Get that Grill back from those harsh weather conditions.
Step 1: Disassemble the BBQ Grill
Ok lets rip into it, first unscrew all wooden parts, handles, side trays, etc. Keep all the nuts bolts and washers so you can either reuse them or find the same size at the hardware store. You will most likely need only a crescent wrench and a screw driver for this, bolts may break if they are too rusty. Remove plastic caps from the burner switches, they should just pull right off, otherwise look for a small hole in the plastic that may have a set screw in it (most likely a hex key). If your igniter is broken take that off as well. leave the grates intact for now, but you may take off any baskets or other outside accessories.
Step 2: Clean the Inside
So the easiest way to start this process is to move your grill into an open area just as a precaution, and cover the grates with aluminum foil. Turn on the grill (high) and close the lid for 15-20 minutes this is going to let off a lot of smoke for it is burning all the caked on grease inside to a powdery ash. Just like the auto clean function on your stove. turn grill off and let it cool a few minutes then you can get out the wire brush, and spatula, and go to town scraping all that old grease off. this may or may not be good enough for your standards (it is a grill). Or you can get out the degreaser and spray it on and leave it sit for a while then wash it, and wipe it out, completely free of grease. I would suggest to do this if you are planning to paint the inside of the grill (steps upcoming).
Step 3: Wash Everything
Clean, clean, clean, take a scotch bright pad and dish soap and water to everything. The scotch bright will act as a mild sandpaper so be cautious around lettering and signage, but really go after any rust spots you see. If you cant get rust off take out the real sand paper to get rid of it. Hose off all soap and let dry.
Step 4: Paint It
As we were cleaning the grill with the scotch bright pad, we were also scuffing the surface a bit for good adhesion of paint, but if you think it could use some more use a light sand paper like 220-320 grit.
When painting a grill you must use two different types of paint. For the grill housing itself use High Heat Paint (DO NOT USE ON THE GRATES OR ANY THING IN DIRECT CONTACT WITH YOUR FOOD). You may spray the inside and outside of the housing and lid as well as the burners themselves if you are careful as to not clog the holes. Spray paint on a clean surface, also free from rust, in even strokes overlapping each line by 1/2 to 1/3 for even coverage. After letting this dry for a few hours youmust cure this type of paint with heat. (read can for instructions) Turn grill on high for 20 min or so should cure it.
Next is a standard spray paint for wood metal plastic. This will be used on all other parts of the grill using the same application methods as above, minus the curing process, and possibly adding a light sanding and second application if necessary. If needed replace any wood pieces that have broken or split, then sand and prep all surfaces for painting. Tape off any branding or operational guides as to not lose them. ( or you can re paint them on if you want) Precaution as to sanding and painting the propane tank. Only lightly sand surface rust, (if it is pitted you are best off to leave it alone and look into getting a new tank for safety) and cover all connecting hardware before painting. also do not paint if you are one to trade in propane tanks at the local gas station or convenience store, they may not take it.
Once again you are best off replacing any badly rusted and pitted grates do not paint. Or you can mix two cups vinegar and one-cup salt in a bowl. Place your rusty grates in a large heavy-duty garbage sack. Pour the vinegar and salt into the bag and tie it shut. Lay the bag flat on the ground and let the grill soak over night. After soaking, wipe the rust off with an old rag. The salt should act as a mild abrasive to scrape off the rust. These are food products so they are safe to eat off.
Step 5: Put It Back Together and Get to Dinner
Replace all the parts, screws, grates, knobs, emblems, etc. Hook back up propane and make sure every thing works. HOLD UP! Don't through the meal on that grill just yet. Time to talk about maintenance, That grate you just got so pretty and clean, is actually a lot like a cast iron skillet you actually need to heat up and spread vegetable oil on it (don't use spray oil its flammable) as to prevent rust in the future. Also do this after scraping the grate clean after each meal. Buy or make a grill cover, it will save you from doing this every year. Now only every few years.
Now what's for dinner? Enjoy!
Step 6: Afterthoughts and Comments.
Ok so after reading through the Instructable I realized I may have skipped over a few things. Also I've got some feedback from you folks that got me to thinking I may need to add a couple precautionary statements for health and safety.
" Reconsider painting the inside of any grill. Even dry paint can off-gas some nasty stuff when heated." True if you want to be the safest. Read up on all precautions of products you are using, you won't always find them on the bottle, do research on job specific safety hazards. In this case you have Heat, fumes, open flame, grease, oil, paint, propane, rust, food, and more to think about, in combination with each other.
"Recommend leaving the inside as-is or cleaning down to bare metal and seasoning with down type of oil."
I do this same thing to prevent rust it is way easier than stripping it down all the way.
From a finishing aspect painting of the inside of a grill is a real nightmare for adhesion, because of all the built up grease. Unless you strip the inside grill to bare metal I wouldn't advise painting it. I personally don't paint the inside of my grills because after the fire cleaning it is pretty smooth and evenly charred. Plus after you cook on it a couple times you wouldn't notice anyway from the grease buildup.
I will spray a little paint on areas like the drip holes but only to prevent rust that commonly occurs in these areas. But only if it has already started to rust. Also the heat in these areas are NOT AS high because of direct airflow (still hot none the less, but hopefully your grill will not rust all the way through) allowing the high temp paint a little relief. Though if cured properly it should withstand 1200°f when most grills will only reach 550-700° at the hottest point in the center.
I realized I did not bring up a few things.
Parts: If you go to your local BBQ dealer you can usually find all the parts you need for your grill, just long as they sell the same brand BBQ, if not I will let you in on this little secret I've heard about, a place of wonder and amazement that you can find almost anything you could possibly imagine, its called the internet....... ?Wait, what, your telling me you know about this place already?
Well then my friend! You know then of a place to find burners, and electric igniters, and hoses, and grates, even knobs, and covers, whatever you may need.!.!.
Oh one important thing about igniters even though they spark, if the ring around them is not screwed to metal they are likely to fail due to no ground, its just a bonus that it holds it in place as well.