# W12 Engine Radiator Cooling Fans Problem



## vitop (Aug 22, 2012)

Just received my 2004 W12 and of course the car has undisclosed issues - even after being inspected by a VW dealer.

The car is running too hot. It runs at about 260 and that just seems too hot. I don't have any diagnostic equipment in terms of being able to read codes, etc.

Wondering if I should just do the easy thing and switch out the thermostat (although not sure how easy that is on a W12 anyway).

Any suggestions on where to start? Maybe a trip to the dealer?

I had read some people had issues with thermostats and I read of one where the water pump was not completely engaging.

Anyway, there is a lot of expertise here and I thought I would try and leverage some of that.


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## PanEuropean (Nov 3, 2001)

If the engine is running hotter than normal (normal being 200°F or 90°C), some of the things you might want to check include:

*1) *Checking the coolant level in the engine, and checking the quality of the coolant (freeze protection level, which correlates with boiling point) - see this post: W12 Coolant Specification

*2)* Checking to ensure that the electric radiator fans operate (they won't operate if the hood is open, so make sure the hood is closed), and that they are not blocked by debris,

*3)* Carrying out a diagnostic scan of the vehicle using a diagnostic scan tool to determine if there are any fault codes present that will identify the cause of the problem,

*4)* Confirming that the dashboard indication (the high temperature reading) is actually correct, perhaps by comparing the temperature of the coolant entering the radiator to the value shown on the gauge, or by looking at MVBs (Measured Value Blocks) that show the coolant temperature as measured by other sensors within the vehicle,

If you don't find the cause of the high temperature reading after carrying out the above investigations, you may want to take a closer look at the following two components:

*5)* The coolant recirculation pump(s) - in other words, the 'water pump', and;

*6)* The map controlled engine thermostat - see this post: F265 Map Controlled Engine Thermostat Replacement (W12 - BAP engine)

It's a very complex engine, which means that you will need to take a methodological approach to troubleshooting, otherwise, you could waste a huge amount of time and money 'shotgunning' the problem.

Michael


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## vitop (Aug 22, 2012)

I guess you can see if the fans are operating with the hood closed? seems like you would not be able to see the fans then.

I don't think I can get past step 2 without a scan tool, so I can check the first two and then may have to go to the dealer.


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## PanEuropean (Nov 3, 2001)

vitop said:


> I guess you can see if the fans are operating with the hood closed?


Hi:

You can't see the fans with the hood closed, but it is pretty easy to hear the 'whirr' sound if the car is parked and the engine is running. Note also that it is common for the fans to continue to run after the engine is shut off and the car is locked up - in that case, it is really easy to hear the fans operating.

Concerning the scan tool - I'm not sure where you live (your profile does not indicate your country), but it is not difficult to find other VW enthusiasts who may own a scan tool. The most common scan tool is called a VAG-COM or VCDS. The scanning procedure is the same for all VW models, so, if you find a fellow owner who drives a Golf but has a scan tool, no problem asking them to connect to your car and retrieve fault codes.

Michael


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## vitop (Aug 22, 2012)

Michael:

I didn't realize - I need to fix that. I am in Houston.


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## PanEuropean (Nov 3, 2001)

Hi Again:

Within the broader Vortex forum, there are regional sub-forums that are not model specific. In these sub-forums, you can find information about get-togethers, who has a diagnostic scan tool, etc.

So, try looking here: Regional Forums (VWvortex) - United States - South and also here Vag-Com Locator searchable map style! - that will probably let you find someone who has a diagnostic scan tool who could run a scan on your car and then give you a copy of it (it is a text file) if you provide a USB stick or similar.

Michael


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## vitop (Aug 22, 2012)

Well, just when I thought I was out of the woods.....

I had misread the temp gauge. My wife was sitting in the car and we had just gotten the car. She thought it was running hot and I looked in over her shoulder and saw the bottom gauge number at 280 and saw the needle in the middle of the next highest number and assumed it was 260 (if I would have looked at the next number up which as 160, I would have realized the gauge was at 200). So the car is rock solid at 200 no matter how long I drive it. I don't have a temp issue, but I do have an issue.

