My W6 won't run

My w6 has been running great all fall and so far this winter. I move hay bales twice a week (800 lb bales) to feed and have been pushing snow with it lately. I moved snow all morning until lunch time. Then, went down to the neighbors to dig them out and after running for about an hour it seized up and died. I towed it home with my pick up and cannot get it to start. it turns and turns without starting. I have good spark and good fuel flow. Is the motor locked up?

Back up a little and think about what your asking. If it turns over then the engine can not be locked up. I would do things like check compression and see if maybe you didn't brake a cam gear or something like that but if you have spark that probably isn't the problem but you may have stuck valves or something odd
Hobby farm

you say it seized up and died, then towed it home and it turns and turns!then asking if the motor is locked up?....somebody had too much eggnogg today!

Yor are going to have to tell us if the motor is locked up. Can you spin the engine with the starter? If not you probably have a crank shaft or rod issue. You say it seized up. If it was running and it seized up I would get inside the crank case and see what happened before any more damage is done. Look for holes in the side of the crank case. larry m

sounds like you have a loader on it, and were moving snow when it died. i think old is on the right track, sounds like the cam gear let go. tractor prolly has a live pump mounted at the distributor. pop the distributor cap off, crank the engine and watch the rotor. if the rotor isnt turning, or turning erratic, more than likely its the cam gear. you can pull the valve cover and watch the valve train too. if its the gear, get one from the super w6 or super m -400 engines, they are the heavier gear for the live pump.

You need to pull No1 plug near the radiator and bring No1 piston to TDC on the compression stroke.
You can drop a LARGE handle screwdriver on top of the piston once you feel compression against your thumb. Then watch the screwdriver rise as someone slowly cranks the engine. When it quits rising you should be at TDC. Your timing marks should aligned and both valves on No1 should be closed.

Then remove the cap and see if your rotor is pointing to the No1 plug tower. Something may have jumped time. The timing gear may have lost some teeth. If the engine will spin with the starter it isn't seized. I think they've had problems with the timing gears on the M's and W6's since it may drive the hydraulic pump.
Do a compression check and see how all the readings compare. Hal

Sorry, I was a bit frantic earlier trying to figure out how to feed tomorrow without my tractor. Let me warn you, I'm no mechanic and need all the help I can get. I'm pretty sure that all four valves are stuck. I didn't notice it until just now but one of the spark plugs has gas leaking from it. I can turn the hand crank and the starter turns. But, none of the valves move at all when the starter is turning. Perhaps bent rods? I'm not sure.

if none of the valves are moving when you crank the engine over, about 99% sure the camshaft gear let go. pretty big job to change it.

Sorry, I was a bit frantic earlier trying to figure out how to feed tomorrow without my tractor. Let me warn you, I'm no mechanic and need all the help I can get. I'm pretty sure that all four valves are stuck. I didn't notice it until just now but one of the spark plugs has gas leaking from it. I can turn the hand crank and the starter turns. But, none of the valves move at all when the starter is turning. Perhaps bent rods? I'm not sure.

I knew there was a reason to keep a few square bales around to feed by hand. I hope you are able to come up with a rental or something. You might be down a few days. larry m

Actually, there are 8 valves, two per cylinder. How do you know the valves are "stuck"? Did you take the valve cover off and watch them move? The distributor/magneto drive off the cam gear, so if you have spark the cam gear is turning.

Do you have compression? Even putting your thumb over each spark plug hole will tell you if there's any compression at all.

Did you check to see if the ignition timing is close, i.e, spark occurs close to top dead center on each cylinder?

Start with the basics. An engine needs fuel, spark and compression in the right sequence in order to run.

Not sure what you mean by "a spark plug has gas leaking from it". Is the plug loose in the cylinder? Otherwise, there's no way for fuel to get from the cylinder to the outside of the plug unless the plug itself is broken.

Post the results of some very basic tests, and we'll go from there.

1. Do you have compression, even enough to feel with a finger over the spark plug hole? Are all four cylinders the same?

2. Assuming you have spark at each cylinder, does it occur about the same time as the piston is at the top of its travel. Watch piston travel as someone else described, and note the position of the piston when the spark for that cylinder occurs.

3. If you have low or no compression, pull the valve cover and watch for rocker motion as you crank the engine. If you have good compression, the valves are functioning and can't be "stuck".

Hope this helps.

Keith

Take a deep breath, then read what has already been posted. There are EIGHT valves that should be moving when the engine turns over, if they aren't = cam gear is broken. Don't know how you determined you have good spark the distributor shouldn't be turning.

I did pull the valve cover off. All EIGHT valves remain motionless when pushing the start button or turning the motor manually. I think there is no compression, but won't know for sure until I can get someone else to turn the motor while I put my thumb over the hole.

I pulled the plugs out, re-hooked the plug wires to them and watched the spark as the motor turned over. There was a bright blue spark that actually shocked me pretty good once.

Is the distributor rotor supposed to turn in one fluid motion, or almost come to a stop at each point? I pulled the cap off and watched the rotor as the starter was turning and the rotor almost stops where each point would be. It sort of creates a ticking noise.

The pause-snap motion on the rotor is the impulse on the magneto doing its thing. At cranking speeds the magneto isn't turning fast enough to generate much of a spark, so there's a spring mechanisms that holds the shaft for part of a turn and then releases it to "snap" to the next position, thereby turning fast enough to make a good spark.

If none of the valves are moving, then the camshaft isn't turning even though the camshaft gear is. You'll need to pull the timing gear cover to see what's going on. Sounds like you sheared a key where the cam gear mounts to the camshaft, or broke the camshaft itself. It'll never run like that.

Some of the valves are held in the open position by the camshaft. In a higher compression engine, you'd have had pistons banging into the open valves, and at the very least would have bent valves to deal with as well. However, I believe there's enough clearance in these engines to avoid that problem.

Don't bother checking compression. If the valves aren't opening and closing, you won't have any...

Time to pull the timing cover and take a look. Not a trivial undertaking. I have a WD-6 (diesel), and assume that getting to the timing cover on a gas engine would be similar. You'll have to remove the radiator along with all the front sheet meta just to get access to the front of the engine. I don't have my manual handy, so not sure what else would have to come off the front of the engine to get to the timing cover.

Might be time to call a mechanic if you're not real confident in your own abilities and/or don't have a good service manual, or really need the tractor right away.

I know this isn't what you want to hear, but you're looking at some relatively major engine work.

Good luck, and keep us posted.

Keith

Here's the instructions that's required to remove
all the parts just to get to that cam gear. That tractor needs to be well supported for safety and you need to take a lot of pictures and make a lot of notes. You will need equipment to handle those heavy parts too. Hal

One more thing...

When i put my hand over the exhaust when trying to start it, i do feel intake and exhaust (suction and exhaust). I'm not understanding why i can feel that without the valves moving.

There should be no suction on the exhaust. I suspect that the cam stopped such that one exhaust valve is open, and what you're feeling is that piston sucking air in when it moves down & pushing it back out when it moves up.

Keith

The problem is behind the front cover of the engine. It's a pretty major problem, unfortunately.

It sounds like the keyway on the cam gear let go, or the camshaft broke.

You're getting "suck and blow" on the exhaust because some of the valves are open.