Morning all,
I start my 01 disco up in the morning to let it warm up prior to taking off and discovered that the temp gauge on dash is up to normal operating temp and shes blowing cold air out of vents until I stepped on the gas and increased rpm's a bit. I did notice that my coolant overflow tank was full until I did that and she went back down to where she normally sits at. Curious if this could be the viscious unit on the fan causing the issue...? Any advice is appreciated.

Thanks

 

if you have no heat, you are low on coolant. top off the system and bleed it properly, then preasure test the coolant system to see where the coolant went.

 

the thing is it's not leaking coolant.

 

The coolant system is a closed loop. If no external leak (anything from gaskets to bad coolant cap venting while driving), the head gaskets could be converting it into steam. Slowly at first. Or it can enter the oil and make oil dip stick look higher, perhaps milkshake color. But once coolant is below a certain point, there is just a steam pocket to circulate out the top of the manifold. You may hear a sound like a waterfall or gurgling under the dash. As for the gauge, the truck can be overheating and it will still report normal. Anything above 50% is trouble. At 50% it can still be trouble. Use a scanner or Ultra Gauge to see digital temps.

You can also improve idle heat performance with a thermostat called the "soft spring" version, a popular one is 180F. The softer bypass spring allows improved flow to the heater when main stat is closed in colder weather cycles. When the main sat opens, it shoves the bypass disk closed. At idle the water pump does not make enough pressure to overcome the oem bypass spring. You rev up, disk descends, plenty of flow to core.

 

Thanks for the info, I know the head gaskets are fine. I will investigate further and report findings. thanks

 

if its not leaking it? its burning it, hope for a leak.

 

I have not added any anti-freeze and its been holding at the same place in the over flow tank for quite some time now. What are the symptoms of the viscous drive failing?

 

a bad viscous fan would cause you to overheat not lose heat