I took the car out today to get a state inspection done on it. Everything was fine. passed inspection. I had an errand to run when I picked up the car and I started it and it gave me the warning that the brakes are worn and that the TPMS is non-functional. Both are issues I knew about. It also gave me a service car warning. I had never seen that before.

I drove it off and about a half hour later noticed that the check engine light was on. It was probably on when I first started it but didn't notice. So I went back to the dealer and asked them to look at it and told them that the car was fine when I brought it in for a simple inspection.

I got them to put it on the computer and read the codes and turn off the light. It found three issues (I had the car checked out previous to purchase and it had no codes). 

18359 P1951 002
Coolant Fan 2-V177
diffulty of movement/blocked
static

18308 P1900 004
Fan 2 control circuit
Open circuit/short circuit to ground
Intermittant

16716 P0332 002
Knock Sensor 2 Circ.
Low Input
Intermittant

Next time I shut off and turned on the car, the check engine light came on again, so turning it off doesn't fix it. I seem to have a real issue.


This is for a 04 W12 

Is there anyone that knows this stuff? I am assuming a new fan is in my future. I do hear a fan running when I turn off the car, but have no way of knowing if it is one or two fans.

Has anyone replaced the fan on a W12? I assume it takes an hour just to get to where you can even see the fan? Is this hard or expensive (or even worse both)?

Thanks!


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## vitop (Aug 22, 2012)

I'm going to make some speculations on this until someone that knows more than I do (pretty large pool of people!) responds on those codes. From looking at other fan issues and some of the responses, I take it that this issue is an intermittent one and so a fuse would not be the culprit. I would think a fuse would be an issue if it were a hard fail.

If this is true, I would say that it is wiring, controller, or fan.

I have no idea where the controller lives (or how to test it for that matter), and I can only speculate that the fan sits in front of the condensor. On a W12, I am also guessing that the wiring will not be easy to trace because of the space contraints.

Is it hard to replace the fan on this car? I hate to just start replacing parts, but it would probably be cheaper for me to replace the fan and clean the contacts than to have the dealer look at it for two hours. Of course, I stand the chance that I put on a new fan and still have to take it to the dealer. 

Boy, I really miss old cars. You could see everything, test everything and I could fix most everything. I feel helpless with this.


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## PanEuropean (Nov 3, 2001)

vitop said:


> Coolant Fan 2-V177
> diffulty of movement/blocked
> static



By itself, this would suggest exactly what it says - something external is blocking the fan from rotating. Or, much less likely but still possible, the internal friction within the fan is preventing it from rotating as freely as it should. Note that this fault is present at the moment, it is not an intermittent fault.

However, together with the second fault code relating to the same fan (fan 2 control circuit open or short to ground), there may be a problem with the fan itself.

The big question mark is "when was the fan 2 open circuit fault recorded"? If someone investigated that fan a long time ago, and (quite reasonably) unplugged it during the investigation, then the fault code would have been generated by the simple (and innocent) act of the technician unplugging the fan or fan control circuit during troubleshooting. Then again - if you know your car was totally free of fault codes a week ago, and no-one has worked on the fan since then, that fault code suggests an intermittent problem (failure) in the fan control system.

I suggest you clear all the fault codes (save the history first), then go through a few driving cycles, and scan the car again. At the same time, you might want to stuff your hand down into the area of the fan (best to do this first thing in the morning, when the car is stone cold, and for sure do it when the ignition is off) and see if the fan rotates freely. You might find that you have a piece of debris - or even something more unusual, like a dead mouse or similar - stuck in the fan, and all you have to do is clear the debris and that will solve the problem.

Michael


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## Paximus (Aug 26, 2011)

> Boy, I really miss old cars. You could see everything, test everything and I could fix most everything. I feel helpless with this.


Hi,

I know what you mean - in the 'old' days you could rotate a distributor to see the effect of the timing, put a hand over the exhaust pipe to feel the back pressure, or run the car with the coolant cap off to watch the fluid circulating... On this car you would have a hard job even finding things, if they exist. But it's the same for all recent cars.

