Hey guys.

Quick question. I have noticed lately that when I start my 2004 MCS in the morning, I hear a clicking noise coming somewhere from the back of the car for about 10 - 20 seconds. It has nothing to do with motion, because I hear it right after I start the car, and before I start moving. It has a steady rhythm to it, so it seems to be something mechanical.

Any ideas?

 

That's a warning sound for you to speed up!

 

There is an emissions control device (actually a pump) relating to the evaporative emissions control system back there. Most cars nowadays have these, you will occasionally hear a rhythmic tick-tock sound for about 30 seconds, mostly when starting off cold or after refueling. This is the pump that puts a slight pressure in the fuel tank to test the evaporative (fuel vapor) control system, and part of the system that will illuminate the check engine light if you don't fully tighten the fuel cap.

 

Greatbear - You have described exactly what I am hearing. Thanks for clearing that up for me.

 

After V39 updated I started to hear that noise now! Will it go away?

 

I still have V36 and mine still makes this noise, don't think it has anything to do with the software although I can see the connection given the emissions recall thing and V39.. :smile:

My VW R32 makes the same noise.....Nothing to worry about

 

V.39 is part of the voluntary 'recall' for the evap emissions system. My understanding is that it operates the LDP (leak detection pump) more agressively, meaning more often than previous versions. The system would sometimes fail to find a leak in the evaporative emissions control system. I can verify that it did not always work, since one time I was distracted at the gas station and drove off without replacing the cap. This SHOULD have lit the check engine light, but didnt. V.39 runs this pump more often and would catch the loose cap.

You will end up hearing the tick-tock more often with V.39.

 

i've been hearing that clicking sound for months now.