2006 L3940 GST Diesel engine performance/tuneup?

okiecraig · Jan 12, 2021

Hey guys, back for help once again.....my 2006 L3940 with diesel engine is now at 1960 hrs. Over the past several years, I have noticed the engine will blow a poof of black smoke when it starts and sometimes under heavy load and RPM 15-1800. it may be my imagination, but it also seems a little sluggish and is using more fuel. (or that could be me since I am nearing 70).

What are the engine parts/systems to check and or replace at this point in time, if any? It has a fairly new, clean fuel filter and new air filters. If I posted a video of the tractor stating, at idle and at 100 RPM, would that help/

maybe I am just getting old.

Thanks much

moship · Jan 13, 2021

Compression and leakdown test is a good starting point to confirm the combustion chamber sealing (piston rings, valves, head gasket) are healthy. From there it might be worth having the injectors tests.

Might also be worth noting if your thermostat is regulating temperature as it should. Many can fail open by design and lead to colder combustion chambers.

RjCorazza · Jan 13, 2021

My previous L3410 would puff a little smoke on startup. I think it had around 1400 hours when I traded it. The maintenance items that come to mind are valve adjustment (800h on the L3410) and injector cleaning (1500h).
I don't know if you have done this maintenance, or when specified for you model tractor. Just a thought.

Roadworthy · Jan 13, 2021

I like to start really basic. Clean or replace the air filter. Make sure there is no blockage in the passage from there to the intake manifold. If there's any break or small opening in the line mice could have nested.

arto98607 · Jan 13, 2021

If it starts and idles well, does not burn excess oil or leak oil, runs at normal temperature and power just do the scheduled maintenance (yes that includes adjusting valve clearances) and leave it as is!
Little puff of black smoke at tractor Diesel engine startup would not bother me.

I have been running Diesel cars, pickups & tractors since 1990 - each was min 10 years old when I bought them.

okiecraig · Jan 16, 2021

Thanks you all for comments. I have not done any valve work on it since I got it. Gotta figure out whether I am gonna try that myself or have to haul it to a dealer (ugh).