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What has happened here ? (I am not happy...)


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Right, en route to the Alps, the 300 Tdi started to makes weird mechanical tapping noises.

Nothing was to be seen but it sounded awful..

Eventually, the charge light etc. came up and the "fan belt" was in pieces and the viscous driving pulley waay off.

Took stuff apart and found this..

image.png.b87a10fbe7e949cf2ccfe9e3b04fc2cd.png

Tried a side of the road repair but it eventually gave up, some 200 miles from home.

Recovery to home is planed for tomorrow.

But what caused this ?

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Water pump fan mounting failure probably due to a poor casting from new that had hairline cracks develop on cooling of the metal or in the boring and thread tapping process. Your best course of action is to fit a new water pump, probably the cheapest and only option. Bad luck that!

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I'd suggest that the bolts in the two that aren't cracked worked loose, leaving the pulley to move against the belt tension every rotation. The noise will have been the pulley flapping about almost invisibly. Eventually the two that stayed tight failed due to metal fatigue.

Hope recovery isn't too stressful. 

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4 hours ago, Farmerfred said:

Water pump fan mounting failure probably due to a poor casting from new that had hairline cracks develop on cooling of the metal or in the boring and thread tapping process. Your best course of action is to fit a new water pump, probably the cheapest and only option. Bad luck that!

That's not the water pump. It's the viscous fan mounted on idler. 

Only available with replacement front cover 

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" Only available with replacement front cover  "

Yes....... <deep deep sigh>

Tomorrow off for the 400+ miles to recover the thing.

The garage where it sits now does not allow me to work on the vehicle there as I have the parts so that would be much easier....

Oh well....

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Hi Arjan, 

I have tried the same thing, it doesn't exactlly give a Happy missis as it was on the way to a eventing competition with to horses in the trailer...

It is possible to remove the flange. I made a puller from an old viscosefannut which I cut of and put a bolt in to use as extractor. Worked a treat, but the front cover needs to come off for the New flange to be pushed home. 

/mads

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There is a replacement bearing , a John Deere water pump shaft (see my build thread), but that probably does not help you much because you need the flange as well. I do agree that it probably worked loose and did this. As a bodge I always carry a shorter belt with me, so If any unnecessary pulley fails you can have a go at changing the routing temporarily (proper Jungle tech, but could save the day). Hope you're back on the road soon.

Daan 

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Usually I'd say the same but I've heard credible suggestions that electric fans create too sudden a cooling effect on TDi's and lead to the head gasket failing, as the block is iron but the head's ali they expand & contract at different speeds and a sudden cooling blast from a leccy fan creates too much movement between the two.

However, I'd go for Daan's suggestion - TDi's are overcooled anyway so just fit a smaller belt and run home fanless.

Also worth checking the viscous for damage as an out-of-balance fan might aggravate a fault like this.

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4 hours ago, FridgeFreezer said:

Usually I'd say the same but I've heard credible suggestions that electric fans create too sudden a cooling effect on TDi's and lead to the head gasket failing...

That is people setting up the fan control wrong.  They use the radiator outlet temperature as the control.  You want to use the inlet line as it is the engine temperature you are controlling, not the radiator.  With the control in the right place, there are no temperature swings beyond what is normally seen with a thermostat.

You certainly need a good fan in certain situations.  Off road is most situation, it is needed.  Any long climbs that are not at motorway speed.  Basically any situation that you use it for what it was intended....

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Well.... it is home again. And again on a trailer.... The Mrs. is not impressed...

image.png.3afe476a93ced102bb3ca93a292accee.png

Due to my limited tech skills, I did not see a way to fit a smaller fan belt and tension it on the 300 Tdi. I'd love to see this done.

This weekend, he goes in the workshop but I'm not sure I'll have time before I leave for Kalingingrad and Holland...

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On 3/25/2019 at 7:01 PM, Red90 said:

That is people setting up the fan control wrong.  They use the radiator outlet temperature as the control.  You want to use the inlet line as it is the engine temperature you are controlling, not the radiator.  With the control in the right place, there are no temperature swings beyond what is normally seen with a thermostat.

You certainly need a good fan in certain situations.  Off road is most situation, it is needed.  Any long climbs that are not at motorway speed.  Basically any situation that you use it for what it was intended....

This is a different can of worms. The fan only needs to run if the radiator is not doing its job. That is how the viscous unit works, so the temp control should be on the return or low level on the radiator. a better system would be a two stage temp control with either two fans or high and low speeds. Let the fight begin.

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The fan thing was more about the on/off thermal shock rather than the gradual increase/decrease  with temperature you get with the viscous, changing the sensing point etc. won't change that - you'd need a variable speed fan (which LR did on the Freelander) or possibly electric water pump (ugh) to achieve that.

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3 hours ago, ballcock said:

This is a different can of worms. The fan only needs to run if the radiator is not doing its job. That is how the viscous unit works, so the temp control should be on the return or low level on the radiator. a better system would be a two stage temp control with either two fans or high and low speeds. Let the fight begin.

I'm sorry but you are wrong.  I've been designing complex control systems for decades and building and designing testing facilities.  Controlling on the engine temperature is the correct way and prevents swings in engine temperature leading to shock. This is how every car with an electric fan built in the world works.

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33 minutes ago, FridgeFreezer said:

The fan thing was more about the on/off thermal shock rather than the gradual increase/decrease  with temperature you get with the viscous, changing the sensing point etc. won't change that - you'd need a variable speed fan (which LR did on the Freelander) or possibly electric water pump (ugh) to achieve that.

The viscous unit is an on/off control device.  It is not gradual.  It is no different to an electric fan cycling on and off.  I'm not sure that you understand how a viscous unit works.

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4 minutes ago, Red90 said:

I'm sorry but you are wrong.  I've been designing complex control systems for decades and building and designing testing facilities.  Controlling on the engine temperature is the correct way and prevents swings in engine temperature leading to shock. This is how every car with an electric fan built in the world works.

As I say a can of worms, I have my opinion and you are entitled to yours.

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7 hours ago, Red90 said:

I'm sorry but you are wrong.  I've been designing complex control systems for decades and building and designing testing facilities.  Controlling on the engine temperature is the correct way and prevents swings in engine temperature leading to shock. This is how every car with an electric fan built in the world works.

Actually, my audi uses a switch in the bottom(outlet) of the radiator, it also has iron block and aluminium head.

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