Can't find this part

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
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Shoppinit
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Re: Can't find this part

Post by Shoppinit » Sat Feb 23, 2019 10:38 pm

Best to eliminate all the other causes before diving into a thermostat change.

Log the coolant temp with the Vagcom to see what’s going on with the thermostat. Make sure it’s not a dodgy coolant temp sensor.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Classik
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Re: Can't find this part

Post by Classik » Wed Mar 06, 2019 12:26 am

I'm sorry it took a while to reply, but days are only 24 hours on this end..
Very quickly : with the vag-com I get a steady 98°C coolant once the engine is hot, and with the Aircon on (=main cooling fan spinning), it's more like 93°C. Maybe unrelated, but as the problem arised following a recent coolant temp sensor change (Valeo from memory), I thought appropriate to install a genuine one before making wrong assumptions. I'll report when it's done. Yeah, I know I should have read the faq before... :) More later!
Last edited by Classik on Wed Mar 06, 2019 11:07 am, edited 1 time in total.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

Classik
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Re: Can't find this part

Post by Classik » Wed Mar 06, 2019 10:23 am

Oh and I can't access the climatronic module from the Vag-com. It's been the case since I had the car but I didn't bother. But taking into account the interaction of my engine cooling issue with the aircon, it would be good to see what's going on there.. I suppose I should start by checking the connectors behing the Aircon module...
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Shoppinit
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Re: Can't find this part

Post by Shoppinit » Wed Mar 06, 2019 10:29 am

Same with mine. I've been able to access it maybe once or twice since I've owned the car. Most of the time it's just invisible to the Vagcom.

I think it's a Vagcom issue, nothing to do with the climatronic. I was able to access it no problem with someone else's much older Vagcom cable that I tried at a meet a few years ago. I am pretty sure that messing with the comms settings would sort it, if you can be bothered. Ironically his cable wouldn't talk to his RS2 but mine would. Go figure.

Anyway, before you do yourself an injury trying to extract the climatronic, have a play with the settings.

Now I come to think about it, I might have contacted Rosstech support about it. As usual they were worse than useless though.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Classik
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Re: Can't find this part

Post by Classik » Wed Mar 06, 2019 1:26 pm

Good to know! Surprisingly I could access the climatronic on my former 2000 S6 C5..
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

Classik
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Re: Can't find this part

Post by Classik » Sat Mar 30, 2019 9:51 pm

Some news to share, which could hopefully lead to a solution :
1/ I now have the latest HEX-NET VCDS interface from Ross-Tech and I'm pleased ro report I've now access to the Climatronic controller. No defaults whatsoever, so that's one thing covered.

Back on the original reason for this thread, namely the secondary fan ecu issue and excessive coolant temperature:
2/ The output test is now quite clear : now there's no way I can make the secondary cooling fan spin (despite some 'noises' during the test, meaning something is definitely activated by the output test). The primary fan can be started fine by the same procedure. So knowing I've cleaned all contacts located close the power steering fluid container, cleaned and checked all fuses (no relays involved as per Shoppinit so I left that out), checked the inner electronic components of the ecu, I'd say the secondary fan itself is the culprit. Would you agree with the conclusion? And if yes, could a faulty fan lead to a fault on the Ecu?
3/ The oem coolant sensor is now a trusted oem part, but I still get readings between 93 and 100 deg Celsius when driving 'calmly' (provided this is feasible with an rs6..). Activating the Aircon helps a bit as it triggers the big fan so the coolant stays around 95°C, which is still above the target (90° if I'm coreect). Without Aircon, the coolant is more in the 98-100° range. We're not quite there yet, so does the above definitely points to a faulty thermostat? A tired water pump?
4/ In the process I've also cleaned the 200 amp fuses (those in the water compartment) which clearly deserved some maintenance. Unfortunately it didn't change anything for the above, so they were still doing their job, but hey, being clean can't hurt, right?

As always all comments or suggestions are very welcome and appreciated!

Best
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Shoppinit
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Re: Can't find this part

Post by Shoppinit » Sat Mar 30, 2019 11:16 pm

Definitely sounds like the fan is knackered.

Weird that the big fan isn’t kicking in without the AC being activated. Doesn’t seem logical but maybe that’s how it’s programmed.

Temps sound high. Suspect thermostat. Irritating that they are such a pain to change. On the M3 it’s a 10 min job. VW do like to make money on their cam belt changes though.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Classik
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Posts: 701
Joined: Sun Jul 15, 2018 1:13 pm
Location: Paris

Re: Can't find this part

Post by Classik » Sun Mar 31, 2019 9:04 pm

Thanks for the educated response and recommendations Shoppinit. This thermostat stuff is no good news indeed but eh, what needs to be done will be done..
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

Classik
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Posts: 701
Joined: Sun Jul 15, 2018 1:13 pm
Location: Paris

Re: Can't find this part

Post by Classik » Mon Apr 08, 2019 5:29 pm

Got an appointement with my mechanic next week. We'll change the small fan and the thermostat of course, and while we're at it we'll do the cambelt (kit 077198119A) + belt tensionner (077109479D) + waterpump (077121004PX).
Hopefully this should put an end to both issues (faulty secondary fan system and high temperature coolant). Unfortunately I'm still having issues with those MAFs (see viewtopic.php?f=2&t=131749) :?
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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