Only poorly maintained diesels die of gasket failure and cracked noggins... 😭

I don't think so. That M51 head is its weak point. That's why later models pull in the aircon fans as well. That's on top of the Land Rover rad which is a thicker core than the aftermarket ones. Most of the time it is fine but work it hard all the time and that head cracks, especially if you put a tuning box on it to throw more fuel in.
 
Not convinced my viscous is as efficient as it should be. Or maybe the radiator. Although the needle doesn't move my Engine Guard informs me the head temperature is creeping up over 95C on long steep hills.
That is perfectly normal, the max operating temperature is 105C.
 
I don't think so. That M51 head is its weak point. That's why later models pull in the aircon fans as well. That's on top of the Land Rover rad which is a thicker core than the aftermarket ones. Most of the time it is fine but work it hard all the time and that head cracks, especially if you put a tuning box on it to throw more fuel in.
The aircon fans on later models kick in from the third sensor at about 110C
 
what temp is the thermostat fully open at? i'd go a couple of degrees or so above that

My sensor is bolted to the head so probably a few degrees cooler than the head itself and maybe a few degrees below the coolant as well.

Usually it runs between 85 and 95C on my sensor. Thermostat opens at 82, I think. The air con fans come in too late on the later models for my liking. Already cooking the head by then.
 
My sensor is bolted to the head so probably a few degrees cooler than the head itself and maybe a few degrees below the coolant as well.

Usually it runs between 85 and 95C on my sensor. Thermostat opens at 82, I think. The air con fans come in too late on the later models for my liking. Already cooking the head by then.
Yes, the sensor for the aircon fans comes on much too late at between 110 & 115C on my tests so is actually useless.
 

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