Help with 782D Overheating Issues

[TLoschen84]

Hi everyone, I just found this site the other day and I am excited that its here. I was a member of ihregistry for years until it went down and I wasn't even aware this site was up until now. Anyway, I have a 782D that is having overheating issues. It will idle fine for an extended period of time, but as soon as you give it some throttle and put it under load with the deck engaged it will start overheating and blowing black smoke in two minutes time. I have had this tractor since it was new, so I am all too familiar with the radiator issues, so I have already cleaned it out and flushed it and it has new antifreeze in it. It also has a new water pump and has good flow through the block and radiator. I pulled the head off and found a small hairline crack going into one of the glowplug ports so I replaced the head with one that I had magnafluxed and is free of cracks. All that did for me was get into my pocketbook even further. I have heard that problems with injection pump timing can cause overheating issues, but have no experience adjusting the pump or checking for correct timing. I am about at my wits end with this engine and would greatly appreciate any advice, suggestions, or help from fellow members who have experience with these Kubota D600's. Thanks for the site and thanks in advance for the help!

[Farmallgray]

Travis,
I will try to give you some help but I have limited experience in troubleshooting diesels. Black smoke and overheating can indicate too much fuel. But since diesels are throttled by fuel, there must be some reason that it isn't liking the extra fuel it is getting. Normally if you give it more fuel it will make more power. I assume you have checked the air filter to make sure it isn't clogged. Timing could be an issue but I don't know what could have made the timing change. Maybe an injector is sticking open? Could be something in the injector pump. The timing is adjusted by adding or removing shims from under the injector pump flange. The timing checking procedure is kind of complicated and somewhat crude. I have a PDF of the CCC service manual. I may be able to upload it here so you can read it. I'll try that sometime over the weekend. It might help to know what conditions this happened under. Was it sudden? or gradual?

[TLoschen84]

Thanks Todd,
I should have put more information on my original post i guess. I have replaced the air filter, taken off all of the hoses to make sure they are free of obstruction and replaced them with new ones, and put new belts on and set the tension correctly to make sure there is no slipping of the water pump. The tractor had been sitting for about 4 years without any use. The original reason for it getting parked was that the starter was bad and you have to pull the engine to replace the starter. I decided at that time I wanted a zero turn to mow with, so I bought a new mower and the cub sat for awhile. Last year I pulled it out and put a new starter on it and after a new battery it fired up after only a few seconds of cranking. It ran rough for a few minutes just because of the old fuel still in the pump, but once the new fuel I put in the tank hit the injectors it smoothed out and ran fine at idle. Once I let it idle for ahile I took it out and engaged the deck and then gave it throttle and it ran fine for about two minutes and then it started overheating. I am familiar with diesel engines and know my way around them for the most part, but I am not, however, familiar with the fuel pump and timing on these Kubota engines. This tractor was purchased new in 1984 by my dad, and I did 75% of the mowing with it growing up. Shortly before the starter went out he gave it to me and I have had it ever since. I would like to have this thing running correctly before we plant our garden in a few weeks, since I want to use it with the 3 point cub cadet tiller to till the garden up first. Just about all that is left that could be wrong with it is the fuel system, but thats where I have no experience. I'm hoping that there is something small that I am overlooking that is causing this. It does seem strange that prior to being parked for a few years it ran fine once it was started, and now it overheats almost immediately. Any more input is very much appreciated.

[red82s]

Have you made sure the fins on the radiator are unclogged? Mine was running hot and from a few feet away the radiator looked really clean. After looking really good, all the fins in radiator were clogged bad. After fixing that issue and putting some insulation wrap stuff around the top radiator hose, it runs cool. I hope you find out what it is.

[Amigatec]

Is it possible to remove a freeze plug and check from sludge around the cylinders? After sitting for 4 years some of the rust in the water jacket my have settled in the bottom of the block. I have seen this before in other motors. This was a 440 Chrysler that had been sitting for a number of years. What i did then was remove the center freeze plugs and found the the rust had about half filled the block, the Antifreeze looked good and clean, I took a high pressure washer and washed as much of the sludge out as possible. I replaced with rubber ones, I then poured Cyrstal Drano in the raditor, filled it with water and ran it until it got hot. Shut it off, removed the rubber freeze plugs and drained all the mud out of the block, I did this a couple of time until the water came out clear. I then had the radiator rodded out. Never had any more problems with it.

