My temperature gauge seems to hover between 1/4 and 1/2 temperature so I am guessing the thermostat is stuck partially open. 

Where is the thermostat located and how would I go about replacing it?

Sandwiched between the diesel pump and the alternator I think. Alternator probably has to come off. The stat is a bit of a pig to get to. See pic in below post.....

Edited 4 October, 20205 yr by TMB

In the yellow circle....

 

16 minutes ago, TMB said:

In the yellow circle....

 

Looks like a real pain to access.

Is it worth emptying the coolant first or just letting it drain out when the thermostat is removed?

2 minutes ago, JoeF said:

Is it worth emptying the coolant first or just letting it drain out when the thermostat is removed?

 

Probably be easier to drain it first but it can be done either way.

On 04/10/2020 at 18:36, TMB said:

 

Probably be easier to drain it first but it can be done either way.

Do you happen to know what size bolt holds the thermostat housing on? I dropped one and can't find it anywhere.

M7 thread I think, awkwardly. Will look up part number and length shortly.