B7500 Overheating after 30 mins mowing

[Dave1117]

Just purchased a 2003 B7500 HST with 60" belly mower and front bucket. Tractor overheats (red lines the temp gauge, coolant boils into overflow tank) after about 30-40 minutes mowing. Mower set at 4". Took off bucket to lighten the load. No help. New air filter, new oil change, made sure radiator screen is clear. Engine has 1100 hours on it. Normal operation with bucket and just driving around is no problem. Overheating happens only with belly mower in operation. The grass was quite tall and I do see that the end couple of inches of the exhaust pipe may be rusted so that it could blow towards the lower part of the radiator, but that did not seem to make it overheat when using just the bucket. So, has anyone had a similar experience? This is the smallest tractor I have used, but everyone tells me they are very tough and should run all day without overheating. Tractor seems in very good condition, but hoping I did not buy someone else's headache.

 

[Eric McCarthy]

Could be that the grass is just too tall and the tractor is working its butt off trying to mow the grass. If the grass is at a height it should ideally be bush hogged and your cuting it with a belly mower, yeah I can see that over heating the tractor quick.

 

[Rusty46]

Just purchased a 2003 B7500 HST with 60" belly mower and front bucket. Tractor overheats (red lines the temp gauge, coolant boils into overflow tank) after about 30-40 minutes mowing. Mower set at 4". Took off bucket to lighten the load. No help. New air filter, new oil change, made sure radiator screen is clear. Engine has 1100 hours on it. Normal operation with bucket and just driving around is no problem. Overheating happens only with belly mower in operation. The grass was quite tall and I do see that the end couple of inches of the exhaust pipe may be rusted so that it could blow towards the lower part of the radiator, but that did not seem to make it overheat when using just the bucket. So, has anyone had a similar experience? This is the smallest tractor I have used, but everyone tells me they are very tough and should run all day without overheating. Tractor seems in very good condition, but hoping I did not buy someone else's headache.

Dave1117 - My 2003 B7500 HSD-R does the same thing when mowing, especially when the grass is dry. When my temperature gets near the high end red area, I idle down the engine, remove and clean the front grille, remove and clean the screen in front of the radiator, remove and clean the shutter plate (heavy gauge metal screen) below the radiator, AND blow off the front of the radiator. If possible, I use compressed air to blow off the radiator. In a pinch, I huff and puff. I repeat these items as required. At the end of the mowing session, I repeat once more, plus blow out the radiator from the back (with the engine OFF). I highly recommend blowing the radiator from the back before you do any mowing. I bought an extended length blow off nozzle for this purpose. Also, check the engine coolant level in the radiator overflow reservoir. My RCK60-24B MMM seems to throw chaff out the left front corner towards the radiator intakes. My B7500 has 1,400 hours, mostly mowing.

Best Wishes!

 

[kubotab6100d]

Just purchased a 2003 B7500 HST with 60" belly mower and front bucket. Tractor overheats (red lines the temp gauge, coolant boils into overflow tank) after about 30-40 minutes mowing. Mower set at 4". Took off bucket to lighten the load. No help. New air filter, new oil change, made sure radiator screen is clear. Engine has 1100 hours on it. Normal operation with bucket and just driving around is no problem. Overheating happens only with belly mower in operation. The grass was quite tall and I do see that the end couple of inches of the exhaust pipe may be rusted so that it could blow towards the lower part of the radiator, but that did not seem to make it overheat when using just the bucket. So, has anyone had a similar experience? This is the smallest tractor I have used, but everyone tells me they are very tough and should run all day without overheating. Tractor seems in very good condition, but hoping I did not buy someone else's headache.

Hi, check the coolant. If its old. Its worn down and won't work properly. It also will turn acidic which is bad to radiators and water pumps.

 

[Gordon Jones]

You might try running a water hose thru the radiator. I did after using an air gun to blow out the radiator on my L 1500. It took about 10 minutes before the water ran clear out the other side of the radiator. G

 

[Stubbyie]

Keeping radiator clean can be problematic. Blowing gently with compressed air to not bend fins and same with water can be beneficial. Blow or flow from 'backside' toward 'intake' side to push the debris back the way it came in. If never done the first time will take some patience. Dish soap squirted onto radiator fins seems to help sometimes making water 'wetter'.

If fins bent use a plastic fin-comb like HVAC guys use to straighten out the fins. Be gentle and can get it almost new looking.

On our two Oranges we use cheap HVAC "filters" (white/green/blue fiberglass in cardboard frame, $1 at WM) on the "intake" side of the radiator in addition to the pull-up-to-clean prescreen ahead of radiator. When temp rises we just pull out the blue filter, shake it clean, reinstall it same direction. When too dirty we just toss it. Sure makes life easier.

Never tried the more expensive pleated high-efficiency HVAC filters (3M Filtrete comes to mind) due to expense and suspicion that air flow would be too greatly restricted.

Since using blue 'cat hair' filters never had a problem with radiator getting so dirty it raises coolant temp.

 

[Bulldog]

Unless you know it has been changed I would dump the anti-freeze. Normal AF needs to be changed every 2 yrs. Over time it looses it's ability to disipate heat.

 

[YotaBota]

I have a BX25, and was just complaning about the same thing. Mine is 3 years old. What I found after re-reading the owners manual was that there is a second screen with a handle near the rad cap. Pulled out that screen, it was clear, BUT there was a load of matted grass and debris packed in there against the rad like a 3m scoth brite pad! Blew out with the air hose (an extender is most helpful) and I'm running midway in the normal zone again. Maybe yours is the same way. Good luck.

 

[G-Man]

Mine was running a little warm the other day changed the anti freeze and alone made big difference. Now just bearly run past the C mark.

 

[4x4toys]

A faulty radiator cap will give overheating problems also. Have it checked or install a new one of the correct pressure.

 

[kubotasam]

Use an air compressor to blow out the radiator fins. If I forget to do it each time I mow my tractor will run hot.

 

[oldbear]

All the above makes sense, however if that fails I've one other suggestion. I recently (SATURDAY!!) shipped a JD 455 garden tractor with hst and a 60 inch deck. About a year ago it started getting too hot when mowing (never happened before). I could cut off the PTO and it would cool down, but start cutting and in just a few minutes it would overheat again. Changed the thermostat, checked coolant, cleaned filters (air and radiator guard) and nothing worked. Finally checked the hydraulic fluid (ran HST and PTO) The filter was "dinged" and the fluid had a burnt smell. Long story short I drained the fluid, replaced the filter and put in new hydraulic fluid and the problem went away!!!! I don't know "why" it happened, but that did fix it. If nothing else works, give it a shot.

 

[Yogi]

Unless you know it has been changed I would dump the anti-freeze. Normal AF needs to be changed every 2 yrs. Over time it looses it's ability to disipate heat.

I tried everything listed on here and nothing works . It doesn't matter how high or how low my grass is wet or dry it still gets hot