first time diesel owner - few Q's 1996 C250D
 

after smashing up my 2.5 16v :( i need a cheap car to run about in whilst I fix it.

got myself a 1996 C250D

got a few minor probs and as a diesel (never had one before) i dont have a clue!

if anyone could offer any advice, it would be appreciated.

(1) engine fan, runs continuously - i assume the clutch is toasted....you can feel it sapping what little power you have! engine temp is at 80....i assume i need a new clutch?

(2) speedo dont work - is it a cable or more complex than that?

(3) knocking noise......quite a loud, engine speed related knock on start up- goes after about 20-30 secs.....any ideas? seems to be coming from top part of engine

Any help appreciated

many thanks

steve

1.) do you mean the viscous clutch fan or the electric fan...usually the viscous ones fail by slipping too much and not moving enough air...

2.) I assume the speedo on that car is fairly complex, at the very least its a sensor from the tranny to the electronic speedo, but could even be routed through a car computer, I am not sure for that model...I'd check the tranny-speedo sensor though.

3.) This sounds like a case of one or more failed glowplugs. These cars have an after-glow system that wears them out faster, but also it becomes way more noticeable (clacking and rough idle for a min or so) if one or more of them goes bad. I'd just replace them all to be safe, and it will solve the rough startup issue.

i mean the clutch fan directly at the front of the engine that hoofs air at the radiator....i thought it should come on when the engine temp increase via a clutch, i figures cos the clutch is dead, its default is on all the time?

The viscous fan generally stops working very well when the clutch fails. It more or less will "freewheel" most of the time rather than clutching and moving a lot of air. A possibility is that the clutch is too full of fluid, causing it to be always-on...or some other prev-owner induced problem, I'm not sure. I am just sure that when they fail they blow less air and won't engage....

Some MB's have a tab on the viscous clutch which when bent allows permanent engagement. This is to get the clutch working when the viscous fails. Perhaps the previous owner engaged the tab.

Temp at 80 is good.

Does the car smoke and shake at startup ? If so, consider replacing the timing chain, tensioner and, maybe, even the cam sprocket.

Let us know if the above suggestions made a difference.

no smoke but it does chug and knock quite bad for the first 30 secs....

It may also be sucking in air.

If ur car has under body panels, remove them for a period of time. Little puddles on the ground could help point out any leaks. The panels do not let any oil or fuel drip on the ground.

Go around the fuel path and tighten all clamps on the fuel lines.

I would guess that, after the temp goes up, the system pruges the air in the fuel lines and the car smoothes out. Also, when the car heats up, the rubber seals better and prevents air from getting into the system.

U may want to consider replacing all rubber hoses in ur car's fuel path. If u do replace the rubber hoses, u may want to retighten the clamps again after a few days.