When I operate my tractor at PTO speed it overheats in about 20 minutes. If I return to idle it drops back down to ab3/4 on the gauge. This works until the coolant gets low then naturally it just stays hot. I have flushed the system three times. The last time I let it idle for 1 hr and it stayed at half gauge. Filled it back up with a 50/50 mix and still the same. I took off the radiator and thermostat flushed out radiator and block and reassembled without the thermostat. Put in straight water and same results. A friend said if have bubbles in the radiator while running while running it could be head gasket or cracked block. I ran it without the cap and have some bubbles. Could it be anything else. About how much would head gasket repair cost if that’s it. Tractor is a 1997 M4700S with about 650 hrs.
Overheating problem
- Thread starter TexasGlenn
- Start date
Yeah, bubbles in coolant while it's running is not good. Could be either the head gasket or a cracked head.
Does it emit any white smoke when it is started after setting a while?
If so, coolant is getting into a cylinder.
Is the oil milky looking?
Does it emit any white smoke when it is started after setting a while?
If so, coolant is getting into a cylinder.
Is the oil milky looking?
No. The oil looks normal and is at normal level. Haven’t seen any white smoke either..
I was hoping it could be the water pump or maybe having the radiator rodded. I could handle those. Not sure I can tackle the head gasket or cracked block. I know it’s not the best option but do you think it would help to try something like Bars Leak?
I was hoping it could be the water pump or maybe having the radiator rodded. I could handle those. Not sure I can tackle the head gasket or cracked block. I know it’s not the best option but do you think it would help to try something like Bars Leak?
TexasGlenn, welcome to the forum. I'd suggest finding a radiator pressure tester to give you some more clues before adding anything to it. I wouldn't be spooked by the idea of a cracked block. Chances are very slim of that.
If you personally know any mechanics, or a radiator repair shop, they may have a tester they would lend you for the test. You can buy a kit at Harbor Freight, but it's like $100 and you may not ever use it again. You simply put the testers cap on your radiator and pump it to the required pressure (on your tractor cap) and see if/how it holds, and maybe where it's leaking.
I'd say find the problem and solve it and not add anything, because you'll always be wondering when it'll overheat again. And in your climate you need an efficient cooling system.
Replacing a head gasket, if that's what it ends up being, is not a big deal. A few wrenches, some time, and a little coaching can get that done!
If you personally know any mechanics, or a radiator repair shop, they may have a tester they would lend you for the test. You can buy a kit at Harbor Freight, but it's like $100 and you may not ever use it again. You simply put the testers cap on your radiator and pump it to the required pressure (on your tractor cap) and see if/how it holds, and maybe where it's leaking.
I'd say find the problem and solve it and not add anything, because you'll always be wondering when it'll overheat again. And in your climate you need an efficient cooling system.
Replacing a head gasket, if that's what it ends up being, is not a big deal. A few wrenches, some time, and a little coaching can get that done!
Using tap water can cause you problems too.
Out of curiosity have you cleaned out the radiator fins on the outside and made sure you get enough air flow?
shootem604
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L245DT with Kubota (Arps Model 22) FEL and Kubota B/L4520B (Woods 650) BH
Pull the rad hoses, check for crud buildup, flush everything, and see if it still happens. Maybe scale or a wonky thermostat (if it has one?)?
Probably not transferring enough heat at the radiator fins to air. Need to have good air flow, and no insulation on fins. So need to get dirt and chaff cleaned out from radiator fins.
Once that is done, should not overheat. If it overheats after cleanup outside, then would look at cylinder head which requires new gasket anyway. When the cylinder head cracks enough, the engine oil will have water on the bottom of the sump.
Bubbles in the coolant are obviously coming from SOMEWHERE!! Be sure it's bubbles and not just the flow of water caused by the water pump. If you do elect to change the head gasket it is not really that major, mostly just a nuisance. Look the job over first. You don't JUST change the head gasket. You'll probably find yourself replacing intake manifold gasket, exhaust gasket, and adjusting the valves at the same time. Explore your options carefully.
