Which injector is guilty

[stuckmotor]

The tachometer on my MF 261 swings back at regular intervals so, I suspect a problem with one particular injector. Is there a quick and painless way to find out which injector is in need of service? I've thought of an engine stethoscope or an infared thermometer.

 

[TomSeller]

The tachometer on my MF 261 swings back at regular intervals so, I suspect a problem with one particular injector. Is there a quick and painless way to find out which injector is in need of service? I've thought of an engine stethoscope or an infared thermometer.

I would crack the injector lines at the injector one at a time while the engine is running until you notice no or little difference in engine operation from one of them. By cracking, I mean loosen the injector nut until the diesel is dripping off of the threads. If it is dripping off of the threads it will not have enough pressure to be injecting into the cylinder. If one is not operational, you will not notice a difference in the engine tone. Do not take the nut fully oft to prevent contamination.

 

[stuckmotor]

Tom,
Thanks for your reply. At this point my query has has 197 views and nobody else has responded. I guess you nailed it on the first effort.

 

[timster2]

If you have a dead injector the infrared thermometer aimed at the exhaust manifold will show a cold/misfiring cylinder. Cracking an injector line as previously mentioned will help detect a misfiring cylinder.

 

[stuckmotor]

Timster2,
Thank you. I've been looking for an excuse to buy one of those infared thermometers.

 

[timster2]

The infrared thermometer is a very useful tool that I use often. Anything that involves heat including but not limited to, brakes,cooling systems, exhaust, tires, bearings, wiring, HVAC, insulation can be diagnosed with infrared. Automobiles, trucks, tractors or just about anything with an engine is one big heat exchanger. Fuel in, combustion, heat out, minus friction, brakes, bearings etc.