The window into this car is not generally a physical response to touching things, it's usually the VCDS scanner running on your laptop presenting a picture. That is, unless you find that dead mouse in the fan, or watch some creature nesting in an insulation panel! But the fix still usually involves the toolbox! 

Anyway, if you want to participate in the diagnosis of a problem on the Phaeton there's little choice but to get a scanner. The alternative is pretty much to let the dealer run the show.

Good luck,
Chris


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## vitop (Aug 22, 2012)

Chris:

I know that I have a W12, but the car I really want is the V10tdi that I see you have. I wish that car had been available in the US. We never get the diesels. The V10 was available here on the Touareg for several years but has not been available on anything for years. I have not heard that they are considering bring it back either. I did drive a Touareg with it and it has plenty of power and way better mileage than the W12.

Well, I've never wished for a dead animal in my car, but I'll go dead animal hunting later. Hopefully there is something stuck in the fan. That would be a great find. Michael said that I needed to stick my hane in there, so I take that to mean that it is somewhat accessable. Even if I find something and clear it, I assume I will need a tool to actually clear the message.

Thanks for the help guys.


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## vitop (Aug 22, 2012)

It seems the best access to the fans is from underneath. I turned them both and neither really seems harder to turn than the other. If I absolutely had to pick one that was harder to turn, it would be the fan on the right (no idea if this is #2 or not), but if it is, it is very subtle. Although electronically, it may be seeing more resistance than the other. By hand they seem about the same. From what I can see, you might have to take apart most of the plastic above the radiator to get to these. I assume they can be changed out fairly easily once this is done? 

It may be the controller though. Is there some sort of resistance test I can do to the fans or do I just shotgun it and replace them?


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## Paximus (Aug 26, 2011)

Hi,

Best try peripheral checks first, because those fans with controllers list at $900 each. But the whole frame can be imported used.

Your first scan item says that the fan is not rotating as fast as the controller is telling it to, so the controller complains that the blades are mechanically sticky, which is what the designers would interpret as the most likely cause. But clearly it isn't sticky, so that leaves a weak motor (I don't recall seeing a thread reporting that) or a wiring, power or control issue. However, it would have to be happening frequently enough to be interpreted as a 'permanent' fault, not intermittent.

The other scan report says that the control connection is intermittent. This 'kind-of' agrees with the above.

So either the reports are false (that would be an aged left battery) or it's worth cleaning the connectors and seeing if something has pinched a cable.

Removing the fan assembly requires draining the coolant, removing the bumper cover, and setting the radiator forward into its 'service' position.

Chris


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## vitop (Aug 22, 2012)

Paximus said:


> So either the reports are false (that would be an aged left battery) or it's worth cleaning the connectors and seeing if something has pinched a cable.
> 
> Removing the fan assembly requires draining the coolant, removing the bumper cover, and setting the radiator forward into its 'service' position.
> 
> Chris


Please tell me you are kidding. You have to drain the coolant and remove a bumper to change a radiator fan?!

And $900 for a fan!!!!!!!

I didn't even know that there was a "service position" for a radiator. LOL

I can see this is not going to be much fun.

Do I have to take the front of the car apart just to clean the contacts?


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## PanEuropean (Nov 3, 2001)

vitop said:


> You have to drain the coolant and remove a bumper to change a radiator fan?!
> 
> 
> 
> I didn't even know that there was a "service position" for a radiator. LOL


You don't have to drain the coolant, but there is a fair amount of work involved in sliding the front bumper and radiator assembly forward to the "service position", to allow you to get access to all the parts at the front of the engine - for example, the fans, the serpentine belt, the timing chain or belt (depending on what engine you have), the various accessories on the front of the engine such as water pumps and so forth.

It is quite common for contemporary cars with large engines to have the ability - and the requirement - to move the front bumper and radiators out to a "service position" in order to create sufficient clearance between the radiators and the engine to get in there. In the case of the Phaeton, you need to remove the bumper cover, then a few bolts, then install a couple of small rods (special tools) that the whole radiator/bumper assembly slides forward on. You don't have to disconnect the coolant hoses, at least, not on the W12.

