Last week my JD 750 started great, but when I tried to do some bush hogging, the engine quit without warning. It restared fairly easily, but whenever I tried to put a small load on the engine it would quit again (I also noticed a lot of blow-by coming from the hose attached to the valve cover). This happened about 3 or 4 times (stalling as soon as I put a load on it), then on the last stall, I heard a loud "rush of air" sound coming from an unknown place.....not from the exhaust though. I've heard bad head gaskets that have a "hissing" sound, but this didn't sound the same. This sounded alot like removing an air compressor hose from the compressor....a loud and "quick" release of air. After this noise, the engine wouldn't fire at all. The coolant level was low, and my hoses are in bad shape. I've since topped off the coolant, but haven't been able to bring the engine to operating temp to see if the noise was from a cracked hose, or from within the engine. No hose leaks as of yet though.
More info:
The tractor was filled with diesel in March, and sat in a Kansas barn until December. The temperature was in the 20's when it was giving me the problems. I've since brought the tractor back to Alabama, and done some troubleshooting.
I removed the fuel filter and checked the fuel supply all the way to the injectors, and it seems OK. I removed the fuel lines from the injectors, and am getting a pulse of fuel from all 3 fuel lines. I removed the return lines from the top of the injectors and sprayed carb cleaner into them. I reattached them and attempted another start. This time, the engine sounded like one cylinder was trying to work....engine would "knock" a little but wouldn't start. Also, a little black smoke from the muffler, and a little black soot (like black ash) mixed with the smoke???
On the last start attempt, I noticed a white mist coming out of the rearmost part of the intake manifold....where the intake meets the head. I'm guessing the intake gasket failed in that area, but I was confused
....... I'm fairly knowledgeable on gasoline engines, but know ZERO about diesels. I was confused why there was a positive pressure in the intake, so I removed the intake manifold. This is where I became even more confused. Rather than seeing an intake runner for each of the three cylinders, there are intake runners and smaller runners beside them. I motored the engine with the intake removed and a white mist comes from the other ports (not the intake runners). I'm guessing this mist is from the exhuast side??? and the engine reuses some of the exhaust gases???? and this is normal???
I've also removed the muffler and valve cover. I've verified that none of the valves are stuck.
At first I thought it was fuel gelling from the cold temperature, but after taking it to 60 degree weather, it still won't start. I'm not really sure which way to troubleshoot this thing.
Thanks in advance,
Chris
More info:
The tractor was filled with diesel in March, and sat in a Kansas barn until December. The temperature was in the 20's when it was giving me the problems. I've since brought the tractor back to Alabama, and done some troubleshooting.
I removed the fuel filter and checked the fuel supply all the way to the injectors, and it seems OK. I removed the fuel lines from the injectors, and am getting a pulse of fuel from all 3 fuel lines. I removed the return lines from the top of the injectors and sprayed carb cleaner into them. I reattached them and attempted another start. This time, the engine sounded like one cylinder was trying to work....engine would "knock" a little but wouldn't start. Also, a little black smoke from the muffler, and a little black soot (like black ash) mixed with the smoke???
On the last start attempt, I noticed a white mist coming out of the rearmost part of the intake manifold....where the intake meets the head. I'm guessing the intake gasket failed in that area, but I was confused
....... I'm fairly knowledgeable on gasoline engines, but know ZERO about diesels. I was confused why there was a positive pressure in the intake, so I removed the intake manifold. This is where I became even more confused. Rather than seeing an intake runner for each of the three cylinders, there are intake runners and smaller runners beside them. I motored the engine with the intake removed and a white mist comes from the other ports (not the intake runners). I'm guessing this mist is from the exhuast side??? and the engine reuses some of the exhaust gases???? and this is normal??? I've also removed the muffler and valve cover. I've verified that none of the valves are stuck.
At first I thought it was fuel gelling from the cold temperature, but after taking it to 60 degree weather, it still won't start. I'm not really sure which way to troubleshoot this thing.
Thanks in advance,
Chris
