405 running cold

[carlo]

Hi all, I'am wondering how easy this issue will be to resolve, which I'm presuming is a thermostat problem.

 

The silver 405 always runs very cold, the temperature gauge will barely if ever move off the zero position with a corresponding fairly lukewarm heater output.  As soon at the car hits significant traffic though or is in a jam it will quite quickly rise up, it reached alarming levels in a bad jam recently (over 100 degrees) without seeming to overheat; fans kicked in OK.

 

If it is a thermostat are they easy to fit, or swap from another similar car?

 

Thanks 

[Station]

I've never had a diesel that didn't need a new thermostat, every single one.

I did my XUD thermostat and it took minutes, heat was awesome and improved mpg.

Your overheating may be a sludged up radiator/coolant system or failing water pump. Nothing better than sticking a hose down a pipe and watching all the poo come out the other end with the engine running.

[carlo]

Mine's a petrol actually, and the problem seems to be it's not getting hot enough.

[richardmorris]

Thermostat by the sound of it. Similar to my Mercedes- would sit at low temp until traffic then shot up over 100. When I tested the old one in a pan of boiling water it was opening partially at a low temp but never opening fully.

[holbeck]

Yeah, classic symptoms of thermostat either missing or stuck open.

[Mally]

Used to have to run the heater quite often when towing on hills with my 405, to keep it from boiling.