I've attached a PDF that explains how the process works on a Phaeton with a W12 engine. There might be variations for the other engines, but the general idea will be the same. Once you have slid the radiator/bumper assembly forward to the service position, you gain about 10 cm (4 inches) of free space between the aft face of the radiator and the forward end of the engine. That is sufficient to do most of the work required up in that area.

Michael


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## Paximus (Aug 26, 2011)

Sorry to mislead, I find that you only need that hose off when removing the entire fan frame from the car. _[edit - double apology, I was looking at the V10 fans, which are larger...]_

It's useful to remember Michael's observation somewhere in the forum that the cost of maintenance is related to the new cost, not the present value. And the Phaeton and its design twin the Bentley Continental are hardly cheap when new; in UK mine was stickered at $120k several years ago, and the equivalent 2012 Bentley FS is about $225k.

Meanwhile, I recommend you get a VCDS scanner, if you are happy to do some diagnostic monitoring, and not worry too much about the possible fault pending further thought. As long as the engine temperature stays rock solid, even if the scan is correct, one fan should keep things rolling along comfortably under normal operation if your climate is moderate.

Chris


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## vitop (Aug 22, 2012)

Thank you Michael.

Does the V8 have the same servicing requirements? I guess the rods are available from VW? And I would guess that you need this clearance to even get to the contacts to try and clean them?

I appreciate the help on this. 

It is an eye opener.


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## PanEuropean (Nov 3, 2001)

Vitop:

As far as I know, you also need to slide the radiator out to the service position on the V8 if you want to do any work on the forward portion of the engine.

You could buy the two rods from a VW dealership (they would order them for you from their 'special tool' program), but be aware that VW special tools are normally quite expensive - in North America, they are made for VW by Snap-On, and Snap-On tools are very high quality and very expensive. Perhaps a less expensive way of getting a tool would be to have a look at the tool at a VW dealer, measure the thread pitch and diameter, then have a machine shop put a similar thread on the end of a stainless steel rod for you. It will be a metric size thread.

You *might *be able to get access to the fans without all this fuss by coming up at them from below. If you have the facilities, remove the lower cover from the engine compartment and see if you can reach up from below to do what you want to do.

Michael


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## johnmo (Jul 28, 2013)

Can anyone tell me which is the right and which is the left fan. They are not identified in the parts diagram I have, both are labeled item 20. Would right be facing the car (driver side) or right side from drivers perspective (passenger side)? 
Also does anyone have instructions on changing the fan. I have found the instructions on moving the radiator to the "service position" and can make the special tools needed. Should I assume that the balance is intuitive?


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## Paximus (Aug 26, 2011)

Hi John,

Automotive convention has it that Left and Right _always _refer to a viewer standing behind the car, ie looking forward over the trunk/boot.

The official procedure for removal of the fan assembly is to drain the coolant, pull off the radiator hoses, remove the front bumper, move the radiator lock carrier forward about 10cm to the service position, then remove the fan assembly. However, this is described as part of the procedure to remove the entire radiator, so maybe there's a short-cut if it's only the fan you want to work on - but that's a guess on my part.

Quite a few folks here have carried out the lock carrier move in connection with timing belts and/or water pump replacement, but there are no special mentions of problems with setting the lock carrier to the service position.

The manual gives no specific instructions for removing the fans, it just lists the torque settings for the bolts (10Nm). 

The fan part numbers have not changed over the years. They are eye-wateringly expensive new, so always check the various engine controller systems first :

-- Left fan 360mm: 3D0 959 453F
-- Right fan 360mm : 3D0 959 453G

Chris


*Typical used fan assembly. "Left fan" is on the right of the photo*








image (c) allegro.pl


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## cbh123 (Aug 25, 2013)

On the v8 cars, (mine) I have removed the fan (left in my case, but right is the same) without any other dismantling. I just removed the tray under the engine, and worked from below and above. With a few screws the fan and module come out easily.

The two fans are identical, except the length of the wires.


