Running temperature

Hi all,

Just acquired a 54 plate TD5. Have had a 300Tdi previously. TD5 is a different machine altogether, much different (in a good way).

My 300TDi never seemed to run hot (according to the gauge) just hovering below the halfway mark all year long, whatever it was towing, whatever it was carrying.

The TD5 seems to be running just above halfway, all the time (takes quite a while to warm up). My journey to work involves a long but gentle slog up an A road. Keeping at a steady 55/60 mph the temp gauge doesn't rise but the temp of the air coming out of the heater gets very hot. Hoses and radiator all look good, very clean coolant, pink, correct concentration. Only had it a couple of days so haven't even had a chance to check the temp of the hoses. Could a stuck thermostat be at fault?

Just wanted to know whether they tend to run warm or whether I should have a more thorough investigation? Am a bit worried because of all I've read about warped/cracked heads!

Many thanks, Julian.

My temp gauge (TD5 defender 110) rarely gets as high as half way. Even when running without a viscous fan.

You could get a garage to put a thermal camera heat thingy onto it for accurate temperature measurements. Maybe something will stand out.

I would check your thermostat. Mine was stuck and and my td5 was running the same as yours, a little beyond halfway, which on mine was about 95-98 degrees (using a Nanocom to read it). It should be running at 84-87 degrees. Unfortunately the stock temp gauge on a Td5 isn't very accurate, it's fed from the ECU and is configured to not move within a fairly wide range. A Nanocom or similar would be helpful to see your real temperatures. It would be worth feeling the hoses to the rad to see if they are good and hot after a drive. I think the ECU limits power to the engine if it sees hotter temps as well, as mine had quite a bit more power after replacing the thermostat. Mine once sprung a leak, coolant went to over 105, and the only way I knew about it was my Nanocom alerted me with a pre-set alarm. Temp gauge didn't look like it was that hot, it was a little further beyond halfway...

Thanks for these replies - this is sort of what I have suspected as the heat output from the heater is varying even when the gauge is staying steady. Working it hard up a long hill the hot air coming out of the heater gets very hot!! New thermostat at the weekend.

Can anybody recommend a suitable antifreeze for the TD5 - all my experience is with 300TDi's.

Thanks, Julian.

Danceable said:

Thanks for these replies - this is sort of what I have suspected as the heat output from the heater is varying even when the gauge is staying steady. Working it hard up a long hill the hot air coming out of the heater gets very hot!! New thermostat at the weekend.

Can anybody recommend a suitable antifreeze for the TD5 - all my experience is with 300TDi's.

Thanks, Julian.

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you want OAT (pink) in a TD5

I used Zerex Dexcool, which is spec'd for GM vehicles. I believe Dexcool is GMs term for OAT which stands for organic acid technology -- corrosion inhibitors. I've found VW oem coolant is OAT as well. When I couldn't find anything else I bought some VW coolant from the dealer (but that was when I was in Nepal so I didn't have many options).