Now out of nowhere my vents are spewing bits of crunchy dark foam coating my dash & rear console hump. My question is where is it & is it integral for the system to function efficiently.

Thanks in advance

 

The foam was used all around the system blend doors and everywhere a duct had a joint. Anywhere to pieces were joined the foam was the sealing gasket. The worst case is on the blend doors because it affects the cold/hot air mixture for maintaining the set temperature. You might have to raise or lower the automatic setting a degree or 2 for comfort.

 

Sounds correct as I have had to adjust temp. kudos sir !

 

Yours are crunchy, mine are little disintegrating pieces that if I try to pick them up, they dissipate to into the carpet. I have to make sure I vacuum them up or its a mess.

 

Since we're keeping both of the XJ's, I wonder how hard it is to pull the dash out and replace all that foam? I would go as far as pulling the evaporator and cleaning all the debris out. Man I can't imagine what it looks like after 236K miles with no cabin filter.

 

I was pelted in the face w/ stray foam projectile whilest doing 85 mph on the freeway, courtesy of my son setting the AC on "lo" temp. w/ high fan. Oh the joy lol !

 

As mentioned, the foam is used in all sorts of locations, and after a decade or so starts to disintegrate...not unique to Jaguars BTW. My Buicks and Hondas have done it after a decade+ too.

But as far as replacing it, the answer is "kinda". It depends on where it has deteriorated and what you want to replace. If it is just a gasket between two ducts for example, you can buy coiled adhesive weatherseal foam from your local home improvement store, or even use high quality sealing tape for male/female duct unions. But in other locations like duct/vent doors, the foam is sandwiched in between two edges of plastic panels that make up the door so that the foam makes an edge seal and there really isn't any way I know of to put the foam back in that gap.

So unless you buy a new part, you probably can't fix all of the foam, and even most "new" parts are really NOS and their foam is probably about dead too.

.

 

Since the X300 and X308 are built on the same basic structure as the XJ40, I would assume that removing the dash is no more difficult in the later models. It's just a matter of removing the knee bolsters (a few screws and fir tree plastic retainers), the instrument cluster (4 screws), the glove box and passenger air bag if so equipped (several screws), and the dash (6 or 8 screws), disconnecting electrical connectors as you go. Here's our '93 dash on the kitchen table for demist vent repair and replacement of the foam and tweeters:



And here's the car with the dash removed:





For the replacement foam I bought sheets of black craft foam from Hobby Lobby and just cut them to shape to fit on the blower motor doors, etc. As I recall, it came in thicknesses of 2 mm and 3 mm and I mostly used the 2 mm. To adhere the foam I used high-temp spray adhesive. For the foam around the heater core and evaporator I think I used some stock foam weatherstrip from Lowes.

I used a shop vac to remove all the foam crumbs that had accumulated between the heater core and evaporator - it was a real mess.

Not difficult at all, just time consuming.

P.S. Accessing your blower motor housings will never be easier than while the dash is out...

Cheers,

Don

 

Thanks for that informative post Don! I've pulled a dash out of a 94' XJ6 about a year ago to do an evaporator that we ordered out of England. I just wasn't real sure how much different it would be to do it on my 98'. I knows it's just nuts, bolts, clips & screws that hold them all in anyways. I'll get time around Christmas to maybe tackle it then. Thanks again!

 

As a former squeak and rattle guy, I suggest using
some lubricant between each moving surface on
assembly. That addresses any post assembly
squeaks that'll drive you nuts.

Silicone spray where impossible to use silicone
grease.

 

My vents are now cracking & breaking, I've sourced good condition used ones from an '03. Since I'm going in to do vents, I'll have a good look @ what foam I can get to & replace.

 

There is a good thread kicking round from a few years ago about this foam issue, the major pieces that can block vents are on the fan motor doors, as seen in my picture, that has literally fallen off the door and is slowly disintegrating - I removed and replaced most of my system while I had the chance.
If you're flexible, you can pull these bits out with a flexi grabber tool and a torch without attempting to dismantle the dash, which is far more substantial than Don B's images.

 

I had to figure out the problem with your pic Sean, then I realized you Brits drive on the wrong side....lol