What do you do? I have a Kubota M108 here with a severe engine miss. I have isolated the problem to cylinder number three. I did a compression test and compression is at the low end of the specification, but not below the spec for acceptable use.
Now the tricky part. The tractor has 10,000 hours of operation on the original engine which is about the expected life of the engine. I could just replace the bad injector and it would run. I could put a set of injectors in it and it would run better. To replace the injectors costs about $4500. A new complete engine costs $8500.
Installing one injector in an engine with this many hours is not a good plan. I have replaced injectors one at a time only to have another injector fail within a few days. A whole set of injectors is expensive, more than half the cost of a new engine. It is a lot of labor to get the injectors out.
So now the lines blur. If I just repair the fault, it will be back. If I replace all the injectors, it will cost more than half of a new engine and will most likely need more repairs very soon. If I put in a new engine, the rest of the tractor is still worn out.
What would you do?