Viscous fan behaving oddly

[Rick1956]

Hi All.
Some advice please.
Set off for work this morning and noticed that the viscous fan didnt fade away after 30 secs or 100 metres as usual. Drove the 10 miles to work with the fan roaring away till I got there.
I turned her off, popped the bonnet and noticed the following;
The fan turned by hand with a little resistance, as normal I think.
The Rad top hose was hard and hot.
The bottom hose was cold and softer.
The coolant level was spot on.
The temp guage read normal running temp.
It was a frosty morning.
The viscous fan is only about 6 months old.

On returning home from a cold start a couple of hours later everything ran as normal and as it should.
Any ideas would be appreciated, could it be the thermostat?
Thanks in advance

 

[jims-terrano]

My fans been doing that too but havent checked the hoses, will try and take note.

Jim T

 

[bigjim]

Was it frosty

 

[Deleted Member]

Could there maybe be an air pocket in the cooling system,and when you drove it later,maybe it had worked it's way out,are you loosing any water??
is your radiator ok,no white residue on it?
I ain't no mechanic...lol just trying to help.. :lol: :lol:

 

[jims-terrano]

Was it frosty

Didn't even know you had met my wife -rotfl-

Jim T

 

[Rick1956]

As stated coolant levels are fine, no leaks and yes it was frosty but surely that wouldnt affect things???
Oh yes and the radiator is about 6 months old as well!!

 

[Jocky]

I don't think the fan would have been fully engaged, if it was the temp wouldn't have reached normal running temp. FAN running rad getting cooled.

:smile:

 

[Terranosaurus]

Is your coolant (antifreeze) at the right concentration? Theres no chance anything as frozen, viscous frozen say and bits of the rad?

 

[Rick1956]

Nope, new rad had new mix added to the correct s.g. It was frosty that morning but not heavy.

 

[rossco]

Did you have the heater on and was it running hot ?
When you replaced the coolant did you bleed it properly?
Did you have the heater fully on when you replaced the coolant?

My guess is either a air lock in the radiator or blockage in the radiator

I have to be careful here. :wink:
A hard hot hose at the top ,looks like a pressure build up and nothing flowing through into the radiator. Either top tank or core blocked.

If an air lock it eventually goes and your water level will drop because of the air gone, also the overflow tank might shows signs of a blow back e.g water sprayed out.
This would make it go back to normal.
Recheck your coolant level and overflow tank.


If the radiator, you will have to take the bottom hose off and see how much fluid comes out from the radiator, this should give you an idea if it is blocked,
try and catch your radiator fluid that comes out into a tray so you can reuse it, then give the radiator a good flush to see if the core is clear.

 

[jace]

thermostat could lock water in top rad,itd be cheapest solution aswell

 

[rossco]

Basically the water flows from the radiator bottom hose through the pump, around the engine, then thermostat into the top hose to the radiator.

If you hose is tight and hot the water has gone through the thermostat but not into the top tank of the radiator or through the radiator.

If your bottom hose was tight and hot then the thermostat could be closed and stopping the water going through.

 

[bigjim]

Is your coolant (antifreeze) at the right concentration? Theres no chance anything as frozen, viscous frozen say and bits of the rad?

Hence my quetion????? -banghead-

 

[gazz]

same problem

I am wonderign what it is that controls the fan ?
I mean must be some sensor that tells the fan
Please help
The problem is that when it is warm outside ( mean not under 0 ) it works perfect but if it is freasing outside it is allvays on and the engine never warms to normal.

 

[jims-terrano]

I think it's just some kind of oil.

I have heard of people removing the old fan and fitting an electric one instead. Supposed to be better temp control and also saves on fuel but that is as much as I know.


Jim T

 

[johnston_evo3]

just outta interest and on a sideline to this how long does it take for your mavs to heat up at tick over..

had mine running today for bout an hour but no heat got into her...

 

[rossco]

I think you need to check the thermostat, if thats open all the time then you want get a warm up as quick because the water is going through the radiator and cooling down.


Take out your thermostat and check that first.

1. Check for valve seating condition at ordinary temperature. It should seat tightly.

2. Check valve opening temperature and maximum valve lift

Valve opening temperature 82c or 180 f

Maximum valve lift = 8mm /95c or 0.31 in / 203 f

3. Then check if valve closes at 5c (9f) below valve opening temperature. 82c - 5c = 77c or 180 f - 9f = 171 f


.

 

[gazz]

I don´t understand, what is is that controls the viscus fan is it the thermostat or is it oil inside the viscus fan ?
My problem is that everything works perfect when the wehater is ower freesing temp but if the wheater goes under - the viscus fan is allvays on ?!

 

[jace]

oil in fan afected by engine temp no fancy electrinics or anything else just oil/liquid in the ally boss fan bolts to

 

[gazz]

can someone tell me the price for the Viscous Fan drive for 2,7 TDI engine in UK ?