Disco 1 Thermostat question.

Hi.
I have a 300tdi in my 69 series 2 project (been run about a mile to test the brakes).
I have just replaced the water pump and thermostat and it appears when left idling and revved that the top hose stays cool when all the others are hot.
Could this be anything other than the thermostat? When fitting I can't remember fitting it in any particular orientation, is there a top/bottom that would stop it opening if fitted the wrong way around?
Cheers
Toby

jiggle pin at the top , worth a check

What does the pin do and can it only be fitted at the top?
Thanks

tobyd10 said:

What does the pin do and can it only be fitted at the top?
Thanks

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Pins for bleeding.
The 200Tdi I had was a very over cooled engine and I'd bet the 300 is too.
I got rid of the viscous fan in favour of an electric that never needed to be turned on and the engine heated up quicker and the top hose got hot too.
It may not be reaching temperature properly. Is the gauge temp up?
If temp gauge shows hot then test thermostat in boiling water before refitting with the larger spring end down.

tobyd10 said:

What does the pin do and can it only be fitted at the top?
Thanks

Click to expand...

lets air out,last thing you want is air around the thermostat and aids filling the system

Cheers. Bought another thermostat so will test that and the one I will take out tomorrow and fit the best performer.
If they both work I will have to presume that I was chicken and perhaps didn't let it heat enough but I doubt it.
Will also have to get a temp sender that works with my dash gauge too.
Regards

I have 2 thermostats. Both open but the new one I bought is shorter than the one I took out.
Which is the right one?
Also when fitted I guess the little vent bit is at the top?
Cheers

220deg for 15mins and they should taste lovely.....might need seasoning

tobyd10 said:

View attachment 156520
I have 2 thermostats. Both open but the new one I bought is shorter than the one I took out.
Which is the right one?
Also when fitted I guess the little vent bit is at the top?
Cheers

Click to expand...

thermostat has to be long enough to shut the bypass port, if the short one doesnt its no good,long one shouldnt close the bypass port when its shut ie cold

jamesmartin said:

thermostat has to be long enough to shut the bypass port, if the short one doesnt its no good,long one shouldnt close the bypass port when its shut ie cold

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Gone with the longer one and seems fine. Could the 'new' one be a 200tdi?

tobyd10 said:

Gone with the longer one and seems fine. Could the 'new' one be a 200tdi?

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Nope 200 has bypass bit as well

Your average 200/300/td5 wll take 5 miles ish to get to full operating temperature, less if you can get it on a fast road and longer if pottering around town.