Preventive Maintenance Inspection: Do It Properly to Increase Profits

Wrenches Preventive Maintenance Inspection

Do you like it when your truck breaks down unexpectedly? Probably not. No one does. But what can you do about it? A Preventive Maintenance Inspection (PMI) is a simple way to prevent costly repairs and breakdowns and maximize uptime. Whether you manage an entire fleet of trucks, or if you're an owner/operator with just one truck, conducting regular inspections is a great, low-cost, high-reward practice. Among other things, PMI can improve your profitability, prevent customer service problems, and, perhaps most importantly, increase safety. There are many things that can cause your engine issues, possibly leading to an overhaul, and regular inspections can help you spot these earlier on.


Good vs. Bad Preventive Maintenance Inspections

A bad inspection does nothing for you but cost you money. But having a detailed PMI conducted by a knowledgeable, experienced technician can save you thousands of dollars. An improperly conducted PMI, on the other hand, can cost you thousands and still be a complete waste of time—it won't actually give you the information you need to help keep your engine running.

Changing your filters on a regular basis is only part of a good PMI program. To take full advantage of a preventive maintenance program, a PMI technician must be able to recognize the state and function of every system on a truck, and be comfortable with the electrical system, cooling, steering, regular and air brakes, and all parts of the engine, chassis, and cab. As an indicator of the technical knowledge required of PMI, there's an ASE T8 certification for Preventive Maintenance Inspection included in their Medium/Heavy Truck Series.


What Does a Preventive Maintenance Inspection Include?

PMI includes evaluation of the engine systems, inside the cab, electrical components and truck electronics, truck frame and chassis, and a road test. Some of the systems that should be looked at include:

  • Fuel Systems
  • Exhaust Systems
  • Lubrication System
  • Cab Components
  • Battery
  • Brakes and Air Brakes
  • Steering
  • Tires

Starting with the engine, a PMI checklist includes things like the obvious: changing the oil and oil/air filters. It also calls for checking for oil, coolant, air, and fuel leaks and over two dozen other steps.

For the electrical systems PMI includes checking the charging output of the alternator, or the battery state-of-charge and condition, along with several other important inspections. The inspection of the battery condition in diesel engines is very important during the winter seasons to ensure that the glow plugs (if included in the engine) are being heated properly to help warm the fuel so it can vaporize.

Under the chassis PMI calls for checking parking brakes or looking for leaks in the air system and checking the air pressure build-up time. All brake systems, including lines, need to be inspected for leaks or damage. Some seals may show a small bit of seepage with telltale oil, fuel, or coolant residue, but this may be normal. A trained technician can tell you the difference between a true leak which needs to be serviced, and a small bit of seepage, avoiding unnecessary repair costs.

Ensuring proper lubrication is another important part of preventive maintenance inspection, including flushing old grease and diagnosing potential problems. For example, when lubing U-joints, if the old grease is blackened it may be a sign of joint failure. The road/operational portion of PMI calls for testing operation of the clutch and gear shift, the road speed governor, the operation of all instruments, checking the steering wheel for play and centering, and so on.


The bottom line is your bottom line: take PMI seriously and in the long haul your profits will increase. It's important to acknowledge, though, that sometimes unforeseen circumstances arise, but with inspections, you're more likely to catch an issues before it becomes a major inconvenience. Should you find yourself in need of an engine overhaul, though, we have a large selection and the expertise to help you find the right one for your engine.

If you have any questions about your diesel engine needs, please give us a call at 844-304-7688. You can also request a quote online for additional help.

Originally posted May 12, 2014, Updated January 15, 2019