ZD331 Overheating

[Russewb]

I've had issues with my ZD331 running hot. I can generally mow for up to an hour before it gets too hot for me to be comfortable. I have a 72" deck with a mulching kit.

It doesn't matter if it is cool outside, there is still the same problem. I've changed the thermostat, pulled the radiator and cleaned it, and flushed the system twice. The only thing left that I haven't worked on is the water pump. What are the odds that the pump is my issue?

Any help would be appreciated.

 

[lugbolt]

The odds of a water pump failing aren't great, IMO. Usually when they die, they start to leak out of the weep hole. You'll want to check your fan belt to make sure it's not slipping. Check the fan for broken/cracked blades. I've seen them cracked at the base and I guess the blades would flex/flatten out at speed. Replacing the fan solved it. The #1 cause is the radiator itself being plugged externally with dirt, but you said you've already cleaned it. Make sure air can flow through the hood screen that falls in front of the radiator when you lower the hood.

I've seen a few gauges that were 'off' too. It's not uncommon for them to read near the red at normal operation in the heat of summer. The last one I tested, right at the red mark on the gauge, was 202 degrees coolant temp (measured at the cylinder head where the sender was); so it wasn't really "that" hot.

 

[85Hokie]

ok.....first stupid question....

how hot ? MOST people believe that a diesel should run cool.....and in fact MOST diesels run cooler than gassers....but AN ENGINE THAT runs cool is NOT efficient ......right around 200 is a good number to be at ----- now 210 -220 ....thats HOT, 185 - 190 is about right when everything is working under a good load....

so - tell me how hot......(not being a smart ass) but hot is a different hot to some!

 

[Russewb]

The last time I let it get hot to the point I needed to shut it down, I was short of the red on the temperature gauge, but heard the relief on the radiator. I shut it down and the coolant in the overflow was boiling....so I'd say well over 220.

 

[Russewb]

Just heated it up again and it was at 224 on upper radiator hose by the temperature sending unit.

 

[rjcorazza]

The gauge on my zd331 has always read on the low end about 1/4 scale. Boiling is boiling though. Assuming the fan and belt check out, I would put a new water pump on it.

 

[lugbolt]

So you've already done the thermostat, flushed the coolant and radiator. Only things left are airflow related (fan belt, fan, shroud, dirty/plugged radiator fins and/or screen, or the hood itself could be restricting airflow), and water pump.

Years ago I changed a water pump that was leaking a little. Nothing severe, but it was discovered during normal servicing. Upon removal, the impeller had fallen off of the water pump shaft. First and only one I've seen like that. IIRC it was a RTV1100.

 

[helomech]

Don't forget a pin hole in the suction side of the line will allow air in, which will make it to the pump and cause the pump to cavitate. I had this issue on my toyota rav4. Took me forever to figure out.

 

[BrentB]

The gauge on my zd331 has always read on the low end about 1/4 scale. Boiling is boiling though. Assuming the fan and belt check out, I would put a new water pump on it.[/QUOT

 

[Ktech101]

Check your coolant temp and external block temp with a temp gun to see what your temps actually are before you go on you could be dealing with an electrical issue instead. I found with a lot of zds that the radiators had to be thoroughly cleaned almost every time you use them first with air then water. I have never seen a water pump or thermostat fail in those particular engines. I would put a pressure pump on your radiator and check for it's ability to hold pressure or for abnormal pressure build up in the cooling system

 

[BrentB]

The gauge on my zd331 has always read on the low end about 1/4 scale. Boiling is boiling though. Assuming the fan and belt check out, I would put a new water pump on it.[/QUOT

Did you ever figure out what the issue was?
I'm having same problem with mine. Dealer has replaced thermostat, but still overheating after running it for about 30-40 minutes.

 

[rjcorazza]

Did you ever figure out what the issue was?
I'm having same problem with mine. Dealer has replaced thermostat, but still overheating after running it for about 30-40 minutes.

This was not my machine. I believe the op cleaned the radiator, checked fan belt, coolant, thermostat. Basically everything except the water pump.

 

[screwsloose]

My bx2350 has this issue all the time in the summer. I usually clean the radiator with compressed air and if that doesnt do it i use water. On a side note i wrapped my muffler with exhaust wrap. The heat coming off the muffler got everything in there all toasty. Wraping the exhaust lowered the under hood temprature at least 30-40 degrees and i have less overheating issues. Not sure if you can wrap your exhaust on your machine. It helped tremendously on mine.

 

[screwsloose]

My bx2350 has this issue all the time in the summer. I usually clean the radiator with compressed air and if that doesnt do it i use water. On a side note i wrapped my muffler with exhaust wrap. The heat coming off the muffler got everything in there all toasty. Wraping the exhaust lowered the under hood temprature at least 30-40 degrees and i have less overheating issues. Not sure if you can wrap your exhaust on your machine. It helped tremendously on mine.

The book in the 2350manual says check the belt for proper tension. The water pump is a simple design. They either work or they dont. I have seen some volkswagons use a plastic impelller. You can tell those are bad cause they act like a stuck thermostat. If you are using your tractor for a half hour or so and the it overheats it could only be low air flow, belt tension or thermostat. I have installed bad thermostats from kubota. I personally run a car thermostat stant part #45848

 

[mikester]

My ZD326 radiator holds a LOT of dust and its difficult to get all of it clean. Part of my regular PM routine is to blow out the rad dust with an air compressor.

If you leave your machine outdoors the dust and added moisture will get caked or cemented in place. In that case you are going to need a pressure washer and you will have to be extra careful. I would avoid pressure washing things if you can because its easy to damage fins and make the dirt lock in even more creating cooling dead spots in your rad.

First thing I would check is that your radiators and screens are clean and you are getting good air flow.

 

[lugbolt]

Also look at the radiator filler neck. Remove cap (engine cold!) and take a look-see at the BOTTOM of the neck, there's a step down at the bottom where the lower rubber gasket contacts it. The entire area should be SMOOTH. If there's any roughness, the radiator filler neck is deformed and will no longer seal, which usually leads to the coolant boiling prematurely, as well as venting into the catch can prematurely. If the cap won't seal, the pressure in the system won't get up high enough and WILL overheat/boil. The system needs pressure. A lot of times you can grab the upper radiator hose on a hot engine and it will be soft-a dead giveaway of a cap failure or a sealing surface failure.

Only way to fix a deformed radiator is to replace it. New one comes with the cap. You can buy the cap separately, however.

The #1 cause of radiator filler neck failure is--overheating--all it takes is one good overheat (from a dirt-filled radiator or screen) and it can deform the filler neck to the point where it won't seal anymore. Also....while you're looking into it....if you see any white junk at the filler neck, it's junk and needs to be replaced. The white junk is deposits left from boiled/worn out coolant mix.

Also worth mentioning is that you MUST use 50/50 mix of antifreeze and distilled water. Tap water boils at a lower temp due to the chemicals it's got in it.

 

[evan waa]

A Kubota BX 2200 series have overheat problems I have both a BX 2200 and a BX-22 problems are the same on both done many changes but really haven't got where I want to be the changes have been new thermostat new fan belt new radiator coolant replacement new fan from a bx2680 was my best Improvement and Cooling but still not where I want to be these things are very marginal and Cooling and grossly affected by any debris need cleaning frequently pain in the butt next I'm going to check chemically for an exhaust leak into the coolant see what the situation is with head leakage or gasket failure it does tend to run cooler with the hood off any other ideas please reply don't need any replies about airflow which I well know about and debris thank you