Yanmar 4lh valve adjustment

[brian sutton]

I’m going to attempt to adjust valves for the first time on a diesel engine, yanmar 4lha-stp.I will explain the procedure from what I have researched.
Turn engine over by hand infill exhaust valve for #1 cylinder is fully open.Then adjust the exhaust valve for the #4 cylinder.Then turn engine over a little more infill the intake valve for the #1 cylinder is fully open and then adjust the intake valve for the #4 cylinder.Then turn over the motor unroll the next exhaust valve is fully open (#3 cylinder) and adjust the exhaust valve for the #2 cylinder,then the intake.Then move on to opening the #4 cylinder valves to adjust the#1 valves followed by rotating motor to open up #2 valves to adjust #3 valves.
Adjust the intake valves at 0.004 in and adjust the exhaust valve to 0.012 in.The exhaust valve can be spaced by as much as 0.19.
This is based on firing order 1-3-4-2.Is this the best/easiest procedure?
Thanks for any replies,Brian

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[Tony Athens]

Brian,

Good post, IMO I personally prefer a different method for any diesel engine when adjusting valves..

I look at the firing order and label each cylinder.. Pull the valve cover and start barring over the engine (in the correct rotation).. I watch for any intake valve that is closing and when is stops moving, I adjust the EXH valve as I know it is now 100% closed.. I keep rotating while watching the next cylinder inline and feeling for TDC ( easy to feel).. I then do that cylinders exhaust and I am now close to the next cylinder in line.. Remember, on any 4 cyl engine, a cylinder is at at TDC “compression” every 180 degrees of rotation..

Tony

[brian sutton]

The adjustment for the exhaust valve should have said “can be spaced as much as 0.019 before adjustment is needed”.
The way I explaind the procedure sounds confusing but basicly I was saying,with the firing order 1-3-4-2, when the valves are open for cylinder 1–>adjust valves for cylinder 4.
Open valves on cylinder 3 –> adjust valves for cylinder 2.
” ” ” ” 4 –> ” ” ” ” 1.
” ” ” ” 2 –> ” ” ” ” 3.
Theory being when one valve is open (at the top of lobe on camshaft) the sister pistons valves are 180 degrees on the other side on the cam lobe where the adjustment is suposed to be made, right?
1-3
4-2

[Author]

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