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Agco 512H wont start


Jason

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Hi I got a 1992 Agco 512H hydro that will not start.When we first got the 512H last winter it was not running. We started by replacing the old battery with a new battery and cleaning off the corrosions on the wires and put them back on. We then could not get the tractor started so we took the engine apart and found that the fuel intake valve was stuck open.We had to take the intake valve out and applied a bit of oil, that got the intake valve to come in and out.We then put the engine back together.After that we then tried to start it, but it would not start, we cleaned the spark plug, still would not fire. We had the gas turn off valve on, but the gas was not reaching the engine after the carbarator, we got a carbarator kit, and fixed the carbarator, the tractor would now start, it sounded rough and smoked a bit after it started. We drove it around a bit, but then it overheated and we had to put it away for the night.The next day we tried the mower deck and cut some grass, but then the engine overheated and started smoking again. We shut it down, let it cool off and then restarted it again, no smoke this time, and we cut some grass with it and it was fine, however we had to keep stopping to put the hydrostatic drive belt back on underneath the tractor, we broke a few belts and we still don't know how to keep the belt from slipping off. Does anyone know how to fix this problem? I forgot to metion that when we had the engine apart we replaced the head gaskets before putting the engine back together. Despite always having to stop once awhile to put the drive belt back on we were able to use the tractor to cut some grass, until one day when we were cutting grass at our Church.We were running it and suddenly it died. We let it cool off and then we came back to try and start it again, would not start, but would turn over. Checked the carbarator, it was fine, pulled off the cover for the intake valves, they were fine, we checked to see if it was out of gas but the tank was half full.We checked the spark plug it was ok. I am not sure what happend but we have not been able to start the tractor since it died. Could anyone help me with this problem? I am thinking we might have to tear the engine apart again. The engine is a Briggs and Stratton 12.5hp with a vertical drive shaft. I would really like some help with this tractor if possible. Thanks very much Jason B
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Hi, Sorry to hear about the problems you are having with your tractor. As far as the drive belt is concerned, is the correct size belt being used. I prefer the OEM belts for my tractors. They cost alittle more, but they are designed just for the application. If you have the correct belt, perhaps you may be missing a belt guide, which helps keep the belt from jumping off of the pulleys. I have included a link below for Simplicity's Tech Manuals site. Just type in your catalog number found on the frame of your tractor (169****). Perhaps if you find a parts manual in there, you can look and see if you are missing anything. http://www.simplicitytechpubs.com/techpubsearch.php As far as the starting problem goes, did you check to see if you now have spark? Maybe a coil problem. Is it now getting fuel? Is the sparkplug wet with fuel when you take it out? Keep us posted.
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Hi Yes it does spark and the spark plug is not wet with fuel when I take it out. Thanks for the information on the belt, the belt is the correct size but it is a cheap end belt bought at a hardware store, I will have to get an OEM belt for it as they last longer. Thanks very much for the link to the tech manuels, however my serial number on the frame of my tractor is missing, I only got the first three numbers the others are missing. As for the coils we checked them out and there was no damage done to them nor were they worn out. I will keep you guys posted on the trouble I am having. Also for those who own a simular tractor to my Agco 512H hydro, do you guys/girls have problems with them overheating quit quickly? I find that I can only go for about 30 -40 minutes before the tractor overheats, my old 1614H Hydro never had problems with over heating.Thanks Take Care Jason B
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My guess is your engine is full of mouse nests and not getting proper air flow, thus overheating. Also, when you had the valve out, did you check your valve stem clearence? Maybe when the engine gets warmed up your valve are not closing and thats why it dies, not really from overheatting.
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Hi Never though of that,I will have to check the valves again and see if they are not closing all the way. I will have to look and see if there are any mouse nests in and around the engine and clean them out. Thanks Jason
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I agree with MPH about the mouse nests they may also be chowing down on your wiring if they are nesting in the tractor or you might have a bad nuetral or seat switch put a jumper on them if you don't find any nibbled wiring.
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Yes definitely check for blocked cooling fins, also check the stem to tappet clearance also if you take the valves out check to see if you have a burned valve seeing as how it overheated could be a possibility.Is this and overhead valve engine?? or and older L-Head Engine on Some of the older L Head Engines with Aluminum Blocks I Have Seen the Valve Seat Loosen Up and pop out of its bore and hold the valve open.Also if you have valves out check to see if you have at least a 1/32 Margin between the valve angle and the top of the valve. Hope This is of some help, one more thing did you take the spark plug out and try to crank it over with your finger over the hole?? it should blast your finger off if it doesn't that would show you have weak to no compression if you do not have a compression tester. Good Luck and take care Jim Noeske
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