One of these these is not like the others

Don Hooks

Member
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Cutting grass and got a power drop and funny exhaust sound. Pulled spark plugs and #4 had no pressure. Naturally, I had just filled the gas tank so I had to drain it to get to the valve cover. Then I saw this! Can't find anybody that lists the part except Tisco so I will drop by Larry's tomorrow and get him to order a kit (830703M91) unless one of you knows where I can mail order it. I've never seen a retainer fail like this - have you? The valve looks like it dropped about 3/4 inch and "sounds" like it is not bent when I pop it up to closed position. Anyone know if there is room enough above the piston that it may have actually survived?

Don
 
Hook an air hose up thru the spark plug hole, like a compression test. Turn the shop air, from air compressor up to full pressure and pull up the bad valve, if the air holds up the valve then the valve is not bent, and hopefully the piston wasn't damaged by the valve also.
I used to put new valve seals in small block engines by doing this, so I know shop air will hold the valves closed with no leaks if the valve seals properly and is not damaged.
Good luck.
 
(quoted from post at 09:34:18 08/28/15) Hook an air hose up thru the spark plug hole, like a compression test. Turn the shop air, from air compressor up to full pressure and pull up the bad valve, if the air holds up the valve then the valve is not bent, and hopefully the piston wasn't damaged by the valve also.
I used to put new valve seals in small block engines by doing this, so I know shop air will hold the valves closed with no leaks if the valve seals properly and is not damaged.
Good luck.

Thanks. That is a good idea since I will be changing all four retainers if I can find them and I can use air easier than rubber padded vise grips to hold each of the stems.
 
I don't think it would hit the piston being the retainer is still on it. Good advise on using air pressure to
hold it closed. You'll have to rig up something to compress the spring, so you'll need the valve held firmly
up while you do that.

I don't recall seeing a retainer break like that. Make sure nothing strange is happening there, like the
retainer hitting the bottom of the rocker arm, or valve cover bent and hitting the retainer.
 
I had a valve spring break on my FE35 and I wanted to change it without removing the head . I got some good advice from this forum .
Remove the plugs,
Feed soft , clean and pliable sash cord into the plug hole , as much as you can ,
Compress the rope by turning the engine .
This holds up the valve really firmly and allows you to remove the collets and retainer ,as well as the spring . If you hold the stem and loosen the rope it will also let you feel the valve travel within the guide to see if it runs smoothly .
Do this one piston at a time . It is really effective and easy to do , a tractor enthusiast's version of the Indian rope trick :)
 
Found a new AGCO parts dealer about 15 minutes away and ordered a retainer kit (four retainers and four pins) and should get them next week. I will check valve leakage with compressed air but I like Charles' suggestion to use rope for the changeout.

Thanks everyone.

Don
 

I was pleasantly surprised. I had several gasket seeps that had the outside pretty gunky but the inside looked good for nine years since putting it back together. Jerry, you may have noticed I don't have any lash caps - what is your feeling on the necessity of having them?

Don
 
(quoted from post at 05:19:50 08/30/15)
I was pleasantly surprised. I had several gasket seeps that had the outside pretty gunky but the inside looked good for nine years since putting it back together. Jerry, you may have noticed I don't have any lash caps - what is your feeling on the necessity of having them?

Don

The valves that do not require the caps are longer to compensate for the difference with the caps removed. I know people run them without caps with the shorter valves but it throws the valvetrain geometry off and a shortend valve train life will be the result. If you use air in the cylinder to hold the valves in, make sure the tractor is out of gear. When you hook the air up it forces the piston to the bottom of the cylinder.
 
I have them on my TO-30 but every time I pull the valve cover I"ve found some of them laying on the head. And I hot adjust my valves! I can"t believe that they make a significant difference on a 1940"s technology engine especially since the valves have adjusters on them. I don"t have data to support that so it"s just my opinion. I am a firm believer of trying to maintain the OEM configuration but sometimes it is just not practical to do so. This is a case in point.
 

Interesting thought about air pressure moving the piston. In first gear the tire could move a few inches but in fourth it could move far enough to get on your foot. After your comments and Jerry's below I think I will go ahead and get caps just to surprise whoever buys it from my estate (hopefully a long time from now).

Don
 

I kind of gave you a short answer but the valves that are made to be ran without caps are not only longer but are also hardened on the tip so the rocker arm doesn't hammer it into a nice mushroom shape...and that will happen over a period of time. Ever take some old heads apart and had to grind the ends of the valve to pull it out? That is why. Also running the shorter valve without the caps will cause faster valve guide wear because the rocker will not push down in the center of the valve stem. It will push down to one side and as the engine is ran it will cause the valve to try to turn sideways as the guide wears. Take a black sharpie and color the end of the valve stem and then turn the engine over and see where the rocker arm has rubbed the ink off. It should be in the center of the tip. If the valve is too short or too long the ink will be gone on one side of the tip or the other.
 

Got the old gal back together and did a cold compression check and got 110, 110, 100, 105 so #4 is back to about where it was before. I found that the #4 intake rocker was not in its proper spot on the rocker shaft by about 3/32" so I presume the retainer was being flexed every cycle and eventually fatigued. Looks like there was a extra washer spacing the rocker away from the support pedestal. While I had the tank off I etched it and coated the inside with epoxy in hopes of avoiding the monthly shutoff valve cleaning. Started and ran well.

Thanks for the advice.

Don
 

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