source of loboy engine knock found (photos)

coppersmythe

coppersmythe

501 Club
Hello all from the deep south Mardi Gras party state . Well , I finally took some time to dig into the loboy's mystery knock ( knock started last summer ) . It being my main grass cutter , pretty important tractor. We often have to cut grass twice a week. I had the good fortune to find a great loboy for $1000, which gave me some breathing room , thus the delay to repair . Wellllll, I found , ultimately , that the rod bearings on the crank were fine . Next , i took off the head today . WOW . Even a neophyte engine mechanic like myself feels pretty confident in the diagnoses . Photos are of the #1 cylinder / head ....................The valve stem broke , and about a half inch imbedded into the head , and somehow a hole broken into the piston. I popped the imbedded piece of valve stem out , which left a "divet " in the head . Is the head shot ? The area on the head will not interfere with the piston. New piston/rings , new valve minimum ? How much further in makes sense . all opinions welcome . Coppersmythe.................................................... .20260204_161408.jpg 20260204_161437.jpg 20260204_162136.jpg 20260204_162240.jpg
 
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JMHO. a replacement head is readily available (Buddy probably has one) at nominal cost, so I vote to replace the head (checked for true of course), replace the piston, check the valve seats and resurface the valves and seats as needed, while you're there a new set of rings will get you probably another 50 years. Now that I think about it, sounds like a good Cubfest project for next month. Stan
 
head is fine, color of rust all over looks like coolant leak ? valves do not just seize and break, something caused it, looks like head gasket is blown out by broken valve
 
tst said:
head is fine, color of rust all over looks like coolant leak ? valves do not just seize and break, something caused it, looks like head gasket is blown out by broken valve
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Sorry about the quality of the photo .the color is "off" . The gasket is still stuck to the head , its hard to tell. Also , i keep extra gaskets so good there, where would be a good place to find piston/rings/valve. ect...coppersmythe.....*****.Engine was running great with very good compression, until this happened *****. Buddies sounds like the place to do the work..
 
use IH part # to fine a valve, probably need a guide also, most want to sell it in sets now, piston measure to see the born size, or clean the piston to see if its stamped in it, look careful at the corner of the head gasket where the valve broke, where its black you can see its silver around the other parts of it, remember pan gasket and new head bolts also, filter and oil, pull the valve cover and make sure the spring and retainers are still there also
 
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X2 on the rings. Mill the head. Touch up the valves and seats. 50 more years life. I’m on about year 10 with my similar job.
One used to be able to get parts from Oreilly, but forum sponsors will be a good bet too.
 
I once got a single domed piston from Skeet Cooper, forum member by advertising in the VINE, Classified Forum. The picture shows where to look for the IH Part number on the domed piston. Also, just FYI, there is a different part number for the connecting rods for the domed pistons and the flat pistons. You might be lucky too. Stan
 

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tst said:
use IH part # to fine a valve, probably need a guide also, most want to sell it in sets now, piston measure to see the born size, or clean the piston to see if its stamped in it, look careful at the corner of the head gasket where the valve broke, where its black you can see its silver around the other parts of it, remember pan gasket and new head bolts also, filter and oil, pull the valve cover and make sure the spring and retainers are still there also
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Tim would you leave the divot in the head as is or try do something?
 
In the first photo, am I seeing the head of the broken valve turned around mostly upside down, and jammed too far back into the intake? That could be fun to get out if you reuse the head.
 
Crimson Tim said:
In the first photo, am I seeing the head of the broken valve turned around mostly upside down, and jammed too far back into the intake? That could be fun to get out if you reuse the head.
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I tried a little to get the broken valve "head" out. It does flop around easily but It is fighting back to not come out . Hoping someone has an idea . The "divot" in the head is about 1/16 " deep , 1/2" long . That piece of the valve stem was really stuck , i had to pop it out with a wooden mallet and screwdriver.............reusing the head is a good question. Weld and grind smooth ? re-use as is ? i will look for a head in the meantime .......... And , a few weeks ago i just sold a motor that has been hanging around the corner of the shop for years , that would have probably provided everything i need !! Argggg.
 
Update : I was able to take a closer look at the head in the daylight . The "divot" has a small hole that opens up to the water jacket . The people on this forum have to be experienced to be believed. Most of the critical parts have been offered by others on this forum. I dont know how to say it , other than thank you all , for the help through the years . VAL........................................................
 
You could still have it welded. That would take care of the hole and the divot, but that's cast iron and it takes some special skills. I'm not sure I would even mess it with given there's still plenty of used heads available.
 
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If the divit went into the water jacket I would replace the head….No need to attempt repair with constant heat cycles. I would definitely to a top overhaul….new valves, new rings if everything is in specification, and re-hone the cylinder walls. All of this can be done in the tractor without splitting.

NJ Farmer
 
JP tractor salavage ( sponsor) will have a head that is clean and inspected. You can even ask them to look for the same casting year, which they may have
 
Crimson Tim said:
In the first photo, am I seeing the head of the broken valve turned around mostly upside down, and jammed too far back into the intake? That could be fun to get out if you reuse the head.
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You had it right . i wiggled it and cajoled it , turned it , and it would not come out . I could not see how it got in there , except forced by pressure . I was about to attach a shopvac, use a dremel tool and grind some off two edges at 180* when I guess it turned just right and popped out . I checked it with a micrometer and it was not deformed ! So, anyway, its ready for the repair . Buddy , here i come , coppersmythe................................................PS: And no damage to the valve seat . strange
 
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