91 300D excessive knocking noise
 

I have a 91 300D with 2.5L TD that has seemingly excessive noise on one cylinder. It has been suggested by a couple garages that it is a bad/weak/whatever injector that is not doing its thing correctly so there is incomplete combustion. One mechanic suggested that I should check the temp of each exhaust port with an IR thermometer as it warms up to see which one is the furthest off from the others - was hard to tell as they were all close within 5-10c of each other.

As it was running I pinched (with my bare fingers) each metal fuel line going to the injectors and low and behold, on injector one, it felt like someone was hitting the injector line each time it fired with a small hammer - none of the other injectors lines felt like this - it seemed like I had found the culprit.

So, what would make an injector line feel like that? Is it a faulty injector, bad valve, ????

Any good suggestion for where to get a replacement injector if that is the case? should it be a bosch or can it be a BWD or an Accel peformance injector?

I am new to this forum but an avid diesel fan - went from a 12v CTD in an old dodge to my new found joy - gets much better mileage. I would appreciate some insight on what seems to be a great motor...

Thanks,
tv