How can i test my 300 tdi thermostat?

Hello,

How can i test my 300 tdi thermostat to see if it is working?

Take it out and drop it in boiling water. If it expands its working if not well....... you get the idea

yep put it in water and bring it to the boil

Do i need to drain system, or just catch any leaking coolant and put back into system once done?

your only going to lose a bit mate till it drops below stat housing just top it back up

Perfect, will perform this test on my defender 90 soon

CameronW1996 said:

Hello,

How can i test my 300 tdi thermostat to see if it is working?

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you could feel top hose when engines hot ,hose only gets hot when thermostat opens

THe boiling water test can show the thermostat is opening, but you should test it opens at the right time. I find that a new thermostat is best when your doubtful. Quinton Hazel are the best for pattern ones, avoid cheap ones. Waxstat was the original supplier. Testing a thermostat involves using a thermometer and a boiling vessel. On the thermostat there is a temp at which it opens, check yours is the right type. i.e. 88 degrees C. The workshop manual should state the right type. Fluid loss is minor, make sure you top up and monitor the level for leaks.

For the cost just change it as you are taking the housing apart anyway - will remove any niggling doubt about serviceability if you test old one, put it back in and still have same problems!

Kwakerman said:

For the cost just change it as you are taking the housing apart anyway - will remove any niggling doubt about serviceability if you test old one, put it back in and still have same problems!

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Agreed they're only £8-£10 anyway so you might as well just change it