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[robson]

I am trying to diagnose whether my thermostat is working Starting from cold The 2 small rubber pipes on drivers side of engine bay going through a pump? get hot very quickly , heater off, whilst the top hose to rad is cold.After a short time heat does appear at the top hose but the temperature gauge is still not moving. keep running and the gauge begins to register and on normal driving settles at 85-90.but can take quite a while to get to this temp. Why are the 2 small rubber hoses getting hot first do they go to the heater? why would they get hot with heater off does that pump? run all the time.I hope this makes sense I dont want to replace the thermostat if it OK.

[Johnny English]

If everything worked normally the heater pipes would be the first hot place then the gauge should be seen as movig mate. The rad top hose is the last in this order. I bet your stat is stuck opened and gives circulation to the main rad before reaching normal running temp.

Laszlo

[Entwood]

Simple check .. ignore all pipes EXCEPT the main big one from the thermostat to the top of the radiator.

Start engine from cold, preferably overnight, and rest one hand lightly on that large pipe. Remain in that position for about 10 minutes ..

What you SHOULD feel is the pipes remaining cold until a sudden surge of heat as the thermostat opens, and it is a distinct surge of HOT water, not warm. .... this is how it should be.

What you might feel is a slow, gradual warming of the pipe. This is the thermostat stuck open. This is wrong and the thermostat needs changing.

It really is THAT simple ....   

[Andy B]

....

It really is THAT simple ....   

If only changing it was that simple too!     

[Entwood]

....

It really is THAT simple ....   

If only changing it was that simple too!     

It was .... drive to Stoke ... watch Daz do it .. drive home ... what could be simpler    

[Andy B]

....

It really is THAT simple ....   

If only changing it was that simple too!     

It was .... drive to Stoke ... watch Daz do it .. drive home ... what could be simpler    

           I never thought of that! 

[albitz]

I don't find them too bad to do tbh.Its just a matter of whether or not the lug on the transfer pipe survives the ordeal or not.

[Shackeng]

I don't find them too bad to do tbh.Its just a matter of whether or not the lug on the transfer pipe survives the ordeal or not.

Have you forgotten the B Bolt Albs?

[albitz]

I think Ive had beginners luck with that one.Done it three times now and not too much grief from it.

[robson]

Thanks Entwood Thats a shame I thought that when I visit my daughter in Wiltshire  you could have done it for me. On a serious note does that rush of hot water start when the temperature gauge is showing a highish reading. And reading some old posts those small pipes feed the heater matrix and the pump runs basically all the time is that correct.As both pipes are hot at least the matrix seems ok.

[amba]

I found the worst part was how to find the B bolt everytime I dropped it into the bottom of the engine bay.

Good torch and a magnetic bolt retriever was my best friend..the rest was just unbolting bits and refitting them.

[Nick W]

I struggled with the original bolt for about 15minutes.
Then I installed it in the bin, and replaced it with a normal hex-head bolt. Which went in first time, without any swearing.