Last Friday morning, I started up my 200 Focus (SE - Zetec) for my short morning commute and noted that the engine seemed to be running rough. The car had been driven the night before and ran normally. The night was cool and misty and during the night, the temperature dropped to below freezing, so the grass was white and there was a thin layer of frost on the car when I started it. After cleaning off the frost, I took off down the street and noted the engine wasn't running quite right, but I arrived at the office without significant trouble. I guessed that there might have been some moisture that had gotten into something (sensor or ignition module) and figured that maybe in the daytime heating, the problem would clear itself. After work, I got back in the car and, to my chagrin, the rough performance persisted.
The next time I got in the car was to drive to the airport to drop off my daughter. I took the Focus because I thought the longer ride might clear out whatever was causing the problem, or would trigger the computer to record a diagnostic code. Well, about half way to the airport, the condition got significantly worse. Now the engine felt like it was running only on three cylinders. The check engine light started flashing furiously. At this point, I was committed to completing the trip, so I pushed on to the airport. When I arrived and parked the car, there was a smell coming from the engine . . . it wasn't oil and it wasn't antifreeze. I popped the hood and noticed steam whisping from one of the spark plug boots.
I pulled out the spark plug boot and, to my surprise, there was water on the head that was deep enough to fill each spark plug well and bridge from cylinder to cylinder!
I let the car cool for a while and then went about trying to wick out the water with paper towel. I couldn't get the paper towel down into the spark plug wells, so I used the pump from a window cleaner spray bottle to pump out the last of the rusty water. When all of the water was out, I reconnected the spark plug boots and the engine started and ran perfectly.
When I got back from the airport, I once again pulled a spark plug boot and looked inside. I found what I expected to see, a completely dry head. But I also noticed that the spark plug boot was fully covered in rust from the water that had been standing inside.
Has anyone else experienced a problem like this? I can't imaging where so much water could have come from or how long it could have been there. I would have thought that the head gets hot enough to drive off any moisture that might condense in this area!