Carbon Cleaning Engine thru running it hard
 

Hi, I saw this comment on a thread about the above subject from a 25 year time served mechanic on Quora
"When I do tune ups on Alfa Romeo (especially spiders) after the filters, plugs etc I would take them on a 10 mile trip to burn off carbon build up in the cylinders. I'd take first gear up to redline and take my time on the one two shift due to the difference in ratios then run the hell out of it from second gear to fourth gear spending about a minute just below redline then when the owners would leave I'd get a call later that day or the next swearing I was a god because it hasn't ran like that since they drove it off the lot new. At which time I'd tell them to take it out on the highway and drive it in each gear for a minute at redline about once a week depending on how often it's driven and how often in stop and go traffic. And the Italian cars are something like a race horse and need to run wide open or they foul up and get hard to start, gas mileage drops, and they get unpleasant to drive. I would apply that to any high-performance engine from any manufacturer I know my uncle's 69 boss 429 Mustang didn't like to drive in town it would foul plugs and snort but take it to the drag strip and it was happy as a hog in a mud water. "

I was wondering whether it would be advisable to do something like this on an old D24tic engine. I've had my 1996 Volvo 940tdi for 14 years, it has 280k on the clock, 170k I am responsible for. I rarely take it above 3k revs, and more recently rarely take it above 2.5k revs, and do mostly city driving. Any experiences, or advice welcome.

Sorry posted this in the wrong section by mistake.

Ah the Italian Tuneup! Count me as a fan.

Diesel engines in general like to be worked hard. Otherwise they are prone to wet stacking, ring deposits, oil dilution, and with EGR system, buildup in the intake.

If your engine is in otherwise decent shape (esp. timing belt, valves adjusted, good injectors, healthy cooling system) you may help things by working it hard at least once per drive, when thoroughly warmed up (important!) and when the chance presents itself.

I do not agree completely with your Quora thread source "drive it in each gear for a minute at redline," that seems excessive to me but if you come across some steep hills or freeway onramps just wind it out at WOT to burn out any carbon buildup. I notice the first time I do this each time it leaves a pretty thick brownish haze, second and consecutive times it's clear.

I too had an Alfa, and the Italian Tuneup was a given. Mostly to make me smile and remind me why I put up with all the other tribulations of maintaining an old Italian sports car. That all-alloy DOHC engine (not common in a street car in its time) was basically a detuned version of a well proven highly regarded long career racing engine. Enzo Ferrari was one of their engineers before he went off and started his own company.

I'll move this thread to the more appropriate "Diesel Engine and Drivetrain" section.

Many thanks ngoma for your interesting reply, wish I had known about this before!