# W12 Auxiliary (Supplemental) Radiator



## 5049 (Aug 7, 2005)

*bad radiator*

Has anyone had a radiator replaced. One of my secondary radiators is bad. 
P.S. over a grand to replace it.....


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## PhaetonChix (Dec 16, 2004)

*Re: bad radiator (5049)*

I'm curious why your radiator was not covered under warranty. Was your vehicle in an accident? (I noticed you had a bad windshield too.)

A handy number for all US Phaeton owners is Phaeton Customer Care at 1-877-Phaeton. (1-877-742-3866). Please note this is an 877 and not an 866 or 800 number. Dial one of those area codes and you'll think you dialed a 900 number...

PC


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## 5049 (Aug 7, 2005)

*Re: bad radiator (PhaetonChix)*

My car has 61k. When I called Phaeton care, I was told the radiator was covered by the bumper to bumper. Not the drivetrain.


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## Paldi (Sep 4, 2004)

*Re: bad radiator (5049)*

Welcome to the Forum. It's probably the highest milage Phaeton W12 here. How do you like the car? http://****************.com/smile/emthup.gif


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## 5049 (Aug 7, 2005)

*Re: bad radiator (Paldi)*

I do have an extended warranty. The Phaeton has three radiators and the warranty company will only cover the main radiator. I have appealed to the warranty company and am awaiting a response. Other than the problems with the TPS I love this car.


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## Motorista (Oct 28, 2005)

*Re: bad radiator (5049)*

I wonder if you could tell us a little more about the problem? in what way is it "bad", is it leaking, and, if so, where from? 
I recently had to replace the radiator in my '91 Acura Legend because of a small but diffuse leak along 3/4 of the plastic header, where it's crimped onto the aluminum radiator matrix. By the way, the Acura radiator cost almost $400, so the price you got quoted (assuming a more complex/larger unit) is not so bad, by comparison.


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## car_guy (Aug 19, 2005)

*Re: bad radiator (Motorista)*


_Quote, originally posted by *Motorista* »_
I recently had to replace the radiator in my '91 Acura Legend because of a small but diffuse leak along 3/4 of the plastic header, where it's crimped onto the aluminum radiator matrix. By the way, the Acura radiator cost almost $400, so the price you got quoted (assuming a more complex/larger unit) is not so bad, by comparison.

Don't forget he's replacing a secondary radiator, not the main engine cooling radiator. I believe the secondary radiators (oil? transmission?) are quite small. But who knows what has to be removed to get to them? Could be quite labor intensive.
Which radiator was it? How much were the materials and how much was the labor?


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## PanEuropean (Nov 3, 2001)

*Re: bad radiator (5049)*


_Quote, originally posted by *5049* »_Has anyone had a radiator replaced. One of my secondary radiators is bad. 

Yes - I had the secondary radiator (the one on the passenger side at the lower front) replaced about 6 months ago. It is not a particularly difficult job to do, however, it is easier to do the job if you remove the front right wheel well liner, as well as the front bumper cover.
Once those two parts are off, the radiator is there in plain sight and easy to get at. It is a snap to replace it - just disconnect two hoses, and then remove a couple of bolts.
Be sure to check your coolant level every day for a few days afterwards, until the cooling system 'burps' and the air bubble comes out. The technician can't force the car to 'burp' the air bubble out - so, you just watch for the coolant level in the round tank to drop by about an inch and a half, and when that happens, you top it up.
Perhaps ask the technican to give you about 10 ounces of coolant to take home - you can then add it yourself, this will save you a trip back to the dealership.
Michael


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## murphybaileysam (Dec 29, 2005)

Michael, your car doesn't have a ton of miles on it and I know you are a pretty meticulous person about service. Why did the radiator have to be replaced? Did it just leak or was there another reason? It is probably something that is specific to the W12 because of the configuration of the radiators I guess.
Let us know.


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## PanEuropean (Nov 3, 2001)

*Re: (murphybaileysam)*

I'm not sure if the radiator just sprung a leak, or if it was some kind of delayed reaction (6 month delay) from the small front end accident I had the previous summer.
It had a tiny leak, right in the middle of it, with no evidence of any external damage of any kind. Pictures of the leak are below.
Michael

*Evidence of leak - Supplemental Radiator, W12 Engine*


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## 5049 (Aug 7, 2005)

*Re: (PanEuropean)*

I has the same situation with my car. I had a little incident with a curb last year. VW replaced the oil pan and the plastic shrouds under the car. Now this radiator problem has occured. Maybe we have a common problem here.


