299C - Temperature Gauge Increase / Fan Control Switch

[DanTX]

299C - S/N JSP00547

I have been chasing an overheating problem on my 299C for way too long. While looking for possible coolant leaks I discovered that the heater core valve was leaking coolant, replaced valve (480-8589: Valve Assembly-Water). I also noticed that the engine temperature would jump 10+/- degrees when I turned on the fan control switch. After looking at the ac/heat blower motor decided to replace it ($80 aftermarket on ebay) as well as the fan control switch ($20 from Cat). I have also replaced the thermostat and engine temperature sensor. All of this was done after the head gasket was replaced. Bottom line, old parts and new parts showed the same results of increased engine temperature 10+/- degrees when fan blower turned on. Temperature decreased by the 10+/- degrees when the fan blower motor was turned off. The only error codes on the display monitor is E361-3 (high engine temp). Any suggestions would be appreciated. Thanks

 

[reganj]

Have you verified the temp increase with a non contact thermometer??
I am stupidly thinking something electrical causing the gauge, which I assume is electric, to read higher when you turn on the fan blower.

 

[DanTX]

Unfortunately I have not verified with a non contact thermometer since I'm in the cab and working alone.

I also agree with your thoughts on the issue being electrical since when the fan in turned on, the temp goes up and when turned off, it goes back down.

 

[DanTX]

OK, checked the temperature of the machine with a non contact thermometer and compared it to the temperature display this morning. The display read 195 degrees, non contact thermometer read 194 with the blower fan in the off position. With the blower fan turned on the display jumped to 217 degrees. Once I turned the blower fan off temp display returned back to 195 degrees.

I'm getting a false temperature reading. Any ideas on trouble shooting?

 

[Nige]

Do you have an electrical schematic.?
That would allow you to take a detailed look at the blower fan motor circuit and how it relates to the engine coolant temp sensor circuit.

 

[Simon C]

Is your radiator full, and I do not mean the overflow bottle.
Have you put the radiator level, taken the rad cap off and actually checked the fluid level. Have seen this a few times, so just asking. Cannot go by overflow bottles, because if there is a leak in the system, when the radiator cools off and shrinks, it will suck air instead of coolant back into the radiator system.
I realize that you did some repairs, but sometimes some air locks can leave a system low.
Simple cheap check.
Simon C

 

[DanTX]

Do you have an electrical schematic.?
That would allow you to take a detailed look at the blower fan motor circuit and how it relates to the engine coolant temp sensor circuit.

Nige, Yes, I do have the schematic. Nothing has jumped out to me. I need to get it printed out as blue print.

 

[Simon C]

If the engine temperature actually rises to 217 (not gauge temp) with the cooling fan working, there must be something stopping coolant flow, or the fan is turning too slow.
Could a thermostat be staying stuck on.
Just wondering? How do the coolant hoses at the radiator feel, or measure with a heat gun.
Simon C

 

[DanTX]

Is your radiator full, and I do not mean the overflow bottle.
Have you put the radiator level, taken the rad cap off and actually checked the fluid level. Have seen this a few times, so just asking. Cannot go by overflow bottles, because if there is a leak in the system, when the radiator cools off and shrinks, it will suck air instead of coolant back into the radiator system.
I realize that you did some repairs, but sometimes some air locks can leave a system low.
Simple cheap check.
Simon C

Simon C, Thanks for your questions. Yes the machine is parked on a level surface and the radiator is full. Checked with the cap off, coolant is at the top of the fill spout and visible in the sight glass.

Here are recent repairs to the machine;

New head gasket
New radiator cap
New engine temperature sensor
New thermostat
New overflow bottle
New sight glass
New radiator hoses (all) and clamps
New heater core valve
New blower motor for heater core / ac evaporator coil
New fan blower motor switch

 

[DanTX]

If the engine temperature actually rises to 217 (not gauge temp) with the cooling fan working, there must be something stopping coolant flow, or the fan is turning too slow.
Could a thermostat be staying stuck on.
Just wondering? How do the coolant hoses at the radiator feel, or measure with a heat gun.

 

[DanTX]

OK, started the machine back up to check coolant hoses. This time when I turned on the fan control switch the temp did not jump like it did previously to 217. It only jumped 5 degrees to 204. The non contact engine temp read 202 at the head next to the thermostat housing. The upper coolant hose read 167 degrees and the lower hose read 126. Was able to grab both hoses with my hand.

When I drove the machine when I first reported the 217 degrees, the display continued to climb past 230 causing the overhead alarm. The actual temp was around 204.

I believe something is causing a false alarm.

The radiator fan may be running a little slow. It doesn't run anywhere near the speed when you disconnect the wiring harness from the fan solenoid.

 

[Simon C]

You have changed a lot of parts. Sounds like you have some kind of control problem on the cooling fan.
It should be wide open by 204 is my guess. That rad fan will dictate coolant temperature if rad is all clean. Fact that there is a difference between in and out of rad tells me there is cooling happening. Not sure how much it should be at. Could put tape on fan and check RPM with a hand held tester.
Simon C

 

[Nige]

Was the replacement thermostat that you installed a genuine OEM part or an eBay special.?

 

[Nige]

The upper coolant hose read 167 degrees and the lower hose read 126.

That is far too high. The normal difference between inlet and outlet for a radiator in good condition with optimum coolant flow through it should be no more than 20 Fahrenheit degrees

 

[DanTX]

Simon, thanks for the input. The radiator is clean. When you say, there may be some kind of control problem on the cooling fan. There are basically only two things that I could see that may fail, the hydraulic fan motor and the solenoid. The fan runs wide open when the solenoid wiring harness is removed and an alarm code of 1076-5 is generated. Plug the harness back in, the fan slows down and the alarm goes away.

 

[DanTX]

Was the replacement thermostat that you installed a genuine OEM part or an eBay special.?

Thermostat is Cat OEM. The only part I purchased off of eBay was the blower motor, $80 compared to $540 from CAT. All other parts are OEM CAT.

 

[Nige]

There are basically only two things that I could see that may fail, the hydraulic fan motor and the solenoid. The fan runs wide open when the solenoid wiring harness is removed and an alarm code of 1076-5 is generated. Plug the harness back in, the fan slows down and the alarm goes away.

Be aware that fan speed is controlled by a signal from the ECM to the fan motor solenoid based on the signals from BOTH the engine coolant temperature and hydraulic oil temperature sensors.

 

[DanTX]

Understood, do you happen to know what engine coolant temperature would activate the signal from the ECM to engage the fan motor solenoid, i.e. wire open?

 

[Nige]

Understood, do you happen to know what engine coolant temperature would activate the signal from the ECM to engage the fan motor solenoid, i.e. wire open?

I'm sorry I don't. I would suspect that a wire open would trigger a Diagnostic Code.

However both the coolant temp and hydraulic temp sensors are a fairly simple 2-wire passive type with one side connected to ground. So it must be a variable resistance with temperature.

I think the very high difference in radiator inlet/outlet temperature warrants further investigation.

 

[Simon C]

I wondered what was acceptable difference for the two radiator hoses. As I said in post #12, Not sure how much it should be at. Wonder if there could be some blockage in that radiator, and thought as you said Nige, that the trigger wire is either working or not working. I guess he will have to verify the simple stuff first.
Simon C