The other day I thought that it would a good idea to wash the engine compartment of my 89 325I. Maybe not such a good idea after all. Although I did find that my spark plug wires were arching when wet so I replaced those. Another problem that arose is that my temperature gauge started to give an erratic reading and after about 10 minutes it drop to zero. I replaced the sending unit to no avail. If the car sits for a few hours the gauge will climb to about the quarter mark but then start bouncing up and down and then finally just going to the cold position. After running the car for a few minutes like that it starts to stumble and miss. I’ll stop the car for a few minutes and it will run fine for another ten minutes and then the same thing happens. I have read a lot about the possibility that it might be the ground on the instrument cluster but I don’t see how water in the engine compartment could cause that.
Thanks for your help.