850 with 3 point problem

[lilburr]

As mentioned yesterday, I cranked the 850 and Idled at 1250RPM with the cap off, hoping to 'burp' the air outta the system. This is the only theory Ive got with this running hot and spewing coolant deal Ive got. Idled more than 30 minutes, maybe 45 or 50 minutes and coolant level would move up and down, sometimes pushing coolant outta the radiator, sometimes dropping into the radiator. At one point, I added 2 - 3 quarts of coolant and then it resumed with the rising and dropping, temp gauge never registering a movement off bottom end (while under no pressure). After quite a while (above), I replaced rad cap and idled it up and rode around in a quick loop to re-place it in barn. By the time i was half-way thru this move, temp gauge was up to ~190 mark and when I pulled in and killed the engine, it popped up to ~220, and cooled from there. Steam was escaping from the cap area; it was heated up.

Any more ideas would be helpful. So far, I have tried pretty much all suggestions but it seems that extended worktimes will overheat this unit.

 

[wolftree]

List all that you have done or replaced on the cooling system thus far.

Is the radiator copper or aluminum?

 

[lilburr]

Thermostat replaced (160), flush (twice), and antifreeze (twice). I dont know but me thinks aluminum. On inspection, hoses appear almost new (paper wrappings still fresh).

 

[wolftree]

I would take the cheap route and replace the radiator cap first. Second really look the radiator hoses over, both of them.

Scrape a small area on the radiator, if silver color, then it is aluminum. Copper radiator will be goldish in color. I expect yours is aluminum. Copper can be boiled out

 

[lilburr]

oops, forgot... new cap too. wolf, it seems that the rad is clear, when pressing on upper or lower hose, level of coolant will visibly rise or fall.

 

[Henri88]

I ask the question before but did not get an answer. Did you replace the cap with the same spec as the old one or did you look up what was recommended for your tractor.

 

[dwellonrooftop]

Maybe your water pump is going out. Sometimes you can wiggle the fan blade.

 

[wolftree]

lilburr,

That says nothing is broken. That now only leaves something not working quite up to specification.

Have you looked at the hoses as it is overheating? A wore out hose will collapse, then restrict water flow. There may be no visible appearance from outside of the hose while cold.

I assume you blew through the radiator fins from the engine side with compressed air. Spraying water does not always get everything unless it is very high pressure.

There is a small chance that the water pump is not moving the water sufficiently (worn out pump). Try wiggling the shaft of water pump, it should not wiggle.

If all of these things checkout, then that leaves only the radiator and 20 years of built up scale deposits in the tubes. You can try running radiator flush for longer periods of time in hopes of removing more deposits.

 

[Bailout]

My vote is for a new water pump... My 750 did the same thing - the fan was loose and after a several hour pump change, it's run perfect for years now...

Brian

 

[jd110]

Another possibility that no one has mentioned is a bad head gasket or cracked head. Hate to suggest major problem, but it is a real possibility with the symptoms you have.