wants to be thrashed.

[Yostumpy]

 brief history. Wallace, a 300 tdi '98 hard top, with 185k on the clock. Had van Aaken  fuel pump mod about 12 years ago, has straight thro centre pipe,and new timing belt /rad last year. Went very well,  but I 've been driving it a bit gentler these days. Lately (last 6 months) the engine note had changed, was deeper, and slower. uses / looses no oil or water.  When driving in walled areas, I was getting embarresed by the noise, No longer the deeper note of the straight thro pipe, but a ragged , 'farty' exhaust note, as if the rear box was hanging off. Started to look at prices for centrebox,  and google injection pump timing,  as it was getting a bit sluggish as well. Definately sounded a bit retarded,and mpg had dropped a bit as well.

Anyway, had a reasonably long journey a month ago, ( most journeys are local), and 220 miles up to Shropshire a 60-62 mph into strong headwind. Then another 250 miles home,with a good tail wind.  So rather than sit at 60mph, I gave it some beans, so prob 3+hours at 75+, with a burst up to indicated 95 occasionally..  

well the truck is now back to it old self, farty exhaust has now gone deeper and  hoarser, engine revs are back up a tad on tickover, and its much crisper in mid range. But the thing is, it wants to be thrashed. I don't mean rag it, but it prefers bursting from 50-75 and staying there, than sitting at 58. Its like a race horse in the blocks. Now I know the 'italian tune up' is supposed to work, but this is amazing.  I am intrigued what the prolonged high speed thrash has actually done to the engine. has it burnt of some carbon, has it blown the carbon out of the exhaust,  has it cleaned out the injectors. Should diesels be driven  reasonably hard to keep them clean? maybe I was to kind to it.  MPG is back up too.

Edited March 12, 2019 by Yostumpy

[FridgeFreezer]

Do you ever run premium diesel through it?

[Yostumpy]

^{nornmally supermarket stuff,with added rapeseed oil, maybe 10 l per fill up this weather, but on the return trip i filled up with Shell, not good stuff, just normal. Have since gone back to sainsburys , but its still very perky.}

Edited March 12, 2019 by Yostumpy

[landroversforever]

I reckon some of the additives have cleaned the fuel system out a bit then. I noticed the difference in my pug when running premium unleaded. I’d think the diesel equivalent would do the same. 

[FridgeFreezer]

22 hours ago, Yostumpy said:

nornmally supermarket stuff,with added rapeseed oil, maybe 10 l per fill up

Not that mysterious then

[ClimberTom]

Diesels do have a tendancey to 'Coke up' if ran at low load for long periods if time. More modern engines can cope better with this but the principle still applies. Obviously older engines suffer more.

Fuel quality will have an affect too of course. But yes, Diesels do like a 'good run' from time to time.

[Snagger]

On 3/12/2019 at 8:33 PM, Yostumpy said:

. Should diesels be driven  reasonably hard to keep them clean? maybe I was to kind to it.

In a nutshell, yes.  The same applies to all combustion engines, even turbines.  Clogged injectors, gumming rings and coked valves are all symptoms of excessively gently run engines.  Bore glazing and spark plug glazing are also typical.

[reb78]

My 200tdi is all good then. 4 hours of fairly hard motorway work twice a week. 

[Yostumpy]

At the moment I'm running Wallace in ECO mode. I read about the VW 'umwelt' ( environment) engine from the early 90's , just before the tdi.  Basically it had a catalyst in the exhaust, but more importantly, they omitted the boost compensator from the FIP. So engine had turbo at lower revs working with the fuel delivery, but no extra boost fuelling at high revs. They reasoned that the xtra fuel that was boosted, wasn't all combusted, so was thrown as as black smoke / soot. It was the cleanest diesel of its time by a long way, and the eco golf would still top 106 mph. Interestingly, it was so clean, it was allowed to be sold in California. So I've now pulled the plug on Wallace's boost fuelling. Apart from a small puff on start up, there is no smoke whatsoever, still very sprightly up to 50mph bit sluggish after if you let the revs drop too low, but will still bowl along at 75-80 + on the flat, but I stick t 60-62, as it will still pull away at that,  56 mph and it won't if there is a hill. It might be better mpg, not sure yet,  pulls very well, but just sounds clean, if you know what I mean. The theory is extra turbo' air will force all fuel to be thoroughly combusted. I like it. The other day I had 60 x 1.8m , and 22 x 2.4m wet decking boards in there, and it works very well under load, and even working hard up hill with this load, no smoke at all.

Edited April 9, 2019 by Yostumpy