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Old 6th February 2020, 14:10   #11
Roverguest
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Quote:
Originally Posted by SD1too View Post
David, your profile says that you have a 1.8T engine but you are definitely asking about a KV6? Please confirm. By the way, it's not a relay it's a resistor.

As Trikey says that usually means low speed failure, or in the case of a 3 speed fan low and medium speed failure, which you should repair immediately. This will involve removing the front bumper.
  1. Start the engine from cold.
  2. Press the windscreen demist button.
  3. Get out of the car and walk to the radiator grille.
  4. Is the radiator fan running continuously or is it pulsing on and off periodically?

Please report back asap.

Simon
Hi Simon, thanks for the info!

Yes I have my 1.8t but a friend who is new to discover these great cars got himself a lovely Wedgewood 2.5 auto with Neptune leather.

Just ironing out some foibles and bits, as I have never really touched the V6s before.

Having done a little research and what Trikey says, I have advised he needs to go for the uprated fan which is available on ebay from 75ztspecialist?

Thanks for the advice
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Old 6th February 2020, 18:04   #12
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David; I would like you to perform the test I listed because your evidence doesn't point immediately to a straightforward diagnosis. Your friend should not buy anything yet as there is a risk that he could waste his time and money. The cheapest and most reliable solution is to repair the original fan system. Ebay fans will not be "uprated". If a replacement is proven to be necessary, and we don't know that yet, I'd strongly recommend that you take the advice of club members Arctic and Jules.

Simon
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Old 7th February 2020, 10:43   #13
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Quote:
Originally Posted by SD1too View Post
David, your profile says that you have a 1.8T engine but you are definitely asking about a KV6? Please confirm. By the way, it's not a relay it's a resistor.

As Trikey says that usually means low speed failure, or in the case of a 3 speed fan low and medium speed failure, which you should repair immediately. This will involve removing the front bumper.
  1. Start the engine from cold.
  2. Press the windscreen demist button.
  3. Get out of the car and walk to the radiator grille.
  4. Is the radiator fan running continuously or is it pulsing on and off periodically?

Please report back asap.

Simon
Hi Simon,

My friend did this today and says when he pressed Demist the fan did not operate. The interior dual zone controls were set to 27 if that would alter anything?
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Old 7th February 2020, 12:20   #14
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No the fan should kick in straight away regardless the tempreture so i do suspect a fan failure
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Old 7th February 2020, 12:25   #15
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My friend did this today and says when he pressed Demist the fan did not operate.
Thanks David. That clears up the earlier post which didn't make sense:
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Originally Posted by Roverguest View Post
Fan works with AC
So your friend's V6 has two problems: an air lock and loss of the low speed radiator fan. Is he also based in Bromley? Will he be repairing it himself? Will you be doing it for him? If he wants to pay someone, I strongly recommend not taking it to a local garage. Instead, contact club trader cb750Chris who is based in Portsmouth and doesn't mind travelling.

Tips:
  • Chris will know the specialist bleeding procedure for the V6 involving raising the expansion tank.
  • If the radiator fan turns out to be a 3 speed unit, fitting new motor brushes is a cheap and durable repair provided that you have DIY skills. If you decide to replace it with a 2 speed unit, ensure that it has a high power 'gold' resistor fitted.

I've done both these jobs on my V6 so can provide further detail if it would help.

Simon
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Last edited by SD1too; 7th February 2020 at 12:29.. Reason: Correcting earlier mistake concerning faulty thermostat
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Old 7th February 2020, 12:28   #16
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Quote:
Originally Posted by SD1too View Post
Thanks David. That clears up the earlier post which didn't make sense:


So your friend's V6 has two problems: a faulty thermostat and loss of the low speed radiator fan. Is he also based in Bromley? Will he be repairing it himself? Will you be doing it for him? If he wants to pay someone, I strongly recommend not taking it to a local garage. Instead, contact club trader cb750Chris who is based in Portsmouth and doesn't mind travelling.

Tips:
  • After replacing the thermostat, ensure that the two plastic clips on the straight pipe are pushed fully outwards to keep the assembly rigid and leak-free.
  • If the radiator fan turns out to be a 3 speed unit, fitting new motor brushes is a cheap and durable repair provided that you have DIY skills. If you decide to replace it with a 2 speed unit, ensure that it has a high power 'gold' resistor fitted.

I've done both these jobs on my V6 so can provide further detail if it would help.

Simon
What I don’t understand is, people say fan “failure” although the fan clearly does work, as per when AC is requested or when the temperature hits 112 degrees.


If the fan motor brushes had failed and or worn out, surely that would render the fan motor inoperable?

Thanks for the advice
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Old 7th February 2020, 12:35   #17
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What I don’t understand is, people say fan “failure” although the fan clearly does work, as per when AC is requested or when the temperature hits 112 degrees.
Only your highest speed is working which triggers at 112 degrees. That is much too hot. You need the lower speed which triggers at 100 degrees.

The windscreen demist button test proves that the fan does not work when air conditioning is requested. Don't rely on auto mode for a diagnosis.
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Originally Posted by Roverguest View Post
If the fan motor brushes had failed and or worn out, surely that would render the fan motor inoperable?
No. On the 3 speed system there are 4 brushes. Usually the low and medium speed common earth brush fails first so you're left only with "high" speed which triggers at 112 degrees. But the motor won't be running at high speed because of the worn out brush. It will be running at medium speed. Your cooling system is running at low efficiency and liable to overheat.

Simon
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Last edited by SD1too; 7th February 2020 at 12:47..
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Old 7th February 2020, 13:49   #18
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That’s all great info and really helpful.


If he wants to refurb the existing fan motor, which is the best replacement brushes, and where can they he obtained?

I’ll probably end up doing the motor brushes for him.

If CB750 can contact me and maybe if he is willing to come to Bromley he could help out?

Thanks
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Old 7th February 2020, 16:16   #19
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... which is the best replacement brushes, and where can they he obtained? I’ll probably end up doing the motor brushes for him.
Buy them from Croydon based Engineering Carbon Products Ltd. This company used my sample to select the best material and to design and manufacture an exact replacement. They are high quality and durable. Don't be tempted by cheap alternatives on eBay. Others have tried them and they last five minutes.

You might like to have a look at Arctic's many helpful photographs of what to expect when you remove the motor end cap. Do the job sooner rather than later as every time the motor runs you're risking the worn brush popping out of its holder and damaging the commutator beyond repair.

Here's the recommended MGR procedure for bleeding the cooling system of air.

Simon
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Old 7th February 2020, 16:52   #20
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Superb, thank you!

That company is only a few miles away so will probably go and get the bits asap.

Any words of warning for doing the brushes?

Do you think having the car run up to 112 a few times now will have caused any issues on a KV6? As you know I’m a 4 pot guy.
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