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Dead Cylinder


thebunns

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The #1 cylinder on my -14 has quit firing.  I swapped injectors and blew out the line going to it but nothing helped.  What's next---a valve stuck open?  If so, is there some kind of gunk I can dump in the oil in an attempt to free it up?

Vic

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Vic, Does it fire on the gasoline cycle? You can pull the plug wire off while running to see if any difference in the sound or RPM. If starting valve is stuck open, pull the spark plug, set the engine on diesel and turn over. If air comes out, the start valve is leaking off. May be able to pull valve cover and with penetrant and patience get it to close again. Check the easy options first, then move to the more difficult ( expensive) options. Jim.

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14 hours ago, crawlernut said:

Vic, Does it fire on the gasoline cycle? You can pull the plug wire off while running to see if any difference in the sound or RPM. If starting valve is stuck open, pull the spark plug, set the engine on diesel and turn over. If air comes out, the start valve is leaking off. May be able to pull valve cover and with penetrant and patience get it to close again. Check the easy options first, then move to the more difficult ( expensive) options. Jim.

Given that I'm almost 80, I'm looking for the easy way out of just about everything!  Is the starting valve cover behind the intake manifold or under the regular valve cover on top?  I ask because if I have to go on top I have to rig up a pulley system for raising the hood up.  I don't want to do that for nothing.

Vic

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13 hours ago, mmi said:

try valve test   and or actually work it hard but dont brake it

....checked for blockage at pump/>>>?

The pump is not blocked as the injector bleeds just fine.  What is this "valve test" you're talking about?  It sounds like you are reading it out of a book.

Vic

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Vic,  Check the starting valve first for sealing. If it blows air out the #1 sparkplug  hole when cranked on diesel cycle then the starting valve is leaking.  Starting valves are under the rocker arms so you need to remove the valve cover so you will need to remove the hood . The valves are set down in a recessed area. You will need to remove the rocker arm assembly to get access to the starting valves. Often times they are gunked up and can be freed by using penetrating oil and light tapping on the stem under the cap. THe service manual shows a closeup of the assembly that makes the teardown easier. Good luck, Jim.

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23 hours ago, crawlernut said:

Vic,  Check the starting valve first for sealing. If it blows air out the #1 sparkplug  hole when cranked on diesel cycle then the starting valve is leaking.  Starting valves are under the rocker arms so you need to remove the valve cover so you will need to remove the hood . The valves are set down in a recessed area. You will need to remove the rocker arm assembly to get access to the starting valves. Often times they are gunked up and can be freed by using penetrating oil and light tapping on the stem under the cap. THe service manual shows a closeup of the assembly that makes the teardown easier. Good luck, Jim.

I removed the hood, valve cover (gasket is shot) & rocker arm assembly.  I set a crowbar on top of the #1 cap & it didn't move.  It appeared to be sitting a bit lower than the other three.  The other three move down against their springs just a little bit.  I pushed down on the bar & it moved down like the other ones.  It was sticking at times so I shot WD-40 into the spring and pushed on it a few hundred times.  They all acted alike so I put the rocker arm assembly back on and I think that air comes out of the #1 spark plug hole worse than before I played with it.  Am I supposed to take the cotter pin & cap off to tap directly on the valve end?  How will I know if I've done any good other than reinstalling the rocker arm assy.?

Vic

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  • 2 weeks later...

Vic,  Sorry for the late reply. Work is very busy and I had some family medical issues to attend to. On the start valve, all you can do is get the stem loosened up so the valve comes back up into it's seat on diesel cycle.  Could have some carbon or other gunk on the face that prevents a complete seal. You could try to borrow a borescope to see if you can see the valve head and face to check for clean mating surfaces. Possible the valve has warped due to the heat of combustion on an always opened valve. If the spark plug hole still blows air on the diesel cycle, you may need to resort to pulling the head and have a shop run thru the valves to make sure all are seating correctly. Probably not the best news you have heard. Jim.

