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Old 01-01-2020, 16:30   #1
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Newbie: adjusting valve clearance / valve lash

Hi,
Iím attempting to adjust the valve clearance on my Nanni 3.21 engines (Kubota D722).
Iíve never done this before and looking for some tips from the pros!
I downloaded the Kubota shop manual which details the process. The manual talks about lining up marks on the fly wheel to bring the cylinder to the top when measuring gap in the valves.
I donít see any marks to know the position of the cylinder. How do I know when to check each valve?
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Old 01-01-2020, 16:49   #2
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Re: Newbie: adjusting valve clearance / valve lash

In essence, make sure the piston is at top dead centre of the compression stroke and then adjust for that cylinder.

The timing marks make it easier but they are not essential.
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Old 01-01-2020, 16:49   #3
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Re: Newbie: adjusting valve clearance / valve lash

Is there an inspection window in the bell housing that covers the flywheel, may have a plate over the top to keep fingers out which needs removing first.

Pete
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Old 01-01-2020, 16:53   #4
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Re: Newbie: adjusting valve clearance / valve lash

TDC is a good place to start but not necessary. You can also simply start turning the main pulley (injectors out) watch for both valves to close on the same cylinder and watch for the exhaust valve to start opening, roll back until they are both fully closed. Adjust that set of valves for the clearances in your manual then move into the next one in order. If you start rotating the engine with a spanner you will be able to pick up which cylinder is closed pretty quick, probably within 1-2 full rotations of youíve never done it before.
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Old 01-01-2020, 17:01   #5
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Re: Newbie: adjusting valve clearance / valve lash

Rotate 6.28 radians??? really???
How about just turning the engine over until one intake valve is just starting to open and its exhaust valve is just closing, then one more rotation and that's TDC for that cylinder. Set the valves for that one, and then on to the next.
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Old 01-01-2020, 17:01   #6
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Re: Newbie: adjusting valve clearance / valve lash

I see from your picture that you have already removed the injectors rather than the glow plugs as suggested by the manual.

Removing the glow plugs only saves having to bleed the high pressure side of the injection pump / injectors. However, IMO removing the injectors occasionally is a good thing - stops them from getting stuck in the head!
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Old 01-01-2020, 19:56   #7
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Re: Newbie: adjusting valve clearance / valve lash

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Originally Posted by Wotname View Post
In essence, make sure the piston is at top dead centre of the compression stroke and then adjust for that cylinder.

The timing marks make it easier but they are not essential.


Yeah, but how do I know when the piston is at the top dead center without marks?
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Old 01-01-2020, 20:01   #8
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Re: Newbie: adjusting valve clearance / valve lash

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I see from your picture that you have already removed the injectors rather than the glow plugs as suggested by the manual.

Removing the glow plugs only saves having to bleed the high pressure side of the injection pump / injectors. However, IMO removing the injectors occasionally is a good thing - stops them from getting stuck in the head!


I removed the injectors to have them tested.
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Old 01-01-2020, 20:03   #9
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Re: Newbie: adjusting valve clearance / valve lash

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Is there an inspection window in the bell housing that covers the flywheel, may have a plate over the top to keep fingers out which needs removing first.



Pete


I donít think so, but Iíll have a closer look.
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Old 01-01-2020, 20:10   #10
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Re: Newbie: adjusting valve clearance / valve lash

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Yeah, but how do I know when the piston is at the top dead center without marks?
If its a direct injected engine use a soda straw to place on the piston top and then you can watch exactly when the piston is at TDC don’t use anything that can break off or could possibly cause any damage, and be sure it’s never gets pinned. Often times you access the piston from the side a little and if you use say a screwdriver you can get it wedged in at an angle and that could damage something.
If it’s an IDI engine, without marks I don’t think you can. Not worth pulling the head.
Personally I do not think you can swag the right spot, maybe if you have a lot of experience as you can often feel the little lack of resistance in the crank when a piston stops its travel, but that’s tough to do and probably not reliable.
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Old 01-01-2020, 20:15   #11
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Re: Newbie: adjusting valve clearance / valve las

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Originally Posted by Pete7 View Post
Is there an inspection window in the bell housing that covers the flywheel, may have a plate over the top to keep fingers out which needs removing first.

Pete
Iím betting Pete is right, your book did say flywheel. That is of course under the bell housing behind the engine.

Before I tried just guess at it, Iíd hire someone and watch. But there has to be an inspection window, has to be.
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Old 01-01-2020, 20:23   #12
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Re: Newbie: adjusting valve clearance / valve lash

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Yeah, but how do I know when the piston is at the top dead center without marks?
Look at the valves and the front crankshaft pulley.

Rotate engine and watch say #1 exhaust valve, when it begins to open then that cylinder is beginning it's exhaust stroke.

Rotate crankshaft 180 degrees and the exhaust valve will be closing and the inlet valve will be opening. This is the start of the intake stroke.

Rotate another 180 degrees and the inlet valve will be closed as will the exhaust valve, this is the start of the compression stroke.

Rotate another 180 degrees and the piston will be a TDC.

At this point, rock the crankshaft back and forward a few degrees (say 15 to 20) and confirm the valve clearance (lash) on both valves remains steady. When both valves are at the maximum clearance and not changing while rocking say 5 to 10 degrees, the piston is at TDC at the middle of the rock. Mark the crankshaft pulley and block for future reference.

If you are really fussy, do it again on the next cylinder and finally the third one. Your marks should be 120 degrees apart, if not check each one again until they all are 120 degrees apart.

First time will take some finesse and really you only have to do it once.

This engine is indirectly indirectly injected otherwise you could look down the injector hole. I don't know how the glow plugs are fitted on this engine but maybe they go straight into the head. If so, remove one and place a thin rigid rod down the hole and feel for the piston to rise up to TDC as you rotate the front pulley.
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Old 01-01-2020, 20:30   #13
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Re: Newbie: adjusting valve clearance / valve lash

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Yeah, but how do I know when the piston is at the top dead center without marks?
You really donít need a perfect TDC, both valves need to be closed and both pushrods slack. There is a fairly large window to adjust, maybe 1/8-1/4 turn on the crank.
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Old 01-01-2020, 20:39   #14
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Re: Newbie: adjusting valve clearance / valve lash

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Originally Posted by Wotname View Post
.......
This engine is indirectly indirectly injected otherwise you could look down the injector hole. I don't know how the glow plugs are fitted on this engine but maybe they go straight into the head. If so, remove one and place a thin rigid rod down the hole and feel for the piston to rise up to TDC as you rotate the front pulley.
This guy suggests the glow plug removal method does work - see post 8 here
https://www.orangetractortalks.com/f...ead.php?t=4314
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Old 02-01-2020, 10:00   #15
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Re: Newbie: adjusting valve clearance / valve lash

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