Passat B5, B5.5 plenum drain cleaning

[Col]

Aug 2015, plenum re-seal on page 2

This covers the following cars;

B5 Passat 1997-2000
B5.5 Pasat 2000-2005
C5 Audi A6 1997-2005
Not sure about the A4 of the same vintage


A really important job to do, as if these are blocked all sorts of problems can occur; water ingress through the pollen filter housing causing the central convenience module and wiring to fail, rotting out the brake servo which can possibly lead to a very expensive repair bill.

Anyway, this is how I did it. Please note I thought about taking the pics part way through the job so some may appear to be out of sequence.

Tools,
10mm spanner for battery terminals.
13mm socket with 10" bar for battery clamp.
13mm spanner for battery cradle.
Pressue washer (if you have one).

So;

1, Pull the rubber seal off at the front edge of the plenum cover.
2, Ease the plastic plenum cover out.

Some say that the wiper arms and the scuttle cover that butts up to the screen needs to come off to remove the battery. This isn't the case, you can move the rubber incased loom forwards to provide access to remove the battery but you need to be careful not to damage the very brittle windscreen scutte panel.

3, Picture below shows the 3 clips securing the loom in place, you need to roll the loom over the bulkhead to release the clips and also release the grommit where the loom pases through the bulkhead. Also shown is the scuttle panel part removed. (Ignore the fact all of the engine covers are also off as I was going on to clean the engine bay as well as doing this, you don't need to remove them to clean the plenum drains).

http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20clean/Photo0492.jpg

4, Undo the battery terminals, 10mm spanner, and set aside.

5, Undo and remove the battery clamp, 13mm socket on 10" bar. See picture below for location.

http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20clean/Photo0490.jpg

6, Remove battery cradle, x2 13mm nuts and one 13mm bolt, see picture below. Note that the alarm sounder is secured by one of the nuts. Note this was taken on re-assembly so it appears clean!

http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20clean/Photo0489.jpg

7, This is what I was faced with, a dirty but dry plenum! The location of the battery side drain is shown arrowed and the approx location of the drain under the servo is also arrowed. I chose to poke the grommits out. There are two schools of thought on this, one being that they should remian in place as they stop fumes rising into the plenum as thus into the car interior via the pollen filter which is in the plenum. The other is to remove and not worry about fumes unless your exhaust is blowing. Im not worried and so poked them out! You can make your own decision on this.

http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20clean/Photo0484.jpg

8, Cleaned with TFR (traffic film remover) and my pressure washer. I also ran an open hose in there as well to ensure all crud was removed.

http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20clean/Photo0487.jpg

9, With battery back in.

http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20clean/Photo0491.jpg

10, Connect everthing back up, replace plenum cover and rubber seal, job done! Took me about 45 minutes in total.

[Eugheugh]

I had this done under warranty about 4 years ago but not before the rear carpet got soaked the previous year and I unblocked it but left the bung in!. Anyhow, good on you for putting this preventative measure up on the forum.

[Hex69]

Have you done it since? I did it twice a year when I had my Passats.

[Col]

I think it is something that needs to be checked once a year if not sooner.

[Col]

What is new on here?

My last post is showing as requiring moderator approval ?

[attila_tdi]

Good write up. How did you manage to get the battery out? I tried removing it but it fouled on the plastic lower windshield lip.

[Sam]

What is new on here?

My last post is showing as requiring moderator approval ?

I moved the thread to the How To section as it's another one of your damned good posts.

I've moved it back now and copied the first post only.

[Col]

I moved the thread to the How To section as it's another one of your damned good posts.

I've moved it back now and copied the first post only.

Excellent, cheers Sam.

[Col]

Good write up. How did you manage to get the battery out? I tried removing it but it fouled on the plastic lower windshield lip.


Read Nr3. above, you need to roll the loom forwards to create room.

[defever]

Bump for wet winter and thanks for the guide!

Shared on A4 B5 forum!

