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Servicing the new diesels

If you’ve been avoiding working on diesel vehicles it may be time to reconsider that decision, as there’s money to be made under those hoods.
Thursday, January 23, 2014 - 09:00
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Remember when diesel vehicles were smelly, smoky, noisy units that needed minimal service work to run trouble-free? Well, the new diesel vehicles aren’t like that at all. New diesel vehicles with common rail fuel injection systems are quieter, more efficient and less polluting than ever before, and they’re becoming so popular that odds are good that they’ll be rolling through a bay near you if they haven’t already. And thanks to their unique service requirements, there’s money to be made servicing them if you’re prepared for the challenge.

The bigger fuel door is an indication that the diesel fluid is filled back here. The reality of work trucks is that dirt and debris build up by the filler necks and can easily work their way into the systems. Keeping the filler neck area clean and wiping up after spills is important even if it's seldom done.

Because new generation common rail diesel vehicles are similar in operation to the fuel injection systems most of us are familiar with, it’s not very difficult to get comfortable working on them. They’re controlled by a module which gets operating data from various sensors and controls fuel injector operation to meet demands while keeping emissions as low as possible.  They warm up much more quickly than before, and they have sensors and emission-reducing technology to meet strict new requirements. And they set and store diagnostic trouble codes to help diagnosis. But even if you just perform maintenance services on these vehicles, it’s still important to get comfortable working on and around the systems.

Even though many systems are familiar to the systems you’ve known for years there are a few important differences to be aware of to keep repairs quick, safe and profitable and to keep the job safe.

Here’s what you need to know.

Diesel exhaust fluid is one of the most discussed and mentioned systems found on new-generation diesel vehicles. Actually, some early versions of these diesel vehicles didn’t use it (and some still don’t) but it’s extremely common now so it’s important to understand when to top it up, what to top it up with and what goes wrong when you don’t (and of course, how to fix it).

Note the difference in the location of the dipsticks on these two Ford Power Stroke trucks. It's all the way at the back on the newer model.


In brief, exhaust fluid is the consumable fluid injected into the exhaust to help keep emissions low. Vehicles with high fuel consumption, such as ones that tow trailers or vehicles and drivers with aggressive driving habits, will use more of the fluid than their fuel-efficient friends.

The diesel exhaust fluid reservoir has a monitoring system to let the driver know when the fluid needs to be added, and it does this at various levels so that there’s plenty of warning before the system runs to empty. This warning system is needed because when the fluid runs out, the vehicle imposes a speed-limiting condition, which means that the vehicle cannot go above a certain speed until fluid is added. And if fluid still isn’t added at that stage, eventually an idle-only condition is imposed until the fluid level is corrected (the vehicle will only idle). The system doesn’t mess around.

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