Wednesday, October 15, 2008

Diesel Engine Troubleshooting

Today's diesel engine troubleshooting procedures have changed since the introduction to computers and higher fuel emission standards.

A laptop is a necessity and software is rampant among all the major diesel engine manufacturers. There is still things you can do to overcome the electronic learning curve a lot of technicians have trouble with.

If I were to think of the best advice to give someone embarking on a diesel engine troubleshooting scenario, it would be one thing.
That one thing is "always check the source".

Don't go to the injectors or valves unless you hear a noise of some sort. If there's mechanical noise coming from the crankcase then you're going to pull the valve cover and inspect the top end. Then you need to drain the oil and pull the oil pan looking for scored cylinders or tidbits/chunks of metal.

For a no start always check the fuel tank. This sounds so easy but it's happened caused embarassing moments. The tank gets overlooked and parts get replaced for no reason because of a cracked or rubbed through fuel line coming out of the tank.

Start at the pressure side [after the second fuel filter or fuel pump] of the fuel system and start cracking lines open. If you've got fuel keep going forward if not go backwards checking for fuel.

If the engine runs and craps out after a minute or so check for air in the system caused by a cracked or rubbed through fuel line. Run the fuel line into a bucket of fuel and see if that makes a difference. If so, start going backwards from there. Hook up a clear line to the return fuel line and check for air that way.

This isn't the technical way of diesel engine troubleshooting but it has worked for me many times finding some really goofy problems that are easily resolved. So check the simple things first and don't get too wrapped up in the high tech side of the engine until you're sure you've covered these basics.


Sue said...

I came accoss your blog while searching for school bus blogs and am glad I found you.

Our company had a lot of problems keeping our 2008's running.

They did finally got the problems sorted, but now we have several new 2009 internationals waiting in the yard that we are hoping will be problem free.

New buses are packed with some great new features but it seems the more they add is just more that can go wrong.

But thanks for your insights into the inner workings.
My Blog
School Bus Drivers

Anonymous said...

Food for thought on this John,alway's check the vent tube on fuel tank's to.over the year's i have seen road crudd and dirt clog up the quick thing to do is loosen fuel cap and run bus on test drive.

Anonymous said...

if you run Cummins especially ISB engines buy a fuel pressure gauge kit from OTC. These engines are notorious for fuel delivery problems