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## PanEuropean (Nov 3, 2001)

*Re: (5049)*

I think this small radiator is quite well protected from impact damage, because it is well behind the front bumper cover, and the parts of the air shroud that fit up against it are soft and flexible. I noticed that there had been a part number increment (from B to C) when mine was replaced, and that the construction of the C version was slightly different. Whether this is significant or not - meaning, whether it was changed to fix a problem, or just changed as part of ongoing manufacturing process improvements - I don't know.
Just a reminder to all that this small radiator is only fitted on the W12 engine, not on the V8 engine.
Michael
*Small Radiator Replacement*


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## 5049 (Aug 7, 2005)

*Re: bad radiator (5049)*

I got my Phaeton back after a three week stay at the dealership. I had the supplemental radiator, water pump and thermostat replaced. The cost of the service was a few bills less then 3K. I made a call to Phaeton Care about the water pump. The pump should be covered by the 60K warranty. The radiator will have to go to arbitration and have a third party define "Radiator" vs "Supplemental Radiator". Has anyone had any of the problems I am having?? Ill keep you posted on what I find out.


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## dcowan699 (Nov 22, 2004)

*Re: bad radiator (5049)*

My W12 is in the shop right now for this very reason. I suspect this thread will become more and more bumped up in the future for us W12 owners.


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## Itzmann (Jan 16, 2006)

*Re: (PanEuropean)*

It is interesing that you received a "C" version replacement radiator a few months ago.
As you can see in my recent http://forums.vwvortex.com/zer...42204 maintenance report, this week I received a "B" replacement radiator. According to the no-charge invoice I received, they replaced part:
3D0-121-212-B


_Modified by Itzmann at 10:19 PM 5-26-2006_


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## car_guy (Aug 19, 2005)

*Re: (Itzmann)*


_Quote, originally posted by *Itzmann* »_It is interesing that you received a "C" version replacement radiator a few months ago.
As you can see in my recent http://forums.vwvortex.com/zer...42204 maintenance report, this week I received a "B" replacement radiator. According to the no-charge invoice I received, they replaced part:
3D0-121-212-B

Does the invoice indicate the part they replaced (3D0-121-212-B) _and_ the part number they installed? Could it have been replaced by a 3D0-121-212-C?


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## murphybaileysam (Dec 29, 2005)

*Re: bad radiator (dcowan699)*

Now I look under the right front end of the car every time I pull out of the garage to see if there is any evidence of a leak! I assume if it is that small, the car probably has to sit in the same place for at least a week to see any coolant that has come out. At least the trunk is big enough to hold a coolant container in case I have to top it off on the road! I don't feel too bad about that though because when I had my old Jaguar I had to keep an extra fan belt, trans fluid, coolant, and 2 quarts of oil in the trunk whenever I took a road trip!


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## Itzmann (Jan 16, 2006)

*Re: (car_guy)*

Apparently, the invoices I receive from this dealer (with all values at $0 b/c VW takes care of them), list the part that was purchased, not the part that was, presumably, thrown away.
Therefore, I would have received a "B" radiator last week.


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## mkell (Jan 8, 2005)

Mine was replaced aswell under warranty - will check to see if I have down why it needer replacement.


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## PanEuropean (Nov 3, 2001)

*Re: (Itzmann)*

If you were given a B radiator, then you can be certain that the changes made to the design that resulted in the C version were only improvements in the production (manufacturing) process, and not changes that were made to address any flaw in the design or functionality of the B version.


Volkswagen - across the board, worldwide - is very good about pulling stock from the warehouses and not shipping it if the part number supercession signifies a 'problem fix' for a part.

Below is a picture I forgot to add when I made the post above - it shows the process of pressure-testing the cooling system after replacing the supplemental radiator, to make sure that there are no leaks in the system.
Michael

*Pressure Testing the System after Replacing the Supplemental Radiator*


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## PanEuropean (Nov 3, 2001)

*Re: (PanEuropean)*

*Archival Note -*
Related post: "Insufficient Coolant" Advisory Message.
Michael


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## murphybaileysam (Dec 29, 2005)

*Re: (PanEuropean)*

After leaving my car parked for 2 weeks, I too found a small puddle of coolant under my car (about an amount equal to a spilled can of soda).
It caused me to re-read the posts about the auxiliary radiator replacements on the W12's. The only thing is, I never saw the message on my screen that said the "coolant was low", as has been described on these posts. I have only 31,000 miles on the car so I am not due for service for a while. I guess I'll check the coolant level visually. I am wondering whether to just keep topping it off as is needed or whether the leak can get to the point of causeing the unit to fail and then have a major problem? Will the main radiator keep working or does the coolant actually circulate between the two and a leak in one will cause loss of all the coolant eventually?


