Hi Tom, mine will not go above 82-84 as well.. I'm not sure if that's a good thing tho. Did you changed the thermostat at one point?I've got genuine thermostats and pretty sure I've got some 78*C ones too (stamped). Let me know and I'll sort you out at tradeI run the 78*C one on my D2 and have not seen coolant temps higher than 84*C.
Just looking at these again and the latest new GENUINE PEM100990 are stamped 82*C, and so are the PEL500110. So presumably the only difference is the bypass valve which would open sooner on the PEL500110 (so more cooling to the engine / slower engine warm up time?)
That's a bit strange, once up at normal running temp it's not supposed to drop so much at idle actually it should not drop at all, some questions:
Thanks that's really helpful. So you think the engine cover might retain some heat? I think it was removed the day I got the vehicle! It's almost as if the thermostat is stuck open, which comes back the whole stamping issue where very few are stamped, and the ones that are seem to be stamped 82*C, even genuine LR thermostats. The manual states they start opening at around 82*C and are fully open at 96*C - but that must be based on when the thermostats were 88*C (stamped)
It should have some effect IMO cos your's has a very strange behaviour exactly like you observed
the only one which seems OK these days is the PEM100990LR, that's what i have and as you saw the ECT is behaving well(with engine cover fitted and 50% OAT mix cos the coolant's concentration has some effect too)The manual states they start opening at around 82*C and are fully open at 96*C - but that must be based on when the thermostats were 88*C (stamped)
They are also stamped 82*C now, i am sure they used to be 88*C but could be wrong! The coolant is mixed to protect to -20*C (measured with a refractometer)
The mix must be 50% antifreeze(oat) / 50% water for the system to work as it should and choose the antifreeze temperature range based on that to achieve the desired protection, the refractometer test is irrelevant hence the note from the WSM which is valid the other way too so if it's more than 50% water it will run cooler or vice versa, in a nutshell: the lower the concentration is the cooler it runs.
That makes sense. I knew too much antifreeze concentrate reduces cooling efficiency, but hadn't thought it would actually run cooler with more water as the engine is still generating the same heat. I will adjust it and check again. Although i think I also have another issue now as it's holding pressure in the cooling system overnight so possible head gasket time anyway!
the tank's cap has a pressure valve to keep 1.4 bar in the system so as long as the top hose doesnt become rock solid while driving and it runs cooler rather than hotter i dont think it's a HG problem which would create overheating or coolant loss
There's isn't any pressure when the engine is cold
Why? it's supposed to be a sealed system and the valve works with the air which is in the expansion tank , for example if you pump up a tyre to 1.4 bar and let it over night will it be no pressure in the morning?
Pressure is only applied to the cooling system (all being well) by the heating up of the system and expansion of the water. Overnight it cools so should be back to zero.
To use a tyre analogy...
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