Harmonic balancer / engine vibration

I should change my handle to "stupid" as that is the way I feel. I spent $575.00 to have the trani pulled to check the flex plate for cracks. That is what the shop foreman at Richmond Mercedes said was probably the cause of the vibration. He quoted $1,200.00 to do the re & re. I guess someone has to pay for their new show room. Not me!
After the ”Train Shop” guys did a magnetic iron powder test on the flexplate and determined no cracks I went home very frustrated and $575.00 poorer as well as the proud owner of a new flex plate $37.50 and 12 necked bolts at $75.00 for the set. These parts, still in the package, I acquired from the BenzBin as there was no stock in Canada. Oh yes did I mention that had paid Mercedes $125.00 to analyze and determine the problem in the first place. I think the Mercedes shop is to concerned more with the bottom line than the honesty of their work.
When I came home I removed the belts to isolate the alternator and fan to eliminate them as a source of the vibration. All ok there. Next off came the cam shaft cover and a tappet inspection found a couple of valves very close. After a complete valve setting the engine ran as smooth as a new car. What I don't understand is how a close valve or two can cause a vibration between 2000 to 3000rpm. Why not all the time? I am very relieved that this is over but very pissed of that I spent about a thousand $ didn't have to.
A valve cover gasket is only $5.50
Oh My God!

There are two possible scenarios. Scenario number one, you take the care in and tell them to pull the transmission and check/replace the flex disk. Scenario number two, the dealer does the analysis and tells YOU that they should pull the transmission and check/replace the flex plate.

If it were scenario number one, you should pay them, learn from it, know that it was your call, learn from it and go forward. If it, as I understood from your post, was scenario number two, you do NOT owe them for removing the transmission and checking the flex plate.

My $0.02,

[stevenstevensteven]

John,

I'm currently trying to isolate my own vibration problem, but I have yet to determine if this problem is coming from the engine, tires or suspension. But you mentioned "valve setting" being the problem. Do you mind telling me what you saw and how your fixed it, as I have yet to explore my valves yet.

To stevenx3
If you have determind the vibration is in the engine the least expensive thing to do is set the valves. Valve cam cover gasket must be replaced but is very cheep. $6 bucks or so.
As I have found out the hard way, that even a close valve setting can cause a vibration at a specific RPM range.
Hope this helps. keep in touch John Winter