Bobcat 743B Getting hot

[prowedge]

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.

That's a good idea. I'll pull one of those hoses off when I get back to the machine. The temp gauge slowing rises up to the line between normal and hot within 5 minutes of starting it. The water pump is definitely making noise and it sounds a lot like something rattling around in there more than it does a bearing that has gone out. Thanks everyone for the help on this!

 

[brdgbldr]

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!

The 743 models were all diesel.
The original 742 came with the Ford engine and the later model 742b and 742B came with the Mitsubishi engine.

 

[garymac1007]

they came with either motor depends on serial number of machine when built

 

[oiu789]

Thanks I will look up my ser#. Good catch on your part I was looking for info on a 742 not a 743 I mistakenly got here thru an email I got from the forum.

 

[prowedge]

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

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.

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.

I pulled the thermostat out and it's not fully open until a little of 200 F . It's a 180 f thermostat. It also opens very slowly. Coolant is circulating as the cab heater blows warm air after running for 5 minutes or so. I did notice that right when I flip the cab heater on the temp gauge drops down about and eight of an inch and goes back up immediately after turning the fan off. It happens immediately, so I know it has nothing to do with the fan blowing on the heater core cooling down the coolant.

 

[prowedge]

I pulled the thermostat out and it's not fully open until a little of 200 F . It's a 180 f thermostat. It also opens very slowly. Coolant is circulating as the cab heater blows warm air after running for 5 minutes or so. I did notice that right when I flip the cab heater on the temp gauge drops down about and eight of an inch and goes back up immediately after turning the fan off. It happens immediately, so I know it has nothing to do with the fan blowing on the heater core cooling down the coolant.

 

[prowedge]

I

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?

I

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?

I pulled the thermostat out and it doesn't begin to open until after 200°F And closes around 180°F. I noticed it did not have the rubber O-ring around the edges of it, could that cause a problem? I checked the engine and radiator with an infrared thermometer, The highest reading I got was just under 195 right below the thermostat and the temp gauge was just beginning to hit the hot side on the gauge. Since I had the thermometer on it and knew it wasn't getting extremely hot I let it run for longer than normal and I could begin to feel warm coolant coming back down out of the radiator so I can tell it is circulating

 

[wwb]

I have an 843 and there was an oil leak at the rear of the motor and it was spraying oil into the radiator. It would run hot quite often especially on a hot day and working hard. When I cleaned the rad with a pressure washer it was much better. I eventually pulled the motor and fixed the leak, and it has been great since. I would suggest to check the radiator to make sure it is clean.

 

[prowedge]

I have an 843 and there was an oil leak at the rear of the motor and it was spraying oil into the radiator. It would run hot quite often especially on a hot day and working hard. When I cleaned the rad with a pressure washer it was much better. I eventually pulled the motor and fixed the leak, and it has been great since. I would suggest to check the radiator to make sure it is clean.

I have an 843 and there was an oil leak at the rear of the motor and it was spraying oil into the radiator. It would run hot quite often especially on a hot day and working hard. When I cleaned the rad with a pressure washer it was much better. I eventually pulled the motor and fixed the leak, and it has been great since. I would suggest to check the radiator to make sure it is clean.

I just cleaned up the oil cooler and the radiator today and didn't have much luck with it changing the operating temperature. I'm going to run it tomorrow for a little while without the thermostat and see what that does. Thanks for the reply!

 

[prowedge]

I cleaned the block heater or coolant heater today and it was plugged halfway with Some sort of deposit, maybe calcium or cooked coolant not sure but it now stays in the 180 to 190 range even on a day when it was 103 here in nor cal. I noticed a yellow wire with a blue stripe hanging down near the coolant temp sensor wire behind the alternator and I'm not sure where it goes. Any ideas?

 

[prowedge]

Well I thought I had the problem fixed by flushing the radiator and clean buildup out of the in-line coolant heater but it started getting hot again today. It was 104 outside yesterday and it stayed 3/4 of the way on the normal portion of the temp gauge. Is there a good type of radiator cleaner to recommend? I was thinking some of the debris from the heater in the lower picture may have made it up to the radiator and plugged some of the passages.

 

[laurencen]

someone cook musht peas in that?

 

[Mustang Guy]

I don't know what you're using for coolant, but it's wrong. That's some serious electrolytic corrosion going on. Your aluminum is being carried away.

 

[prowedge]

I'm not sure either, I bought it this way. I'll be sure to us the correct stuff when I re-assemble it. So I would imagine that I probably have a plugged radiator from the looks of the build up. The inside of the radiator looks good at least the small portion I can see. Is there any way that I would be able to flush it properly without removing it from the machine? Is the any cleaner that you would recommend? Below is a picture of the coolant before I drained it.

 

[foton]

I do not know if this is the effect of mixing red and green coolant ,but I heard it makes a sludge if mixed. I think you will need a chemical radiator flush and some diesel mechanics I know swear by peak final charge coolant. (which I am converting to as coolant changes are needed )

 

[UnexpectedBill]

I'd also check the electrical ground to the alternator and chassis. Definitely check the alt ground in the harness for green cheese. Maybe add an extra cable from the alternator bracket to the chassis and block to chassis? I'm not familiar with the setup on that machine but poor grounding will cause trace voltage to pass through the coolant and eat away at the components from the inside out.
Probably not be the whole problem, but worth considering on older machines. A few extra ground cables are cheap. Major parts, not so much.

 

[dfb]

If that is what is in the cooling system I doubt you will be able to clean the radiator yourself. It might be time to have it checked at a radiator shop but you are going to have to get the rest of the system clean before putting a clean radiator back in. Definitely start reading up on electrolysis in a cooling system and do some testing. I have seen new heater cores fail within 1 year of replacement due to electrolysis. Here is a quick link I found...

Northern Radiator | Electrolysis 101

www.northernradiator.com

 

[prowedge]

I'd also check the electrical ground to the alternator and chassis. Definitely check the alt ground in the harness for green cheese. Maybe add an extra cable from the alternator bracket to the chassis and block to chassis? I'm not familiar with the setup on that machine but poor grounding will cause trace voltage to pass through the coolant and eat away at the components from the inside out.
Probably not be the whole problem, but worth considering on older machines. A few extra ground cables are cheap. Major parts, not so much.

When I purchased the machine, the ground that runs to the engine block from the chassis was disconnected and probably had been for quite a while. There are two other grounds from the battery to the chassis. I knew when I saw that ground disconnected It wasn't a good thing. I'm going to pull the radiator and hopefully get it properly cleaned. Thanks for the help!

 

[UnexpectedBill]

You mentioned early in the thread that the water pump was making noise. Maybe I missed it but I don't see anywhere that you said you replaced it. Just wondering considering the corrosion in the system. I've seen the vanes on pump impellers corroded off. Perhaps you've lost enough water pump vanes that it's not moving enough coolant to keep up when you're working the machine. Just something to consider.

 

[Mustang Guy]

After you get the radiator hot tanked and engine flushed, do as UnexpectedBill suggests and inspect the coolant pump impeller for cavitation pitting and electrolysis corrosion. And after you have thoroughly scraped and cleaned out the heater, install an AWG 10 bonding (ground) wire from it to the engine block. In essence, you have a dissimilar metal "battery" here with the transient current being carried in the coolant (this is also why there is usually a separate ground wire on an aluminum alternator).
For a flushing agent I recommend an oxalic acid solution or CRC Evapo-rust (remove the thermostat for flush and rinse). For coolant I recommend (and use it in all my equipment) Final Charge 50/50 premix.