Steam Cleaned Engine PROBLEM on 97 E420

Hey Guys,
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 sentence).
MY QUESTION: 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
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On 2005-04-26 23:13:52 -0700, " snipped-for-privacy@teleport.com"

bad idea as you discovered. This is standard practice for many engine detailers, but good ones know how to avoid the trouble spots and usually leave the engine running, so they can tell if/when they are getting something important wet (also the heat keeps critical areas drier).
I would never clean an engine that way myself, as I would rather have some dirt on the outside, then have water on the inside.
They might have been able to dry the Coils with pressurized air, or more likely if you just waited, they would have dried out all on there own and been ok.
Now you have new ones which is also ok.
Marty
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i have always used GUNK foaming cleaner. works good on a cool motor garden hose rinse and it looks pretty good
the case, minus a few cans!
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First, never spray water (especially cold water) on a hot engine. A sudden cooling effect may warp something and that something may be costly.
Second, cover or avoid ignition circuit when cleaning. Water can definitely disturb the high voltage spark generation. Depending on where the short occurs, I believe component (coil, connector, wire) failure is possible.
Last, completely dry the engine, especially electrical parts and wiring before taking the car on road.
snipped-for-privacy@teleport.com wrote:

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Alot of time, when you first noticed rough engine after a wash, you can blow out the water with air and everything should be fine. WD-40? No idea... would not even try to use it.
However, if you continue to drive the car with water shorting out the coils, it will ruin it.
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Wow Tiger, This is definite information. Have you had luck doing this - or, someone you know? The DETAIL Shop claims they could have salvaged the coils by doing just that. If it was the traditional distributor / coil combination, I'd agree with them. With the COIL-ON-PLUG (COP), I don't know what to expect. Anyway, the mechanic cleaned up one that was not as wet and the other and it performed O.K. but later failed while he was finishing up on the work. Thanks a bunch for your input on this. One of the joys of buying a "seasoned" (aka, older) car is that some or most of the secrets are common knowledge, if you get into the right circle of folks.
Ciao for now.........Hez
============================ Tiger wrote:

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Well, it _is_ a lousy lubricant, but it's original application was as a Water Displacer, so it probably would have been worth a try. OTOH, steam cleaning an engine has always struck me as a dicey proposition, and replacing the effected parts is the definitiive cure...
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Ahh! Is that what WD means???
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When I brought my E420 Sport to Ziebart for engine steam cleaning they told me they wouldn't do Mercedes. I figured they had a good reason.
On Wed, 27 Apr 2005 06:13:52 GMT, " snipped-for-privacy@teleport.com"

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