Viscous Coupling

[Guest]

Help please. The engine was started for the first time in over 12 months last weekend - no problems (thanks to previous help on starting after a lay up). However, there is now a disturbing grating sound coming from the engine bay. Dipping the clutch doesn't affect the noise and you can't hear it with the bonnet closed. (The noise wasn't present when the car was last started.)

The cooling fan can be spun by hand for 5 - 6 revolutions - is this 'viscous coupling failure'?
If it is, can this be the source of the noise.

On a more positive note, it failed it's MOT on Monday on very minor points and goes for a re-test on Tuesday - subject to solving the 'noise'. (the MOT tester thought that the noise was "pulley related"!)

I know it's asking a lot for a diagnosis via the forum but before I splash out on buying the unit any opinions or thoughts?

Steve

[redstag]

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The fan should only spin bya few blades.

Your couplinghas definitely failed if you can spin it 6 revolutions. It could well be the cause of your noise.

If you can feel any play at all in the bearing then you should replace the unit promptly bfore the bearing lets go completely.

Pete

[stustag]

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Hi Steveg

Does the viscous feel notchy or rough when you turn it by hand? I have checked mine just and it truns freely and very smoothly.

Reading other threads on viscous DJT say's it should not turn at all by hand so maay be our are both shot! However I have no ove rheating problems or noises?

Maybe the other guys will help latter today.

Stuart

[steveg]

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Thanks for the response:
Does the viscous feel notchy or rough when you turn it by hand? No, it spins freely but it can be rocked fore and aft by 1/4" or so.

Unfortunately, the car is still at the body/workshop and I'm worried that if they take it to be re-tested (even though I've told them to wait) they will cause major damage.

Steve

[stustag]

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Hi Steveg

Any play in the bearing is bad very bad order a new coupling but rememeber you will need to remove the rad to get to it so buy some antifreeze and flush the system at the same time!

[seaside bill]

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steveg wrote:

but it can be rocked fore and aft by 1/4" or so.

Steve

In that case it'swell and truly knackered. :?Once the radiator is out, it's an easy job - the only bit that can be tricky is undoing the crankshaft pully bolt if you've got an auto. Also, if yours is Mk1 have a look at DJT's revent post concerning the size of the retaining washer.

[Stagdad]

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Iunderstand if you give the fan a good push round it should stop within 3-5 blades as already mentioned,not totally solid as there would be no point in having a viscous coupling.

Steve

[steveg]

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Thanks everyone - shouldn't you allbe out enjoying the sun!

A new coupling will be ordered on Monday - I'll let you know if it sorts out the problem.

Steve

[stustag]

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Been out all day with the top down and lovin' it

Stuart

[seaside bill]

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stustag wrote:

Been out all day with the top down and lovin' it

Me to, I've been giving both of my toys an outing in the late summer sunshine....

[DJT]

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steveg wrote:

No, it spins freely but it can be rocked fore and aft by 1/4" or so.

Hi, Steve,

From your description it definitely sounds as if the coupling is like Monty Python's parrot .

There should be NO play at all in the coupling, and it should stop within a couple of blade widths if spun by hand. Any play such as you describe and it is likely that youcould be buying a new radiator as well as a new coupling.

As already stated, the radiator has to come out for this job. Here's a tip I picked up recently for draining the radiator without getting it all up your sleeve: Use a length of hose pipe (Fuel hose will do) and feed it into the radiator via the filling plug. Push it right down the bottom against the side tankand syphon the coolant into a bucket. This way, when you remove the lower hose it will come off dry and you won't be lying in spilt coolant as you remove it.

If you have a manual, you should be able to undo the pulley securing bolt by putting the car in gear and applying the handbrake hard. A breaker bar and socket will be needed. An air-driven impact socket is even better. If you have an automatic you will need alarge Stillsons on the shaft behind thepulley. Wedge the Stillsons against a piece of wood on the ground or chassis rail. When replacing the securing bolt, use some threadlock and tighten to 120 ft/lb. Failure to do this can result in the bolt coming undone and ruining the radiator.

Take care when securing the bottom hose. It is possible for the alternator pulley to rub against the hose-clip, causing an annoying rattle and eventually leading to failure of the clip and subsequent loss of coolant.

Finally; filling the cooling system is a bit of an art. I raise the n/side front corner as high as possible to eliminate any airlocks. It also pays to have the heater in the HOT position.

Dave

[DJT]

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stustag wrote:

Been out all day with the top down and lovin' it

Stuart

B****r! I am stuck 90' North East of the Shetlands. We had 70mph winds yesterday and up to 11m seas! :shock:

At least the weather was good for the 3 weeks I had at home. Hopefullythere will be some left for the end of the month and my next 2 week's leave

Dave

[steveg]

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The coupling was changed and the noise problem disappeared, so, that's one now for the memory/experience bank!

Thanks to all for your help.

Steve

[DJT]

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Thanks for the update, Steve. Always good to hear a success story.

Dave