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cam on 9 has been welded from them sticking closed

6 will gum up from not being used enough  had to take cam and cup off,soak....soak heat tap and finally   tiny forceps to make it turn on seat and get some carbon out  as 248 gaskets are $$$$

patience and photos

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1 hour ago, crawlernut said:

Vic,  Sorry for the late reply. Work is very busy and I had some family medical issues to attend to. On the start valve, all you can do is get the stem loosened up so the valve comes back up into it's seat on diesel cycle.  Could have some carbon or other gunk on the face that prevents a complete seal. You could try to borrow a borescope to see if you can see the valve head and face to check for clean mating surfaces. Possible the valve has warped due to the heat of combustion on an always opened valve. If the spark plug hole still blows air on the diesel cycle, you may need to resort to pulling the head and have a shop run thru the valves to make sure all are seating correctly. Probably not the best news you have heard. Jim.

Thanks Jim for getting back to me!  What I'd really like to know is---do I need to pull the cotter pin and work directly on the valve stem or is merely tapping on the top of the cap good enough?  If it would help to remove the cap, what happens when I pull the cotter pin?  Does the spring send the cap flying and can I get the cotter pin back in the hole after pulling it?  I've decided that I don't need to reinstall the rocker arm assy. to check if the start valve is seated or not.

Vic

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Vic,  If the valve is clean and not warped (just stuck) then the penetrant and tapping will get it to seal. You can remove the cap and try turning the stem with small vice grips or similar, but you need to find a way to keep the valve stem up and not drop it down into cylinder chamber. If you can rig up a rod that holds the valve up from the head (thru the sparkplug hole) then the turning of the stem to clean the valve sealing surfaces becomes a lot easier.

I have loosened sticky valves several times by spraying and tapping and they always resealed well enough to start and run on diesel. Your valve sounds like it may have some carbon or crud on the faces which is preventing a good seal. Jim.

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2 hours ago, crawlernut said:

Vic,  If the valve is clean and not warped (just stuck) then the penetrant and tapping will get it to seal. You can remove the cap and try turning the stem with small vice grips or similar, but you need to find a way to keep the valve stem up and not drop it down into cylinder chamber. If you can rig up a rod that holds the valve up from the head (thru the sparkplug hole) then the turning of the stem to clean the valve sealing surfaces becomes a lot easier.

I have loosened sticky valves several times by spraying and tapping and they always resealed well enough to start and run on diesel. Your valve sounds like it may have some carbon or crud on the faces which is preventing a good seal. Jim.

Thanks, Jim!  I'm getting the picture now.  I guess the only thing left for me to visualize is,  how is the spring fastened to the valve stem?  Does that cotter pin go through something besides the cap?  I'm away from home for a few days but am anxious to hit it when I get there.

Vic

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Vic,

All of the starting valves that I have seen use a spring retainer and keepers to connect the valve stem to the spring similar to your intake and exhaust valves just smaller.  I have never seen a cotter key used to retain the spring.  The cap should just sit on top of the valve stem.  As crawler nut said working it up and down should loosen it up.  a photo may allow a quicker diagnosis.  

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I'll be home in a couple of days and will take a picture of the cap with a cotter pin going through it.  That's been one of my main concerns---what happens when I pull it and will it be irreversible without pulling the head.

Vic

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5 hours ago, Redwood said:

Vic,

All of the starting valves that I have seen use a spring retainer and keepers to connect the valve stem to the spring similar to your intake and exhaust valves just smaller.  I have never seen a cotter key used to retain the spring.  The cap should just sit on top of the valve stem.  As crawler nut said working it up and down should loosen it up.  a photo may allow a quicker diagnosis.  

2x unless something changed ....your over complicating..lift the centering cup off....   being s valves are small ,plug wire/boot pliers may fit to lift and turn the whole deal strait up to work carbon loose

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mmi, now you're oversimplifying the process---I can't merely lift the cap off because the cotter pin has to come out first as it goes through it, plus whatever else I don't know about.

Vic 

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OK, guys---here's a couple of pictures of cotter pins going through starting valve caps.  The first one shows one tab missing where I put pliers to it & it immediately broke off.  I fished it ot of the oil.  The question is, and has been, what happens when I pull the pin and can I get it back in?

