966H coolant overheat issue

[YulMY]

Hye, new guy here at work and need some experienced people advise.

We have a CAT 966H here and need some opinions on troubleshooting this issue (as per title).
Not sure if this was posted anywhere in the forum previously but can't find any similar forum title.
Thanks in advance to anyone that helps.

Details as per below:

Model: 966H
Machine SN: A6J1268
Engine SN: RSX13038
Machine running hours ~37k

Previous error codes/issue:
Coolant overheat and triggered high coolant temp warning - E361(2)
Engine cooling fan solenoid: current below normal - 291-5

1. So, we've changed the solenoid + valves for the fan speed control and recalibrated the fan speed to max rpm even at lower engine speeds. Double checked the fan rpm using a stroboscope and confirmed it works. Idle fan speed around 1200rpm, at max engine rpm fan speed was around 3000rpm.

2. Also, changed the thermostat and water pump just in case. During this we found that the thermostat was stuck open.

3. Took the machine histogram of time vs coolant temp (at 36960hrs and 36998hrs) and found that machine operates at around 95C-105C most of the time when doing high load tasks between these 2 machine hours. Occasionally reached above 105C few mins. Although the histogram shows the machine average overall should be around 85C-95C. And I think the overheat code will trigger at around 110C-115C maybe?

Also, to note, the temp gradually increases after around few hours, not instantly.

My question is, what is the usual operating temperature for these machines? The machine overheated twice this month, both times with the "Engine cooling fan solenoid: current below normal - 291-5" error logged. However, after changing both the harness and the solenoid, I doubt this will occur again anytime soon. And we have yet to get overheating errors after that.

Even so, after looking at the histograms, the guys here are kinda scared to let the machine running for long periods if the average temps are at 105+C or even 110+C. Are these normal coolant temps? Does this sound like a head gasket issue? Or are the temps look normal and just let the machine run as per usual?

 

[Nige]

And I think the overheat code will trigger at around 110C-115C maybe?

Nope. E361(2) triggers if the temperature passes 105DegC for more than 20 seconds.

Also, to note, the temp gradually increases after around few hours, not instantly.

That suggests to me that the problem could be in the radiator. After reading through all the action you have taken so far I note that the radiator was never mentioned. Has it been removed and cleaned thoroughly yet.?

Even so, after looking at the histograms, the guys here are kinda scared to let the machine running for long periods if the average temps are at 105+C or even 110+C. Are these normal coolant temps?

So they should be. "Normal" should be somewhere around the temp at which the temperature regulator (Cat don't call them thermostats) is fully open which is 92 DegC.

Does this sound like a head gasket issue?

Only if you are losing coolant in significant quantities. Are you.?

Here's a curve ball from left field. Has anyone checked temperature with an infra red thermometer to confirm that what the machine electronics are regaistering (based on a single coolant temp sensor) are actually correct.?

 

[Nige]

Also, and this is probably significant bearing in mind your geographical location, your loader was not equipped with a High Ambient temperature cooling package when it was origianlly built.

A6J01268 was built with a Standard radiator - core Part Number 256-5309. The High Ambient cooling package radiator core is a 256-6627. Everything else in the radiator is common.

Was the loader bought used from another country and imported to Malaysia.?

 

[YulMY]

Nope. E361(2) triggers if the temperature passes 105DegC for more than 20 seconds.

That suggests to me that the problem could be in the radiator. After reading through all the action you have taken so far I note that the radiator was never mentioned. Has it been removed and cleaned thoroughly yet.?

So they should be. "Normal" should be somewhere around the temp at which the temperature regulator (Cat don't call them thermostats) is fully open which is 92 DegC.

Only if you are losing coolant in significant quantities. Are you.?

Here's a curve ball from left field. Has anyone checked temperature with an infra red thermometer to confirm that what the machine electronics are regaistering (based on a single coolant temp sensor) are actually correct.?

As for the radiator, we have cleaned it externally with water jet. This has been done weekly previously too since we are iron factory and dust tends to block the rads. Have not done any internal service/cleaning yet. However, am planning to do a radiator swap since we have some spare cores here and service the used ones. Just need to find the time to schedule it.

As for coolant levels, might need to double check again in the upcoming days.

No, we have not use infrared thermometer to confirm this. But on the second occasion it overheated, it was sent to the workshop and was reported engine was smoking even through the breather. So, I doubt it was faulty sensor. Unless, the overheating was due to the fan solenoid error (which was logged and rectified after) and the high average operating temps was due to a faulty sensor. But just to be safe, I'll schedule to change the sensor.

 

[YulMY]

Also, and this is probably significant bearing in mind your geographical location, your loader was not equipped with a High Ambient temperature cooling package when it was origianlly built.

A6J01268 was built with a Standard radiator - core Part Number 256-5309. The High Ambient cooling package radiator core is a 256-6627. Everything else in the radiator is common.

Was the loader bought used from another country and imported to Malaysia.?

I do not have the purchasing history for this loader since it was purchased in 2009 I believe?
But the spare radiator here is the PN 256-5309. May look into it in the future when ordering spares.

This is new news to me, since all this while the rad used was the standard radiator and overheating issue was rare.

