If just the clear is peeling, can it be sanded off and resprayed? Or is a total repaint the way to go?

 

It will all need to be sanded down to solid material and repainted.
Even if somehow manage to sand fine enough that the clear would fill the scratch and have no bad feather edges that would show or lift when solvents attack the thin edge, it would probably never adhere to that old base that has been exposed to the elements with no clear providing protection, and you will soon be in the same boat. Also if it is a metallic or pearl color, when you sand it, it would disturb the metallic and it would most likely be streaked and blotchy and be magnified with the clear on it.
At the very minimum it will need to be sprayed with either a single stage, or rebased and cleared within the time window given for the base. Base and clear are really made to adhere chemically. I'd probably atvery least thow on a coat or two of epoxy reduced as a sealer after sanding it down well, all the old clear layer off, and apply the sealer just prior to when I plan on spraying the paint, at least an hour before you blow on color coats, no longer then a few days. This will give you the opportunity to sand out defects and use a bit courser paper then if you were going to just be painting over the old paint. Also sealing is a good idea, cause it can prevent a lot of possible problems that could arise otherwise. Check your epoxy for window without sanding, generally have up to 3 to 7 days before it should be scuffed and re applied and paint can be applied over without sanding. Check the product data sheets for the materials you will be using. Can't tell exaclty what color you have there, but looks dark to me, so maybe a black epoxy, or something closest in shade to the color you will be spraying.

 

you still have to sand it down and tape it up, it would be stupid to only put clear on it... the color is the cheapest thing and its no extra work to put it on...

 

Color is sure not the cheapest part. Ever price a color like red pearl lately? Where is clear is pretty consistent in price, running in the neighborhood from 100 to 300 a gallon depending on brand and quality, color can run all over the place depending on what tints and additives are in it, and the price code it falls into. The color shifters such as chromalusion and chamelion run somewhere around 3 grand a a gallon. Few years ago I bought an indigo blue pearl and was shocked to find that it fell in the highest price code, blues normally being middle of the road in price. It was 80 per pint then. I just priced a silver metallic which is usually not too bad priced as far as colors go. In ppg dbc it was 100 a quart, and even a smaller car and an efficient gun meant I'd need two quarts of color. So two quarts of color, once mixed yielding a gallon was around the same price as a gallon of clear, a little more once you figure in the cost of reducer.
With the cost color can run is a good reason to have an gun with good transfer efficiency and pay attention to the recommended primer or sealer shade for best coverage, or in the case of a complete seal everything one color and don't have different colored primer spots all over.

 

well none of these materials are cheap by any means, and i dont think hes gonna be putting color changing paint on his truck, but it would still be very dumb to pnly put clear on a vehicle...

 

A guy I know took all the clear coat off of a Toyota Supra (which had started to peal in places) with an Air Duster Gun on a good air line. I think he then flatted it and sprayed new color and clear coat.

 

Simply put, you will need to completely sand the hood, seal it (because you WILL end up sanding to bare metal), spray your color and clear. I suggest that you undercoat the inside of the hood to reduce the heat transfer from the engine.

Looks like you have a late 70's hood, is there checkering in the paint too?

 

Thanks for the replies, I'm inexperienced when it comes to paint.
The truck was actually repainted in '96. I'm not sure what condition the original paint was in, or what prep work was done to it, but the clear is like this all over the truck. Mostly on the horizontal surfaces, I'm guessing from UV exposure. I just used a pic of the hood for example.