I'm in conversation with a detailing outfit that used high pressure hot
water to clean my 1997 E420 engine.
Well, a rough idle developed the same day I picked up the car. I had a
scheduled servicing done a week later (I basically parked the car during
most of that time; especially after the CHECK ENGINE light came on a
couple of days later) and the mechanic had to change the COP (coil on
plug) for #8 cylinder. He said it was all wet when he went to change
the spark plug. #4 cylinder COP wasn't that wet and he dried it off and
reinstalled the COP.
Fortunately for me, the #4 COP failed during the test run and it had to
be changed, too. Now, the car runs great!!! Including the price of 2 COPs.
The detail guy claims I should have brought the car back to them right
away to allow him to try to correct the problem - basically, blow it out
with air and/or spray it with WD-40. He claims to never had any
problems with cleaning engines and said any problems were usually solved
by blowing out and spraying with WD-40 (a contradiction in the same
Are COPs fixable by blowing out and flushing with WD-40? Or, do these
units short out and become inoperable? Can a COP be bench tested?
I have one of the COPs as exhibit #1.
Any similar experiences or horror stories anyone have that I may learn from?
Thanks in advance.
Hez of the Pacific NW