>>Bet I'm going to be slated for running whilst stationary.
Neither of my two diesels will actually warm up if left to idle after a cold start. Well, they might eventually, but certainly after 15-20 mins the gauges remain on the bottom, and the heater stone cold.
Another phenomenon occurs on both engines when the engine is only partially up to operating temperature and you idle for an extended period (traffic jam etc). The temperature gauge will actually drop back towards cold. This is much more noticeable on the Renault.
In normal driving conditions, both show normal operating temperature within 2 miles or so. I tend to just drive both reasonably normally from the off, but go a bit easy on the loud pedal.
An old Peugeot (petrol) I had with an oil temperature gauge showed me the complete lack of relationship between coolant and oil temperature anyway.
Cheers
DP
|
coolant / oil
which warmed up first?
|
coolant / oil which warmed up first?
Coolant, by a long way.
On a normal drive, not driving hard or exploring the rev range, the coolant temperature would be up at its normal reading for a good 2-3 miles before the oil temperature gauge even moved off its rest position.
The oil temperature gauge would also fluctuate depending on how the car was being driven. Prolonged hard driving would see it climb quite quickly while the coolant gauge remained constant. In traffic, the coolant temperature would climb (until the rad fan cut in) and the oil temperature would drop back. A very educational gauge!
If you're wondering, the car was a mk1 106 XSi.
Cheers
DP
|
|
|
|
>>Bet i'm going to be slated for running whilst stationary.
How did you guess!
There are good reasons for getting the engine working once the oil pressure has built up. The last thing you want is to allow the engine to lurk in mid range of temperatures where corrosive combustion by-products can condense out.
Once the oil is circulating, I can't see any good reason for not using the engine.
For the OP, I don't see what the problem is in using 3000rpm once the engine has begum to warm a little - for example when really cold a diesel knocks a bit, once it has stopped knocking, why not use the revs?
Number_Cruncher
|
i dont know - i have limited knowledge on this. At 3k rpm my engine is producing around 170bhp; i just thought this was a little much when cold since the turbo starts spooling up from 1.6k and reaches max torque between 2 and 2.6k.
So turbo is on constantly from then on
If it doesnt matter then thats fine i just wanted to find out at what point its un-heathly for the turbo/engine in a diesel when cold.
|
What make/model?
I start and let the engine idle for 15-20 seconds while I sort out mirrors, lights, audio, H&V etc (and in the Xantia while the ride height stabilises). Once moving I change 1 to 2 at around 2500rpm and thereafter at around 3k - but that's near the end of the torque band and where I'd change in any normal driving. Changing up at 2.2k would worry me on account of labouring in the higher gear.
Only ever pull over 3k rpm in a hard overtake, and would avoid that until the coolant gauge was well off the bottom stop.
Edited by Bromptonaut on 09/02/2008 at 20:59
|
|
|
At 3k rpm my engine is producing around 170bhp;
Only if your foot is hard on the gas pedal.
|
|
|
|
There are good reasons for getting the engine working once the oil pressure has built up. The last thing you want is to allow the engine to lurk in mid range of temperatures where corrosive combustion by-products can condense out.
Ah, so i'm doing damage then, where are these chemicals going and what are they doing once they're there. Ah there there. (note to self grow up....no never says i).
|
|
Most of the heat is transferred to the oil by the cylinder head and the bores so until the coolant is hot.,the oil won't warm up.
|
Have always let the engines tickover for 30 seconds from cold to get oil up to the camshaft.
Not worried about whatever this does to the oil as i change it and the filter at half the manufacturers interval anyway.
Unnecessary? sure I can accept that, but won`t change my habits ;)
I suspect a lot of the concerns about oil contamination and warming up originated back in the 1920`s and have now taken on a `folk law` dimension.
I have serviced a car over 17yrs that never went more than 4 miles in a trip and was largely running permanent choke in winter (85 Polo C) every year on servicing it I looked in the cambox and no sign of sludge. There was a slight leak from the mechanical fuel pump running of the camshaft for the last few years and I would fill the sump to minimum, then find it half a litre up a year later at the change.
The engine must have been `condensing` into its oil like a coal burning power station but it used no oil and ran well at 117,000 miles and 17 years, when my father gave up driving.
That engine used mineral oil, changed annually but I think you can do whatever you like with a car (exception of cold high revs) if the oil and filter are changed at half the manufacturers interval.
To the OP,
Re warm up, diesel`s forte is multi cold start running, I would just keep the revs down and use the torque. 3,000 revs is pointless.
Some of the small three cylinder gaspers (once owned one)will need almost that as they are bereft of torque at under 2,300 revs and are left `gasping` at the lights while same size four cylinder jobs put out max torque at 1,750 revs.
Some of the bigger diesels have even lower max torque and I think a good starting point is to find your peak torque and then change gear to put the engine 200 to 250 revs above that point when the revs drop back after the change.
