Today will I was waiting to dump my trailer and my coolant temp rose to 230f. on my autometer gauge. I was sitting and not moving for about 10 min but the temp was only about 45 out. My sender for my gauge is mounted in the port on the block so I think it is accurate. As soon as I was moving it dropped right back down to 190f. Could this be the sign of a problem with the EGR cooler? I was running an aggresive towing tune at the time. What is the maximum for coolant temp? Thanks for any help.

 

Some say fan kicks on at 210, some say 215, others say 220. Full explanation: see below. Engine begins to defuel at 227 deg. The thermostat begins to open at about 195*F and is not fully open until about 215*F.

Explanation:
Engine temperature is not the only parameter that the PCM monitors to determine cooling fan operation. This is the reason that you will see some variation in engine temperature as it correlates to fan operation. The operation/description of the FSS (Fan Speed Sensor) from the PC/ED manual has a fairly good explanation as to how the system "thinks". This is not your traditional engine hits temp X and the fan clutch locks up. The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The powertrain control module (PCM) will monitor the sensor input and control the VDF speed based upon engine coolant temperature (ECT), transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. When an increase in fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid port valve within the VDF.

It may be that your coolant pump is malfunctioning. The fins on the pump have been known to "come loose".

 

Thanks Biismic. The fan came on as soon as I started to move but I was just surprised that it got that hot with it being only about 45f out. Is there a way to check the pump?

 

My hat's off to you bismic, Good job. you sure know these rigs, and I,m glad your willing to help people out like you do.

 

Do you have any DTC's (Diagnostic Trouble Codes)?

It may be the thermostat also - with that, you may get DTC P0125 or P0128. Although, with these, the malfunction light should be lit too.

Here is a good read::
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For an easy/quick check:

For coolant pump check:
Start the engine.
Allow the engine to run for 10 minutes. Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose.
Is the heater outlet hose hot? (This isn't completely definitive, but it is a first thing to check)

If the heater outlet hose is hot:
Start the engine.
Allow the engine to run for 10 minutes. Feel the upper radiator hose.
Is the upper radiator hose hot?

Read the info in the link - there are a lot things you should check if you don't have codes (or can't pull them).

 

I know I jumped at the water pump - probably shouldn't have so quickly since there really are a lot of things to cause overheating (or apparent overheating). Again, the link spells them all out.

There are the basic questions like: what coolant are you using, have you added any additives to the system, have you lost any coolant or do you smell coolant, etc.

It also could be your temperature sensor.
A set of analog sensors and gauges are a world of help in these situations.
You can also compare ECT to EOT (coolant temp to oil temp) and learn some important things (the delta should be around 20 degrees IIRC) - if you have a system monitoring device.

Troubleshooting is a lot easier w/ information (I really hope that the $'s are available this month for a DashDaq / Phalanx!!).

 

The coolant is stock and all I have added is some distillled water when my degas cap went bad and it puked. The gauge is a Autometer ultralite with a electrical sending unit. I reads fine all the time it just got hot this time. Over the weekend I plan to go for a ride, get it up to temp and the sit and idle and see what happens. I will also conduct your quick checks. Thanks for the input, suggestions and link Bismic - very helpful! I also just got my sneeky pipe and plan on getting it in over the holiday and that should help with the coolant temp.