300TDI overheating

You have to be a little careful reading too much into the expansion tank cap opened when hot as any vehicle will bubble over with the sudden decrease in system pressure.

It needs to be cracked and then observed for bubbles when the system has settled.

You can also do a combustion gas test on the cooling system if you aren't sure.
Have done this on my 300Tdi a few times when it's been a bit too hot for my liking.
Luckily it was OK everytime, including blowing the header tank on the heater when climbing a range.
I really thought I'd done the head and h/gasket that time as it pumped most all the coolant out of the system.

As Pat said, the Defender really needs the fan clutch working properly too, ram air isn't enough to overcome the underbonnet air pressure at speed.

Thanks for the replies , I will get the test done to check for ex. gas .
Yes the heater was looped out properly .
I will replace the fan hub with a known good one .
Should know more in a week or so .

Thanks to all .

There is a couple ways you can check if the viscous clutch is working correctly. If you need to replace will need a long skinny spanner to get in there. A little expansion when opening the cap is normal but if it burbles for a prolonged period I would still be inclined to think head (propensity for 300's to do them and vehicles age)


Hopefully it is just fan hub but I would be surprised. Get it up to operating temp and then roll up a magazine or news paper and gradually push it into fan from behind. If it resists and starts to shred paper you have a good idea if it's engaged for the most part. If it just stops without much of a fight then then viscous unit is US. Even just rev it at fuel pump and feel if it increases air flow with higher rpms. Or if engine is cool, rev it with cap off expansion tank and watch if stream of bubbles come rushing out.

Replaced the fan today , with a good one off another landy .
Joy of joys , gave it a good workout and all OK .
Thanks for all the advice .

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Originally Posted by dero

Replaced the fan today , with a good one off another landy .
Joy of joys , gave it a good workout and all OK .
Thanks for all the advice .

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That's fantastic mate, great to hear. Dodged a bullet there!