How Long Does an Automatic Timing Advance Unit Last?

The automatic timing advance unit is a component in vehicles with diesel engines. Of course gas and diesel engines both work on the internal combustion principle, but they are quite different, and require different means of controlling the flow of fuel during operation.

Gas combusts much more quickly than diesel. With diesel fuel, combustion can take place long after the timing reaches TDC (top dead center). When this happens, lag occurs and adversely affects performance. To prevent lag, the diesel fuel has to be injected before TDC. This is the function of that automatic timing advance unit – basically, it makes sure that no matter what the engine speed, the fuel is delivered in time for combustion to take place before TDC. The unit is located on the fuel pump, and operated by means of the primary drive gear on the engine.

Whenever you are driving your diesel vehicle, the automatic timing advance unit has to do its job. If it doesn’t, the engine will not get a consistent fuel supply. There is no specific point at which you should replace the automatic timing advance unit – essentially, it lasts as long as it lasts. It could last the life of your vehicle, or it could start to go bad, or even fail entirely with little warning. Signs that your automatic timing advance unit needs to be replaced include:

  • Sluggish engine
  • More black smoke from exhaust than is usual with diesel operation
  • White exhaust smoke
  • Engine knock

Performance issues can make for dangerous driving, so if you think that your automatic timing advance unit is failing or has failed, consult a qualified mechanic to further assist you in replacing the failing part.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How Long Do the Timing Gears Last?
The The timing gears work with the timing belt and chains in the engine to ensure your vehicle runs smoothly. The gears are connected to the crankshaft at one end and the camshaft at the other end. They have small...
How to Avoid Muffler Repair
Mufflers break when debris builds in the undercarriage, the muffler rubs against driving surfaces, or there is smoke emitting from the engine.
How to Replace Timing Gears
Timing gears control are connected to the crankshaft and the camshaft and how much fuel and air enter the cylinder to ensure your car runs smoothly.

Related questions

Engine knocking.
The most common noise like this is the serpentine belt tensioner (https://www.yourmechanic.com/services/serpentine-drive-belt-replacement) knocking noise. The belt and tensioner replacement is the most common fix.
The car shut-off as I pulled into my driveway and has not started since. It will "turn over" but will not start.
The vehicle may have jumped timing from the timing belt (https://www.yourmechanic.com/services/timing-belt-replacement) teeth broken off. This is why you got it to make backfire noises. You should have the timing belt timing checked to see if the timing jumped. Another problem...
What may cause my transmission to jerk?
These types of rough running issues are very hard to diagnose without taking a look at the vehicle and doing some diagnostic testing. This could be caused by the vehicle needing a tune up (https://www.yourmechanic.com/services/tune-up), a fuel pressure problem, a...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com