I plan on doing all my trucks body work myself over maybe a years time I hope. Im not doing a show truck but I want it to look nice. Should I take it all down to the metal when sanding it or only on the sections I repair. What primer should I use on metal surfaces vs finished surfaced that have been sanded but still have some portion of the original paint on them. Do I put another type of primer over all that when I'm finally ready to paint it?
Thanks
Sometimes there's too much information to go through and it all starts to make no sense.

 

Repair areas go down to bare metal. Then etching primer if ya got more to do. Primer surfacer to wetsand. Primer sealer before top coat or if ya move to working another area.

Original enamel paint (and its primer) are generally OK to apply a high-build primer surfacer to block sand, then a primer sealer before the top coat.

Yes, primer sealer over the entire vehicle before top coat. Wet sanding primer sealer is OK too when there is little to no block sanding involved.

Primer surfacer is porous so avoid exposing to moisture over extended periods of time. Primer sealer is not as porous but will too show flash rust through the coat if left for exposed.

 

Good advice from HIO Silver. I've done similar with good results.

Another approach is to start with epoxy primer. Do the repairs, sand the rest smooth with something like 150 grit then hit the whole thing first with epoxy primer. Follow that with primer surfacer. If repairs are done over time, its fine to spot prime with epoxy then sand and re-prime the whole thing when you are ready.

You just have to judge the condition of the existing paint and metal underneath it. If the paint is in bad shape in large areas or you see rust starting underneath it, it should come off to get a good lasting result.

 

+1

Epoxy primer over bare metal then primer surfacer then primer sealer then finally..........top coat....woooohooooo.