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## PanEuropean (Nov 3, 2001)

*Re: (murphybaileysam)*

Jay:
As best I can recall, the amount of coolant that exists between the 'minimum' and 'maximum' fill levels is greater than what a can of soda would contain (even allowing for coolant expansion), which is probably why you have not seen a "Low Coolant" message. If the temperature was getting colder (going down below freezing), you might see the message as the coolant shrinks, but that is not the case at this time of year.
Perhaps ask your VW tech to have a close look at the cooling system next time you bring the car in for service. There are a few 'hidden' components - for example, the supplemental expansion tank that is directly aft of the main (spherical) expansion tank, in the cabin air intake plenum, and of course the auxiliary radiator.
When an oil change is done on a W12, it's generally good practice to remove the front right wheel and the front right wheel well liner. That is really the only way to get access to the oil filter without deforming all sorts of stuff. When that front right wheel well liner has been removed, it is then possible to carefully inspect the back side of the supplemental radiator for evidence of leaking. If there is any leak, there will be pink stains on the back side of the radiator - they are easy to spot, provided you have removed that wheel well liner. There are some good photos of all of the parts that I have referred to at this post: "Insufficient Coolant" Advisory Message.
Lastly - when the oil is changed on a W12 engine, it needs to be drained - it is not acceptable to suction the oil out, as is the practice with other engines. The Phaeton repair manual is quite explicit about this.
Michael


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## murphybaileysam (Dec 29, 2005)

Thanks for your quick response. I'm not scheduled for an oil change for several months so I better keep some coolant handy and monitor that the leak doesn't get worse.
Since my service is done at Autobarn Evanston I feel they should be quite well informed about the various procedures due to the large volume (relatively speaking) of Phaetons they service. To be on the safe side though, I will point out those things to them.
Thanks again.
Jay


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## PanEuropean (Nov 3, 2001)

*Re: (PanEuropean)*

Photos re-hosted.


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## Auzivision (Apr 19, 2007)

*Re: (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_Jay:

Lastly - when the oil is changed on a W12 engine, it needs to be drained - it is not acceptable to suction the oil out, as is the practice with other engines. The Phaeton repair manual is quite explicit about this.
Michael

I thought I read somewhere else on this site that sucking oil out the dipstick was the approved method of oil extraction for a W12. 
Based on a couple photos from my last oil change, I think I might have this same leak.
















I wish I noticed this pink drip when I had everything apart.


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## PanEuropean (Nov 3, 2001)

*Re: (Auzivision)*

Hi Kurt:
Based on what I can see in those pictures, I don't think you have anything to worry about.
When I had the leak, the coolant level in the reservoir (the round sphere) visibly declined. Unless you are seeing a noticeable decrease in the quantity of coolant in that sphere, I would not be concerned at all. The coolant is a fairly 'sticky' fluid - that little droplet you see in the pictures could have been there for quite a while. It could also have come from weepage at a hose connection - nothing to do with the supplemental radiator itself.
Michael


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## Auzivision (Apr 19, 2007)

*Re: (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_Hi Kurt:

When I had the leak, the coolant level in the reservoir (the round sphere) visibly declined. Unless you are seeing a noticeable decrease in the quantity of coolant in that sphere, I would not be concerned at all. The coolant is a fairly 'sticky' fluid - that little droplet you see in the pictures could have been there for quite a while. It could also have come from weepage at a hose connection - nothing to do with the supplemental radiator itself.
Michael

Thanks Michael,
Is this the reservoir you are referring to? 








I remember opening the cap and looking in, but didn't see much. I do recall having a thought that I should be able to see some fluid, but then again the lighting wasn't that good. It was getting late and I didn't have a flashlight handy. 
No message or warning on the dash and the temperature (both coolant and oil) behave as expected. I’ll double check it tonight with a flash light.