[aks1989]

This is THE best write-up on this topic online, anywhere.
Really helpful, makes sense.
Just did mine in about 30/45 mins (helps if you have a 3/4inch extension)
I was dreading this, but really was quite simple, once I had the battery out anyway.
I couldn't see where the original seal went for the pollen filter (it was missing), but as the original was fire-lighter dry I figured no need ;)
the 2 drain away plugs were gunked up to the max, finger wiggling it's way through 10 litres of water on top, beautiful ;)
Checked the bonnet release but even the foam on the inside was dry so I knew there was no ingress through there, the door seals are sound, so no issue there.
Fingers crossed I don't have to do that one for 6 months or so ;)

Did make me chuckle when I saw the DO NOT BEND sign on the back of that thick loom bundle though

[Doctle Odd]

You just cant get any better than this

[Col]

Glad it is of use.

Its been on here a fair while now and I'm surprised it hasn't been added to by others who have done it. My way might not be the best way.

[Doctle Odd]

Glad it is of use.

Its been on here a fair while now and I'm surprised it hasn't been added to by others who have done it. My way might not be the best way.

I'm looking forward to whenever you write a sex manual

[Doctor-X]

Can I just ask, is it obvious to see if water is collected in the chamber before removing everything? I have never had problems with water getting into the car so don't want to start messing if there is no need.

[aks1989]

well I had what looked like silt dried up all around under the pollen filter and a tonne of leaves but again to get that far, you may as well do the whole thing only another 20 mins work ;)

[Col]

Yes, you quite often see a lake sloshing about in there.

Check it after heavy rain or after washing the car. When blocked, they still drain but very very slowly and not fast enough for the water coming in to reach a level where it can go over the top of the pollen filter seal.

[Doctle Odd]

Nearly 11,000 views of this topic and less than 20 comments. That's amazing

[KieranM]

Yes indeed I concur, did mine today, again not had wetness issues, and it was dry and not as dirty as the above post, I couldn't poke the gromet out from under the master cylinder as there was something else attached to it, or else I would have, the drain hole under the battery was clear (previous owner must have removed the gromet), the other one had dreaded detritus in it, but only a bit. No signs of water being kept there, but my god there was so much detritus in the corners up by the pollen filter and the ECU, that took a while to get out.

Thank you so much for fantastic instructions, they worked a treat - I did slightly crack my cowling getting the battery out, but it's not too bad- rather that than risking breaking the windscreen putting the cowling back in.

[Col]

Update.

It has been four years and one month since I did this. I still own the car and it is now fast approaching 140,000 miles, when I did the original I think it was a touch over 90,000 miles. I still love the car despite it being 11 years old now and have no plans on changing it.

Anyway, I thought it was time to do this again.

So.........


I whipped the plenum cover off. I knew it was still quite clean topside as I've done a few pollen filters in the time since I originally did it but wanted to check the drain holes and also to re-seal the ECU and pollen filter housings as they are renowned (well the pollen filter housing is) notorious for leaking even if the plenum drains themselves are clear.

What happens quite simply is the water wicks through the pollen filter housing gasket and down into the car. This would be water that comes down off the screen. The gasket on the pollen filter housing is a nasty thing, being rubber coated sponge. In time the coating breaks down and the water simply wicks through it.

Although I was aware of this issue I didn't know what to expect. As part of this little adventure I planned to do both the ECU and pollen filter housing and check the wiper rack. The wiper racks certainly on MK4 Golfs which are of similar vintage to the Passat are renowned for seizing up, so I thought I'd check it.

Plenum still clean, I put this down to me being careful where I park it and that it is garaged overnight.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4857_zpsts6ociyp.jpg

Still clean from the other side as well
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4858_zpsrwa2obgz.jpg

Amazingly I think the car is still on its original eleven year old battery
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4859_zpsnujemnhz.jpg

VW part number on the battery, I've tempted fate now, I'll probably need to replace it soon now..
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4860_zpsopdzc1pl.jpg

Battery carrier off, still remarkably clean four years after I last did this.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4862_zpsksr033iw.jpg

ECU housing, this is with the lid off and after I'd jet washed the plenum.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4863_zps1syviy5y.jpg

Wiper rack. To get this out you need to remove the motor from the rack so you can then wiggle it out.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4864_zpscpc9bbcf.jpg

Wiper rack out, loads of cack behind
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4865_zpsf43zfed1.jpg

