My personal vehicle always had this problem but I was not able to trace as every time I wanted too take it further the vehicle effected parts had dried up, after moving from Johannesburg or Joburg as our foreign visitors will know it down to the sunshine coastal city of Durban where it can rain a lot and it does…… I one day pounced on the vehicle and solved the riddle.
Without further delay here are my findings and remedy, since the fix there has not been one drop of water or misting up of the windscreen during any type of rain drives recently.
First up you need to remove both wiper blades
Remove Windscreen side finishers – trim
Remove windscreen lower finisher – trim
Remove plenum plastics that allow air through the grills and into vehicle (vent intake)
By now you would have gone through the pictures, important to note that a quality silicon sealant must be used in the sealing up of the effected parts.
Consult someone who knows sealants and not your spares guys, they will sell and miss inform you just to sell a product, very few parts guys really know anything technical, the rest are know jack shit.
Do Not be over whelmed by the many picutres below, once you start its not that bad, for a quality repair put aside 5 to 6 hours, if you have someone to help you it goes alot quicker, we charge 4 to 5 hours for this repair, depending if there are no major issues like re-meshing vent intake
Please note the beow pics are for Right hand drive vehicles but doubt its much different for LHD
Remove trim from under dash, as circled these are wet patches and is a sure sign that water is leaking in
Wiper arms and lower trim needs to be removed
Windscreen side finisher - trim to be removed, there are screws that hold this in place and are hidden under the rubber flap of the trim
Once you have all the vent intake trim (Plenum) removed you can start by sealing this section.
Not in the picture there is a rubber blank that goes in here, apply sealant around edge and insert rubber blank
Its all wet and it should not be (Red cross) right circled indicates one of the problems where water seeps past , left circle shows where water has been dripping on to wiper arm mechanism, this should be dry.
By now you would have inspected and cleaned all the removed parts, this is the steel plate that covers the pollen filter cavity, the circled section is where the water is making its way past the foam seal, in effect this is a bad design that is now only starting to pop up, when it was new all was ok....so we thought.
As the water works past the foam it absorbs the water and allows it to run along the entire length of the foam seal (blue), this was identified by using a flex mirror to poke under this panel prior to removal, this is only one of the problem areas.
All three circles is where the water works past, the right circles is the area that needs serious attention and is detailed in the below picture, the middle is where one of the bolt's goes through that retains the plate in position, the left circle is also a major leak area, all three need proper cleaning and sealing up.
Sealant needs to be applied with great detail in this area, work the sealant as far up under or up to the windscreen glass edge and along the panel edge, note that the panel was re-installed after cleaning and sealant was applied to the foam seal, DO NOT apply sealant to the foam seal and then mount the panel, if you do it will promote rust in no time
This part is abit tricky but not dangerous, the plastic piece here is for when the windscreen is replaced and aids the installer to mount the windscreen correctly, this part however needs to be lifted up to allow abit of sealant to be applied underneath, just lift it up a little, one of two tags may give but that's ok as its going to be sealed up anyway, do not try and remove it. The blue indicates how the water works past in this critical and main area of concern
Water works its way around and under this plastic screw insert, you need to clean and properly seal around this section. Water here drips past and onto arm (circled) and then drips onto pollen filter where it saturates the filters and pours through the fans into the vehicle.
No doubt you know where this is, well its another area that needs attention
And this is what you need to do, apply and work in the sealant well.
Assemble the trim panel while the silicon is still not cured as this will allow for better sealing all round, note I even applied sealant into the screw hole.
Now you can see why you need to seal very well in the previous pictures, this plastic finisher panel was removed and as you can see there is water around (not through) this screw insert, the insert itself does not leak but will do if you use screws which are too long
At the start I assume you would have removed the pollen filter, if so you can give it a wash or replace.
To wash simply soak it in a cold bucket of water with abit of dish washing liquid, let soak for awhile and rinse well, leave in the sun to dry while you carry out the sealing up repair.
It is important to make sure that the pollen filters are installed, failure to do so will allow dust to settle on the fine fins of the AC system and block it up, this in turn will make the AC compressor over work and cause premature failure due to accelerated wear (High duty cycles).
Three years later after installing the mesh instead of the foam on the vent intake it still looks pretty good, note the absence of leaves, twigs etc, a good rinse out is all it required and the water flowed through the drain channels quickly, mesh repair is detailed on this blog in depth
Water water everywhere
To spike you all a cure has been found for the really bad water entry into spare wheel compartment and here is one of the pictures detailing one of five problem areas, the rest is to follow very shortly
This is a problem on ALL p38s, from 1994 to 2002
The green indicates ok as this is not the problem area.
Blue is how the water runs
Red is where one of the problems start.