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## PanEuropean (Nov 3, 2001)

*Re: (Auzivision)*

Hi Kurt:
Yes, that is the reservoir - and the fluid level in your reservoir is below the minimum acceptable level.
I'm actually a bit surprised that you have not yet seen the "Insufficient Coolant" Advisory Message.
Anyway - if you have not yet been presented with a message, no big deal. Just drop by the VW dealer sometime in the near future and buy a jug of coolant. The W12 engines are filled with a very specific type of coolant, I most strongly recommend that you get exactly the same fluid that was put in the car at the factory, and use that fluid only. If you buy a jug, it will last you forever.
Once you fill it up (fill it exactly to the max level when it is stone cold), just leave it alone for a month, then go back and check again. That will let you know how much you are losing. My guess is that you just have very slight weepage - and for that particular condition, it is better to leave things alone than to try and obtain perfection. If you go digging around to try and solve a leak of one teaspoon a month, the odds are that you will stir up a hornet's nest.
Below is a photo of the fluid that you want to get. Accept no substitutes.
Michael


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## VAPHAETON (Jan 15, 2005)

*Interesting Coincidence*

My last 2004 W12 developed a leak in the aux radiator that I happened to notice by way of colored fluid on the floor the exact same day that the CEL came on. It was later determined that the CEL was caused by infamous internal transmission seal leak that requires replacement of the torque converter.

Now with my second 2004 W12 the exact same thing happened with the same results ( leaking aux radiator and CEL ) except this time there are also codes for intermittent fan control faults in both fans.

Thankfully, I have the Real Driver extended warranty. I think they probably choked a bit when the dealer called in the claim, but after sending in an inspector to look at the car they have approved all work except the wheel alignment which VW says is required after reassembly. I did not hesitate to offer to pay for the alignment. 

While the engine is out of the car I am having the dealer replace the rubber belt at my expense. Is there anything else that would not be covered under the warranty that I should consider replacing while the engine is out ?


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## Zaphh (Jul 5, 2008)

Throwing in a new thermostat while you're there would do no wrong, I would think.

P.


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## PanEuropean (Nov 3, 2001)

Photos re-hosted.

Michael


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## zeextt (Mar 17, 2013)

My car has a "C" radiator made in 2006 and it just started to leak..


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## PowerDubs (Jul 22, 2001)

I am about to pull my front bumper off to fix a parking sensor and figure I will inspect the secondary radiator while I am in there.

I looked on ETKA and it mentions BAN or BAP (I forget) next to the part, but not BRP.

Does anyone know if the BRP even has the same radiator?

Thanks.


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## PanEuropean (Nov 3, 2001)

Hi Josh:

I can't recall the meaning of the engine code designations off the top of my head. I think your car is a 2006 W12, is that correct? If so, the main differences between the 444 HP 'later version' W12 and the 420 HP 'early version' engine are dry sump, modified PCV system, and the different intake manifold on top. I suspect that the supplemental radiator is the same on both early and later versions of the engines.

Michael


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## PowerDubs (Jul 22, 2001)

Hi Michael,

You are correct the PVC system is different.

The dry sump is a falsehood. The earlier Audi A8 had it and then switched to a wet sump as well.

The 2006 VW W12 appears to have an extra coolant overflow tank according to ETKA. I guess I'll find out soon enough on the radiator when I pull the bumper.


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## PanEuropean (Nov 3, 2001)

PowerDubs said:


> The 2006 VW W12 appears to have an extra coolant overflow tank according to ETKA. I guess I'll find out soon enough on the radiator when I pull the bumper.


The earlier versions of the W12 also had a second coolant expansion tank. It was located in the air intake plenum area, on the right side of the car, just above the two engine controllers (more or less symmetrically opposite the brake fluid container). Perhaps VW relocated this tank when they made the changes to the W12 engine?

Michael


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## Phaetonlvr (Feb 26, 2013)

I figured I'll update this thread so any future W12 owners can prepare themselves for this being a recurring issue even with the revised version of this radiator.



PanEuropean said:


> If you were given a B radiator, then you can be certain that the changes made to the design that resulted in the C version were only improvements in the production (manufacturing) process, and not changes that were made to address any flaw in the design or functionality of the B version.


Well, judging by the need to replace the supplemental radiator on three of my W12s I can say that the C version doesn't seem to be any better than the B version. The mileage shown in the photo is the odometer reading when I replaced it but those three radiators had actually been replaced before at one point so have even less miles on them and still started to leak. It's interesting to note that two of them (the two on the right side) have the leak at the exact same spot on the upper end tank while the one on the left leaked at the lower end tank. It sure looks like this is a manufacturing issue because none of them had any external damage to it. 

At least by now they have dropped in price a little (still pricey at about $260 when bought online) and it's a pretty straight forward job if one is comfortable removing the front bumper cover.


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## veedub00 (Mar 31, 2000)

I hit a tire with my W12 and was inspecting the front end damage. Looks like a previous owner bypassed this radiator altogether. What does this radiator even do? Should I even worry about it?


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