Does Anyone Buy Used Tractors?

[Hay Dude]

No machine shop needed for repair or rebuild as long as the crank doesn't need to be turned. A rebuild can be accomplished any where any time quickly and easily.

Yep, you can order a reman/rebuild kit and do it in frame, short of a head resurfacing or crank turning

 

[alexpops]

Target markets and local demographics? In a market like the Philippines, Pakistan, Cambodia (take your pick of third world cesspool), the government could care less about climate change and you need to provide an economic, long-lived product that allows locals to be able to rebuild on the beach with hand tools/no machine shop/no computer scanners or they won't buy from you. No need to retool/ we'll sell them the 40-60 year old design we sold in developed markets back in the day, & extend the useful life (ROI) on our old tooling. In the US/EU/AU markets, you have the government demanding changes & partnering with the manufacturer at the expense of the end-user, so that 40-60 year old design is dead here. We pay for "better" unless we want to import a used engine (sight unseen) from the third world along with questionable quality rebuild parts. If the US dropped all environmental regs tomorrow & someone started importing old-school, owner repairable diesels here from China or wherever that were economic, the majors would be forced to match the market or go out of business.

 

[alexpops]

^^

It sounds like a bored block is cheaper. So it isn't manufacturing cost.

So why would Yanmar make so many small 12 to 20 hp multicylinder diesels with wet sleeves? You see them all over the world in everything from dugout canoes to water pumps to generators and tractorss. All those small diesels are easy to lift from the chassis, easy to work on, and all are wet sleeve.

 

[5030]

You'll rarely find a parent bore engine in a big truck. 99% are wet sleeved with crevice seals at the bottom. Wet sleeved engines transfer heat to the coolant much better and with a diesel under load, efficient transfer is very important to mitigate oxygen impingement and the resulting holes in the liners.

 

[finn1]

You'll rarely find a parent bore engine in a big truck. 99% are wet sleeved with crevice seals at the bottom. Wet sleeved engines transfer heat to the coolant much better and with a diesel under load, efficient transfer is very important to mitigate oxygen impingement and the resulting holes in the liners.

Correct. Big bore engines are pretty much exclusively wet sleeve.But you’re talking engines that have a manufacturing cost of close to $20000 in the case of a class 8 big bore truck engine, and that’s not taking in profit or return on investment into consideration.

It’s also why mid range and small Diesels are almost exclusively parent bore now. The market won’t support the price of a wet sleeve engine.

Cavitation is a subject entirely unto itself. I never heard it described as oxygen impingement, and don’t pretend to know what that means.

Cavitation is caused by low pressure zones at the interface of the liner and the coolant. The coolant effectively boils at those low pressure points and plucks material from the outside of the liner. Crevice seals are sort of like a packing that keeps coolant away from the relatively tight areas at the bottom of the sleeves. If there’s no coolant in that tight area, then the cooland doesn’t “boil” in a low pressure caused by sleeve vibration. Not all wet sleeve engines use crevice seals though. There are many different designs. One engine I worked on early in my career had a field problem that was misdiagnosed as cavitation erosion around the oring at the bottom of the sleeve. We found that the problem was actually a manufacturing issue. The steel shot used at the foundry to clean the cylinder head water jackets wasn’t getting cleaned out adequately. The shot would get flushed out of the head in operation and lodge in the area of the oring and block. Vibration from the combustion event would create enough micro motion that the shot would create what looked like wormholes around the oring.

And, yes, parent bore engines can also cavitation, developing pinholes that allow coolant to leak into the cylinder. A good coolant SCA treatment protects the engine from cavitation damage, both on wet sleeve and parent bore engines.

 

[finn1]

I don't know the all the advantages of sleeved vs bored block diesels.
Maybe someone could explain more.
I do know that Yanmar used sleeved bore for their small diesel tractor & marine engines for many years. Maybe they still do. I haven't had a recent one open. What kind of cylinder is common for other compact/utility size tractors?
rScotty

Best I can tell Yanmar engines introduced in the last, say five or so years are all parent bore. They don’t really talk much about it but the cutaways in their new product release videos sure look like parent bore blocks.

Legacy engines retain liners, as it’s very difficult to economically change transfer line machinery from one design to the other. At that point it would be advantageous ti start a totally new engine design from scratch, using new technology. Looks like that’s what they did with their 4TN101 and 107 series engines. Four valve, Direct injection, common rail, two stage turbocharging, DOC, DPF, EGR, urea scr , etc

 

[jjeff]

Yes I do buy used tractors lol

 

[rScotty]

Yes I do buy used tractors lol

So do I. It sounds like the OP has his answer - quite a few people buy used. It's been mentioned before, but I actually prefer buying low hour used over new. Lots of reasons, and saving money is just a side benefit. And I especially lean toward low hour used now that I am not doing much of my own mechanical work.
rScotty

 

[jjeff]

So do I. It sounds like the OP has his answer - quite a few people buy used. It's been mentioned before, but I actually prefer buying low hour used over new. Lots of reasons, and saving money is just a side benefit. And I especially lean toward low hour used now that I am not doing much of my own mechanical work.
rScotty

Most would consider my tractors used "up" lol

 

[5030]

Cavitation is a subject entirely unto itself. I never heard it described as oxygen impingement, and don’t pretend to know what that means.

cavitation and oxygen impingement are the same thing. When a bubble forms on the side of a liner and it 'explodes', it initiates the process as it removes a tiny amount of the outer treated part of the liner and allows the resultant hole to bore into the liner and eventually compromise the liner causing engine failure. I retired from a class 8 heavy duty truck dealership and we rarely saw that happening because most trucks either came with a coolant filter with a block of potassium permagnate inside or the owners used DCA4 additive which is deionized water with the Potassium in solution. The DCA 4 or or the charged coolant filters allows the potassium to 'coat' the outside of the liner, preventing cavitation or oxygen impingement. Kind of like taking water in a pan and heating it. The bubbles that form on the bottom of the pan as the water heats are exactly what happens with a liner.

Like I said, did a few, but not many and it always resulted in engine failure.