Karst wrote:Here's the latest -
Today I got some advice from someone "who knows a mechanic". He said he would drive a few miles down the motorway at high speed in second gear, and this would clear out coking in the engine which is causing the black smoke...
He swore he'd done it a few times and it always worked.
Anyone heard of this?
I've done that in third gear on much older, more basic diesels, in conjunction with a bottle of injector cleaner. The theory is it maximises the effect of the injector cleaner as driving at full throttle for 20 minutes runs the injectors at the highest duty cycle. The reason it's done on the road is it's not advisable to run an engine at full throttle with no load. But it wouldn't be effective unless the problem was gummed-up injector nozzles.
I agree with Knobby: it doesn't address the root of the problem.