viscous fan clarification

[asmith88]

recently my g/friend has been driving the e30, i notice when the car starts and drives off, standing from outside it sounds like a helicopter taking off, and this is when stone cold,

the viscous was replaced a year ago but has always made the same noise since it was replaced, (a very noticeable difference over the old unit)

car dosent overheat,

just for clarification, the viscous clutch shouldnt engage until the engine is warm, and shouldnt make noise like this until warm,

is my new fan faulty?

cheers

[capri_rob]

Have you done the "newspaper" test when its cold ?

Start the engine, and then gently try to stop the fan blades turning with a loosely rolled up newspaper. When the engine is cold you should be able to easily stop the fan. If it shreds the newspaper when run from cold your viscous is fooked.

If it was replaced with a new part do you still have the invoice ? - Shouldnt have failed in less than a year.

[daimlerman]

Two or three years back,both E30's needed a new viscous at the same time.
I went to my local GSF and was asked if I wanted a cheap one or a good one...

In the name of research I bought one of each.
The cheap one packed up 12 months later,the good one is still in use....

[asmith88]

it was sachs and i paid about 70 quid on trade i think, so thats bound to be the good one,

[rix313]

Mine sounds like a V8 discovery lol! Thought it was normal always quietens down after driving for a while though. Will batter a news paper then see if I need to change mine too.

[lamby]

mines a sachs one,is new and does seem to engage on start up,cuts out fairly quick though then re engages when hot etc so.............normal?plus its the second one i,ve had as i returned first one as faulty as it engaged on start up !didn,t like skin on my knuckles anyway

[GuyM]

Have you done the "newspaper" test when its cold ?

Start the engine, and then gently try to stop the fan blades turning with a loosely rolled up newspaper. When the engine is cold you should be able to easily stop the fan. If it shreds the newspaper when run from cold your viscous is fooked.

If it was replaced with a new part do you still have the invoice ? - Shouldnt have failed in less than a year.

forgive my ignorance but i'm slightly confused on this......

i thought if you could stop the fan with a rolled up newspaper the the viscous until was knackered?
must admit hadn't thought about whether the engine should be hot or cold - should i do the test under both conditions

....could someone confirm the exact test and conditions i should do it under to check all is ok.

(just bought new hoses to replace all the existing ones and thought i'd check the fan at the same time)

[mattycoops43]

if the engine is cold, the fan is not really driven, hence you can stop it, and as it heats up, the coupling engages, driving the fan. If it runs all the time due to being faulty, you will have an engine that never reaches temp, it noisy and uses a ton of fuel.

For the record, V8 discos also have one and they sound like that when they are knackered too.

[asmith88]

engine reaches temperature fine, but the same as above, it starts off like that then quietens down, only on start up do i really here it,

[Brianmoooore]

Sounds like your viscous works OK, but for some reason is a bit stiff until warmed a little by the radiator.
A locked on coupling won't affect the running temperature of your engine at all, but will use a surprising amount of extra fuel. As long as it frees up within a couple of minutes from cold, I wouldn't worry about it.

[mattycoops43]

Well, I am much better on V8's than bmw engines, but on a rover, a locked up fan decreases engine temp dramatically, even though the thermostat stays shut all the time, due to temp. The fan is enough blowing over the block to keep it very cool. But then they do have a big fan.

[jimbob29]

when my engine cold no noise from fan reaches temp ok never goes over half but when sat in traffic for ages it will sound like those old 4x4 troopers when moving of then temp will drop then the trooper sound will stop is this the sign of a failing fan??

[GuyM]

if the engine is cold, the fan is not really driven, hence you can stop it, and as it heats up, the coupling engages, driving the fan. If it runs all the time due to being faulty, you will have an engine that never reaches temp, it noisy and uses a ton of fuel.

For the record, V8 discos also have one and they sound like that when they are knackered too.

ah, so i'm guessing if i put the rolled up newspaper in when its well up to engine temp, it should shred the paper....if i can still stop it when its hot, i assume the coupling is knackered....

[mattycoops43]

Yep, although it's not a completely mechanical lock up. so you could still stop it, but it would be very hard.

[Brianmoooore]

when my engine cold no noise from fan reaches temp ok never goes over half but when sat in traffic for ages it will sound like those old 4x4 troopers when moving of then temp will drop then the trooper sound will stop is this the sign of a failing fan??

No, this is a sign of a fan in full working order doing exactly as it should!

[asmith88]

cheers for clearing everything up

[Andyboy]

I've never thought much of the newspaper test. The viscous either works, or it doesn't. If the car overheats in traffic or sub 30 mph driving on a warm day, it's shagged. If it doesn't, it works.
A good viscous will engage from cold and disengage after a few seconds - it's the cold oil dragging.

Viscous fans are cheap enough these days so it's worth replacing it if yours looks a bit oily. The reason they fail is because the oil leaks out past the seal - couplings that are grimy with caked on dirt are about to fail if they haven't already. Andrew Page factors do a decent Borg Warner made one for about £35.