Viscous fan question (and stat observation)

[NikTheGeek]

I've tested my stat and its stuck open. I did this by starting the engine and letting it idle. Within 5 mins at idle and with the temp gauge still on zero, all rad hoses were equally warm including the little hard plastic one that connects to the reservoir. So I assume its either missing or stuck open.

Which leads me to my question:

I gather these things have a viscous fan? So how is that meant to operate? Mine, from the moment I start the engine, is turning at full chat sucking loads of cold air over the engine. Is it supposed to operated at cold? Is it not supposed to be stopped at idle and only kick in as the engine speed or temperature increases?

tnx

Nik

 

[West Slope Rover]

I've tested my stat and its stuck open. I did this by starting the engine and letting it idle. Within 5 mins at idle and with the temp gauge still on zero, all rad hoses were equally warm including the little hard plastic one that connects to the reservoir. So I assume its either missing or stuck open.

Which leads me to my question:

I gather these things have a viscous fan? So how is that meant to operate? Mine, from the moment I start the engine, is turning at full chat sucking loads of cold air over the engine. Is it supposed to operated at cold? Is it not supposed to be stopped at idle and only kick in as the engine speed or temperature increases?

tnx

Nik

The fan doesn't really stop, it just doesn't spin as fast when it's cool. It's sort of like a slipping clutch turns the tranny, but not at full speed.

 

[Datatek]

They always run at full chat from cold for a minute or two until the viscous gel frees up, it should then slow until the rad gets hot when the heat will operate a bi-mettalic strip on the front of the viscous unit to lock it up.
If it stays locked it's seized.

 

[wammers]

Wax stats do not stick open, they always fail shut. There is a method for checking viscous fan in my How to.

 

[dogsbody]

If your temp gauge is struggling to get out of the bottom, blue section then, like me, you'll find a void where the stat should be. The question is why? On mine it was a new water pump and rad.

 

[NikTheGeek]

Wax stats do not stick open, they always fail shut. There is a method for checking viscous fan in my How to.

Can you post a link please as I can't see it. I only see 5 threads and the only one from you is for a L322

tnx

Nik

 

[NikTheGeek]

If your temp gauge is struggling to get out of the bottom, blue section then, like me, you'll find a void where the stat should be. The question is why? On mine it was a new water pump and rad.

I don't follow, do you mean it had been removed because of a fault?

Anyway, it does go up to half way when towing a double horsebox and 2 horses, just not on a normal run...

Nik

 

[wammers]

Can you post a link please as I can't see it. I only see 5 threads and the only one from you is for a L322

tnx

Nik

If you read through my "How to" there is a method for checking the viscous fan function. Amongst other information. My HOW TO is for the P38 EAS read it..

 

[NikTheGeek]

If you read through my "How to" there is a method for checking the viscous fan function. Amongst other information. My HOW TO is for the P38 EAS read it..

Yes, sorry, found it:

"CHECKING VISCOUS FAN FOR SEIZURE.

With the engine cold and NOT running. Turn the viscous fan by hand, it maybe slightly stiff but should free off after a couple of turns. If it cannot be freed or is very hard to turn it is seized. If it frees off. Start engine and run up to normal temp. Stop engine, turn fan by hand it should be stiff to turn but not impossible to turn."

I was mixing your Howto up with Saint's

Edit: Mine's fine, turns very easily with the engine off and cold

tnx

Nik

 

[wammers]

Yes, sorry, found it:

"CHECKING VISCOUS FAN FOR SEIZURE.

With the engine cold and NOT running. Turn the viscous fan by hand, it maybe slightly stiff but should free off after a couple of turns. If it cannot be freed or is very hard to turn it is seized. If it frees off. Start engine and run up to normal temp. Stop engine, turn fan by hand it should be stiff to turn but not impossible to turn."

I was mixing your Howto up with Saint's

Edit: Mine's fine, turns very easily with the engine off and cold

tnx

Nik

Temp gauge should be up to middle position after a few minutes of driving. If it's not then i would think your thermostat is missing. Wax stats only have one fail mode, that is closed, if the wax pellet ruptures and the wax is lost. They cannot fail open unless the spring has failed and that is very, very rare indeed. If you are running cool you will be using more fuel as a result.

 

[dogsbody]

I don't follow, do you mean it had been removed because of a fault?

Anyway, it does go up to half way when towing a double horsebox and 2 horses, just not on a normal run...

Nik

Yup, mine used to get up to a 'normal' temperature only on a good climb. Haldon Hill in Devon and up over Shap Fell in Cumbria were the two places that I remember.