BX2660 still getting hot

[AshleyBS55]

I recently changed the oil, installed new thermostat, flushed radiator and filled with fresh antifreeze (<50% per manual). I mowed for less than 30 minutes in 78 degree weather and my gauge was just below the red line. The overfill tank was on the right level, but boiling. Last night before I put the tractor away, I blew the radiator and screen with a leaf blower and then hosed everything with a garden hose, not a pressure washer.

Any thoughts on why my tractor is running so hot?

Thanks,
Bruce

 

[mickeyd]

Re: BXS2660 still getting hot

1. Normally it is that the radiator fins are clogged so that not enough air can pass through.

2. Check the fan belt tension to make sure it isn't slipping.

3. If it isn't either of the 2 items above, then it might be the water pump.

4. Last but not least, it could be a clog in the water passage through the radiator or engine.

 

[AshleyBS55]

Re: BXS2660 still getting hot

1. If the fins are clogged, what can I do? New radiator?
2. Belt tension is fine.
3. Any way to determine if it's the water pump before buying and installing a new one?
4. I ran water through the radiator and engine when right after I drained it before flushing. Water seemed to flow ok.

Thanks for getting back so quickly.

Bruce

 

[North Idaho Wolfman]

Are you removing the screen to clean it?
If not that will make a ton of differance.
When you used a hose on the radiator are you using it straight or with a spray nozzle?

You can find out 2 things real fast, with it cool take off the radiator cap, start it up top the fluid off to the top.
Now watch the fluid, if the water pump is good you'll see flow, if it has bubbles you have a blown head gasket.

 

[anthonyv]

I can only guess at this point you may have a sticky thermostat not opening enough. You can try removing thermostat & run without it to see if engine is running cooler. One way to check water pump flow is to wait until radiator is cool, remove cap, start engine & see if it possible to see movement or flow. Before you do this check with a WSM & see if there are different procedures. Some more modern radiators today, this may not work.

"DO NOT REMOVE RADIATOR CAP WHEN HOT !!"

 

[kubotasam]

I recently changed the oil, installed new thermostat, flushed radiator and filled with fresh antifreeze (<50% per manual). I mowed for less than 30 minutes in 78 degree weather and my gauge was just below the red line. The overfill tank was on the right level, but boiling. Last night before I put the tractor away, I blew the radiator and screen with a leaf blower and then hosed everything with a garden hose, not a pressure washer.

Any thoughts on why my tractor is running so hot?

Thanks,
Bruce

The boiling you see in the overflow tank could be not boiling from heat but bubbles being blown from a leaking head gasket. The make kits to check for combustion gasses in coolant.

 

[Jim L.]

Remove the radiator from the tractor. Look through the fins to see how much blockage against air flow. Get a plastic tray like for mixing concrete and fill with warm water and Dawn. Soak the radiator and use very low pressure water to clean out the gunk. It may take awhile.

Thermostat has been covered above.

Please resist the temptation to keep running the tractor. If the problem is a head gasket, then the next progression will be to crack the cylinder head, if not already cracked.

 

[lugbolt]

Been through this more times than I can count. There's even interweb discussions on how "defective" the BX's are in the overheating department. Defective only describes the operator, IMO.

First is first. With a cold engine, remove radiator cap. Look down into the radiator. There are 2 flat surfaces in the neck, one at the very top where the cap seals against it, and another one further down where the bottom part of the cap's rubber seal is supposed to ride. IF there's any deformation in that part of the radiator, it's junk, replace it. If you see any whitish or grayish formations inside the radiator filler neck, that's deposits left behind from a previous overheat, and yes the radiator should be replaced if you see this. I mentioned this because the comment was made about seeing bubbles in the reserve bottle, tells me one of two things. Either the cap ain't sealing OR there's excessive pressure in the system, which overcomes the pressure of the cap's relief (which is about 15 psi or 1 bar roughly).

If the radiator looks ok, leave the cap off and start the engine. Do you see bubbles continually rising? Yes==>head gasket leaking. No==>you're ok. Next step, grab your cooling system pressure test kit (that you borrowed from the parts store or maybe you've got one?)...and pressure test the system. If it won't build pressure, again look real close at the top of the radiator; it's got to seal in both places or you can't build any pressure-and pressure inside the cooling system will escape, even as little as 1-3 psi.

Cleaning. The radiator must be kept clean on these because the engine's mounted backwards in the chassis. Means a garden hose with no nozzle is the best way to clean, IMO. Never a pressure washer, never a nozzle on the hose. And I like to spray water from the fan side back so that anything that's stuck between the fins gets blown back out the way it came in. And yes, they do get dirty in there. #1 cause of overheating actually. And all it takes is one good overheat and the radiator becomes deformed, and will never seal correctly again. Stupid plastic tanks

The cooling system MUST build pressure. If it can't, the engine WILL run hotter than it should and here's why. The water pump is not a very good pump at atmospheric pressure, but at 15psi, it is much more efficient at moving water. Also, 50/50 green coolant/distilled water is the only thing that's supposed to be in it....tap water is a no-no. At normal atmospheric pressure, the 50/50 mix boils at somewhere around 250 degrees. Under 15 psi, it will boil at a higher temp, so you can see why it's got to have pressure in the system in order to work.

