Diesel knocking please help
 

Hello to everyone,
My father has a mercedes w123 200d,and now he is having like a knock when he press the gas expecially on second and third gears.We tought that it was the diesel filters we changed everything,the one with the tank the big filter and the small plastic one but the car stays the same,we checked all fuel lines to see if there is a cracked one but nothing.
Now we are thinking that is something from the injectors or from the fuel pump but the car is not making any strange noises when it's free the engine revs normally.
The problem is most,when the car is loaded when he press the gas it knocks is like it's cutting the fuel.
Can someone help with this pls?

Thanks

Does it sound like banging a nail into a 2x4?
If so, that is nailing and if you haven't done diddley to your injectors lately it may indicate one of them is fouled. There are vastly better experts on the forum that I am sure will chime in with better info, but in the meantime try searching on "nailing" and you should end up with quite a list of things to check.
-nB

If the sound only occurs when the car is moving check the flex disks connecting the driveshaft to the trans.

I had similar symptoms. My problem was fouled injectors. Took them out, soaked them in napatha over night, blew them out with compressed air, reinstalled and problem was fixed.

I'm no expert either. Just relaying my experience.

Cheers,

Bill

Injectors do not last forever, they only last about 100k miles before needing replaced. Replace the injectors and the knocking should go away, no fuel treatment is going to remedy the need for new injectors.

I know of cars that have the original injectors that have never been out with 300K on them. Every other tank has been treated with injector cleaner. Only reason mine screwed up was from using WVO for the last 30,000 miles. My car, a 240 with 238K, never had the injectors out before now. I've got all receipts from day one to back up that claim.

Cheers,

Bill