Originally Posted by arado
If when you try to start the car and all you get is clickety click...Look at the battery cables. Corrosion or being loose can cause your problem. Remove cables, clean post and clamp. Reinstall then coat with petroleum jelly as an antioxidant.
Gary
FP, I'm with Gary. I was so wrapped up thinking about things that could go wrong when you hosed it down, I forgot to mention the #1 most common problem, the battery cable.
There can be enough corrosion to keep it from making a good connection, even if they look clean. Sometimes it just looks like a "black" residue. If ya don't have a battery post/cable cleaner, just use some sand paper.
Like Gary mentioned, I've also used petroleum jelly in the past with no problems. But my "Electrician" buddy tells me to use a special "electrical grease" that conducts the electrical current better, and I guess it has a higher resistance to heat so it doesn't "melt off" as easily.
He says, save the "love lubricant" for other uses.