XJ6 & XJ12 Series I, II & III 1968-1992

XJ12C: Seam sealing?

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Old Dec 4, 2022 | 08:46 AM
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mlindblom's Avatar
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Default XJ12C: Seam sealing?

Hi
I am almost done with all the welding work on the main body, Sprayed some of it with Epoxy primer (inside and underneath).
So I guess its time for seam sealing of all weld seams (new and old) from both sides?
Question:
- Any tips / do & donts regarding this?
- How was this made originally from factory?
I already bough a brushable seam sealer. Will try it out on some scrap parts.
Thanks
Marcus
 
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Old Dec 4, 2022 | 09:46 AM
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With Coupe's stopping the water from getting in is important but more important is letting the water out, Coupe's are sponges, water seeps in from around the wind screens and side glass. Condensation from use also builds up and gets trapped in the body.

There are several design flaws that trap moisture and condensation in the car. They need to be addressed and the car needs to be better vented.

1. No B pillar vent like there is on the XJS. The doors are sealed on the inner flange unlike most modern cars that seal doors at the door skin's edge.
2. Door seals are attached to the body. Funneling water into the shell and Trapping water that wont drain when you open the door but sits on the seal and splashes inward when closing the door,.
3. Front and Rear fender lips are 2 piece and act a aqueduct funneling water into the sills,.
4. Sill drains / vents are to small and clog with scale quickly trapping moisture, Jag enlarged the sill vents on the Series 3
5. Base of rear 1/4 glass area needs to be vented and drain enlarged. Water that seeps in from the glass cant drain out of the paltry OE 3/8 tube bent in a S that quickly cloggs with scale trapping moisture.
6. Water that leaks in from the rear screen runs down and sits in the rear seat pan like a bowl of water always there. This area needs a vent / drain
7. A/C and cowl drains need to be enlarged, Unfiltered air quickly mixes with moisture in the evap and creates a slurry that clogs the drains.
 
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Old Dec 4, 2022 | 12:51 PM
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Jose's Avatar
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the factory used some type of caulking.
 
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Old Dec 4, 2022 | 01:45 PM
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Hi. Great many points. Will look into this.
How would you modify the space underneath 1/4 glass? The drain pipe seems useless. Why not just drill holes directly into the sill and let the water go down there? How would you vent this area?
br
Marcus

 
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Old Dec 5, 2022 | 07:42 AM
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Originally Posted by mlindblom
Hi. Great many points. Will look into this.
How would you modify the space underneath 1/4 glass? The drain pipe seems useless. Why not just drill holes directly into the sill and let the water go down there? How would you vent this area?
br
Marcus

Ideal situation is to add a larger 3/4" drain and add a flap that faces backward or multiple vent holes or slots like Jag did on the rear valance area so it can breath and let water, condensation and debris out. Then add a B pillar vent in the door sill area like Jag did on the XJS. The later is somewhat impractical becasue the door seal is on the body's door flange.

If I was going to refit the vent to an existing design I'd run a 2 inch tube from the top of the rear 1/4 area into and have it vent in the sail panel or rear deck behind a decorative vent panel.

On my next Coupe project, a 6.0 V12 manual I plan on relocating the door seal to the door and take many other design improvements from the XJS.
 

Last edited by icsamerica; Dec 5, 2022 at 08:49 AM.
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Old Dec 5, 2022 | 09:09 AM
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I have used drain plugs from a Mercedes, I believe the W126 and W123 both use this style. They work well wherever you have a relatively flat surface. I have used them in the trunk of an XJ40, front and rear floors of a Saab 900 convertible, as well as the trunk of my Mercedes. They will let water out, but not in. Easy install, drill a 26mm (or close to it) hole and install. I have also replaced the foam backing on carpets/mats with a closed cell design. Open cell foam used on many floor matts and or carpets will hold water like a sponge, which itself is an open cell foam. Closed cell will not absorb and hold water.





 
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Old Dec 6, 2022 | 12:56 PM
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Default Liner Position

Side Note. Noticed that on one side of my XJC, the bottom of the plastic liner was tucked outboard of the flange allowing water to theoretically remain out of the pans under the rear seat where, regardless, I found major corrosion.
 
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