diesel car

24 Apr 2008
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United Kingdom
I have a diesel engine car
I was told that periodically if you add some petrol when you fill up this will
" Clean up the engine "
Is this true ?
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Ive heard various stories like this over the years, maybe it was ok 20 years ago on older technology but not on modern diesel engines.
If you need to put anything in fuel for cleaning purposes stick to well know additives such as forte or wynns.
It was recommended to add some petrol to aid winter cold starts, but today, a definite no!
If you are bothered, the odd fill up with Ultimate diesel or similar is supposed to help......personally I still avoid supermarket fuel outlets.
John :)
I was looking in the handbook the other day for something. I'm fairly sure it said something about putting anything like additives in the fuel, or anything apart from the recommended fuel invalidated the warranty. That's a Peugeot. Could have read it somewhere else though.
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I'm sure if you return to Peugeot with injector issues, they'll at least try it on to prevent a warranty claim.....
The big issue is actually removing the injectors from the cylinder head.....any evidence of external oil indicates blow by, and the thing will be a monster to shift.
Why the hell can't we just screw them in, as we used to? I guess it's to do with steel injectors, alloy heads and so on, so they just clamp them down.
John :)
Too late for any claims with mine now. It's 5 years old. No sign of any blow by though on the injectors yet. . .
You're right though I reckon most of these "do not use" type warnings on all of them are a "get out of jail free" card for them for warranty claims.
Problem with all this modern stuff is it's engineered for the cheapest production cost rather than the best engineering practice.
Ten years down the line?
Obsolete as far as they are concerned.
As far as I can see, modern injectors pass through cooling passages within the cylinder head......the injectors theoretically seal courtesy of O rings, which may be the reason they are clamped rather than screwed in.
Ho hum!
Although it really grieves me to say it, my next vehicle may be petrol - but not the cylinder on demand type! :eek:
Can't beat the diesel torque though.
John :)
I assume they want some cooling for the injectors then. They're very high performance engines by the old standards of course. but o-rings. . .
Like all this clever stuff, it's OK until it gives trouble down the line.
Always had petrol myself before, this one was twelve months old when bought for a specific reason, and a diesel was what it was.
Petrol for me next time too.
With as few complications as possible!
Personally, I wouldn't put anything in there that doesn't come out of a diesel pump! Modern diesel engines are SO finicky about fuel quality! There are plenty of aftermarket potions available though. I've heard good things about BG244 and Stanodyne in particular. Also, a surprising number of good reports regarding adding a bit of 2-stroke oil to each tankful. I'd be tempted to regard this as an old wives' tale, but I've heard quite a few people raving about it on several different fora - about 200ml in a typical 50-60 litre tankful and claiming significant MPG increases after a couple of tankfuls.

I think they use O rings on injectors these days so that they're more tolerant of misalignment (and thermal expansion) between the fuel rail and the heads. Some of that might be cost-saving too, but personally, I wouldn't fancy trying to remove a 10 year old injector if it had been screwed in!
In the '50s adding some petrol to the fuel was almost essential in the winter or the or the diesel set but no longer necessary. The early PSA Hdi 2.0. engine with the 8 valve head up to about 04 is pretty bombproof, I have two both at over 200k and are still mostly original including the clutch, DMF and injectors, we have just returned from a 2000 mile trip around Scotland without incident and round 60 mpg the 406. Unfortunately the newer they get the less reliable they become, I will stick with my early Hdi's.

I can remember working one particularly cold night up in the Midlands. The lorry park at the factory where I was was quite exposed to the North. And there were several drivers overnighting there. Next morning quite a few of them couldn't start due to the diesel waxing up. That would have been early 80s.
They used to light a fire under the engine in the '50s. No health and safty then. :D

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