Diesel thermostat definative answer

[Jules]

You are correct Matt!
Not one of them I've changed in last 2 years has stuck open. (around qty 50 !)

[Frank Incensed]

Originally Posted by Jules

Not one of them I've changed in last 2 years has stuck open. (around qty 50 !)

Now you tell me! Or, if you told me before it must be the short-term memory loss.

[James.uk]

Interesting.. End result is the same though, engine is kept cool due to water going through the rad too early and the owner freezes.. heh heh..

Are 12v heaters any good?
...

[T-Cut]

Originally Posted by Jules

You are correct Matt!
Not one of them I've changed in last 2 years has stuck open. (around qty 50!)

It would be interesting therefore to actually test a duff stat in heating water to see exactly what happens to it. Logically, if the duff stats are always closed when removed, then the obvious explanation is they are opening too early in the engine.

Personally, I'll be surprised if that is the result. Opening at a much lower temperature than normal doesn't come over (to me anyway) as the direct result changes in the wax.

I assume these stats are wax stats and not some other system?

TC

[Matt1960]

TC,
I believe it is wax that controls the opening.
But if it were not the wax degrading, would you be thinking that the spring tension is changing somehow?
My gut feeling is that it is more likely to be the wax.

Matt

[Matt1960]

Originally Posted by James.uk

Interesting.. End result is the same though, engine is kept cool due to water going through the rad too early and the owner freezes.. heh heh..

Are 12v heaters any good?
...

12v heaters are quite poor, I think. But before I retro fitted a fbh to mine, I would run a small fan heater from the garage and after 15 mins it had completely defrosted all the windows from quite thick ice and made the cab toasty.
Unfortunately my extension cable would not reach to drive to work.
Matt

[r44712]

Thanks fo the tips, will have to gove the diagnostics a go! I do have one of those code readers that hooks up to a laptop and gives running info. WOnder if it'd give coolant temp.?

[T-Cut]

Originally Posted by Matt1960

TC,
I believe it is wax that controls the opening.
But if it were not the wax degrading, would you be thinking that the spring tension is changing somehow?
My gut feeling is that it is more likely to be the wax.
Matt

No, I don't go for the spring tension idea for reasons I've explained elsewhere. However, I'm not convinced about the wax either. As an organic chemist by profession, I can't see how a hydrocarbon wax can change under typical service conditions such that it dramatically reduces the opening temperature. Paraffin waxes are amongst the most stable of substances. Very difficult to alter, even using powerful chemistry. So, I'm basically undecided without more data on failed stats. That's why it's important to examine some to see how they operate in heated water. My gut feeling is a mechanical weakness somewhere in the design, but without the tests and observations, we'll probably never really know what happens to them.

TC

[Matt1960]

TC,
Yes, I would agree that proper testing would give us the answer. Unfortunately I gave my faulty stat away to another member for him to source a hotter version, which never materialised. So I am unable to help.
Matt

[Matt1960]

TC,
As I said earlier my gut feeling will be the wax, but could it be that the sealing of the wax might be at fault. Either coolant getting in to mix with the wax, or wax escaping past the seal.
Either might cause the gradual change in opening of the stat I would have thought.
Matt