Thats regular driving and warm up of a diesel with synthetic oil is a non event really, just keep the revs down ( as you do on a diesel) drive steadily.... whoops, that 1920`s fact to rhetoric is out again... well it wouldn`t just go away would it? ;)
Anyone still rotating their tyres from the beam axle days, or perhaps twitching for the redex gun? ;)
Regards
Edited by oilrag on 10/02/2008 at 10:15
|
Well it could be possible that i have been known to rotate the tyres, i couldn't possibly comment, but i dare say when the winter set come off (ok i know) that they will be marked up for swapping front to rear (directional so can't do a full rotate, but i could get them swapped over on the wheels so osf could go to nsr....hmm there's a thought).
I no longer have a redex gun, but its been known for the occasional strong redex solution to go through my petrol merc.
And i freely admit that the hilux (and every other diesel i've owned since the removal of most sulphur from diesel fuel) gets a generous helping of millers with every fill up.
Do i waste money, probably, have i ever had fuel or indeed diesel engine problems, not yet, so nurrh.
Is contamination of the oil the danger of our prewarming of our vehicles?
If so i'm the same as Oilrag, and the very frequent oil changes our vehicles get should hopefully stop any problems there.
I'm sorry if its wrong, but it makes me cringe when i hear diesels especially being hammered up the road still freezing cold, clattering away.
Funnily enough, the black sludge problem you refer to is back, my indy has had to fully strip 2 V12's due to the black death recently, i know 1 was a 60k miler, think i'll carry on with my overservicing.
I'm not saying that its extended servicing causing these problems, but luckily for the time being its not a crime to service a vehicle better than told to (watch this space mind).
|
|
|
Rotating, yes, but then I have two cars with beam axles, and I always try to need 4 tyres at the same time. (Old debate done to death here, but I can cope with the handling changes, and they are much lower than miss-matching sets of tyres).
Upper cylinder lubrication. Talked to oil company chemist on that one. 2 stroke oil is much better, and cheaper to boot. I have a 1927 engine with modern pistons and rings, which was designed around some getting from downstairs to upstairs. The oil I use is cheap insurance.
As for the OP, well yes I wonder, having had diesels for over 10 years. My warming up is give the oil a chance to properly circulate, 20 seconds or so, then move off. Avoid high revs, avoid high loads etc until the temp gauge normal. With the current vehicle I can do all that, and never go above 2500 revs. I always simmer a bit when stopping, although a Land Rover mechanic told me some years ago they'd not had a single turbo failure to deal with, and I know a fair few of their customers take no precautions at all.
|
|
|
>>but it used no oil and ran well at 117,000 miles
I very strongly suspect that that is not *stricty* true.
I have no doubt that you didn't need to add oil; but, *all* engines use oil - when you consider how the cylinders are lubricated, engines cannot fail to use oil. What we see is usually that the rate of oil consumption matches, or slightly exceeds the rate of contamination by blow-by products, so, the dipstick reading looks good, or drops slowly - but what's being measured by the dipstick is not all oil!
Had the car been subjected to a change in usage patterns towards hotter oil and longer journeys, I would expect a thirst for oil would soon have become apparent. Put another way, if the blow-by was adding so much to the oil, how can the oil not have been going the other way too?
Number_Cruncher
|
I never give it a thought. Start car up, out of garage, close door, end of drive, pause, 2500rpm and off. After that anything from 1,200rpm to 3,000.
Worrying about that is imo retentive...and yes all my engines get a hard drive at times and burn about 0.5 to 1litre per 1500-2000 miles.
There are more important things to worry about in life.
When I drove a 1929 Riley 9 with SAE 90 oil in gearbox and backaxle, you HAD to drive slowly when cold as the oil was so thick. Like treacle thick. And thermo syphon cooling systems meant engines took miles and miles on frosty days to warm up.
Imo it's all motoring history with its roots in 50 years ago with poor machining and clearances and carp oil and carp designs of cooling systems.
Lets face it: who stops for a meal and a motorway sevice station and restarts and drives at 50mph on the motroway for 2 miles afterwards? Only HGV drivers, OAPs and little old ladies? Yet if you believe in warming up, that's what you should do.
In the same frame as adding petrol to oil, flushing engines, decarbonising , starting handles etc.
Edited by madf on 10/02/2008 at 16:01
|
"put another way, if the blow-by was adding so much to the oil, how can the oil not have been going the other way too?
Number_Cruncher"
Hi Numbercruncher, not "blow by", the (camshaft driven) petrol pumps diaphram had become porous and petrol was entering the engine oil directly via that.
this was another of my over serviced engines in its early years, half the interval on mileage and the bores and rings were fine.
regards
|
>>pumps diaphram had become porous and petrol was entering the engine oil directly
Wasn't there a drain hole to the outside?
|
|
|
|
|
|
|
|
