Thread: Help Diagnosing my Td5 Cooling issue

I'm not so sure you should be concerned Mundy.

I leave home here and travel up the M1 and it does take me anything up to 10-mins depending on the OAT, for transmission to warm up enough for the torque converter to lock up.

Even on a warm/hot day it still takes about 10km

Sometimes my OEM temp guage doesn't even adopt it's 'neutral' position.

Guage watching sometimes gives niggling thoughts , like my oil pressure when everything is steaming hot out on the open highway it indicates about 25psi or under.

If I watch my temp guage I could get worried too, Like fully loaded all up weight hauling up the Toowoomba range or Cunninghams Gap.

100*c or a bit more is not too hot for lubricated mechanical parts to perform at, as long the cooling system can maintain it without hoses blowing etc.

aircooled VW's run very hot, so do aircooled VM & Deutz diesels.....much higher than a water based cooling system would allow.

you call , if you have cause for alarm and you feel more comfortable change it out.

Originally Posted by Mundy

My temps seem far more variable than those quoted by others here and I am wondering if my 2004 manual Td5's thermostat needs replacing.

My temperature varies depending on outside temp, how fast I go, how steep the terrain is and how loaded I am.

So, the sort of ranges I get are:
1. Around town, ambient 25 deg, speed around 60 to 80kph, not too much stop start, not too loaded, gives me around 88 to 90deg.

2. Open highway, ambient 25, speed 100kph, flat or gentle hills, not loaded gives me 92-93deg

3. Open highway, ambient 35deg, speed 100kph, flat or gentle hills, loaded, gives me 98 to 100deg

4. Open highway, ambient 37deg, speed 100kph, medium grades, loaded, gives me 103deg

Temp measured with a TM2 sensor on back of block.

Also, around town, whilst the control panel temp gauge reaches normal after about 5 minutes, the TM2 sensor shows it not reaching max operating temp for 15 to 20 minutes.

Should I look at replacing the thermostat?

Don't be very scared about that difference though cos the gauge goes to the middle(considered "normal") at 70*C and as normal operating temp is considered around 90 that might not be such big issue cos it depends much on ambiental and driving conditions too

about the thermostat IMO it's a good move to replace it if it's old cos they are loosing theyrs qualities in time anyway BUT if there will be no change after that make sure the viscous fan is locking well cos i've seen many cases when that was the problem... try to stop it with a rolled newspaper when the thermostat is supposed to be fully opened/radiator is hot and if you can then you better get a new one cos it means it doesn't have enough guts to cool well... they used to wear out in time as well

i was thinking many times about this "normal operating temp" thing and there are some unanswered questions in my mind:

the main question is: If 95*C is considered hot (nanocom will warn you at that temp on instrument mode) then:
1. why did they make the original thermostat to fully open only at 96?
2. why did they set the electric(aircon) fan to kick in only at 110(to help cooling) and stop at 105?
3. why did they set the gauge to leave the middle only at 120?

if we think that they knew what they were doing then IMO nothing up to 105 is bad cos it depends very much on environment, vehicle load and driving style