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42 A....valves

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Will

01-31-2003 14:38:42




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paid $500 for the old tractor the guy said it had carb problems, carb looks good and clean to me and works well but there was no gas getting to the plugs, i can pour a capful of gas in block and replace plugs and she tries to start..i removed the valve cover and moved all the valves with my hand and they are all free and then i turned the flywheel over and there was ZERO movement from the valve guides and valves! the valves did not open or close...im just a novice mechanic but when i turn the engine over by hand on the flywheel shouldnt the valves open and close??? why is there no movement in the valves?? the manifold was full of gas and the carb works fine as far as i can tell...just need to know why the valves are not opening.... thanks

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Pat

02-01-2003 08:51:31




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 Re: 42 A....valves in reply to Will, 01-31-2003 14:38:42  
Will,
If the Mag is working, there is no valve movement, and they are ALL CLOSED, It sounds like the camshaft broken. Most likely beside the cam gear. This will allow the gear to still turn, and allow the shaft to swing back wards away from the cam followers due to the valve spring pressure-closing the valves! The gear will remain "located" due to the bearing in the case, and possibly the end of the broken cam pusing against it.

If only the bolts fell out, some of the valves would remain open.

I would definately check the oil pump very well also, as it can lock up and inturn make the cam lock util something gives.

Could even be water in the crankase getting cold and freezing around the pump gears at a previous time.

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Lee

01-31-2003 16:05:06




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 Re: 42 A....valves in reply to Will, 01-31-2003 14:38:42  
If all three bolts that hold the camshaft to the camshaft gear worked out and fell out - you might have a situation such as you describe where the mag works and is in time but no valve movement. You would also have no oil pressure. Only other thing I can think of is all four cam lobes are worn completely off? That's just not possible as it would die and quit running when there was at least a little bit left of the lobes. And the valves would move a little. No valve movement at all means the cam is not turning.

When you push and pull on the pushrods, is there any slack in the pushrods? Some should have just a little and at least one shouldn't move as if it were pushed by the cam lobe. Can you get oil pressure by cranking it? If it's the cam bolts, you'll have to pull the gas tank, and governor case to get at it... I had one that had fallen out when I was in my 43 A last summer but the other two held fast.

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John T Update

01-31-2003 15:57:02




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 Re: 42 A....valves in reply to Will, 01-31-2003 14:38:42  
Will, now that you say the mag is turning but the pushrods are NOT moving, it becomes even more necessary to know in what position the valves are (open or closed), and if the rocker arm shaft is tight down against the head. If the cam followers were frozen as clooney mentioned, they would have to be froze in the full open high cam position to prevent pushrod movement as cam turns (if cam is turning and in place trying to raise the cam followers), but then those valves (if followers stuck open and cam still in place turning) would have to be OPEN resulting in no compression, whereby she wouldnt try to start as you said it does if you add fuel. It sure acts like a broken camshaft thats totally out of place where it cant open any valves, yet the gear still turns the governor shaft. Fun question Let us know, Ol John T

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John T

01-31-2003 15:39:24




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 Re: 42 A....valves in reply to Will, 01-31-2003 14:38:42  
Will,

1) You say the valves are ALL free to move right??, BUT, some are open and others closed right?? Are they all closed?? If the rocker arm shaft is in place, and even if they are adjusted way loose, some should be in the at least partly open and others closed as you rotate the flywheel/crank/cam, if the cam and pushrods and rocker arm shaft is in place that is.

2) When you turn the flywheel, you say theres ZERO valve movement, are the pushrods (rods that go up against the rocker arm on end opposite valve stems) moving at all????

3) Can you remove the mag or distributor cap and see if its turning??? It should turn the same direction and RPM as the crankshaft, and it wont turn UNLESS the cam gear is turning, because thats what drives it (drives the governor shaft).

4) If the mag/distributor turns smooth BUT none of the pushrods move, it must be a camshaft problem, but it would have to be broke so the gear turns, but not the rest of the shaft. (broken shaft just away from gear???) Even so, unless its like broken and out of place completely, at least some of the valves would still be in some open position (unless cam broken off at both ends but gear somehow still turns the mag???

This is tricky lol, we need to know if the pushrods move and if the mag/distributor turns and then go from there. If it tries to start when you pour fuel in the cylinders, that tells me both valves are closed (otherwise no compression), and even the mag must be turning to produce a spark. Im wonderng if you have a broken camshaft, but how its still in place enough to NOT have some valves open and/or turn the disttributior is tricky.

Let us know, Ol John T Nordhoff in Indiana. Also, be sure the rocker arm shaft is tight down against the head

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will

01-31-2003 15:53:22




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 Re: Re: 42 A....valves in reply to John T, 01-31-2003 15:39:24  
hi john T, nope the pushrods do not move at all.....all the valves are closed and i can push the springs with force and open all the valves with my hand,the guy i bought it from had the head reworked and im beginning to wonder if they installed it correctly or left out the cam followers all together, could that have happened?? yes there is great spark and plenty of compression in the cylinders and this is an all fuel and it's and hand start with petcocks on the block, and theres no noise when it turns over like something is broken....gonna tear it down saturday i guess.... thanks

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John T

01-31-2003 16:04:42




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 Re: Re: Re: 42 A....valves in reply to will, 01-31-2003 15:53:22  
Yep lol, if theres no cam followers and all valves are free and the mag turns and you have compression and the cam is all fine and in place, that could explain the dern thing. If you remove the rocker arm shaft and play with the pushrods and turn the cam, you should be able to figure it out. i.e, if the pushrods never bottom out against anything down in the head, but if they dont, Im not quite sure what held them in place against the rocker arms?? Let us know John T

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Clooney

01-31-2003 14:58:39




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 Re: 42 A....valves in reply to Will, 01-31-2003 14:38:42  
Will, are the pushrods even attempting to move? If not you might have a cam that isn't turning or the cam followers are frozen up. You might have to pull the crankcase cover & look [feel around] inside to see what's happening in there. If the mag/distributor is turning the cam gear is at least turning.



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will to clooney

01-31-2003 15:20:30




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 Re: Re: 42 A....valves in reply to Clooney, 01-31-2003 14:58:39  
yes the mag is working good so i know it must be turning, plenty of spark.. but no the pushrods are not moving at all not even a twitch of movement from anything on top of the head when i turn the engine over....but i will try what you recommend and see whats going on in there, thank you



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Clooney

01-31-2003 16:38:20




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 Re: Re: Re: 42 A....valves in reply to will to clooney, 01-31-2003 15:20:30  
Will, there's a good chance you will find broken cam gear bolts if the cam isn't turning. If you do, I hope they just came out & didn't break off as it is a pain to get the broken pieces out of with the cam gear in the tractor.



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will

01-31-2003 14:40:49




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 Re: 42 A....valves in reply to Will, 01-31-2003 14:38:42  
and i tried to adjust them but that really did nothing.



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gwh

01-31-2003 19:49:29




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 Re: Re: 42 A....valves in reply to will, 01-31-2003 14:40:49  
Will, Is there any movement by trying to move the pushrods in and out? I'll go along with the cam gear bolts(2)and stud and nut have fallen out, the 3 fasteners are used w/a steel lock plate and safety wire. Watch out for the holes in the cam gear (for being egg shaped) and the threaded ones in the cam also and this could be from a previous repair (worn holes and or incorrect fasteners).gwh



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