Valve Lash Adjustment 2008 Jinma 284 with QC395T Engine

[Amez]

Thanks for the clarification. My engine is a 2007 Y385, which looks the same as yours in the photos. The valves from front to rear are:
Exhaust - intake , exhaust - intake , exhaust - intake .
I know there have been some confusing posts in the past about the valve order , and it's probably not a big issue since the adjusments are very close. ( Some of mine were out by .4 mm)
Incidentally , at 100 hours my rocker arms and valve stems showed unusual wear.
Mike

 

[3RRL]

Thanks for the clarification. My engine is a 2007 Y385, which looks the same as yours in the photos. The valves from front to rear are:
Exhaust - intake , exhaust - intake , exhaust - intake .
I know there have been some confusing posts in the past about the valve order , and it's probably not a big issue since the adjusments are very close. ( Some of mine were out by .4 mm)
Incidentally , at 100 hours my rocker arms and valve stems showed unusual wear.
Mike

Hi Mike,
Thanks for letting me do so... It's hard to eat crow!
Yeah, your engine looks just like mine. You can see it's really hard to tell to which valve the fuel injector goes and which valve goes to the exhaust manifold. On my big 4 cylinder 55hp Kama, it was easy to see. But you can bet I'm gonna check it that way when I do another valve lash adjustment on it. It's almost got 600 hours on it now.

About the confusion, I learned for sure that when rotating the engine the exhaust valve ALWAYS starts to close just before the intake valve starts to open. So that's the end of the exhaust stroke and beginning of the intake stroke. That is THE sure fire way to determine which valve is which. Continuing the rotation from that point is the intake stroke lasting 180 degrees and the compression stroke follows with another 180 degrees. So when the engine has been rotated 360 degrees that's TDC on the compression stroke. The engine rotation can be checked by turning it over with the starter motor or from the fins on the radiator fan. The fan should be sucking air through the radiator when the engine is running.
BTW, I noticed your compression relief also opens the intake valves. That has been confusing as well.
Rob-

 

[Amez]

Rob
I noticed that it looks like your front tire has hit the loader frame when turning (probably on uneven ground). Is that why your front wheels are flipped and if so did it help? I had that problem and it caused front tire damage.
Mike

 

[3RRL]

Rob
I noticed that it looks like your front tire has hit the loader frame when turning (probably on uneven ground). Is that why your front wheels are flipped and if so did it help? I had that problem and it caused front tire damage.
Mike

Good eye Mike,
Yes that's one of the reasons. The other is for added stability. Some may argue the point since the front axle pivots, but I still feels it helps with the stability and for sure when the axle pivot hits it's maximum deflection.
Moving the fronts (and rears) out to their widest position made an increase in overall stability on my steep slopes. If I crank the front wheels over all the way, they still nick a little. I think I need to set the wheel stop a little. The turning radius is fine right now, so a little restriction wouldn't hurt me.
BTW, do you have an FEL? If so, also check yours to see if your curl is adequate so material doesn't fall out when transporting it in the bucket held low. And see if your cylinder rods are touching the FEL arms and bending. The bending cylinder rods are a must fix.

I had to fix both problems on this Jinma.
Maybe you have already seen these threads: Add More Bucket Curl to Jinma 284

This is my wife's Jinma, but we did a lot of modifications to it. Here's another thread about: MY Very Own Grapples

Also one about changing out the stock ZL-20 loader valve with one from: Ranch Hand Supply Loader Vavle

 

[Momboy007]

Hello All,
I am sorry, but I do not completely understand how to find TDC, Am I correct to assume that I turn the crankshaft until no valves move on the #1 cylinder? Help and I am sorry I don't completely get it!
By the way Rob, I now feel like I may be able to do this after reading your post, Great Job!
BTW, my tractor has never made it to the green area of my tach and my valves have never been adjusted, I am almost ready to tackle this job as soon as I figure out the TDC issue.
Thanks again,
Rick

 

[greg_g]

Hello All,
I am sorry, but I do not completely understand how to find TDC...

TDC occurs when the piston has reached the absolute end (top) of its exhaust stroke. The intake valve was already closed while the cylinder was pushing burned fuel out the exhaust valve. Then by the time the piston reaches the very top, the exhaust valve will have fully closed. That's TDC. After that, the piston starts back down again - the beginning of the intake stroke - at which time the intake valve starts to open again.

Hopefully you don't have a loader mount blocking the flywheel viewing port. There should be a series of marks on the flywheel, one of which indicates TDC. When you rotate the flywheel by the way, you should have the decompression release tied open. If not so equipped, tie the fuel cutoff valve closed. Both are safety measures to prevent accidental starting of the engine.

