08 clk63 cab. Garaged for the winter... I got it out and drove it last weekend at which time it started and ran like a champ and I put maybe 30 miles on it.

Thursday night I pulled it out and gave it the first wash of the year... then put it back in the garage.

Saturday, went to drive it, and it DIDN'T WANT TO START. Had to hold the starter on for a good 5 seconds or more, then just when I was about to give up, it caught and sputtered and spattered and settled into a rougher than usual idle WITH A NEW AND OBVIOUS TICKING COMING FROM THE ENGINE.

Sounded like good old lifter tick (but I have no idea what it really was). Opened the hood, it was loudest and from the top rear center.

So I shut it off and decided to take the truck.

This morning (Sunday) I decided to drive it a little and see it if cleared up or stayed spluttery and ticky.

Started right up (ie touched the start and let the car start itself which it did promply like usual). Ticking was present, but quickly dimished and then stopped. Like 20 seconds from start to not ticking. took it out and drove it some... all back to normal.

WTF? Is that from water getting in someplace? I didn't open the hood while washing, so no direct spray on the engine or electronics. And would electronics cause a ticking like a lifter tick?

Any idea what just happened?

Thanks in advance!

 

Garaged for winter means different things to different people. Being from NY, to me it means parking the car in a garage for a couple of months. In those cases, it’s common to change the oil and get a fresh tank of gas after the car is revived in the spring. Ordinarily, gas can sit a couple of months. However, that’s assuming a FRESH tank was added before it was parked – and it should be full. As for the lifter knock, some schedule an oil change immediately after the winter break. For regularly used cars, some change the oil before parking it for the winter break and again right after. Others will say with today’s synthetics, it’s a waste of time blah blah blah. It’s ultimately up to the owner. If you DIY, it’s only $50.

It’s important to have a full tank of gas when parking it for a few months. The tank itself will degrade if the sides sit exposed to air. This isn’t a Mercedes issue, it’s true of any gas tank. Just ask any motorcyclist. As the tank degrades, the filter will get full of trash if you’re fortunate. If you’re less fortunate, the injector spray pattern will get very bad. That impacts idle, power, and smog.

I have serious doubts that washing the car with the hood closed is a related issue.

 

I don't think it was bad gas either. I drove it last weekend. And once it settled down I drove it all day yesterday. It was one isolated incident that just has me concerned.