This stuff applies to all Kubota equipment...at least everything I see on a daily basis anyway.

 

[Russell King]

One more point is that suggestion to see if there is flow...
You have to remove cap, start tractor, see if there is flow when cold = stuck open thermostat. No flow cold is ok but let tractor keep running until it is warm enough to open the thermostat and you should see flow. Flow may be in surges if thermostat is opening and closing but eventually it should be fairly obvious flow. If not then thermostat is stuck shut.

If you remove the thermostat and put hose back together and start it you should see steady flow if water pump is working

Hope I am not being too basic with the information, we don’t know your level of troubleshooting skill


Sent from my iPad using Tapatalk

 

[JerryMT]

I recently changed the oil, installed new thermostat, flushed radiator and filled with fresh antifreeze (<50% per manual). I mowed for less than 30 minutes in 78 degree weather and my gauge was just below the red line. The overfill tank was on the right level, but boiling. Last night before I put the tractor away, I blew the radiator and screen with a leaf blower and then hosed everything with a garden hose, not a pressure washer.

Any thoughts on why my tractor is running so hot?

Thanks,
Bruce

The usual culprits are: loose fan/water pump drive belt, bad radiator cap or wrong pressure rating, stuck thermostat, clogged rad air side passages, clogged rad coolant passages, lower hose collapsing at higher rpms, corroded impeller in water pump, clogged air filter, leaking head gasket.

 

[Dave_eng]

The only thing that has not changed is what you are using to determine you have an overheating problem. The tractor's own temp gauge.

You need to measure the coolant temp another way to be certain it is hot enough to have coolant boiling in the overflow tank. That is most unusual in my experience. Your real problem may not be overheating.

Dave

 

[AshleyBS55]

I have a gauge, but it only tells me how cold the antifreeze will protect. When the coolant gets hot, it is right at the "hot" line in the overflow. The temperature gauge shows that it goes right to the red line, but not over.

As a reply to a previous post: yes I do take the screen out and when I spray I use a nozzle on "jet" setting.

Thanks again for all the help.
Bruce

 

[Jim L.]

I think that Dave's point is to cross check the coolant sensor/gauge. A laser aimed remote thermometer will not only allow you to cross check, but also measure temperatures at hoses and across the radiator for troubleshooting.

Just short of the red-line does not mean safe. At high temperatures the head gasket will move around more from thermal expansion and contraction. It's accelerating the failure of the gasket, and when that goes there is a higher risk of cracking the cylinder head (very expensive).

 

[AshleyBS55]

LugBolt,

Thanks for all the info. The lips on the cap of my radiator look fine. When I started it cold with the cap on, so many bubbles came up they we splashing like crazy. But if my head gaskets leaking, shouldn't I be losing antifreeze? My antifreeze level always stays the same. It's full when I take off the cap. It's at the correct level in the overflow when it's cold or hot.
I'm not really familiar with all this as you can tell.

 

[Jim L.]

"When I started it cold with the cap on, so many bubbles came up they we splashing like crazy."

Indicates that pressure is higher than cap's rating. Possible gasket failure allowing exhaust gas to leak into coolant.

The combustion chamber operates at a high pressure. Coolant at low pressure. So it is possible that leaks occur with gas at high pressure, but not liquids at low pressure.

JerryMT posted a good list of possible culprits. The usual way to attack this is to start with the easy/cheap/common problems and eliminate them first.

It seems to be overheating. Verify temperature. You changed the thermostat. Take it out and put in hot water with thermometer to verify opens and closes at rated temperatures. Change the cap to eliminate it as a culprit. Make sure the radiator fins are straight and clean.

Water pump can be checked as described. Pressure test cooling system as described.

Last on list, because it is hard/time consuming, would be gasket and cylinder head.

It really is a process of elimination. Lots of good suggestions in this thread.

 

[North Idaho Wolfman]

Yep you have a blown head gasket or a cracked head, and no it will not necessarily leak coolant back into the cylinders.

 

[AshleyBS55]

First off, I want to thank everyone for all of their help. After much time and effort, I finally replaced my radiator. The sensor was fine. I changed the oil and put in a new air filter. Pressure was fine, etc. So I went with a new radiator. When I disconnected the hose that runs from the air cleaner back near the top of the radiator, I discovered an mouse had made a nest, complete with a huge acorn. Not sure why I didn't check this hose earlier, but that appears to have been the problem. Thanks again for all of your help and I'm doing a new post today because I need help replacing the seat. I will submit pics to show what I'm dealing with.

 

[Jim Dandy]

That is great news. Sure glade you didn’t take the head off.
James