2 Speed Fan Poser will my woes end!

[rovertone]

Originally Posted by Union Wheels

Hi rovertone,
you said previously that you had a good rover parts specialist near you with lots of parts. Why not get a working 3 speed fan from him (after all that was the original configuration) and see if that works. He may let you have it on the basis that if it does not work you can take it back.

If it does work and you are then concerned about the longevity of the motor, do my modification (link in my signature) you already have the resistor and bracket on your 2 speed set up.

Cheers, Pete.

Hi Pete,
I went down on Monday, I think he must have everything but fans, he's breaking all the time so I will be keeping in touch. I am going in next week anyway to get a few bits for spares to take with me on my travels so will sound him out on your 'sale or return' idea, thanks for that.
Tony

[Jules]

I've yet to see a second hand 3 speeder which works on all speeds

[RayH]

Originally Posted by T-Cut

Perhaps you don't Simon, but I do. Rovertone is getting there with his issue, but peripheral questions were raised and I think they're interesting. You don't have to join in or comment if they don't interest you. A lost sensor signal while driving is well within the realm of possibility. I'd like to know what happens next. The heat soak connection may or may not exist, but any info is useful. We've had two different answers to the run-on period (three minutes and ten minutes), so what's correct? You'll not find the answer in RAVE.

TC

Okay, disconnected coolant temp sensor on mine today.
Turn ignition on and fan runs at high speed, yes it definitely was high speed.
Turn ignition off and fan cuts out after 3 minutes.

[SD1too]

Originally Posted by RayH

Turn ignition on and fan runs at high speed, yes it definitely was high speed.

Ray,

It's good to have confirmation of what happens when the coolant temperature sensor gives an 'invalid' reading. However, T-Cut also refers to what he calls the "heat soak" condition. On the petrol engines, this is when the engine is stopped and the coolant temperature is above a certain threshold with a fitted and working sensor. The radiator fan then runs on for a pre-determined length of time. There is no mention of this feature in RAVE for the diesel, and the conditions would be difficult to reproduce, but if you can think of a way I would be as interested as T-Cut to know the answer.

Simon

[RayH]

Originally Posted by SD1too

Ray,

It's good to have confirmation of what happens when the coolant temperature sensor gives an 'invalid' reading. However, T-Cut also refers to what he calls the "heat soak" condition. On the petrol engines, this is when the engine is stopped and the coolant temperature is above a certain threshold with a fitted and working sensor. The radiator fan then runs on for a pre-determined length of time. There is no mention of this feature in RAVE for the diesel, and the conditions would be difficult to reproduce, but if you can think of a way I would be as interested as T-Cut to know the answer.

Simon

Interesting.
Does the ECU differentiate between a disconnected sensor and one at a high temp (with the ignition off)?

[T-Cut]

Originally Posted by RayH

Turn ignition off and fan cuts out after 3 minutes.

Thanks for doing the test.
I fear the heat soak experiment for the diesel is unlikely to be done in an intentional, controlled way. I suppose the test could be done using a spare sensor and a hotplate or a heat gun.

TC

[T-Cut]

Originally Posted by RayH

Does the ECU differentiate between a disconnected sensor and one at a high temp (with the ignition off)?

That's the part two question about the fan run-on mechanism. I can't see the experiment being done directly is an intentional, controlled way. However, the spare sensor test could be applied using a heat gun, etc providing the temperature can be controlled.

I suspect, but certaninly don't know, that the heat soak run-on period will be the same as the signal lost period. I'd be surprised if the ECU could differentiate the two in the circumstances. But it's one of the unknowns and needs to be understood.

TC

[T-Cut]

Originally Posted by SD1too

However, T-Cut also refers to what he calls the "heat soak" condition.

Heat Soak: http://cjbfire.com/Heatsoak.pdf

[RayH]

Originally Posted by T-Cut

That's the part two question about the fan run-on mechanism. I can't see the experiment being done directly is an intentional, controlled way. However, the spare sensor test could be applied using a heat gun, etc providing the temperature can be controlled.

I suspect, but certaninly don't know, that the heat soak run-on period will be the same as the signal lost period. I'd be surprised if the ECU could differentiate the two in the circumstances. But it's one of the unknowns and needs to be understood.

TC

Actually there is an easier way, Jules posted on it earlier, use a variable resistor! That way we can set whatever temperature we want using the OBD and maintain that after ignition switch off.

Like you I suspect that it will still be three minutes but who knows, I've been wrong before

[T-Cut]

Originally Posted by RayH

Actually there is an easier way, Jules posted on it earlier, use a variable resistor!

So he did.
And in the interests of furthering diesel engine science, surely some investigative owner will run the test? They'd even get it named after them!

'DieselOwner's Heat Soak Fan Test' - insert your name or ID and become immortal.

TC