As fas as the cracked head, I have seen many cracked Diesel heads in the my life and unless they are leaking water or cracked into the valve seats most of the time the cracks don't hurt a thing.

[Tom Scott]

And I have another anecdotal, "it happened to me"....

I have a 2182 with the similar Kubota gas engine. After I purchased it and drove it for longer than the several minutes that I test drove it when buying, it overheated severely . After starting from cold, the top hose started getting good and hot like it was supposed to and I could see flow from the radiator cap opening, so I decided the thermostat must be ok. Several flushes later with a real clean looking radiator I still had a problem. With no evidence of poor air/fuel mixture, engine running great, timing was correct, radiator cap was holding pressure, and no evidence of blown head gasket, so I figured perhaps there was inadequate flow from the water pump, maybe a rusted impeller that wasn't pumping enough water. Before I went to this effort and expense, I decided that go with the rule of "be sure of the cheap and simple first". So, I pulled the thermostat just to be sure. Kitchen range, pan of water, thermostat suspended above bottom of pan, no opening whatsoever even at boiling .

Why was I getting a hot upper hose and flow? Thermostats generally have a hole or other bypass that allows trapped air from the engine to escape, and provides marginal coolant flow. The hole in this thermostat allowed enough flow to heat the upper hose and looked like flow from the rad cap opening. I still have a hard time accepting just how much hot water got through that little air hole of a closed thermostat to fool me initially. When it did boil over, everything was hot in the radiator.

Check the thermostat just to get the easy stuff out of the way. The Kubota manual even tells you how far it should open at specific temperatures and the fully open distance at the rated temperature. I even checked the new one before I put it in so I didn't get fooled by a bad one from off the shelf (it happens). Also, don't run without the thermostat; many engines (not all) will not pump the water properly without the restriction of the thermostat in the line.

Good Luck! Hope you nail it this weekend!

[Amigatec]

I installed a factory rebuilt engine in a Ford truck once, and after a couple of days the motor started getting hot, it had a new thermostat. When we removed the Thermostat we found that when it opened it had broken the brass loop over the top of the Thermostat and the pin had nothing to push against, this was probably a one-in-a-million problem.

[Dave C]

I think i might check the injection pump.... it almost sounds like u might have a pump thats sticking either 1, 2, or 3. or stuck.
At idle have u tried cutting out a cylinder at a time.... see f u have a lazy pump/injector.... it might not be firing at all at idle but once the block comes up to temp a bit it starts to fire and starts to get wayyy to much fuel......
also have u checked the muffler to make sure its free and clear?

[TLoschen84]

Thanks for all of the input everyone. To answer a few questions and to clarify, the thermostat has been replaced as well, and I even tried running it without a thermostat just to see if it would overheat or not. It still did. Also, as I mention the radiator fins are cleaned out, and it has been boiled too. Dave, the muffler and exhaust system is free and clear, but I agree with the statement that I have pump issues. Do you have any knowl;edge of this pump at all and how to correct any issues with it? I have eliminated basically all other possible problems and that is all that is left. Any more help would be appreciated. Thanks, Travis

[Farmallgray]

I tried uploading the service manual but apparently the file is too big. I was looking over the trouble shooting chart and another thing to check is to make sure the fuel return line isn't clogged. Another is a stuck injector or improper pop-off pressure on an injector.

[Dave C]

Well i believe u need a lot of special tools to get the pump apart... when i took mine out one of the pumps was stuck "up" so at that point i was sure it needed rebuild... i sent it out for a few hundred i think. if you dont know where to sent it look up
username : engine mike and he can help you. (im sure hes out there somewhere... i havent heard back from him in a week)
I think the overheating and black smoke is from the excess fuel and not the other way around.
have u tried to cut out a cylinder at a time? start her up and loosen the nut at the injector one at a time and listen to the engine
no change in sound indicates your on a dead or weak cylinder for some reason. a change in sound means its firing ok.
dave