Originally posted by FourthGenHatch
The spark plug wires should make a good enough seal to keep water from going down that hole for the spark plugs. My valve cover had a pool of water on the top when I was done this and none of it went into the spark plug chambers. Car started up fine right away.
There is no problem with a hose, however I remember looking at a used '95 teg at the local dealer a while back, on the behalf of a friend. I asked a salesman to start it up, he did, and it ran like shit and threw a CEL. I was thinking, uh-oh, stay away from this car.
He looked at me and said, "I know what's wrong." He popped the hood and pulled the #1 spark plug wire. The wire end was dripping wet.
Apparently, they clean the engine bays with a high-pressure water sprayer, and it gets into the plug holes pretty often. The guys in the service area haven't quite figured out how to NOT use the high pressure line when cleaning them out, no matter how often they are told not to.
After standing there watching the salesman dry the plug holes with a couple paper towels, it fired right up and ran fine. The moral of the story: be careful where you spray water under the hood.