Posted by raymond anderson on October 28, 2013 at 16:52:57 from (69.31.221.189):
I have a case 730 gas tractor that developed a knock and started fouling the plugs. I cant remember if it fouled all of them or just one or two. The knock is always there whether you are idling down, have the clutch in, are under load etc. It is a fairly sharp metal on metal sound seems to occur every cam rotation. From what we can tell, it sounds as the the noise is from the front cam area ,though its hard to say for sure. The tractor runs rough and will barely move without wanting to die. Anyway we ended up taking the engine apart and could see no obvious sigs of wear which lead us to rebuilding the entire engine. We replaced crank bearings, cam bushings piston pins,pistons, sleeves points, condenser etc. The only things not changed were the valves(which looked alright) and we didnt have the cranked turned. After reassembling and being very hopeful the engine still knocked and fouled the plugs. We had no idea what the problem was. I did some tests and here are the results: compression : 132psi on 3 cylinders and 138 on 1 of them. ( the book says 140). Oil pressure: 45 psi ( book: 40-50). Crank endplay: 0.011 (book: within tolerence). Cam gear backlash: 0.012- 0.018 measured in different spots (book: 0.006 max). As you can see, the cam backlash is way out but after speaking to a couple people, they say this usualy isnt an issue. Upon 2nd disassembly we noticed one of the push rods was shiny all around where it goes through the block/head though i dont think this was the case the first time, hence i"m not sure its part of the problem. We took the engine into case for a quick look but didnt accomplish to much. Now were on our third disassembly. We ran the engine with the cam cover off and though the sound seems to still be in the front cam area there is still no difinitive sign of the problem. We then pulled the crank gear and turned the cam manually with a 500 rpm drill to see if the knock was still there and if the cam was going in and out. From what we could tell, it was"nt. This is where we are right now. We have spent over $2000 on a rebuild and countless hours on this thing over the years trying to figure it out. This is such a simple engine though the problem remains a mystery. Does anyone have any suggestions. PLEASE HELP!!!! Questions: 1.Can backlash cause knocking and effect timing this badly. 2. Can these cams have endplay issues. 3. Can cam endplay effect timing. 4. Do you think the backlash is an issue. 5. Do you think it could be a lifter problem. 6. How much play can distributor shaft have before its an issue.
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