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I have a 72” Liquid cooled Exmark Lazer Z (model LZ27LKA724 -serial number in the 270000s) that started overheating. We have tried everything I can think of to fix it: new temperature sender; new relay; new oil switch; checked fuses; visual check of wiring; flush and filled the radiator. After we did all that, we hot wired the rad fan to run all of the time. When we did this, it did not over heat. So it sounds like something isn’t telling the fan when to turn on. I would prefer to fix the issue over installing a manual switch permanently to turn the fan on and off manually. Does anyone have any thoughts on where the problem could be?

BEfore we can give specific advice we need to know what mower exactly you have so we can consult the correct wiring diagram.
This should be a tag under the seat .

Have you replaced the thermal switch PN 1-633833? Also you cleaned the radiator did you clean the outside fins?

StarTech said:

Have you replaced the thermal switch PN 1-633833? Also you cleaned the radiator did you clean the outside fins?

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We did not replace the fan thermal switch. I have not been able locate it on the machine. Do you know where to find it?

If remember model format correctly you have a Kawasaki 27hp. We need the actual model and spec number of that engine to see if they located it on the engine. According the IPL the 23hp use the thermal switch so I would think the 27hp would use it too.

StarTech said:

If remember model format correctly you have a Kawasaki 27hp. We need the actual model and spec number of that engine to see if they located it on the engine. According the IPL the 23hp use the thermal switch so I would think the 27hp would use it too.

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The only model and serial numbers I’ve found are the ones I provided. Is there a separate set of numbers just for the engine somewhere? The numbers I have (SN: 271060 Model: LZ27LKA724) are on a plate under the steering control on the right side of the machine. If there is another number we are looking for, do you know where I should look for it?

Yes they should be on the engine. It Kawasaki engine as they are the only water cooled engine I have seen lately. I think you got a FD750D.


It the reason every equipment owner should record these numbers before the decals disappear. I currently just finish working a Hustler Super Z that the engine info is not present nor was the ZTR decal with the model and serial. Luckily the customer had it least recorded the Super Z model number. The engine was either CV740 or CV750 but that is just a guess.

StarTech said:

Yes they should be on the engine. It Kawasaki engine as they are the only water cooled engine I have seen lately. I think you got a FD750D.
View attachment 64240

It the reason every equipment owner should record these numbers before the decals disappear. I currently just finish working a Hustler Super Z that the engine info is not present nor was the ZTR decal with the model and serial. Luckily the customer had it least recorded the Super Z model number. The engine was either CV740 or CV750 but that is just a guess.

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Ok, I found the engine number FD750D002589. The part you highlighted looks to be the sender temperature (part no. 103-0283). That is a part I did replace already. Any other ideas?

If you know what temp the switch is supposed to turn the fan on at you can go old school method.

First verify that the wiring going to the sender will turn the fan on.

Remove the sender but leave wire(s) attached. If it has a single wire you will need to add a ground wire to the body of the sender. Put it in a glass jar with a thermometer and turn mower key to "on" and use a heat gun or torch to heat the jar to see if fan kicks on at or near the proper temp.