CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

VW & wet feet

Have been having a reoccuring problem this year with H2O leaking (actually pouring) into the front passenger footbox on my 2002 Passat GLX 4Motion wagon, seemingly only when driving during heavy rainfall. Water soaks the carpeting in fairly short order, also puddling on the front floor mat (never actually see where the water comes from, just “Hey, the floor’s wet again!”). Never get any water when the car sits outside during rainfall or while going through a car wash, only while driving on highway, esp. with gully washer-type storms.



Dealer has checked and cleared all of the various drain lines (A/C, sunroof, battery tray, cabin air intake plenum) repeatedly, generally without finding any blockages (at least none that would cause such copious amounts of rainwater to flow into the passenger compartment). Their next approach–should the problem return (WHEN the problem returns, that is…)–will be to pull out the front seats and flooring to search for a non-standard point of entry, i.e., a weld failing along a seam.



Anyone else ever experience such a phenomenon with a still relatively young (95k in mileage) VW wagon? BTW, this car has spent its entire life in NE Ohio where winter road salt is death to underbodies (see comment above from dealership re. weld failure).

Can you duplicate the problem with a hose pointed at your windshield and vent openings?

I See That The Dealer Checked The Cabin Air Intake Plenum.

Did they thoroughly inspect the “pollen filter housing” (this must be the cabin air intake plenum) for debris and check the seal for damage or being out of place and plenum drain (located under the battery) for obstructions and proper operation?

There is a Technical Service Bulletin specifically for 2001-2004 Passats and Passat Wagons outlining this issue as it pertains to water on the floor after heavy rain.

I’d be tempeted to turn the blower on and introduce some water into this area and see if the water could be made to accumulate and drip from the blower fan area. The bulletin says to look on top of the fan housing for droplets.

I’m thinking that is leaks while driving and not while parked because the fan is sucking in some moisture. I would reinspect this area of the car for the source of a leak. Your’s isn’t the only Passat with this problem.

CSA

Nope. Been there, done that, both via hand-held garden hose and high-pressure, DIY car wash wand, without leaks. I tend to think that this is an underside, or at least, wheel well located issue, as it only seems to happen while driving at highway speeds and with large amounts of water on the roadway.

Actually, when last seen by the dealer’s repair guys for this problem (last week), they DID replace the plenum seal…again! The TSB advice for replacement had been done some time ago (2-3 yrs, as I recall), so they thought, “What the heck, we can’t seem to find any other cause, so let’s try replacing the seal again”.

Currently, the leak hasn’t YET reoccurred, but I haven’t driven in the frog choker kind of rainfall that seems to bring the leak back to life again, either…(stay tuned)

FLASH! FLASH! Today’s update…after having the problem reoccur while driving in heavy rains (who’d of thought, eh?), I took the car back for further diagnosis. Dealer pulled passenger seat, carpeting, got into the dash, etc. Has found "cracked heater box (not the “heater core”, just the box) that they THINK is the culprate. Is going to run us about $2k ('bout $630 for the box, the rest is labor—requires removal of most of the dash board). Checked into recycled part fromn The Parts Place in Auburn, MI, no luck, so will have to go with factory original. I haven’t seen the actual cracked part with my own eyes, just via the phone.

As the dealer already has the car mostly pulled apart, I advised them to continue…

Bogus or not bogus?

(wife thinks all dealers are inherently dishonest, btw)