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Discussion Starter #1
I am heading into my P38 fresh air intake plenum at the base of the windscrean this weekend to replace the filter but moslty to try and fix the source of water running into both side of my foot wells. The plenum filter is goone and it looks like there is a lot of pine needles in there. I am hoping to find plugged drain holes somewhere in the bottom of the plenum. Can anyone confirm that they exist. It looks like rain water is accumulating in there and then seeping over into my pollen filters and in through the heater fans. I understand its a pretty common problem. I have watched the range rover net video for the removal of the plenum itself and have aspare lower windshield finisher with clips. But are there drain holes in that plenum??
 

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The whole area drains at both corners at the front. Run a hose in there (gently), with all the plastic covers removed and you should see water coming out from under the back of the wing at the bottom.
Rod it out to get rid of the rubbish.
 

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When you remove the bottom trim, all the fixings will stay in the base, there easy enough to remove and slide back into the trim, even though you have a spare. The fact you’ve got water ingress check connectors in foot well before you end up with major headaches,, clean and dry if it’s wet.
 

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Discussion Starter #5

Can you be more specific about "check connectors in footwell"...Are you referring to things like the AC condensation tubes and heater core o-rings? Or something else? I was planning on using some seal and peal wherever it looked like water might be getting "around things" and into the pollen filter recess. When I look down into it now I can see the four screws on each side are rusty so its been getting wet in there for a while.
 

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The whole of the plenum general area was never designed to be watertight. Water can, for example, run down the screen, under the lower screen trim, under the 3 plastic plenum covers and into the base of the plenum area, where it exits through the drains I mention above.
The only (nominally) dry area was under the metal covers that extend from the base of the screen to the bottom of the plenum areas at each end. The ones with the plenum intake (pollen) filter covers built into them. These have seals at the top and bottom edges and, of course, around the plenum intake filter covers.
 

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Replacing that insipid ridiculous "filter" attached to the wiper trimpanel can make life much easier. Ditch the foam that degrades and fails in less than a year and replace it with window screen material. Needles, leaves and the stuff that is plugging up your drains will sit on top and blow off during your first drive.
 

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Discussion Starter #8
Perfect explanation and that's where I was headed - making sure of seals on the two ends of the plenum covers.....gotta love the forum!!
 

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also, check your a/c drains, they become clogged with dust and pollen and the condensation of the a/c makes it into a mud cake. the dry/wet cycle keeps on adding layers.
they are located on the sides of the tunnel. I had to use a bit of comprised air on one of mine, the other cleaned just fine.
 

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After 1 1/2 years of an intermittent leak on both sides I found that although the plugs for the screws holding the plenum grill have seals they are as useful as a chocolate tea pot. I popped a bit of silicon on the seal portion and the car has been watertight now for 3/4s of a year. Such a small thing caused such a lot of trouble!
 

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Discussion Starter #11
All good advise so I am going in "loaded for bear". I have had good luck using a product called seal and peel, which is a clear thick cauling that is waterproof but peels back off easily if you need to dissasemble the parts later. Its like that clear sticky goo they use to stick a card to a piece of letter in the mail and allows you to pull the card off without any residue. I used this on my defender tranny tunnel and floor panels where there is a lot of large gaps and it worked well for years. I've also had good luck with dielectric clear silicone on those screw holes, plastic screw inserts. Can keep the water out but not be a bear to deal with later.

For closure I will report back on my final results - thanks again folks
 

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Question about removing the plenum covers. After removing the wipers can you remove the plenum covers without removing the windshield trip piece. The bottom windshield trim fits over the plenum cover. Can you get the plenum cover back under the windshield bottom trim and into place when putting everything back together or is it easier to remove the bottom windshield trim that also will mean removing the side windshield trim pieces also.

Thanks,
 

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Have to remove windscreen lower trim and side trims.
There are plenum cover fixing screws under the lower trim, and you can't get the lower trim off without removing the side trims
 

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Discussion Starter #14
I've just got mine back together. I removed side windscreen trim, wipers, then lower trim, then all three plastic plenum covers then the two steel plenum covers (one either side). I replaced a bunch of rusty screws and then reassembled using peel 'n seal caulking (removable) above/below rubber seals in pollen filter housing and around all edges of the metal and plastic plenum covers. Installed a new lower windscreen trim piece. Let it rain on her for a couple days. drivers side bone dry but a drip on the passenger side. Went back under the bonnet to have a look and exactly as Cornishboat described

I found that although the plugs for the screws holding the plenum grill have seals they are as useful as a chocolate tea pot. I popped a bit of silicon on the seal portion and the car has been watertight now for 3/4s of a year. Such a small thing caused such a lot of trouble!

in my case the plastic screwinsert on the passenger side was leaking a tad so I pushed it out from below (could raise the plenum cover just enough) put some silicone around it and reinstalled. All bone dry now for a week of serious rain here in Seattle.

My advise is to to this first - remove the single screw in the middle of the two plastic plenum covers that are just above the pollen filter access panels. Open up the pollen filter access panels and pull out the pollen filters. Now reach in and push up/out the plastic nut insert. Add a dab of silicone around the four sides and reinsert. Put the filters back in and close it up and see if your leak goes away. What gave it away for me was that my pollen filter was wet and then i reached up to see where the water might be coming from and it was dripping off the bottom of the plastic insert that hold the screw that comes through plastic plenum cover directly over the pollen filter.

Glad to be able to check that box....
 

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I stripped mine down last year, replaced filter and siliconed all housings, screw heads etc,, but if rhd then the drivers side wiper spindle is directly above the pollen filter, I pretty certain with slight wear in the mechanism this allows water down the shafts to drip into the filter. I no longer get water on the p/s but small amount occasionally on drivers so presumably that's the cause, will investigate again if we ever get a summer. The plastic clips on the windscreen finisher Lower trim are a bit flimsy and a job to line up, plus the odd rusty screw, but a fairly easy but time consuming job, good luck hope u cure yours
 
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