Timing Window

bill18163 · May 21, 2022

I have a L3940HST. I'm working on the 800 hour maintenance which includes checking the engine valve clearance. I have the fuel tank off and I'm ready to remove the valve cover on top of the engine. I decided to quit for the day but then started to look for the timing window. It has to be in the flywheel or clutch housing but for the life of me I can't find it. Can somebody tell me where it is? What side of the tractor is it on? Thanks.

BeezFun · May 21, 2022

I don't have the same tractor, but I didn't find the timing mark that useful. My inspection hole is on the clutch housing but it was obscured by some hydraulic line or something that made it hard to see. There's only one mark for cylinder #1 TDC, and they have a goofy chart in the shop manual on how to adjust the others that made no sense to me. I ended up watching the exhaust valve closing and intake valve opening and then putting the camshaft halfway in between. I experimented with the feeler gauge and there was no difference as long as I was close to that midway point. For what it's worth, I adjusted mine at 800 hours and they were all dead on, so I could have waited a lot longer to do it.

bill18163 · May 22, 2022

Is the number one cylinder at the fan end or the flywheel end of the engine? I can't find any pictures or a diagram.

BeezFun · May 22, 2022

bill18163 said:
Is the number one cylinder at the fan end or the flywheel end of the engine? I can't find any pictures or a diagram.

I went through the same thing in this thread. On my tractor it's closest to the radiator, the shop manual defines it as the cylinder closest to the gear case, but the gear case they're talking about is where the crank and camshaft gears are, which is the radiator end of the engine.

bill18163 · May 24, 2022

Does anyone know the cylinder number order for the 4 cylinder engine in my L3940HST tractor? I know the first cylinder at the radiator end of the engine is the #1 cylinder but what are the designated numbers for the next three cylinders as you move in the direction of the flywheel?

BeezFun · May 24, 2022

The numbering is consecutive 1,2,3,4 starting at radiator and going back to the flywheel.
Or are you asking what the firing order is? You can watch the valves on the other cylinders and identify which one is firing to get the order.
Or the service manual is only $29.

jonsstihl · May 25, 2022

I am in the planning stages of valve clearance check myself on my L4740. shop manual doesn't mention removing the fuel tank although I can see where having a little more room would help. they do say to remove the glow plugs to help when turning the engine over.

are there any gaskets or crush washers between the glow plugs and the cylinder head.

bill18163 · May 25, 2022

jonsstihl said:
I am in the planning stages of valve clearance check myself on my L4740. shop manual doesn't mention removing the fuel tank although I can see where having a little more room would help. they do say to remove the glow plugs to help when turning the engine over.

are there any gaskets or crush washers between the glow plugs and the cylinder head.

jonsstihl,
I took the hood off, the fuel tank and the muffler. I don't think you could do the adjustment on the valves with the tank in the way. The glow plugs have a tapered seat. No washers or gaskets. If you are going to use the timing window to view the flywheel timing marks, the window is on the right side of the flywheel housing as you sit on the tractor. BUT if you have a front end loader you are going to have to take the loader support off on the right side because the timing window is behind the FEL support.

BeezFun · May 25, 2022

jonsstihl said:
they do say to remove the glow plugs to help when turning the engine over.

I'd try to turn it over before you remove the plugs to see how hard it is. Mine was easy to turn over but my engine is smaller. It's easy to get in trouble when you take a glow plug out, they tend to get rusted in place, and the wiring can be fragile. If you break one off you're looking at a major pain.