I've recently experienced excessive diesel knock and occasional slight power loss on acceleration. I'm still getting 30 plus MPG . I've changed the filters several times and this helps temporarily. I can see tiny black flecks in the primary filter. The gist is , I'm going to remove and clean the tank. What's the best way to do this? Particularly, what liquid to flush/clean the tank with? I don't think there is any corrosion in the tank just some kind of crud. Any suggestions would be appreciated. It's a 123 240 D by the way.

 

30+ MPG on a 240? My neighbor has an unmolested original 50k 240 car and he gets around 28 max.

 

Are you saying that simply the higher rpm is drasticaly reducing fuel economy, or is it the engine trying to maintain that rpm?

 

So basicly it's the increased load on the engine.

 

My mentality is still in the stationary engine department