More Passat woes

[smithy602179]

What, water in the footwells of a Passat! No, never!

we all complain about it , but vw must be the only manufacturer that installs its own paddling pools in a car

[KieranM]

The battery drain is something I experienced with my old Passat which had the passenger footwell full of water more often than not. It was the corroded wires and connections that were causing it. Fixing the connections and regaining functions was very rewarding, the un water proofness of it was amazingly annoying.

[Col]

Don't despair, they are good strong cars.

If it were mine (and I've done these on mine) I would;

Change the coolant temp sensor and the thermostat, do both whilst the coolant is drained down. And don't worry about getting an e-bay one as long as it is green in colour.

Clean out the plenum drains if you haven't already.


With regard to the charging and voltage, check to see if it is wet down by the ccm down in the passenger footwell, the carpet surface may feel dry but there can still be water below. Depends what you find when you do the plenum. But the issue could be the battery itself, cannot remember if you said it was new? Investigate the ccm and plenum and report back.

[Doctle Odd]

Col is that the Passat you keep in the unit in your dining room? It's spotless!

[Col]

I wish. That was just after doing a plenum clean last year.

[chapster]

Thanks for the info everyone. Tonight I spent some hours on the car.

Re: Coolant leak - I found that there was some coolant underneath the expansion tank, having come from an overflow hole in the bottom of the tank with no pipe on it or anywhere to be seen. I found that despite adding a litre of G12 a couple of days ago, it had gone below minimum again. There is always pressure released when I remove the expansion cap, even with engine cold, and the coolant level rises as the pressure is released, but it had still lost a fair bit. Is this pressure normal?

I don't know if it's being lost through the overflow or why that would be. I can see no evidence of any other leak under the bonnet so far although I'm unable to fully inspect the radiator.

Re: Heating intermittent - The temperature flap motor visible under the glovebox is moving smoothly when the temp is changed from LO to HI as I tested repeatedly, and I assume the flap itself is also moving as there is a distinct change in the airflow pitch as the flap changes position. With the engine running for about 25 minutes idling, I noticed that all the coolant pipes accessible at the top of the engine remained cool. The large pipe to the expansion vessel was cool, as was the small one near the top which also showed no visible flow of coolant into the vessel...should it? When I helped change a rad in a Vauxhall Combi van I recall that there was a constant flow of coolant from the small upper pipe into the expansion vessel the whole time.

I also found that it took ages until the heater matrix pipes got warm, and that the right one was quite a bit warmer than the left one, but that at that point there was warm air blowing into the cabin. I applied some pressure to the release tags on the clip on the matrix pipe with the hole in it which caused coolant to spurt out under quite some pressure from only a slight release of clip pressure. The whole time the viscous fan was spinning, but the left-hand fan was not, and did not come on at any point. Until my new temp sensor arrives, I do not know what the temp gauge would have shown as it's stuck on 50C.

While driving home I aimed the airflow from the front vents so I could be sure of when the air temp changed and put the Climatronic on HI. It seemed that when doing 30mph, the heating started blowing quite warm, but as I picked up to 60mph on the A roads it went cold. This theory seemed to be concrete until I was almost home and my slow drive through the high street at 20-30mph had only cold air blowing, which then warmed up during the last 200 yards to the house.

The coolant is fairly bright pink, although a slight oily film is visible on the surface and there is a brown sludge in places in the expansion vessel. I can't fathom why the heating seemed to relate to the speed I was doing. When idling, it tends to go from hot to cold as it wishes. The temperature flap remains in the 'heating' position the whole time.

I removed the bits of pollen filter and found the clip that should've been on the front was inside the well resting against the fan turbine. I'm wondering if that caught every now and then and caused the fan to catch... would that explain the occasional going dead of the Climatronic unit perhaps, and the other oddity where the unit stays on and lit, but the fan goes completely off (no segments displayed on the LCD screen at all) then comes back on a few seconds later. Perhaps detecting a change in current draw from the fan?


Battery discharging: with the car off and doors closed, much as it would be overnight, I connected my current meter between the positive clamp and battery positive. Current draw at first connection was 0.5A which then dropped to a constant 0.03A draw. That's miniscule and would imply that the car is not draining the battery, unless something changes at points (water moving about under the carpet - I haven't checked under there yet).

Battery voltage was 11.9V with no load - should be 12.7V. When engine running, the voltage on the terminals was 13.8V rising to 14.5V when revved. After the car had been running 20 minutes, the voltage was 14V at idle. I'm fairly sure this is right, but do not know if this voltage remains stable when driving, but I'd tend to think it is, as the battery light never comes on which indicates alternator voltage < battery voltage. So it's pointing towards the new battery being troublesome. I made the error of not measuring the new battery's voltage when it arrived, as some are left standing for months and go below the critical voltage (is it 12V or 11 point something?) at which point a lead acid battery starts deteriorating internally. It was the cheapest battery I could find anywhere on the internet, so...

Footwell water: for the sake of ruling it out, I'm going to pay the £12 a dealer wants to post me some of the VW sealing cord stuff for the pollen filter housing. I still need to resolve the windscreen leak at the top-middle. I must also lift the carpet and see what's what with the CCM. I'll do that tomorrow after work as I can only do things to the car there, not on the road at home.

I'm wondering if coolant loss and heating trouble are related...

[Crasher]

The sealing cord is not needed as long as the drains are kept clear.

[chapster]

It was a day or two after heavy rain when I checked the plenum chamber and it was empty of water and no leaves or debris visible. There was some sludge, I found tonight, by the side of the pollen housing. I tried to scrape some out with my screwdriver. It was between right side of housing and where bonnet braket is.

There was some rain last night, but when I worked on the car this evening the chamber was all dry.

Don't suppose you have any ideas on the heating/coolant loss problem? Could water pump failing perhaps cause both issues?

[jammy86]

Your battery is dead if it's reading less than 12V.... The clackety start might be glow plugs or glow plug relay or fuse. Check for water coming in from the rear drivers side door, you should see a witness mark on the interior trim when you open the door after it's been raining. The air flow flap dies on most passats and is a big job to replace so most (including me) don't bother.... it's only the recirculating air flap, so it just makes the air-con not as efficient. If your plenum chamber is clear then take out the passenger seat and lift the carpet, clear out all the water and check for corrosion on the pins on the CCM and in the wiring harness, then keep an eye on it to see if it comes back.

[smithy602179]

you may have a big airlock in system .pull left pipe off to expose hole and lift expansion tank higher than pipe hole and see if any water comes out of breather hole . some build up of pressure is normal . thermostat is correctly fitted ???