I discovered that the upper tailgate from my MY2010 Westminster is slightly corroded, what a surprise.
There is only corrosion on both edges on the inside (seam?) and around the locking mechanism.

I already used a can of Dinitrol ML to treat the inside of the body panel.

How should I proceed to treat the corrosion in the area as shown in the picture?

Click image to enlarge

hello, i know this is an old post but id love to know of you managed to correct this and if so how?

Once the rust is visible on the inside of the tailgate then it is too late to treat it successfully, anything you do will just "slightly" postpone the inevitable, the only way to fully cure it is to cut off the bottom outside section of the tailgate, sandblast all the rust off the frame and weld in new metal then treat it all to a good dose of rust prevention...

The rust has developed between the outer and inner skin and once it's there you can't get rid of all of it without surgery... it only takes one crumb of old rust left behind for it to continue to rust....

Keep an eye out for an early tailgate with no rust, the early ones were made out of better quality steel and had some rustproofing....  Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

A rusty tailgate is a badge of honour. It proves you are a dedicated L322 enthusiast and not just any old SUV owner. 2012 TDV8 Vogue (L322)

That did make me chuckle and l totally agree!

Depending on how bad it was it could have maybe been 'saved'. Depending on how the rust was on the inside of the tailgate. I'd say your best bet is to have a shop grind all the seam sealer off and open the lip to see how the rust is in there seam. Hopefully if not bad or just concentrated around the seam then you can treat it, reapply seal sealer, and repaint and get some more time. But I HIGHLY suggest a yearly treatment of cavity wax of sorts in the upper tailgate.

Otherwise your only option is to find a new/used tailgate that is rust free and start treating it from there.

>suggest a yearly treatment of cavity wax of sorts in the upper tailgate.

How much is required, looking inside there seems to be quite a void, would 1L of Dinitrol ML Brown spray do it do you think ?

I have already sprayed in the Dinitrol RC900 ( Rust Convertor ) , and it is slowly dripping out onto my lower tailgate ( I put old towels and rags on the lower tailgate to catch all the drips


https://www.matthys.net/en/dinitrol-ml-cav...n-18193181





Last edited by pcourtney on 20th Feb 2025 4:59pm. Edited 2 times in total

Until it comes out all the drain holes... 1ltr will be plenty...

When you have done that, take off the sill covers and inject all the body sections you can, especially the rear part...  Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I can see the two square drain roles ( they are also getting a little rusty) , but how is water getting into the tailgate box section where it requires those drain holes - a bit puzzling to me ?






I can see along the seam, that the tailgate closes onto the lower tailgate, and there is going to be surface water from driving, and salty water in the winter perhaps, and whenever the rear wiper is used and the water nozzle, a fair amount of surplus water will be raining down onto that weatherstrip, and I get that, and rust will get a hold along that horizontal surface, but how am I ever going to stop that happening, even if I do a really great job getting it back to bare metal and painting again, does anyone have a neat solution for this seam area ?

Haylands wrote:

Until it comes out all the drain holes... 1ltr will be plenty...