Mercedes-Benz Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter #1
This is on a 1984 300D turbodiesel. automatic transmission.

My CCU recently went out. It had been shutting on and off intermittently, though the defrost setting would always still work. Anyway now it's gone completely, and it won't turn back on, even on defrost.

An odd thing I noticed: with the CCU off, the tranny makes a high pitched whistle when shifting between 2nd and 3rd, sometimes also between the other gears as well but usually 2nd and 3rd. Also, when cruising on the highway (i.e. in fourth), it will make the same whine right when I lift my foot off the gas to slow down -- then, if I speed up again, the noise comes back. It's only their at the beginning of a transition between acceleration and deceleration; the tranny sounds normal if I drive at a constant speed.

I had heard these noises before when the CCU would shut off intermittently, but they would go away when it came back on. Anyway, now I'm hearing it on a regular basis.

Any hints?
 

·
Registered
Joined
·
2,653 Posts
It's a vaccum leak that you're experiencing with the CCU which uses actuators in the dash. Unplug all of the vaccum to the interior (plug the lines) and see if you notice a difference driving it around. If you have a vaccum tester check the vaccum pull as well off of the main brake line. Of course leave the vaccum connected to the brakes, you'll need that!
 
1 - 3 of 3 Posts
Top