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Why (I think) we get rust bubbling around the front windscreen on the 80 series

ByronJ

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wales
Once you inspect a number of 80 series trucks you soon realise that bubbling of the paint around the front windscreen is a common problem. This was a puzzle to me as the paint on the 80 series is generally very well applied, My own cruiser (1991) had just a couple of places where there was a small amount of bubbling around the screen. As I had the truck in the garage to service the front axle I decided to take the windscreen out and treat the rust before it became a problem. I was rather surprised by what I found. I wish I had taken some pictures with the windscreen in place to show how minimal the problem seemed.

This is the top of the screen on the drivers side. A couple of things are immediately apparent from this shot:

TopDriversSide.jpg

- There are distinct lines where the paint from the roof ends and the paint on the inner frame for the windscreen begins
- there is rust all along that join although the only bubbling visible when the screen was in place was in the small area top right of the picture.

It appears that a frame to hold the windscreen is bonded onto the body shell. This joint is a weakness for water to penetrate and once into the joint it can work its way along and rust begins in this fault line.

This is a shot of the top of the screen on the passenger side.

TopPassengerSide.jpg

Although there is rust all along the joint there is no bubbling of the paint as yet. In fact the rust line ran all along the top of the windscreen and about one third of the way down each side. Though paint bubbling was only visible in a few places.

I used a wire brush to remove the rust and the seam is exposed.

JointLine.jpg

I found it difficult to get a decent picture under the energy saving bulbs and the flash just reflected on the wire-brushed steel but this is a reasonable compromise. The White strip at the top is masking tape and the joint between the roof of the body shell and the frame is running horizontally across the picture, just below centre.

Once I got back to bright metal I painted on of KuRust and finished with two coats of black hammerite. I applied the paint with a brush but immediately smoothed it over with a fine sponge. Make-up sponges are good for that...

Unfortunately before the second coat dried a load of dust (from my earlier grinding) blew down from the rafters and landed on the paint. I decided to put up with that for now.

Next time I would:

Put masking tape in position before removing the windscreen as the rubber does not cover the steel in a uniform manner - it varies over different sections.

After applying KuRust I would fill the joint with a fine filler so there are no edges for the paint to slide off.

Do the grinding off outside :doh:.
 
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This must be a common problem on 80s, mine had two bubbled areas around the screen, one at the top which had swollen rust and no paint, the other at the bottom was just starting to blister. When I had the truck re sprayed, they removed all of the glass and trust me, it's not only the windscreen that suffers!

They took it all back to the metal and welded in a piece at the top. The bottom wasn't so bad so that just had a grinder on it back to bright and treatment.

Well worth it though, I cringe when I see re-sprays where they mask up the rubbers and even trim! My truck was totally naked before they started with any paint, headliner off and all the door cards, well impressed with the job they did. :icon-biggrin:
 
Can't say as I noticed a particular rust problem in this area on the 80's I looked at when I was buying. Looking at the pics I would say your LC has had a windscreen replacement at some point and the paint has somehow been damaged during the process. Why should there be a paint boundary between the roof and the inner frame unless the roof was sprayed after the glass instal, highly unlikely. Sorry but I just don't buy that they leave the factory like that. JMO
 
The trouble with 18 - 20 year old trucks is you have no idea of what's gone on in the past, even when they look to be mint. I didn't notice any paint lines on mine, like Byron found...:think:
 
I always thought it was where the windscreen basically shakes about when you drive a long, and the windows rubber rubs on the paintwork to make the line. Mine is quite bad as the truck was stood for about 6 months until I bought it so was not kept clean by this movement.

Cheers, Mark
 
I agree Mark. There have been several version of the windscreen mount and surround, but there are very clear rubbing patterns where the screen moves and the surround wears the paint off. Ii have some on my new truck which is a pain. Not sure how to fix it really. I went to my local screen place who said getting the screen out could go one of two ways .....
 
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They bonded my screen in with sealant, rubber to metal and rubber to glass. That ain't gonna move or rub anything now. Didn't Mr T use sealant originally then?
 
The rust occurs in both front and rear screens because water is trapped between the rubber and body which forms a capillary trap and water cannot dry out. Rubber and steel often form a bad rust cause this way. My rear screen leaked so I bonded it in with black polyurethane sealer. The drawback is if you break the glass you need a new rubber and may have difficulty getting the sealer off any paintwork. I masked my rear glass, body and rubber with tape just leaving two narrow cracks into which I could inject the sealer. It makes the glass really firm and there is no possibility of a leak or corrosion.
 
Hi Clive......... beat me to it. The screen is a dry fit originally . Some places inject a rubber sealer, not a glue like the polyurethane, but it does not last long. I should have described the polyurethane as a glue rather than a sealer.
 
Cheers Frank!

Strange to be a dry seal. The spray shop used a black Bostick type stuff on mine when they re-fitted it.

It's gone off like rubber, flexible but not sticky. It looks OK and certainly doesn't leak. What more could I wish for! :icon-biggrin:
 
As Clive and frank describe above, I have just had the body shop I use to sort this problem on my truck plus a couple of other things to tidy the ol girl up for the summer. The body shop seemed confident about removing the windscreen and re fitting it, Hopefully I will get it done next month and we shall see what happens.

Cheers, Mark
 
My truck is booked in to have the windscreen removed and resealed at the end of this month. It started to leak very badly this winter into the passenger footwell. I also have a thin line of rust visible where the rubber meets the roof. Hopefully the rust progression isn't too bad :pray:
 
Byron, I think my/your other one has a little bit of bubbling around the front screen, nothing on the back though.
 
Hi Brian

Yes she does indeed. I thought I would practice sorting this problem out on my overland cruiser before tackling her as I aiming for a full 'baseline' service and a very high standard of finish on L326 (The road to hell is...). I hope to start that project in April and will post progress so you will know what is happening...
 
An update

Thanks for everybody's thoughts and experiences with windscreens. As I mentioned at the beginning I was surprised by what I found behind my windscreen rubber :wtf:. To add some info relating to peoples comments:

The windscreen may well have been replaced at sometime during the past 22 years but it clearly has always been a dry fit (no sealant present) and there is no evidence that paint has been damaged by removing the windscreen. The paint on the body and frame sides of the joint has clean sharp edges with lots of undercoat so looks like original paint to me.

I can find no evidence of a re-spray. It could have been re-sprayed of course but if so they removed the screen to do it as the rubber covers the body/frame joint by a good margin.

I cannot see any evidence of the windscreen rubber abrading the paint on my car, the paint is only missing/damaged along the line of the join and there is no sign of wear on the edges of the paint - most odd :think:.

I had no leaks from the windscreen before it was broken so I hope that is still the case when they fit the replacement screen tomorrow...

Mark and Lorin. Good luck sorting out your rust and leaks. If you have the time and inclination I would be very interested to see a picture of your problem areas once the windscreen is removed.

Thanks again.

Byron
 
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