with applied logic, leads me into these conversations. Take my conclusions with a grain of salt. Please, research the topic for proof that I am either correct, or spreading bull feathers.

When it comes to spark plugs, I tend to leave them alone for 1000 hours if they are working correctly. It sounds as if you're going to need to research spark plug heat ranges and their effects in order to find the right plugs that will work with your engine. I would consider 2 different heat ranges for what is apparently an asymmetrical cooling of the cylinders due to differences in the coolant flow pattern within the engine.

I have no numbers for flow or temperature changes in cooling systems. What I have is experimental data for flow vs temperature change from a solar heating system for my swimming pool from 30+ years ago. Different application, same requirements, extract the maximum amount of heat with an acceptable difference in temperature from the flow available.

Environmental conditions will always affect cooling systems, and GT engines work in widely varying conditions, from -30°F to +100°F or more. This will most definitely have an effect on the rate of cooling through a radiator, as you suggest. The design objective is to have proper cooling to maintain operating temperature under all working conditions. Not easy to accomplish considering the range of ambient temperatures and the work load expected. Both ends of the range will be 'iffy' at best with a correctly functioning thermostat. Heat extraction at a 190° temperature differential is going to be rapid at the lower ambient temperature and not so quick with an 80° temperature differential at the other end of the scale, given the 20° range of a 160° thermostat from just open to fully opened.

I would suspect that the spark plug issue is more of a Kawasaki problem than JD's. Gen sets also live in an enclosed box and I would surmise that they would also experience the same issue.

The thermostat should be rated for 160° with the hydro oil cooler in the rad. Engine oil and hydro fluid share the same properties when they are heated. The difference is that engine oil has a built in cooler, the oil pan, which is hanging in the breeze below the hot engine, and it also has a much lower flow rate.

 

Bob, Thank you very much for clarifying your expertise, thoughtful comments, patience and understanding. I too cannot remember a person's name 30 seconds after an introduction yet I can remember patterns, relationships, places like you say 60 years later; but now even that is getting more cloudy at times. I intend to investigate other applications of this Kawasaki engine to see if there are similar concerns, insights and/or solutions. And hopefully I will learn more about spark plug nomenclature and the validity of using different plugs for different cylinders; that just seems to rub me the wrong way, but, hopefully may actually be a viable option if there is no better solution.

 

Using plugs with different heat ranges on an engine is something that I read about in Popular Science, Science and Mechanix, or a magazine of that type, about 50 years ago as a teenager or young man. I believe that it was the recommended cure for a constantly fouling plug due to poor cooling at the back of a 6 cylinder by the magazine's resident auto mechanic writer. A search for the "Mail for McHale" column, or "Tales from the Model Garage" in those mags, 1960-1975, may find the reference.

In our youth our brains were sponges, soaking up all sorts of oddball info with nothing to use as a reference for applying it until later in life.