Alternatively, there may be a mark on the crankshaft pulley - but on my tractors I find that harder to see without removing the radiator. Either mark should tell you when the #1 cylinder is getting close to TDC. But understand that just rotating the engine till you see the mark - is the gross adjustment. I use a large screwdriver as a lever on the flywheel, or you can use a socket and breaker bar on the crankshaft pulley or alternator). After finding the mark, shift your attention to the valve train. Fine tune the engine rotation until all the spring tension is off BOTH valve stems on the #1 cylinder. That means they're both fully closed, and that you can now start the actual valve lash adjustment on that pair of valves. The firing order determines which cylinder you work on next.

But don't put the cart in front of the horse. After finding TDC of #1 the procedure and sequence often differ slightly between and among engines. Your JM304 probably doesn't have the same engine as Rob or Larry. So you must first take into consideration the number of cylinders and whether intake or exhaust is used for decompression (if so equipped). Then you have to confirm the intake/exhaust/decompression gaps, and the firing order specific to YOUR engine.

//greg//

 

[Momboy007]

Hey Greg,
Thanks for that, it clears up alot for me. The bad news is that I do have a loader blocking the inspection plate for the flywheel. I also have a Jinma 304 with a 3 cylinder. I think after yours and Robs advice I can do this
Thanks again,
Rick

 

[Rich Waugh]

Greg G wrote: "TDC occurs when the piston has reached the absolute end (top) of its exhaust stroke."

Technically, Top Dead Center (TDC) occurs when the piston is at the top of its stroke, regardless of which revolution it is on, I believe. There is a TDC on the exhaust stroke and one the compression stroke as well. For the purpose of setting valve lash, and for fuel injector timing, TDC must be on the compression stroke, since that is where the firing takes place.

I too have a Jinma 304 (with the TY395I-3 engine) and will be doing the valve lash adjustments in the next few days myself. The tutorials posted here and on other forums are an invaluable guide to doing this important procedure correctly. My tractor tool kit came supplied with the proper feeler gauges for setting the valve lash, even. Handy, that.

I hope this hasn't muddied the waters for you. Follow the manual and you'll be fine, I'm sure.

 

[3RRL]

Hi Rick,
Glad to hear you have the confidence to adjust your valves now. Both Greg and Rich gave good information. You want to set the valve lash when the #1 cylinder is at TDC on the compression stroke. To find that point, use the information I gave earlier and also what Greg and Rich wrote.

Here's the sure fire way to find TDC on the compression stroke.
Rotate the engine in the direction it runs. I explained above exactly how to do that. You can click the starter motor and see which way she starts to spin and also use the vanes on the radiator fan. When your engine is running, the fan should be sucking air through the radiator.

After making sure the tractor will not start using the recommended safeties I mentioned, and after removing whatever is in the way and removing the valve cover, you start rotating the engine in the direction it runs.

When you see the two valves working together, one right after the other, the valve that is closing is the exhaust valve and the valve that just starts to open is the intake valve. Make a note of that.
Like said above, to be sure you are right in the middle, move the crankshaft back and forth to the find the spot where they are not moving. That spot should also correspond to a mark on the crankshaft pulley and also on the flywheel. Now the piston is at TDC of the EXHAUST stroke. Do NOT set your valves at this point.

Now rotate the crankshaft 360 degrees in the direction the engine runs.
This is TDC of the COMPRESSION stroke now. The corresponding mark on the pulley and flywheel should again line up.
This is where you set the valve lash for cylinder #1.
Then follow the instructions in the manual to set the next cylinder according to the firing order. For a 3 cylinder engine, you will turn the crankshaft 240 degrees to set the next cylinder according to firing order, and then another 240 degrees to set the last one.
Rob-

 

[3RRL]

I just went through all that again to find TDC on the compression stroke and set the valve lash there.
When I set it before, it was TDC of the exhaust stroke, so I corrected it today. I checked them before I adjusted them and found there was way more lash then what I thought. That's why it clacked so loudly, I'm sure. But dang, those Chinese engines just run and are obviously not too picky, lol. But I got it all re-adjusted and it now runs very quietly like it did before, and I can still get over the green area to 2400 rpm with throttle wide open.
Oh, and this time I propped up the FEL all the way.
It was much easier getting in and out of there like that. Over all, including draining the radiator and removing it all again, it took me about an hour and a half this time from start to finish since I didn't have to take off the rocker arm shaft or torque the head this time.
Here are a couple photos of the loader way up, draining the radiator and the engine reved up to 2400 rpm again.
Rob-