Vic

227.JPG

228.JPG

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VIc, If the top valve is no 1 and lower photo is #2 and #3, no 1 looks like it is stuck in the open position, with the cotter and cap down into the casting well . That will have to come up to remove the cotter. I would bet the cotter holds an adjustment so the valves open the same amount. My caps didnt have the cotter pin. I used a magnetic wand to lift the caps off the valve springs.If the upper picture was after you sprayed and tapped that valve,  there is still  something holding that valve in a downward and open position. The valve and cap should look like the others as far as height.. When you reset the arms to operate, you need to check for clearance under the arms and the cap so the valves are fully seated on diesel cycle.

I would try something like needle nose vice grips to hold The stem between the spring coils and prevent the stem from falling into cylinder. then put a shop towel over the cap to catch the cap in case it is actually spring loaded and pull the cotter pin. Then count to three and throw (just kidding). Good Luck. Jim.

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47 minutes ago, crawlernut said:

VIc, If the top valve is no 1 and lower photo is #2 and #3, no 1 looks like it is stuck in the open position, with the cotter and cap down into the casting well . That will have to come up to remove the cotter. I would bet the cotter holds an adjustment so the valves open the same amount. My caps didn't have the cotter pin. I used a magnetic wand to lift the caps off the valve springs.If the upper picture was after you sprayed and tapped that valve,  there is still  something holding that valve in a downward and open position. The valve and cap should look like the others as far as height.. When you reset the arms to operate, you need to check for clearance under the arms and the cap so the valves are fully seated on diesel cycle.

I would try something like needle nose vice grips to hold The stem between the spring coils and prevent the stem from falling into cylinder. then put a shop towel over the cap to catch the cap in case it is actually spring loaded and pull the cotter pin. Then count to three and throw (just kidding). Good Luck. Jim.

I took another shot in an attempt to show you that the cotter pin is above the casting well.  It wasn't before I started bouncing the spring down & back up with the heavy crowbar.  As near as I can tell, it looks a bit lower than the other three caps & cotter pins.  My whole problem was trying to find out what was going to happen when I pulled the pin.  I have decided, since you (or anybody else) has not seen this type of setup, I'll pull it with the idea of pulling the head to reassemble it if needed.  Would it mean anything to you if I reminded you that the tractor was an Army crawler with possible different specs.?   Just a thought!

Vic

231.JPG

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with 3 grains of salt.......that cotter is holding nothing but the cap    too light duty to keep the spring in which should have the normal keepers

weather a home or military remedy  must be a lot of clearance on cam and mountain climbing done to insure  the cap doesnt pop off into lifters or main valves

with better glasses (young) try to see under how it attaches ...thru which piece ?  which is next to impossible......

the cotter which broke is there spring pressure on the cap? or any you think seated correct?

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VIc, If you can clamp the valve stem to keep it from dropping into cylinder, Then pull the cotter pin and have a look.  Use a shop towel to contain the flying parts, if there are any. I think the cotter either just holds the cap on or holds a threaded adjuster in position so all the valves can be opening the same height, like the adjusters on the rocker arms do for the bigger valves.  Use a small measuring tape to check the cap height against the other caps for comparison. when you start to turn the stem to clean the valve face,  check another functioning valve to see if it feels the same way turning . Hopefully it is just some carbon on the face or seat and a little elbow grease will get it clean again. Jim.

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1 hour ago, crawlernut said:

VIc, If you can clamp the valve stem to keep it from dropping into cylinder, Then pull the cotter pin and have a look.  Use a shop towel to contain the flying parts, if there are any. I think the cotter either just holds the cap on or holds a threaded adjuster in position so all the valves can be opening the same height, like the adjusters on the rocker arms do for the bigger valves.  Use a small measuring tape to check the cap height against the other caps for comparison. when you start to turn the stem to clean the valve face,  check another functioning valve to see if it feels the same way turning . Hopefully it is just some carbon on the face or seat and a little elbow grease will get it clean again. Jim.

I will get to it in a couple of days.  Because I haven't removed the valve housing yet I may try and wedge a piece of tapered wood through the spark plug hole to bind the valve stem.  I tried grabbing the stem with needle nose pliers but it is off center of the hole just a bit.  I'll have some answers then.

Vic

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