How bad is short tripping for a diesel engine?

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Is it basically similar to short tripping a gasoline engine, i.e. you get fuel dilution and moisture accumulation in the crank case? Or are there additional aspects to consider? I am a total diesel engine newbie.

Wife has a fairly short commute - about 3 miles each way. In the winter time, in her current gasoline engine car, coolant doesn't get up to normal temp, much less oil. The car does see an extended 200-mile hwy trip once or twice per month.

Back in the day, I've read diesel engines take longer to reach operating temp, but I'm not sure if this was accurate and if so, if it's still true today. Obviously, any possible MPG gains from a diesel would be lost if it's not running at operating temp.

Anyway, no particular diesel car/engine in mind at this point. I'm just trying to educate myself if there are some specific driving patterns/conditions where a modern diesel engine would not be advisable.

Thanks!
 
Some diesels warm up faster than others-my intercooled ones warm up more slowly than the old IDI N/A ones do. In my opinion, at least with pickups, it is much better to work them hard & get them hot, short trips tend to carbon load.
 
I've got a 2014 BMW 328d (fantastic car - 43-46 mpg urban/city, 51 mpg hwy, and a hoot to drive). It doesn't have a coolant temp gauge but does have oil temp. gauge. I haven't noticed any difference at all between warm up time for this car and other gas BMW's in same trip - - and I do pay close attention to the oil temps, always after a cold start drive it 'til the temp is up to normal (210 degrees) before I shut it down, even if that means going the long way around. I do that, but I'd never be able to convince my wife to do that.
 
It's time at temperature, not just hitting a mark. A long drive now and again does wonders. If very cold, fuel,may be an issue; the problem I've read with the latest ones is that the particle trap may not regenerate properly...

There are lots of stories around about the EPA numbers being artificially low for diesels, perhaps because the warm-up time is longer and is not accomplished at idle the way it is in a gas engine.
 
Diesel engines are better suited to longer trips. If the 3 mile commute is going to be the daily usage, a diesel may not be a good fit. If you had two comparable cars, one a diesel and one a gas-hybrid, the diesel would win the efficiency game on highway driving while hybrid-gas could more cost effective in a short-trip city driving cycle. The diesel really needs at least 10 miles each way on a daily commute to be cost effective.
The basics of ownership are to take very good care of it with very strict maintenance. Air filters need to be of high quality and changed when full of contaminants. Many newer diesel vehicles have a visual indicator on the air-box that is tripped when the filter becomes too restricted. The fuel filters must be changed with OEM intervals at a minimum w/o exception and more often depending on how much crud is collecting in the fuel filter (time as well as miles driven are important on diesel). Very high quality oil and oil filters are a given for good diesel maintenance. Do not forget anti-gel additive in winter nor an
injector-cleaner/ lubricity fuel additive. All of these are key to preventing expensive repairs later. Don't forget oil analysis too- its cheap insurance.
Noting the cars you already drive, a M-Benz diesel would be terrific. Be sure to use an extremely high quality synthetic oil that meets Benz spec 229.51 for example. The VW-TDI is another that needs an extremely good oil.(The VW diesel is much better w/ a manual trans). I have significant experience servicing the above mentioned cars. There are also differences between the non-DPF 2006 and older cars and the 2007 and up ones with a DPF. The M-Benz will require Diesel exhaust fluid(for DPF) for any 2007 or newer vehicles is but one example. Let us know what exact car you eventually consider and I'm sure others who own such can chime in.

Dr. Olds
 
VWAG TDIs that are short tripped suffer from coking the VNT mechanism in the turbocharger, oil buildup in the intercooler (from seeping past the turbo labyrinth seals) and relatively poor fuel economy. Oil dilution was not typically a concern in the past but post-injection engines will have that issue even moreso with short tripping... for that reason alone I would only want a urea SCR system. DPF will also do more frequent active regens with short trips.

Keep them on boost and up to temperature and they typically live long, happy lives.

For short trips, I would only recommend a gasser. Fuel economy will likely be the same and maintenance on a short tripped diesel will erode any savings at the pump very quickly.

FWIW, my Golf is extremely cold blooded and takes much longer than the Mazda to warm up. To help that I have pipe insulation foam blocking off the grill and a kilowatt Zerostart so my first start of the day in my garage is fairly warm... not so much after it's been sitting outside this horrible winter.
 
3 summers ago when we first bought our forklift My dad and brother would just start it,work it for a half hour then shut it down.
We had a sample taken at 250 hours and iron was past 200ppm. Kraemer tractor called us and said they wanted to look at the machine because the previous used oil analysis were at 50ppm iron at 250 hours.
So they came out and did an inspection and found nothing wrong. So the technician asked how it was operated.
Once he heard about the frequent starting and shutting down he explained that's why the iron was so high.
So he told my dad the exact same thing I did. Diesel is cheap compared to an overhaul on one of these engine.
We now let it run all day. It start in the morning and gets shut off at days end. And our used oil analysis look consistent again without any anomalies.
So not really short tripping but it's an example of short runs and the added wear associated with cold starts.
 
Off hand I can think of being stuck in perpetual regeneration with regards to the DPF. I would think slightly higher soot loading depending on whether it's hwy or city.
 
Thanks, all. Sounds like I should stay away from diesel here.


Originally Posted By: friendly_jacek
Even plug-in hybrid will do fine in a 3 mile commute. Or better a bike or walk.

Sure. Please ask your wife to take a 3 mile walk in -10F weather with 2 feet of snow on the ground and report back from where you'll be sleeping tonight.
smile.gif
 
Someone said it already and I agree that the largest issue with short trips on a DPF equipped diesel deals with the regen process. Diesels produce more soot when cold... so the DPF is going to try and regen more frequently. That process takes approx 10-15min to complete (depending on your specific vehicle). So if the trip to & from work only takes 10ish minutes, then the cycle may not have adequate time to complete. If your vehicle uses post-cylinder-injection for igniting the DPF, then you'll more than likely run into fuel dilution issues which is already an issue even with normal operation. If your vehicle has an extra injector in the DPF, then fuel dilution is a moot point by comparison..
 
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There is also the possibility that if the regen never gets to complete, there will over time be enough soot buildup to require the DPF to be replaced.
 
All depends on what your driving? Any pre emission diesel is ok for short trips as the oil doesn't get polluted with water etc like a gasser and a good burn once in awhile will clean it out.
 
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You will have issues QPete.

Short trips round town are bad for even 10yr old turbo diesels. Variable vane turbos sieze up. Egrs clog up. Inlet manifold fills up with ssme rubbish as egr. Like a soft sticky tar.

Now with dpfs they are almost a no go for town work.

My Jag needs to be taken for runs if used round town a lot. And that gets hot and is kept running for hours on end.

Would i have a turbo diesel if i could get a 3.0 supercharged v6 petrol Jag with either affordable fuel or LPG? No. Personal preference would be the NA 5.0 V8.

Hopefully the newer diesels with Urea systems will be better.

But lgv and buses have has these systems for years in Europe and they still have their dpfs cleaned regularly as part of normal maintenance.

One company, Ceramex, has been doig this for many years and has just rolled out the service for cars.
 
Sorry should have added.

DI diesels were the slowest to warm up when they were introduced back in the 90's but they did improve this over the years.

Common rail are much better in this respect.
At least in my experience.
 
They don't like it. I won't buy a diesel truck for many reasons but one of them is all my job sites are close together and in town. I wouldn't ever warm up a Cummins on cold winter days, even with the radiator blocked.

Diesels only really work if you drive a lot. Municipalities that short trip them, especially new trucks with regen have nothing but problems.
 
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