Hi
I have 300D 84, and i feel a lot of viberation underneath the car ( between the front seats) when accerelating from zero real fast but it goes away after reaching normal speed, i though it might be the rubber mount for the intermediat shaft or may be the ball bearing, what do you think,I also have a problem with the heater( weak heat in idal, good heat between 10 to 40 miels and then very week heat over 50 miels on the highway),i tried to test the monovalv by dissconecting the elctrical plug that goes in it and though that this will set it to max heat all the times but it stil acts the same thank you very much for your help.

Don't know about the heater problem but vibration could be any number of things. I'd check (in order) center bearing (on shaft), transmission mounts, engine mounts, and rubber flex-disc on shaft. Because its only during acceleration, the driveshaft is likely not out of balance. The costs of these things are not terrible - particularly if you can do it yourself.

Nic
'85 300CD @ 137k miles.

As far as your heater is concerned, you may have a bad thermostat. Pay attention to your temperature gauge, and if it is not reaching its normal operating temperature than the thermostat may be stuck open. This happened on my 300SD and the car produced very little heat.

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K

hi
no, my thermostat works fine because the temp gage reads little bit over 80, also the heater is fine under 40 mph but not in idle or over 40 mph

As far as the heater is concerned, I think there is a uncooperative valve that does not work good enough any more.
It seems to me that the valve that has to guide the incoming air-flow towards the heat exchanger is only opened/closed half and that there still is a lot of air coming in the interior without being guided through the heat exchanger...
On the european models (non airco's) this valve was controlled by a cable; I don not know whether the US models are controlled by a cable or by a vacuum pot...

Basically I think you get to much unheated air in your car; the heated air will be warm enough, but the mixture (heated-unheated) is not right and the faster you drive, the more unheated air comes in!

greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)