Hunting Down Leak Under Dashboard, Passenger Side[96 850]

[ToriWhite]

Above the (removed) glove compartment, there's a soft patch of puffy fabric that I can only assume is flame retardant insulation or something. It's close to the reverse surface of the dashboard, near the corner with the speaker, and the windshield. With the recent rains, it's underside constantly wet and dripping down onto the passenger floor. It's hard to know where the source is to saturate the padding/fabric, but given the location; my best guess is either something related to those vents by the corner of the hood.. or heaven forbid: the actual seal of the windshield in that corner. Please see attached pictures for clarification.

Anyone run into a leak in this general area before? I'm hoping its one of those characteristic points of failure that's often so well documented for the 850 series.. and doubly hoping that it isn't the windshield

[scot850]

Does your car have a moonroof/sunroof?

If it does, check the headliner is not wet at the 4 corners of the sunroof 'cassette'. There are drains at all 4 corners. Water could be leaking out of the RHF drain and then running down the panel at the side of the windshield and then into the top of the dashboard. You could test this with taping the sunroof up temporarily and pouring a bucket of water over the top of the car and see if there is a leak. Yes, and then then the sunroof is unlikely to be the issue.

Other areas are the drains for the windshield washer recess in front of the windshield under the plastic cover. Again if this blocks water can drain into the cabin including through the cabin cold air intake under the cover mentioned.

Last area would be windshield seal leaking. I have seen leaks at the top of the windshield if the top seal is missing. I have also seen it when it was there on a 98 V70XC we had where the windshield had been replaced prior to our ownership poorly.

The only other longshot is the passenger door seal, but it is less likely. The seal can leak in the area around the door mirror.

Neil.

[erikv11]

One more addition to Neil's points about the cabin air intake under the cowl (plastic cover): The whole area around the intake can accumulate a lot of debris over the years, so that it displaces the intake flute and that adds to the leaking. If you see debris under there then lift the intake flute (looks something like this, although yours may not have a cabin filter https://www.fcpeuro.com/products/volvo- ... vo-9488525?) and just clean everything out well. Use a shop vac or similar, then spray cleaner to clean it up well and put the flute back in.

The cabin intake is my first guess but Neil's points are all good ones.

[Roger_850T]

I'll second checking the air intake. You have to lift the plastic cover in the corner of the engine bay, but it can build up with crud and tree-debris and other stuff, and make it easy for water to overflow into the heating system.

It's free to check, I'd start there and clean it out appropriately.

Roger

[ToriWhite]

Does your car have a moonroof/sunroof?

Thanks for the comprehensive list, Neil- I would have never thought to check my sunroof. Another addition to the "I sure hope it isn't THIS list.. already replaced those rails and working up there is a real PITA

The whole area around the intake can accumulate a lot of debris over the years, so that it displaces the intake flute and that adds to the leaking.

My air intake .. grill? (The set of fluted openings of black plastic facing upward, partially exposed at the upper lip of the hood where it ends at the windshield) Is definitely debris prone and perpetually caked with dead leaves and gunk. I'm fairly certain the drain tube is clogged. Referring to (video linked below) .. I'm assuming that may feed into said air filter, and could be culprit. I'll take a peek under there and see if there's anything suspicious

[scot850]

I don't know is you have done the mod or not. 850's did not come with a cabin filter, and more importantly the plastic holder for it. If you do or don't have it, I would find one, and if you have one, remove it, clean it and silicon it down. That gives more height before water can overflow into the cabin air intake. Also it keeps crap out that can get down into the air vent system and rot out the bottom of you AC evaporator.

If you didn't know, the part from the later 98-00 V/S/C70's fit straight in. I think they are still available new and not terribly expensive.

Neil.

[ToriWhite]

Does your car have a moonroof/sunroof?

If it does, check the headliner is not wet at the 4 corners of the sunroof 'cassette'. There are drains at all 4 corners. Water could be leaking out of the RHF drain and then running down the panel at the side of the windshield and then into the top of the dashboard. You could test this with taping the sunroof up temporarily and pouring a bucket of water over the top of the car and see if there is a leak. Yes, and then then the sunroof is unlikely to be the issue.

Other areas are the drains for the windshield washer recess in front of the windshield under the plastic cover. Again if this blocks water can drain into the cabin including through the cabin cold air intake under the cover mentioned.

Last area would be windshield seal leaking. I have seen leaks at the top of the windshield if the top seal is missing. I have also seen it when it was there on a 98 V70XC we had where the windshield had been replaced prior to our ownership poorly.

The only other longshot is the passenger door seal, but it is less likely. The seal can leak in the area around the door mirror.

Neil.

Unfortunately, clearing the debris revealed my air intake drain for the flutes was not clogged.. it just had a few leaves in the way. Lifting the flute to reveal the compartment where the cabin air intake mouth (where you'd affix a filter, if you had one) is, a moderate amount of debris; but debris that looked pretty dry.

Passenger door seal looked fine, all the joints/potential points of failure between the door and the main body are situated too low to be the source

I took a cursory glance around the sunroof, thought I spotted the two front drain holes. Both the rails were particularly covered in condensation near those two ports .. but I haven't run into any leaking from the sun roof area (onto my head or otherwise) .. so I'm uncertain.

Courtesy of some videos linked below, I now know theres a second drain to contend with, the one that is under the flute, dedicated to the compartment where air intake lives. The leak isn't coming from/near the blower fan motor, so I doubt it's the case of that inner space being flooded to the point of overflowing the air intake.. I wonder if a clog in this second compartment would still cause a leak up near the dashboard?

Going to pour some water down sunroof drains, 2nd compartment drain, and see if either cause a drip to start and/or don't flow.

On another note, my passenger side floor has been Wet for the better part of a week, and probably will remain for a few days while I wrap this up. Besides the risk of mold, is that untreated metal under the carpet, thats going to begin to rust?

Good vid for visuals on sunroof drains


Good vid for visuals on the 2nd compartment drains

[scot850]

Flooring should be treated and so should be fine. Just get it and the carpet dray as soon as you get the leak identified and fixed. Sorry I was not clear. The drain I was referring to was the one under the fluted cover (the other end is hard to see as it is under the main fuse box in an 850 on the driver's side). If that gets block or partially, if you get heavy rain or the car is parked at an angle to that side, the water will overflow into the cabin fan cold air intake.

Once you find the leak (assuming the Davis is Davis CA where there has been a bit of rain recently..........!), you can lift the carpet and put a fun under the carpet and dry it out. Ideally do it in a garage so you can leave all the windows open so as not to get condensation all over the inside.

Neil.

[ToriWhite]

... If that gets block or partially, if you get heavy rain or the car is parked at an angle to that side, the water will overflow into the cabin fan cold air intake.

Correct me if I'm wrong, but wouldnt an overflowed cold air intake leak down into the blower moter fan compartment, and only spill out if that gasket was going bad? (pictured in green below) I'm getting water on the underside of what feels like fabric plastered over some plastic/metal (firewall?) beneath the dash, much higher up, only maybe 4in deeper than the reverse surface of the dash's top (illustrated yellow)

[abscate]

That’s really a position for a windshield leak rather than a dash cowl leak

I have an extra filter housing if you want it but I’m in NY. In Riverside next week!