 

[YulMY]

Also to add, while writing the previous reply, I was also notified that hydraulic oil was significantly less when the second overheating occurred. Which caused the fan to not run at full speed and even stall in certain cases, in combination with the fan speed solenoid error.

There was minor leak at the control valve but not significant enough to cause major hydraulic oil loss. Just some wet marks. The hydraulic oil level was check on the previous 2 days before this happened.
Topped up the hydraulic oil and after 2-3 days, checked again and oil level is good.

Wanted to add this info just incase these are some signs related to the overheating/high average cooling temps.

 

[Nige]

But just to be safe, I'll schedule to change the sensor.

You might be wasting your money. I would suggest to put the temp gun on it first and confirm the sensor reading.

If the atmosphere is full of iron dust then radiator cleanliness is important. Maybe it it time for a radiator removal and thorough cleaning.? It is almost impossible to completely clean a radiator while it is installed in the machine because of all the shrouds around it.

 

[Nige]

This is new news to me, since all this while the rad used was the standard radiator and overheating issue was rare.

Put it this way. If I had specified that machine for work in Malaysia, especially in high dust level environment, it would have been equipped with the High Ambient cooling package.

 

[YulMY]

Put it this way. If I had specified that machine for work in Malaysia, especially in high dust level environment, it would have been equipped with the High Ambient cooling package.

Just wondering, what's the physical difference between the two rads that I can look for to distinguish between them? I'm not familiar with it.
It could be that the currently installed rad is the High Ambient cooling package.

Also, how about the below machine? Did this come with the standard rad also if you don't mind checking? Sorry that I have to ask you for this.

966H
Machine SN: TAL742
Engine SN: TXE02623

If I want to compare the temperatures between these 2 machines, need them to be apple to apple comparison.

However honestly, I can't see any physical difference between these 2 machines radiators.

 

[Nige]

Also, how about the below machine? Did this come with the standard rad also if you don't mind checking? Sorry that I have to ask you for this.

966H
Machine SN: TAL742
Engine SN: TXE02623

No problem. TAL00742 was also built with the Standard 256-5309 Radiator Core.

Just wondering, what's the physical difference between the two rads that I can look for to distinguish between them? I'm not familiar with it.

Sometimes it is more fins per inch of radiator core, other times a different material (one with better heat transfer) used in the manufacture of the cores. Sometimes a combination. Not having seen one of the particular Part Number of HA core for the 966H I'm sorry I can't tell you what the difference(s) might be in your case.

 

[YulMY]

No problem. TAL00742 was also built with the Standard 256-5309 Radiator Core.

Thank you!

Sometimes it is more fins per inch of radiator core, other times a different material (one with better heat transfer) used in the manufacture of the cores. Sometimes a combination. Not having seen one of the particular Part Number of HA core for the 966H I'm sorry I can't tell you what the difference(s) might be in your case.

Ahh I see. Thanks for the heads up tho. Appreciate it.

Today will be doing cleaning on the radiator, we'll see if there's any findings once it's opened up.


Also, apparently yesterday, the operation tried to test run the machine. Was running normally for around 2 hours before temp spiked to OH point. Checked the coolant and was missing quite a lot which we suspect was the cause for OH. Now I'm worried if it's the head gasket. Or maybe the coolant evaporated since we can see the vape coming out from the rad cap hose?

Filled the coolant back up and start the engine with the rad cap off. No signs of bubbles/gas coming out from the radiator. I have ordered a block tester to check if there's any combustion gas in the rad.

 

[Nige]

The loss of coolant is possibly significant. How much is "quite a lot".?

You should keep a good handle on how much coolant is being added to the system and also that the operators are checking the coolant level frequently and reporting if it is low rather than simply running the loader and letting it overheat.

You really need to get hold of a cooling system pressurizing pump to put 10psi or so of pressure in the system when the machine is cold and see if it holds.

 

[Delmer]

We don't see scaled up radiators as much as we used to when it was more normal to add water regularly, and the coolant wasn't as good maybe. If there is any hard water being added, it's possible the water side of the radiator is plugged up. The coolant temps going to and coming back from the radiator while it's overheated should help diagnose that. UNLESS the water and air side are both equally plugged, then you'd need to dig deeper.

 

[YulMY]

If there is any hard water being added, it's possible the water side of the radiator is plugged up.

When we do coolant change out, we use proper coolant mixture.
But for operation side, they will sometimes top up hard water. So yes, there is a possibility of water side of radiator plugged up.

You really need to get hold of a cooling system pressurizing pump to put 10psi or so of pressure in the system when the machine is cold and see if it holds.

Yes, am trying to get hold on said pump. But will take a while until we receive them. I think this is the only way to properly troubleshoot my current situation.



As of now, we've done the radiator change out and the old ones are being serviced now. We've asked for pictures to check if there was any clogged tubing. Yet to get them.

Tested the machine and let it idle for around 1 hour and used it on heavy task for around 30minutes. No water leaks or water level change.
Plan to let it run for half a day and monitor temperature + water levels tomorrow.

 

[Delmer]

I don't know Cat specifically, on some radiators you can blow air back through the overflow tube through the check valve in the radiator cap to pressurize the system. So get a tank with 10PSI and blow it up, then feel the pressure on the hoses, and compare that pressure again in an hour or two, and watch for drips. Not correct, but it does most of what you're looking for.