Thanks to all for the responses and ideas. Some quick history:
I completely removed the radiator, took a water hose using a shower setting on the nozzle and sprayed fins from both sides. The turned to jet and sprayed inside from top and through the bottom hose connect. Didn’t see any real buildup inside. Then took out the thermostat and sprayed out the block from the top and bottom hose connectors. Was a little scale built up in the thermostat housing. Reassembled and left out the thermostat all together. Filled with straight water. Begin shredding at first light the next morning, around 70 degree air temp and in about 20 minutes had almost pegged the gauge. sat at idle for less than 5 minutes and back down to about 3/4 gauge. That works til finally gets low on water.
That afternoon I filled up the radiator again, probably over half the capacity, and cranked it without the radiator cap. Let in run for around a minute and was seeing bubbles. Now I think maybe it could have been a air pocket in the block
This weekend I’m going to start it again and see about the bubbles.
I may try to round up a pressure tester but one time I used a large rag to take off the cap while it was boiling hot and probably a gallon of water sprayed out before it calmed down.
I completely removed the radiator, took a water hose using a shower setting on the nozzle and sprayed fins from both sides. The turned to jet and sprayed inside from top and through the bottom hose connect. Didn’t see any real buildup inside. Then took out the thermostat and sprayed out the block from the top and bottom hose connectors. Was a little scale built up in the thermostat housing. Reassembled and left out the thermostat all together. Filled with straight water. Begin shredding at first light the next morning, around 70 degree air temp and in about 20 minutes had almost pegged the gauge. sat at idle for less than 5 minutes and back down to about 3/4 gauge. That works til finally gets low on water.
That afternoon I filled up the radiator again, probably over half the capacity, and cranked it without the radiator cap. Let in run for around a minute and was seeing bubbles. Now I think maybe it could have been a air pocket in the block
This weekend I’m going to start it again and see about the bubbles.
I may try to round up a pressure tester but one time I used a large rag to take off the cap while it was boiling hot and probably a gallon of water sprayed out before it calmed down.
I winder if the impeller in the water pump isn't loose on the shaft? Would be easier to pull the pump than pull the head. One thing for certain and that is, if you keep getting it that hot, sooner or later the head or head gasket will fail.
If I understood the OP correctly, the tractor is losing coolant. No amount of flushing or internal/external cleaning of radiator will help the situation. Need to fix the root cause of the leak or this is going to get ugly.
Last edited:
TexasGlenn
D2Cat
I'm going to go now with 200mph and D2Cat. The radiator is clean. Coolant is disappearing. On a cool engine, hookup the pressure tester and raise pressure to about the cap rating. If there is a leak, then the pressure should fall. Maybe the glow plugs will need to be removed to check for leak. Follow the directions for the diagnostic equipment and see if a leak can be found.
Very soon this engine will have bent connecting rods to go along with it's compression leak.
To be explicit on eserve's warning, if the pressure tester pushes coolant into a combustion chamber, the incompressible coolant will likely bend the connecting rod.
So make sure that no coolant has been pushed into a combustion chamber before starting the engine.
So make sure that no coolant has been pushed into a combustion chamber before starting the engine.
One clarification. It only loses coolant by boiling it out through the cap when overheating. I see no external leaks and the oil level is consistent and not milky. Don’t see any white smoke while running like it would be water in the cylinders.
I’m getting worried. Found out the tractor would be run and would start loosing power. They would go a while like that a while and when they cut it off it would be steaming out the overflow.
I’m getting worried. Found out the tractor would be run and would start loosing power. They would go a while like that a while and when they cut it off it would be steaming out the overflow.
The problem with that is that the head, block, and gasket are all expanding and contracting with aggravation from temperature extremes. This ups the odds that the gasket or cylinder head could be the problem. Just because the oil is not milky does not rule out a cracked cylinder head.
One other easy thing to try is to make sure that the cooling system can hold pressure. If it won't hold pressure then boiling can occur when it should not.
So I definitely see bubbles. I cranked with cap off and thermostat out. After about 10 minutes of idle in mid 70s temperature the gauge was barely off Cold. Bumped it up to PTO speed and definitely have bubbles. I tried to attach video but couldn’t so I attached a screenshot. After about 67 minutes at PTO speed gauge was a little under half temp. Looked at my videos and counted 15-20 bubbles in a 11 second video so I guess it confirms gasket or cracked head or block.
Attachments
Napa sells a kit to check for exhaust gasses in the radiator. You might try one of those. They are fairly affordable.
North Idaho Wolfman
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Little good news, on a kubota it's almost never the block (like super rare) and almost always the cylinder head (way too common) or head gasket.