Jinma 254 General Questions

I think all farm tractors have a hi – low transfer case , Some tractors do not use decompression to help start the engine and the shift pattern can be anything . Is the tractor equipped with a shuttle shift? That is where you chose a gear for your ground speed and the shuttle changes from forward to reverse.

My 2007 (built in 2006) has the creeper (or crawler) hi/lo that yours does not. That may be a difference between the models or it may have been an option that was not built into your tractor. Not all farm tractors have transfer or hi/lo speed selectors. Some do, some don’t. My 284 has 12 forward and 4 reverse speeds using the two transfer cases in various combinations. However you have the “shuttle shift” and I don’t. For doing loader work it is a great benefit because you can flip back and forth without shifting the transmission. I wish my 284 had that feature when moving snow.

As for shifting gears. Most tractors with manual transmissions don’t have a synchronous gear set, so you don’t up-shift on the move. You come to a compete stop before shifting to avoid grinding the gears.

Decompression levers are nice to have but not a complete necessity. Do you have the two or three cylinder engine?

I am a little surprised you don’t have a decompression lever. Look on the back of the rocker cover to see if you have the mechanism circled in yellow.

I have the Y385 engine.

Here is a picture of the decompression lever and one of where it goes towards the engine. Your may have been removed at some point and all you need is the parts. Speaking of parts, did you find a parts manual?

I like the decompression feature for two reasons. If it has been more than a week since the tractor was used, I like to hold the fuel cutoff and the decompression at the same time and spin the engine until I get oil pressure built up and then for another 5 to 10 seconds. This acts as a pre-oil to minimize wear at startup.  Second, for really cold starts or weak battery conditions. If you use the decompression for the first couple of revolutions when you hit the starter it lets the crankshaft and flywheel get up to speed easier. Then when you drop the lever that inertia helps the starter motor against the compression stroke.

I can take better pictures of it and scan the parts page if you would like.

Yeah, those are older pictures from way back when I put it together out of the crate. At 11 years and 600 hours it doesn’t look that nice any more.

Mine is a little loud, but it is a diesel from China! I am still on the original battery although it is getting week this fall and the new one is in the shop. I have never had any battery go 11 years.

Injector pumps have a couple of known issues. The seal between the pump crankcase and the lift pump likes to leak diesel into the crankcase and that dilutes the oil that is shared with the governor. They can also leak fuel from the injector pump pistons. Mine has done both. I just put in new oil when I change the engine oil which is usually somewhere between 50 and 100 hours.

Here is the throttle parts for the 284. Apparently there were two different variations during the production run but the decompression is about the same for each. Your tractor may be exactly the same or something different entirely.

IF I REMEMBER CORRECTLY the decompression release was not furnished on some of these tractors with shuttle shift because of a linkage conflict( the thread was on the old site maybe two upgrades ago). Since you are the new owner I would retorque the head and reset the valves unless you can verify that it has been done before.

Matthew Prestine wrote:

I have been reading about the hydraulic systems on these tractors. What are the recommendations for adding a relief valve in case of a hose failure? Matt

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Welcome Matt.

Unfortunately, a relief valve won’t help in case of a hose failure. There are double walled hoses for that, but their cost and available space makes them prohibitive for these tractors. A relief valve is already built into your valve body but a relief valve at the pump output could be beneficial if you have the Chinese quick connect fittings on your loader, which have been known to fail.

My Mitsubishi excavator has sleeves over the hydraulic hoses in the cab and engine compartments, but all they would do is keep the oil from spraying all over.

Since you are pretty far up north , Maybe instead of the decompression lever a lower hose coolant heater should be looked at for a ease of starting method. They are pretty easy to do. And in my experience with it only needs a hour to do its job. If you know when you are going to use the tractor I have used a timer to activate so it is ready to go at the set time.

Here is a picture of the tank heater I installed. A lot simpler and more effective than a lower radiator hose one.

Water comes out of the bottom of the block at the drain valve, goes through the heater and back into the top of the engine just below the thermostat. Circulation is all inside the block and not wasted in the radiator. This one is 1000 watts and heats a -20°F engine to melting snow in about 30 minutes.

I made some changes after this was taken because the drain valve failed. Turned out the block was standard SAE pipe thread so the fix was easy.

For your heater here is the topic where I put one on.

http://www.ctoa.net/topic/canister-water-heater/

Remember the fit and finish even when new is probably no where near what you would expect. Yet they run and survive. Kind of a testament to modern oils.

How many hours on that engine? It will be interesting to compare the appearance of new bearings with the old. Also once you get new bearings you can check the clearance and get a better idea of how much wear there is. Do you have specs for new and service clearances?

It doesn’t look all that bad in there and the tractor looks to be in good shape too.

Before I went crazy with taking it down where is your oil pressure readings if they are normal they are normal , unless you are bored I would not go down that splitting road. 189 hrs is not much even semi-neglected. The oil valleys in the head look clean enough in the pictures. At the most drop the front driveshaft and pull the oil pan. look in there for excess metals (there will be some with the poor block manufacturing clean up ) and pull and mic. main and a rod bearings . Good luck

One thing I forgot to mention is do make sure that the clutch is adjusted correctly . I assume it is 2 stage. So make sure you use the right 2 stage settings.

no I overlooked them, yeah  to me it looks like bearings and a crank possibly. The scoring I can see by a dry start but the pitting makes me think corrosion. So maybe oil with a lot of water and ran and maybe let sit awhile before something was done with it. just a guess.

I would go with documented chart of metric bolt hardness to torque values. I can not believe you could go wrong with that. now watch me be wrong.