Why the rust problems with these trucks?

[Jason Mills]

I am headed into some rust repair on the cab of my 67 sweptline, and I am not really sure I understand why it has rusted in the way it has.. In some respects it seems to be rusting due to condensation...

I can understand that it is rusting due to road salt, and yet lots of this truck has rust in places where there was no road salt.. and the front fenders are actually in pretty nice shape..

Did Dodge use poor paint? Super thin metal? or is it a poor grade of steel used? I am asking, as I would like to make some repairs, and stop the rest of the cab from rusting away!

I would appreciate hearing your opinion, perspective, or most educated guess, So as to better understand the WHY of this issue.

Thanks,
Jason

[74w300uteline]

Clogged drain holes

Cause odd rust patterns. Weep holes get clogged, sediment retains moisture and feeds the rust cycle. The weepholes rot out into big rustholes and its hard to imagine anything getting trapped. Pine needles and those oakstring things cause headaches for me when they get into the cowl vent. Clay gets into the rockers and also causes slow release moisture problems. Crazy as it sounds its better for me to blast water into the rockers to get the sediment out

[Jason Mills]

Great answer.... and seeings how I don't have any rocker panels left, It would be hard to imagine a weep hole being the cause.. but now I get it..

any ideas as to why the area in around the door hinge rusts so well from the inside? does the moisture come from the windshield area, or up from the road/ground?

[74w300uteline]

Not sure about sweptline

But the lifestyle era trucks channel water through the cowl grill( slotted panel between hood and windshield) into a trough that empties ahead of the door hinges. This all became clear to me after dissembling a rust free 70s era cab . Metal window screening gets installed when the plastic windshield wiper bushings fail and cowl gets removed for acess to wiper pivvots. I see you 're in Vt , my money is on pine needles clogging drains up. We cant rule out mice nests either. Lots of fluffy moisture holding material.

[Jason Mills]

But the lifestyle era trucks channel water through the cowl grill( slotted panel between hood and windshield) into a trough that empties ahead of the door hinges. This all became clear to me after dissembling a rust free 70s era cab .

That is the type of answer I am looking for, and not knowing how to ask.

Valuable information, which is not immediately apparent when looking at the rusted examples, is gained when seeing a prime example. Thanks for expressing this, as it is helping me understand, and remember to "Look for the Cause" beyond what is apparent or obvious.