How Does Excavator Thermostat Work?

Got stuff taken apart, excavators suck to work on.
Coolant looks good, thermostat looks good but im replacing anyway. Belt to water pump. looks glazed. Water pump not weeping, no play in bearing and very slight resistance when turning it by hand.

The radiator is plugged externally. I soaked it in purple power and flushed the fins for an hour. got most of the crud.

Before pics: This is the intake side of radiator



Look how caked up inside. Could barely see light through it
UPDATE on this.

I flushed the radiator externally 2 times soaking first in purple power cleaner then flushing with the hose then blowing out with the air. Did this twice i got about 95% of the crud. And i straigtned some fins that where flattened over.

I replaced the thermostat, WP pulley belt, 2 gallons coolant and new 13psi cap.

Runs nice and cool now. Its about 85 degrees outside and i just worked it for an hour and half pretty hard and stayed well into the green zone never even coming close to yellow zone on temp gauge. Im guessing the only real problem was the radiator fins where plugged and only allowing a little bit of air to pass through.

Im guessing my hydro oil will stay cooler now too as the plugged radiator must have blocked airflow to the oil cooler as well.

This indicates a leak in the hose between rad-cap and overflow... or bad rad cap.

EDIT: I see you have resolved the issue. I commend you for identifying there was a problem and NOT continue using the machine. Lesser operators may have damaged the engine.

Yeah i dont like making bigger problems for myself if i can help it so i went to resolving it. This excavator has been a pain in the butt, one issue after another but this is the first thats engine related. I got a Bobcat because it has kubota engine and ive been amazed at my other kubota. The bobcat end of things though arent the best and parts are extra expensive.

The expansion tank had a hose that was sort of loose fitting to the radiator nipple so i put a small clamp on it. Maybe that why it wasnt sucking coolant back in or maybe my cap was bad.
hrs on machine so things are wearing out.

Motionclone -

I was really surprised how plugged the radiator was. Bet you were too.
Remember the 185 upper and 170 lower temperatures? For giggles sometime check again….bet the difference will be surprising.

Glad you got it.

Job well done!

Very surprised as the outside of the fins (the only part that i can see while its in the machine) looked fairly clean.
Yeah im going to do a temp check on upper and lower next time i use it to see the difference. The machine seems quieter too not sure whats thats all about except air is moving like it supposed to instead of bouncing around inside engine compartment. UPDATE AGAIN:

Using the excavator this evening for 2 hours the temp gauge was a little erratic. Went up to yellow then back down low green fairly quick. Then up to yellow then red....safety kicked in a shut the machine off.

Looked over things no leaks nothing unusual belt looked good, no weeps from pump etc. Ran it again and did the same thing almost immediately. This time i had my temp gun handy and top hose was 135f, bottom was 125. Thermostat area was 156 so doesnt seem to really be overheating.

Wonder if i had a bad sending unit or wire that just got real bad? Or maybe an air bubble in system? Its got 3 hours of hard work on it since i flushed the radiator.

This time i had my temp gun handy and top hose was 135f, bottom was 125. Thermostat area was 156 so doesnt seem to really be overheating.

I like using 'point and shoot' thermometers.... but they have limitations based on emmissivity of surface.

I have used mine to check the interior walls of my house when it was -20F outside. Quickly located leaks around window-trim.

I have also used to synchronize carburetors on snowmobiles by comparing exhaust temperature of each cylinder.

Even comparing the temperature of radiator inlet/outlet hoses is a good use. (if you check ONLY the hoses with similar emmissivity) Don't compare painted surface against rubber surface.

None of the above uses require accurate measurements.

BEWARE: Those 'point and shoot' thermometers are an APPROXIMATION. Unless you take the time to preset the emmissivity of the surface you are measuring.... it may be quite inaccurate.

This machine has had a couple electrical problems like this.

I have worked with electronics since the 's and have watched the technologies improve over the years.

One thing which remains the same is basic physical properties. In this case, metal will corrode and affect electrical contacts.

Considering this, it is worthwhile to do some PM work (Preventative Maintenance) Which will eliminate goofy electrical gremlins from showing up.

1. Locate every ground connection to the frame, remove, clean to bare metal and re-assemble.
2. Spray oil-based, anti-corrosion over each ground-connection when done. (I use "Fluid Film")
3. Inspect every electrical connection. Clean, use Deoxit and reconnect.

Here is link to Deoxit ==> https://caig.com/deoxit-d-series/

Be aware that many aerospace electrical systems are coated with Deoxit during factory assembly. This is because the stuff WORKS.

I have seen many cases where a bad switch (ie--- keyswitch) have been treated with Deoxit, After sitting for several days.... the switch works flawlessly for many years thereafter. The metal cleaning, protection, and lubricating properties are unmatched.