CAUTION: working around engine "plastic" vacuum tubing, it can break.
A Warning for your information:
I was cleaning up my 1996 S320 engine compartment and wiping gunk off some engine parts at the front of the engine next to the front plastic cover, when I accidentally and unknown to me I wiped and broke a brittle vacuum tube going to the EGR valve. This caused the check engine light to come on and caused me many day's of grief to track down the problem.
The vacuum tubing used on Mercedes is plastic and not rubber like on other makes. So over time the heat from the engine will cause it to become stiff, hard and as brittle as glass. So if you should you try to, or accidentally bend or move to much, it will break in two. Especially the 2 tubing's going over the top of the engine next to the spark plugs and coils {under the top cover} and where they come out from under the top cover at the front of the engine. The tubing will not bend but break, so don't even test it if it looks yellow and not white. You may never know you broke it because it will stay in position and not separate because it is stiff. I just replaced my tubing for about $12 {for 3 meters of tubing you cut to length} with OEM vacuum tubing from an MB dealer. You will see the white {or yellow if old & brittle} plastic vacuum tubing around the engine area. If you chose to replace it. Do one section at a time, the plastic tubing pushes into rubber hose connector's that attach to the components it's going to. Or be aware and leave it be, and get some tubing next time you are at your dealer and keep it available.
When they called to tell me the car was done and explain the bill. They told me it was a half hour diagnoses and 5 hours (MB service book time) to replace the EGR tubing
because it is plastic and is in difficult areas to install.I now find out that the only reason it had to be replaced was it shattered when the service guy was doing the diagnoses. This is the third dealer I have tried and the third costly screwup I have encountered. I feel like I am getting C-Class Service at S-Class prices.