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## Orthrus (Aug 9, 2014)

*Removing Phaeton 'Undertray? Advice please.*

Hi, I need to change the near side front engine cooling fan on my 2003 V6 3.2L petrol FWD. Reading your helpful comment I want to give it a try at home lifting the car on ramps. The only part I am not clear on is removing the Undertray. How far back does it go and are there lots of fasteners? I have to be a bit careful because of a relatively recent heart attack! (I almost got another when I put the car into a VW Dealer for a service and got a bill for £1800GBP!) Regards, Mike


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## invisiblewave (Sep 22, 2008)

Assuming it's the same as on the V8, the undertray isn't a big deal. It's in two pieces, but you'll only need to take the front piece completely off, I left the rear one hanging. I think there were 8 torx screws in total, in two sizes, but they all came out easily. Getting it back on is a little more difficult, it's easier with two people so you have someone to hold it up where they join while you get the first screw in. We managed to do it without lifting the car, if you already have it on ramps it should be even easier.


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## Orthrus (Aug 9, 2014)

invisiblewave said:


> Assuming it's the same as on the V8, the undertray isn't a big deal. It's in two pieces, but you'll only need to take the front piece completely off, I left the rear one hanging. I think there were 8 torx screws in total, in two sizes, but they all came out easily. Getting it back on is a little more difficult, it's easier with two people so you have someone to hold it up where they join while you get the first screw in. We managed to do it without lifting the car, if you already have it on ramps it should be even easier.


Amazingly quick replies from 'cbh123' and 'Invisiblewave' - thanks very much guys - this is a great site. Kind regards, Mike


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## Paximus (Aug 26, 2011)

Hi Mike,

Welcome to the forum. Owners of Phaetons are usually as remarkable as the cars themselves!

Glad you are through the heart problem. Modern techniques mean you are probably fitter than ever.

Chris


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## MIKOBrk (Jan 31, 2015)

Hello Guys!
Vag com shows short to ground coolant fans borh
They sometimes work, even when the hood is open i can see that they start moving and after 10 or 30 sec they stop.
Now, when I turn off the car with 90degree temperature, i dont hear them working
Codes are P1662 and P1660
I have also an error:
Ambient temp sensor 2 (G249) short to ground
P1921 004 no signal/communication

I cant find where is G249

Any ideas whats wrong?
The thing is that I dont know if these fans are broken or not.

I checked what faults others have, and in my case its only written what I mentioned
No control module fan fault or warning about problems in movements.:banghead:
Just short to ground.
When trying output test, sometimes vagcom shows its performing whenever fans dont move, sometimes it only says that requirements for output test not reached.


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## robbie-rocket-pants (Mar 25, 2012)

My Left Fan 2 (V177) failed due to the bearing becoming stiff on my 3.0TDI. I was gobsmacked that they cost around £650 each to buy new, so I bought a used one from ebay (3D0959453F). The VW procedure says that you need to remove the bumper and pull the front end into the service position, but I decided to do what Bruce did and remove the fan from below. 

It was fiddly but manageable:
I put the car on ramps.
Removed the front undertray
Unclipped the fan electrical connector (important as the fan could power up unexpectedly)
Unclipped the lower rubber intercooler pipes and moved out of the way
Unscrewed the lower coolant pipes just to move them an inch out of the way.
Removed the cross bar that holds the intercooler Y piece
Unscrewed the fan (3 screws) and controller (3 screws) and wiggled it out of the housing.

The hardest part in putting it back together was compressing the round intercooler clips to get the pipes back on.

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## Paximus (Aug 26, 2011)

Thanks Rob, interesting info.

As the cars age the bumper becomes just that bit more vulnerable, so the less interference the better I think. Mine has sprung the two lower inserts and detached the headlight washer door after the last removal.

Chris


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## robbie-rocket-pants (Mar 25, 2012)

I've dismantled the old fan to find that the failure is indeed due to a £2 bearing.

I unscrewed the plastic fan.
To remove the motor casing I removed the circlip then drifted the centre shaft out and knocked the bearings out with a suitable size socket.

So, if this happens to you, don't spend £650 on a new fan, spend £4 on some new bearings !

The bearing size is I.D.10mm O.D.26mm depth 8mm. I replaced with Timken 2ZC3 bearings.

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## invisiblewave (Sep 22, 2008)

Nice! It's not just the money, you'll get that little frisson of satisfaction every time you hear the fans come on!


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