Bobcat 743 Overheating

[Snowtom850]

Thank you. I'm pretty much on all of that now. Thanks for the input. Making sure I haven't missed anything stupid

 

[Micheal]

I don't have a hydraulic cooling fan that I am aware of. Belt driven fan that is moving tons of air. I have laser temp gunned it and everything is getting hot evenly. I feel like its something to do with the hydraulics also being it cools down as soon as I stop moving. have tried new fluid and filter on that too.
I pulls a ton of air through the coolers almost will pull my phone ( using flashlight) out of my hand and blowing out both sides of the exhaust. Air get warmer as heats up. The dealer keeps telling me the head and head gasket are the only thing that they see with this issue. I've owned this machine since 2009 have had no issues till last winter. and only randomly. now seems to be pretty consistent

My 743 was have the same problem, my cooler by-pass valve was disconnected, passed owner, when I hooked back up the temperature dropped. I think your cooling system is working properly but because you are getting high pressure in your hydraulic system causing it to over heat.

 

[Snowtom850]

My 743 was have the same problem, my cooler by-pass valve was disconnected, passed owner, when I hooked back up the temperature dropped. I think your cooling system is working properly but because you are getting high pressure in your hydraulic system causing it to over heat.

I have had this machine for over 10 years. I don't think anything is unhooked but I've never heard of a cooler bypass valve. Where was that located on your machine? I'm willing check anything at this point

 

[Micheal]

I have had this machine for over 10 years. I don't think anything is unhooked but I've never heard of a cooler bypass valve. Where was that located on your machine? I'm willing check anything at this point

Tonight I'll look at my schematic, try to send pictures.

 

[Micheal]

Tonight I'll look at my schematic, try to send pictures.

#20 the temperature switch is located in the #18 the port block.
Tomorrow I'll take pictures of where they are located on the bobcat.

 

[Snowtom850]

Thank you I will dig into that.

 

[brdgbldr]

Attached are some color copies of the flow charts. And as a bonus, copies of the electrical diagrams.

Of course somehow the pages are out of order and or missing or not folded out so you have to try to match the lines. Do with them what you will.

Can't remember where I got these from but they were this way when I got them. Just be careful.

 

[SkidTracks]

Working on a similar over heating problem on a T870 which has moved around.

Originally, Engine over heating (previously only seen when debris was blocking air-flow)
Moved to, Hydraulics over heating (never seen before, until several months back)
Moved to, Diesel fuel over heating (never seen before)

Done thus far:
New hydraulic fan motor filter
New hydraulic fan control valve (replaced twice - field / shop)
New hydraulic fan system - motor included
New hydraulic oil-radiator (cooler)
New hydraulic return manifold block
New hydraulic oil return filter by reservoir tank
New hydraulic oil (Bobcat Red after flushing
New hydraulic oil return temperature sensor (replaced twice field / shop)

Bobcat dealer has no ideas at this point.

Next up is Lower plastic fan shroud duct and Thermostat

Thoughts?

 

[oiu789]

Keep us posted on what has been done and what fixed it.

 

[Micheal]

Here is my engine wire harness diagram.
#6 is oil temperature switch and #7 is pressure switch.

The pressure switch has a normally open for temperature switch and normally closed for hour meter.
The temperature switch is grounded through port block.
I hope I'm helping and not making things more complicated.

 

[Micheal]