Hi all,
Going to be looking at some second-hand cars this weekend, and including (for the first time) diesels.
I've always avoided them in the past because I know where to look for problems on a petrol engine, but know little about diesel.
Anyone have any hints on spotting a good diesel engine from a bad, for someone comfortable with checking cars over? (albeit petrol ones)
Cheers Paul
A little white smoke on starting is OK, black smoke at max revs should barely be visible, and blue smoke from a diesel is always bad.
The engine will clatter like a mofo at idle, but by 2000 revs should sound like a noisy petrol. If it sounds unbalanced or hesitant on Idle, let it warm up, then kill and restart. If the stutter is still there, walk away. If it runs on after engine stop, walk away...
Listen for turbo whine. If you can clearly hear it in the cabin on the test drive, walk away...
Look for proof of cam-belt change within service interval, if it's not there, walk away...
Check for proof of regular servicing, oil changes etc. Again, if missing, walk away...
There's plenty of good late model diesels out there - anything peugeot or nissan engined will be good. That includes Peugeot, Citroen, Ford, Nissan, older Vauxhalls...
A high mileage on a diesel is not a bad thing if the rest of the car is good. My V reg Escort has 150,000 on the clock, and I'm adding over
25,000 a year without a hiccup.Remember as well, a diesel will cost 5% more to fill than the equivalent petrol, but will go on average 20% further for the same fuel. A 1.8 TD is about equivalent in engine to a 1.6i non-turbo petrol. Turbo on a Diesel makes the car MORE fuel-efficient, not less, in most cases.
Welcome to the world of oil-burning reliability :-)
Also ask if they've ever put petrol in by mistake. Get it in writing on the receipt if you buy the car.
snipped-for-privacy@spam.vlaad.co.uk (Paul Cummins) wrote in news: snipped-for-privacy@admin.vlaad.co.uk:
equivalent
What a great reply. Mind you with a surname like yours !!!
Same as a petrol really in most repsects.
Alot can be learnt from hearing it start from cold. Modern DI's require little if any pre heat from cold, so turn the key straight to cranking position and expect it to start pretty rapidly on all cylinders, and settle to a smooth idle almost immediately without throttle or excess smoke.
With a IDI some preglowing will be necessary, but should still start cleanly as soon as the light goes out.
with the bonnect open:
0) pre start- the ECU warning lamp lights (if fitted) then goes off on start up. 1) rapid cranking. 2) virtually immediate start, especially from cold, and a smooth idle.(some common railers need a fair bit of churning before they fire, but should jump up to a good tickover when they do fire) 3) no excessive rattling or grumbling from valve gear or bottom end. 4) diesel knock should very quickly reduce after 10-20seconds of running. 5) a clean exhaust once its running. A puff of black at startup is fine. No blue. 6) on the move no hesisations, spluttering or reluctance to go, though some turbo diesels can be very sluggish off boost when cold. 7) no excessive smoke under hard acceleration to the governor. (however some soot may be blown out if the car is habitually driven gently-this should subside) 8) no ECU warning light on 9) Temp gauge warming fully and then remaining constant at op. temp. No overheating. 10) usual hot and cold checks of coolant / oil levels and condition / intermixing.Thats about it.
Mhhmmm, might have to agree to disagree on that one!
My experience of the "older" diesels is exactly the opposite, across several makes. A while ago I went through a stage of swapping cars out about once every two months for two years to find one with a good fuel efficiency (in the end settling on non-turbo'd Renault 19 diesels as the car of choice - 50mpg was easy to acheive). Turbo'd versions of the same cars were always less efficient (my drive is 20k a year of 33% country, 67% motorway), without exception.
I would argue that adding the turbo effectively increases the combustion volume for the higer RPMs as more air and diesel is injected. So the more you use that turbo, the less efficient it is.
At least, applied to the older cars, of course. :)
My current car is an R-reg Rover 420 TD, which had a seized turbo, giving 46 mpg on my run. Now that the turbo is working (as of today) it will be interesting to see how the fuel efficiency changes on exactly the same drive. I'm speculating that it will return less mpg.
The use of a turbo has very little effect on specific fuel consumption. That is, fuel consumed per unit of power output. On your car with a faulty turbo, much of the fuel was wasted because there was not enough air for efficient combustion. Now that the turbo is back in action you should have far more power for the same fuel injected so will be able to pull a higher gear and lower fuel consumption. If this is not the case then you have another problem, like an excessively heavy and indelicate right foot.
Huw
my thoughts exactly.
On a recent run to Scotland, I returned exactly 12 miles per litre of regular diesel on the way up, and 13 miles per litre of b5 blend on the way back down. This was a 90bHp ford turbodiesel with 150k miles on the clock.
Miles per litre? Miles per gallon or litres per 100kms are the usual measures are they not? Where did you find miles per litre for comparisons? I suppose that 13mpl must be the same as 59mpg and 12 is 54.5mpg?
Huw
heavy and indelicate right foot.
Ah, well, you may have hit on an important detail there since my use of the throttle is a little, umm, binary. Perhaps I should revise my driving style.
or even better
"12 (miles per liter) = 179 882.769 inches per US cup"
google is ace
Just remember it's US-centric so you have to use
miles/litre miles/gallon 5 22.7 5.5 25.0 6 27.3 6.5 29.6 7 31.8 7.5 34.1 8 36.4 8.5 38.6 9 40.9 9.5 43.2 10 45.5
(Above that you can do yourself because none of my cars have ever been anywhere near that. :-( ) (I've had one or two that do below 5mpl though :-( :-( )
Err... yes.
Personally I've found that since moving to the Land of the Speed Camera I've had to be better about speed, which has made driving very dull.
I've switched to focussing on other aspects, like driving smoothly, or at minimum throttle, or using the clutch as few times as possible on a whole trip...
Hi Paul
You mentioned the turbo whine. In my espace I can hear the turbo kick in and whine? when driving. Is this a bad thing?
Diesel Espace? I'd get the turbo checked personally.
ON a petrol, turbo whine is common enough, but IME, diesel boost is much lower in any case, and I've never driven a diesel where I could hear the turbo over the general engine noise.
I have to test-drive one of these new "embrace your hate" Honda diesels sometimes.
I was doing specific mileages, but buy fuel in litres... I see no issue
My Nissan diesel has a nice turbo whistle, very reassuring sound.
As posted elsewhere in this ng, the Rover 2 litre L series diesels are pretty bomb proof, I have driven one through a flooded road with no ill effects, but then the intake is quite high up on a 200/25 behind the passenger side headlamp and if you keep a continuous speed through the water the bow wake generated keeps most of the water away. I suspect the problems start when people try to drive gingerly through the flood.
PDH
My brother's citroen ZX 1.9TD has whined ever since he got it with 30K miles on the clock it's still going, and whining, 100K later..
Os
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When i got the car i took a mate with me who used to be a mechanic and he said to listen out for the turbo kicking in. Its a god sign its working and he saw no problem in hearing the whine. That's why I asked. Just wondered if mine was ok. Thaks for the help Paul, cheers
That is good to know. Henceforth I vote that we all quote fuel consumption in 'inches per US cup' or IPUC for short, with an option to use the Imperial 'inches per UK mug' or IPUM. Then there is Metric where I suggest 'cms per French wine glass' or CPFWG. Standardising on these would prevent confusion and promote clarity. Who'll be the first to enter these standards into the Wikipoedia?
A font of useful knowledge. I don't know how we ever managed without.
Huw
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