You can unclip the ECU and other connectors to allow the ECU housing to be moved out the way. The ECU housing used a neoprene gasket with no sponge in it. Mine was good and still doing its job. I could have left it as is, but you never know. It is worth checking.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4867_zps6x7m32an.jpg

A good clean up was needed, lot of debris under the housing.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4869_zpstjkcvyxu.jpg

All clean and drying off,
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4870_zps3jkctbic.jpg

The pollen filter housing out, lot of cack at the back of it.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4871_zps2en1lf6c.jpg

Knackered pollen filter housing gasket
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4872_zps0ctyoqfw.jpg

Knackered gasket shown insitu
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4873_zpslfn7b0yq.jpg

The bridge / water deflector over the pollen filter housing, this tilts to remove and until it is off the housing will not come out. Three nuts secure the actual housing.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4874_zps6yvapf2w.jpg

My goo of choice. This is a butyl rubber sealer that doesn't set, very good stuff for this type of job and cheap as chips.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4875_zpslm2hrfv9.jpg

Polybutene
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4876_zpsto8maqph.jpg

A good bead, then the gasket on top
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4877_zpsgd8wehes.jpg

The gasket on with another bead on that. This isn't ever going to leak!
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4878_zps9qzuoay1.jpg

ECU housing squidged down with the sealer oozing out around the edges, nice.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4879_zpst7kwhmg9.jpg

Pollen filter housing, a very deep bead of sealant! There is just enough room to get it place before you squidge it down.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4881_zpsexs5gxaq.jpg

Wiper rack spindle components cleaned prior to greasing up and re-assembly.
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4883_zpsmjvho7up.jpg

Almost done
http://img.photobucket.com/albums/v602/colin__/AA%20Passat%20Highline/plenum%20seal/DSCF4884_zpsuvtsou86.jpg

A job well worth doing. I was getting mysterious misting up of the car interior which led me to do this.

[Rob69]

Excellent info Col.
Cheers!

[defever]

Great update, thanks very much BigCol!

I removed the rubber bits in winter 2014. Few months later I upgraded the scuttle to the facelift version (the pollen filter is covered alot better than just the gutter rail) with plenum and battery cover that goes across the width: Scuttle and battery Phelum covers. (http://www.vwaudiforum.co.uk/forum/showthread.php/164548-Scuttle-and-battery-Phelum-covers?p=945789#post945789)

I recently removed the battery to do other jobs so I had a quick check; no muck and very dry all around. I don't think I'll do the seals for ECU and pollen filter boxes, as I am confident that any water coming in will pass through the two holes and the plenum cover minimises any foreign object blocking up the space.

I think the facelift scuttle and plenum covers for Passat are the same as B5 A4 so if you get hold of these parts then it might be a good option to consider (unless you want to keep yours all original set up).

[Col]

Interesting.

The B5 Passat pollen filter cover was more complete than the B5.5 where the 5.5 relies on a top cover over the plenum and the diverter bridge.

Either way though the issue is with the design of the gasket and placement of the housing. As can be seen there is a lot of cack built up at the back. What happens is the water off the far egde of the screen goes down and gets trapped by the cack. It can only drain away slowly. The gasket is a terrible design and wicks the water through onto the internal / additional sponge liner.

This is a separate issue to the plenum drains which are much lower. You can get this pollen filter housing issue despite the plenum drains being clear as there is another water trap to the back of and to the wing side of the pollen filter housing.

It is a one-off job on these gracefully aging cars but something that needs to be done.

[defever]

Thanks BigCol for further insight!

Perhaps I should check at some point, but I'm not getting any wet carpet or heavy condensation in the morning so I'm assuming there's no water leakage into the car.

I'll bear it in mind, and I'd like to hear from fellow B5 / B5.5 owners on their thoughts or experiences.

Great thread on a great forum!

[Charliedog]

Hi Col, Thank you for a very informative and graphic displlay on how to clean the drain plugs. I am a newbie to this site so just learning where and how to post. Charliedog

[GrantLDN]

Going to have a crack at this later on this weekend. Although I do have a receipt from VW for have some of this work carried out but that was a few years back.

[mjb2012]

Any chance of the pics for these? thanks