5205 Running hot

[sparky]

Noticed the 5205 was running way in the red zone on coolant temp. Externally the radiator was clogged with dust and hay particles. Blew it out with compressed air and water. Checked and it was about a gallon low on coolant. Holds 2.5 gallons. Filled it up and it was still running deep in the red zone. Put in a new TStat, now it is hovering right at the green/red line, slightly into the red. The Top hose is hot to the touch, the bottom hose is cool at the radiator, hot near the pump. Flushing the system this evening. I sprayed water on the radiator while running and it did not affect the coolant temp. It is not blowing water out of the cap, no leaks. I was able to open the cap while the gauge was reading hot and no plume of water, not under pressure. Seems to be running fine, no loss of power. At one point I put on along section of spare hose on the return, remove the upper hose, filled it with water and hit the starter. Water was being pumped out the upper hose.

Thoughts? Temperature sensor bad? Water pump weak?
Is there a way to test the sensor?

 

[beenthere]

Thermostat?

 

[hosspuller]

Definitely check the thermostat. It's one of the scheduled maintenance items. Supposed to be replaced at 2 years or 2000 hours.
See page 90-3 of the operator's manual.

When you do get it fixed... Help someone else by coming back and sharing the fix with the forum.

 

[rScotty]

You said you'd done the thermostat. Check the old one in a sauce pan with water and candy thermometer.
An ohmmeter will check the temperature sender but only roughly. Easiest thing to do there is to replace it. Cheap to do.
I've never been able to tell anything by feeling of hose temperatures. I've even taped thermometers to them. No info.
I've heard of weak water pumps but never actually seen one. Take a look at the insides of a water pump and ask yourself how it could be weak? It's just a fan for water and not even any critical clearances.

First thing I'd do is make sure what you have is working at best efficiency. clean the radiator from the inside forward with warm soapy water. I use a paint brush so I can poke it between the fins without damaging anything. A garden hose is OK on low spray; don't use a pressure washer.

Then go around the radiator shroud making sure that there are no gaps between the shroud and radiator that would allow air to be pulled into the fan without having to come through the radiator. Seal gaps with foam tape.

Finally, something that makes a small amount of final difference is to make sure that the coolant has the right coolant/water mixture for best heat transfer. Some premixes are mixed for max cold weather protection instead of best heat transfer. For old ethylene glycol mixtures best heat transfer was right around 50/50 glycol to water. Today the mix percent depends on what coolant you are using.
luck,
rScotty

 

[4570Man]

The first step is to verify it’s actually running hot. A fairly cheap IR thermometer makes that easy. It’s a lot harder than expected to completely clean a radiator. It’s still dirty would be my guess.

 

[sparky]

Thanks for the replies! I did test the old Tstat and it seems to be working properly. Replaced it anyway. I pulled the radiator off the tractor so I could make sure I was getting it clean. I am confident that all the fins are unlogged and there is no more debris blocking air flow. Shroud is on correctly. I plan to get an IR thermometer and check that next, maybe replace the temp sending unit as well. Also, no white smoke.

With the cap off, I should be able to see movement in the water, correct? I don't see any movement.

 

[rScotty]

Thanks for the replies! I did test the old Tstat and it seems to be working properly. Replaced it anyway. I pulled the radiator off the tractor so I could make sure I was getting it clean. I am confident that all the fins are unlogged and there is no more debris blocking air flow. Shroud is on correctly. I plan to get an IR thermometer and check that next, maybe replace the temp sending unit as well. Also, no white smoke.

With the cap off, I should be able to see movement in the water, correct? I don't see any movement.

I've never been able to reliably see movement in the water on any radiator I looked into. Lowering the coolant level might work to be able to see movement... but the thermostat still needs to be immersed to open. Flow into the radiator with the coolant lowered is going to depend on the relative levels of the different systems, plus all the system needs to be very hot to open the thermostat and allow flow to the radiator at all.

I'd be curious if you can learn anything that way. Not sure what it would show.

White smoke on startup is usually unburned diesel fog. What has that to do with anything?

rScotty

 

[sparky]

Tested the water temp sender per the manual and it seemed to be out of range, so I was able to get a new one from the dealer. Finished the flush and filled with pre diluted mix. The gauge still reads in the red zone. reading about 180 on the block at the sender location. Reading at the Tstat varied from 165 to 192. I could tell when it opened and closed. 170 at top of radiator, 180 on the pump housing. I think the conclusion is that the gauge is reading high.

 

[rScotty]

How do you test the temperature sender? Ohms? Range? How about replacing it with a fixed resistor to to test the temperature readout?

It may help you to know how the temperature sender works on our older John Deere (2008 model). I'm not saying that this is your problem. Just letting you know that what you are seeing may not be what immediately comes to mind.

On our JD, the temperature sender starts cold at about 5 or 10 ohms and decreases to almost zero as the water temperature goes up. The sender signal goes into the engine computer where it is used to generate a very realistic-looking gauge on the dash. To the operatorin the cab, the gauge on the dash looks like an old-fashioned trustworthy analog gauge - but it isn't. It's a simulation of what a gauge would show at that temperature.

The problem starts as temperature sender's signal comes into the engine computer. It arrives by wire to a 20+ pin connector on the engine computer. Both the connector and the connector's subsequent wiring path into the engine computerare NOT weatherproof even though they are exposed to everything. The problem is then the inevitable corrosion in the connector and the engine computer. This is such a known problem that JD offers an exchange computer and a retrofit mounting kit for approx $5K. Plus shop time. The work must be done in a JD shop that has the computer interface.

Here is how the problem happens as the corrosion in the pin connections, wires, and engine computer grows with time:

First of all, it happens slowly. The corrosion in wire and pin connector causes the resistance that the engine computer sees rises very slowly over time. It can take years. The result is that the engine computer always sees a resistance that is the sum of the sender resistance and the slowly increasing connector corrosion resistance. So the computer then under-reports the actual temperature to the dash gauge. Everything seems fine. In fact, the engine can be cooking, and even losing coolant, but the computer continues to show a normal temperature reading on the dash guage. It may even seem a little low.

Eventually the corrosion that was causing the higher resistance will reach a point where it eats through the wire or causes an open circuit in the pin to socket connection. This is an abrupt change. When that happens, the engine computer suddenly sees no resistance at all. To the computer, seeing zero resistance from the temperature sender means sudden and drastic overheating. The computer gauge suddenly shows a severe overheat condition, throws an emergency overheating code, and sets off an alarm.

Sparky All of this to say that just replacing the sender with another may not get to the problem. In fact, the problem may be electrical and not even related to engine heat at all.... or not.....

First thing is to find out if it really is overheating. When the sequence above happened to our JD, the engine which had always seemed to run a little cool suddenly showed dramatic overheating. But it wasn't, and every test I could think of proved to me that it wasn't.... but I still was unhappy enough with what the gauge was showing to decide to figure it out. That's how I found out the facts above, and it came as a surprise.
enjoy,
rScotty