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Discussion Starter #1
Aloha,

I'm finding this forum to be very helpful having a lot of hands on experienced individuals out there, and I need to call on you again as I am on a quest to find the remedy for a newly found problem with my ressurrected 2510 Mule KAF620-A1 project. Now that my mule runs, my daughter and I have been puting it to good use. However, on long runs (two-three miles), or on long gradual enclines, and at higher speeds (25mph tops) which is good for what we use it for, we see the "overtemp" indicator (red light) coming on. The cooling fan usually comes on quite soon after taking off, but during conditions like mentioned above the indicator light comes on, and in response we stop, shut the engine down, and let the fan cool the system until it shuts it self off, then we can resume driving again, is this typical? I've read on other threads that the thermostat is taken out, is that a remedy to consider? I know the cooling system circulates.

Kalika
 

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There are a few critical cooling system issues.

Make sure you are not running water, but are using an approved coolant mix or you will corrode between the engine block and one or both of the heads and get hot compression gases in the cooling system and overheat. Once that corrosion occurs the only solution is to tear them down and replace or resurface the parts if they even can be resurfaced. Straight water also boils in the engine cylinder water jackets during hard running and will create steam pockets that keep the system from cooling. Once an air lock starts, it will remain until the engine cools enough to condense the steam and start circulating the coolant again.

Check your radiator when the engine is cold. If the water level is below the top and the coolant overflow tank is not siphoning back to keep it full, the engine will air lock and overheat. If the coolant is not right to the top and the overflow tank not up to level, then you need to check to find the air leak in the cooling system and get it corrected. It can be as simple as a bad radiator cap or cracked hose, or as complicated as a blown headgasket or bad waterpump seal.

The waterpump must be in good shape and circulating the coolant. The best way to check this is to wait until the unit is cold, remove the radiator cap and then run it until it gets fully to operating temperature. Then look trough the radiator cap and see if the coolant is circulating. If it is not, you likely need a new water pump.

I never trust the overtemp indicator. I use an automotive thermometer bulb type heat gauge and install it up on the dash. They are available from most autoparts stores for cheap. Sometimes the sensor for the OEM indicator simply goes south, and will trigger that light when nothing is actually wrong. A real gauge gives you the actual temp of the coolant.

As far as removing the thermostat, that is not something I would recommend. The cooling system needs a set amount of backpressure on the water pump when it is cold to properly warm up so it runs and does not get pump impeller cavititation which will create air pockets that will hydrolock the cooling system and keep it from properly circulating the coolant.
 

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Discussion Starter #3
RCW,
Thank you for the solid info, and in accordance with the service manual I have 50-50 coolant/water. I can't precisely say how it was maintained before the "2510 resurrection" however, I did acquire the mule from the company I work for, and it having a regular repair garage and seeing the maintenance schedule for my company truck would lead me to believe they did it right with the mules too. As far as the eye can see, the inner passages look good, and it has new head gaskets since "project rebuild". I did exercise the method you mentioned about getting it up to running temperature and watch the water circulate and it does, thank goodness. Despite the red indicator coming on, the cooling system does not over boil and escape to atmosphere, and what ever accumulates in the overflow bottle, is returning into the system, which is basically why I am somewhat at a dead end, knowledge wise! I am going to implement and integrate your suggestion re; the temperature monitor. Oh, and I wont remove the thermostat... Although unlikely, I hope the red light is a false indication. I'd really like to start using this mule for hunting, but not without reassurance of its dexterity.

Aloha, Kalika
 

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One of those infrared temperature guns is nice in a situation like this as you and point and shoot different spots when the engine temp light isn't on and then check it when it is and see if the light maybe lying to you. Also if the water in your area has minerals in it, be sure and use de-meralized or distilled water in the coolant mix. The radiator may be partially plugged, again the temp gun can be used to find a plugged spot in it. Max
 

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Discussion Starter #5
Thumperacres,
Good tip, I have access to a temperature indicator gun, and I'll give it a try.

Mahalo, Kalika
 

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Discussion Starter #6
[RCW - I never trust the overtemp indicator. I use an automotive thermometer bulb type heat gauge and install it up on the dash. ]

RCW,
I'm going to ask a silly question!
The gauge mounts on the dash, but how does the thermometer bulb integrate? Again, I am not an auto mechanic, but I try.

Aloha, Kalika
 

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I run the capillary tube from the bulb in the cooling system to gauge on the dash. It is a long run, but the mechanical gauges are pretty much trouble free.

You can use an electric system, they use a sensor at the engine end, and a wire to the gauge. Much easier for some to install.
 

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Discussion Starter #8
RCW,
Thanks again, I'll follow up with both, and thereafter determine which works best for me.

Okay, one more "idiot" question, this one will prove why I need this forum!
The electric fan behind the radiator, (works fine with temp rise) which direction should it flow air through the radiator? Should it be pulling air in from the front? Or pushing it through from the back? I'm serious! I am not sure! Mines is currently pushing it through from the back, should I switch the polarity?

Ask me about bio, thermo, or hydro power generation, and applications, I can answer just about any question, but automotive... (?!)

Aloha, Kalika
 

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On our MULe 1000 it pulls air through the radiator like a car. The heat comes back through the opening in the floorboard when it cycles on. However much of the industrial equipment I've used over the years did the reverse, and the later MULES like yours used an industrial engine. 1000 used a Kawasaki 454 parallel twin engine complete with dual carbs adapted to the transmission case of the MULE sharing the same sump. works fine for us, but was trashed when I got it. Expensive to repair but cheaper than a new one.
 

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The 2510 normally pulls air through the radiator from the front to the back toward the operator. In warm climates you will find a lot of enterprising mechanics that have reversed the fan wires to push the air forward so the operator is more comfortable. That presents no problem for most applications, and saves the driver from heat stroke.

Hydropower! I will keep that in mind. I am trying to build a low head hydro project on my farm in Oregon and have been getting engineering advice that even I know sucks!
 

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Discussion Starter #11
Thumperacres,
Thanks for the feedback, were you referring to my mule as an industrial because of the model (2510?). My 2510 model dates back to the early 90's. I think you were telling me I should have the cooling fan drawing air from the front for my model? Am I correct?
I interpreted it that way, and others have told me the same thing so I went ahead and reversed the polarity, and subsequently took the buggy for a long 16 mile run without ever seeing the "over temp" indicator light come on. This is the first!

RCW,
Thanks for your feedback as well! That is good information, but how is it that if I had the air blowing instead of pulling, I will see the indicator light come on? You mentioned that others would blow it through in warmer ambient temperatures for comfort. If I do that with this mule, even in cooler temperatures I would see the light come on. Anyway, I wish not to belabor you, I’ll leave the fan pulling air in and be happy with it.

Hey! Your very own hydro unit, I wish I had the opportunity to build my very own. Unfortunately the only water running thorough my property is contained in a ¾” copper line.
I hope to be of some help to you some day.

Aloha, Kalika
 

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The term industrial is for Mules previously used by businesses, they are all industrial designs that many people now use as recreational. Normally the air is drawn in the front of the radiator, but many businesses that use them in hot climates reverse the wiring and blow the air backwards to reduce operator heat.

Most industrial applications never travel fast enough to have any problem with air backing up and overheating the radiator. They mostly putt around at just above a walk.

My guess is that you are traveling at a pretty good clip and that is causing the air to create a dam and the fan is no longer powerful enough to push it forward against that pressure.
 
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