I’d like to comment my personal experience. My guess is that the cylinder bores are worn from dirt. The 855 John Deere has two air filers that could fit it :AM 102746 and AM 108184. The former is 9” long and the latter is 8.25”. Other than that they are identical. People frequently use the shorter filter without realizing it and that leaves 3/4” air gap around the air filter at the back of the canister.

The bearings and pistons seem to be in pretty rough shape! It will be great to watch you rebuild this and bring it back to life. I cannot wait🙌

Anyone rebuilding a yanmar should be following this! The info and the details are spot on, love your work bruv!

Excellent autopsy and failure analysis; your videos are always a pleasure to watch.

Speaking as a retired LAME with many hrs rebuilding Lycoming Aircraft motors, this is a very good inspection video. The question of bore/piston wear combined with the oil pump wear leads me to the journals as you also indicated the lip on them, with associated big end bearing scouring. I see a situation that this motors oil pump would fail under high loading, disrupting the oil pressure to the bearings, and giving the motor a clear big end bearing "rattle" when over 2,700 rpm. It was close to complete failure, and a rebore, oversized pistons and new oil pump, sump extension, etc obviously necessary. This motor was assembled very poorly, the welded section of the sump extension is actually a shocking example of an obviously shocking repair, with the broken section most likely caused by the partially stripped motor being dropped onto the floor, and that end breaking right off. It was clearly reassembled on the cheap, and in a great hurry. You NEVER HAMMER ALI, but lightly tap a soft block of wood in the middle, that has been laid over the entire part so that even, light pressure is applied. If you are tapping it harder than you would hit your finger with a hammer, then you are tapping it too hard. Personally, I would throw away the valves and seat new valves in, simply due to saving the chances of one being too close to minimum tolerances and splitting, breaking, jamming, and then snapping the valve with the associated piston/bore damage that would result. What did the crack testing around the valve seats and the big end bearing crankcase area show ? Piston "wobble" usually causes cracks in both these areas, with the valves actually also getting some sideways movement putting extra pressure on the head of the chamber. There were many cylinders that we found this damage to, which Aviation Laws prevented repairs being made, and we were required to break off the valve stands with a hammer, rendering the cylinder useless. All reassembled engines should be fully "run in" prior to instillation, with a correct high ISO Bedding Oil, and then secondary compression checks done. Always cut open the internal filter element to check for any metal wear when changing oil/fuel filters. And always friction proof your new engine with a good viscosity additive such as Wynns, etc. I always use additives for engine flush, motor & transmission & diff oils, and every full tank of gas. It gives me a friction proofed motor and box, and very, very stable compressions with high mpg. ( as well as a very long engine life ) These same oils were used in the aviation industry, and are worth every single cent. I get 30% more out of every gallon of gas than anyone who is not using them.

Love your channel! I have a John Deere 430 with the Yanmar diesel engine. For the life of me, I can’t get it to run. Seems like the injection pump isn’t pumping enough fuel. I was hesitant to take the entire engine out to see what’s wrong but now I can see these engines are pretty simple and will probably do a complete rebuild thanks to your videos. Thanks so much!!

An easy mistake to damage the oil pan spacer. Bolt to the block not the spacer. The end of the oil pan spacer can be broken if an engine stand is attached to the flywheel side spacer end bolt holes with the oil pan facing upward. As the oil pan bolts are removed the spacer also separates from the block on the stand end and transfers the hanging engine weight to the remaining spacer bolts on the opposite end of the engine. Snap!

who knew that a lawn mower could have so many issues

How was the oil when you drained it? Any grit or glitter? I'm wondering if the welded intermediate pan is connected to the other issues. Maybe the engine was damaged in an accident and was run with contamination in the oil? Worn valves, scored pistons & bores, welded pan and a replaced fuel pump are a lot of issues with such low hours. Also the edges on the crank journal holes are very strange - like someone enlarged the holes but didn't finish the job. Could there be one event that ties everything together?

I got a yanmar with 3800 hrs I have owed from new and another one with 1500 no problems with either

Random quesiont! If one of these engines runs away - how can you shut it down quickly? Is there any easy trick to kill the intake air somehow?

So, what was the condition that led to the decision to rebuild the engine? Lack of compression, unusual oil consumption, high operating temperature, or ...?

I would like to say thank you so much for sharing this Video,Sir... Anyway,Would you like to share the video on"How the way to replace the engine oil,oil filter,fuel filter and also how to totally replace water/coolant radiator for the YANMAR 3TNV82A Diesel Engine ? once again thank you so much inadvance,Sir.

Hello! when will there be a continuation of the 3 tnv 82a engine?

how many hours yamr engines are usually bullet proof

This 3TNV82A is same with 3TNE82E ?

it seems like everything is scored