Bobcat 743B Getting hot

[prowedge]

I just recently purchased at 743B and it is getting hot. The radiator hose to the right that flows underneath the alternator is cold, and the upper one coming out of the top of the engine is hot. Bad water pump? I need to use a laser thermometer to verify that I don't have a faulty sending unit / gauge. I checked to make sure the oil cooler is not plugged with dirt and the inspection plates are in place. Any help would be greatly appreciated!

Tyler

 

[brdgbldr]

I just recently purchased at 743B and it is getting hot. The radiator hose to the right that flows underneath the alternator is cold, and the upper one coming out of the top of the engine is hot. Bad water pump? I need to use a laser thermometer to verify that I don't have a faulty sending unit / gauge. I checked to make sure the oil cooler is not plugged with dirt and the inspection plates are in place. Any help would be greatly appreciated!

Tyler

Could be a stuck thermostat or a clogged radiator.

 

[foton]

I agree with above do the thermostat first it is easier and cheaper, maybe you will get lucky. I would also flush system with fresh water and use it till you determine if thermostat was problem . If it is a radaitor problem then you can just open up coolant system and drain instead of catching the new coolant you just put in.

 

[prowedge]

Ok will try thermostat first. The reason I wasn't thinking of it being a clogged radiator is because the coolant looks fresh and new with no rust or particles in it. Although when it is up to temperature, only the outsides of the radiator are hot. I've heard the radiator is difficult to remove, Would I be able to flush it in the machine by chance?

 

[7LBSSMALLIE]

if youre smart enough to have a laser thermo, you got this nailed,

 

[7LBSSMALLIE]

if youre smart enough to have a laser thermo, you got this nailed,

 

[prowedge]

if youre smart enough to have a laser thermo, you got this nailed,

I meant infrared thermometer. Hopefully I can nail it!

 

[7LBSSMALLIE]

743b overheat.. boss or non boss, acutal or indicated, 2203 i assume, common casuses cracked head back left hand corner. t/s check for prenseces of combistion gassaes in radiator, positeve test you got your answer, where id start, napa stuipd tool suck the gasssas thru thru fluid if it changes colur you got youre answer KISS

 

[prowedge]

Ok I will get a test kit from Napa and give it a shot. Hoping to not have a cracked head… The engine isn't getting extremely hot, the coolant isn't boiling in the reservoir. it's on the line between normal and hot on the gauge

 

[laurencen]

agree with 7 my 743 would overheat, ran decent but after trying many tests it turned out being a cracked head, previous owner used starting fluid regulary on it

 

[prowedge]

I'll do some tests but that doesn't explain why lower radiator hose is cold and the upper is hot does it?

 

[Tazza]

From what you're telling me, your cooling system is working. Hot coolant in the top, gets cooled by the radiator, and cool coolant out the bottom, normal flow.

Now, if you confirm your engine is getting hot at the thermostat housing and not traveling to the top hose, your thermostat could be stuck closed.

Are you getting bubbles in your radiator? if so, you may have a cracked head, bubbles in the cooling system will not transfer heat, so your engine can over heat.

 

[dfb]

I'll do some tests but that doesn't explain why lower radiator hose is cold and the upper is hot does it?

The upper hose can feel hot from steam without the thermostat actually opening to circulate coolant, be certain the cooling system is full of coolant. You can check the operation of the old thermostat in a pot of water on the stove to see what temp it opens at. If your machine has cab heat, good heat there would suggest adequate circulation in the system.

 

[prowedge]

The upper hose can feel hot from steam without the thermostat actually opening to circulate coolant, be certain the cooling system is full of coolant. You can check the operation of the old thermostat in a pot of water on the stove to see what temp it opens at. If your machine has cab heat, good heat there would suggest adequate circulation in the system.

Yes the machine has cab heat, I have the hoses to the heater core unplugged in the cab. I'll re attach the hoses and turn it on the see how much heat comes out. I'm assuming it should not effect the cooling system with the heater core unplugged? The system is completely full of coolant. It also sounds like the water pump has a bad bearing. I'll check the thermostat with hot water on the stove. Thanks

 

[prowedge]

I

From what you're telling me, your cooling system is working. Hot coolant in the top, gets cooled by the radiator, and cool coolant out the bottom, normal flow.

Now, if you confirm your engine is getting hot at the thermostat housing and not traveling to the top hose, your thermostat could be stuck closed.

Are you getting bubbles in your radiator? if so, you may have a cracked head, bubbles in the cooling system will not transfer heat, so your engine can over heat.

I'm going to check for bubbles in the radiator today. Also, when I put my hand on the center of the radiator fins it is cold, but it's very hot around the edges. I can only feel the wind from the fan to the left side doesn't seem to have much wind flow on the right or center. Is that normal?

 

[laurencen]

you could have a airlock in the system, was it OK when the heater was attached? on my 743 the heater hoses will bleed out the air above the thermostat, on newer there is a bypass hose, when mine was overheating we drilled a 1/8 hole in the thermostst, it worked for a few months until the crack got worse, never saw a sign of bubbles but lots of muck in the water.

the crack was not obvious at first but we used a dye to find it, picked up a new casting off ebay for a few hundred dollars then swapped over the valves, never use starting fluid on a Bobcat Kubotaa motor,

 

[foton]

there is a remote chance that if the water pump uses a stamped impeller , and it has been erroded by a lack of maint. of the cooling system it could be a problem. If the bearing is making noise change out that pump and look at the old impeller to rule out that potential issue.

 

[prowedge]

there is a remote chance that if the water pump uses a stamped impeller , and it has been erroded by a lack of maint. of the cooling system it could be a problem. If the bearing is making noise change out that pump and look at the old impeller to rule out that potential issue.

I was kind of wondering if that was possible, it sounds like something is flopping around in the more than it sounds like a bad bearing. When I ran it yesterday, I tried to see if I was getting heat at the heater core inside the cab and it never got warm. The engine heats up (temp gauge gets close to hot) before the radiator even gets warm. I'm sure it's the original water pump from 92. The machine didn't have a whole lot of maintenance done to it and the water pump is painted the same blue color that the engine block is. I'm going to pull the water pump off as soon as I get a chance. Thanks Foton

 

[dfb]

I was kind of wondering if that was possible, it sounds like something is flopping around in the more than it sounds like a bad bearing. When I ran it yesterday, I tried to see if I was getting heat at the heater core inside the cab and it never got warm. The engine heats up (temp gauge gets close to hot) before the radiator even gets warm. I'm sure it's the original water pump from 92. The machine didn't have a whole lot of maintenance done to it and the water pump is painted the same blue color that the engine block is. I'm going to pull the water pump off as soon as I get a chance. Thanks Foton

With the engine cold on startup you could check the water pumps ability to move coolant by pulling a hose off at the heater core. It should be pumping coolant even at idle with more movement at higher idle speed. The engine temp would likely be increasing very quickly if the pump was not circulating coolant.

 

[oiu789]

What make of engine do you have? I am not sure but what I have seen it could be a Mitsubishi or maybe a Ford. If any one knows if they came with a Mitsubishi or a Ford or both please respond!