Ford 850 Overheating - Timing?

[Ford850]

My Ford 850 is suddenly overheating even while idling. The radiator, while not in the best shape (small lower leak at times) seems ok with both hoses hot, fins clean and clear. Yesterday I needed to run the tractor for a short time to level my drive after washout damage, so I paid close attention to the temp gauge. Driving slowly from the barn towards the work area, the temp was already close to red within a few minutes. I was about to turn around when the temp suddenly started to drop to mid range. This happened as I was driving down a long slope and the engine was compression braking. As soon as the path leveled out the temp began to rise again. I was able to drag gravel up my drive as the temp went up to peak, and I could turn around and drive slowly drive back down under compression with the temp dropping back to medium range each time. When I park it, it does not cool down no matter how long I let it idle.
I"ve read where overheating can be caused by timing issues. I know nothing about timing, or how to adjust it. Can someone give advice on trouble shooting or correcting the issue? Thanks.

 

[641Dave]

I'm no expert but when I hear about erratic temps I always think sticky thermostat.

What about your fan belt? Slipping?

Your fan look okay? Dirt and weed pollen cleared out of your radiator core?

 

[Ford850]

Radiator is very clean and can I blow air/water through the fins easily. Belt is tight and fan works fine. Like I said it will only drop temp (and rapidly) when I let the engine slow the tractor while driving downhill.
Some other history in case it helps:
I rebuilt the carb several years ago, and while it starts and runs very well, still on 6 volts, I was never able to get the idle below 600. Also, I rarely need the choke to start it.

 

[Errin OH]

My 4000 4cyl got to running hot when working to the point it would boil the gas in the tank. Mind you I never let it get above 205. After checking timing and thermostat I found it was running lean. If I pulled the choke about half way out the engine would come down 10-15 deg. I either have a vac leak or something because the carb is clean, jets are clear but I can not adjust it out to run rich. I suspect a new manifold is in my future, as it is getting thin in spots.

 

[souNdguy]

sticky theremo.. low water.. loose belt.. etc.

 

[old]

Timing does not just go out of place on tractor engines unless your distributor is loose. You more then likely have a cooling system that is full of rust and lime and the block is clogged up with the same thing and or you have a bad thermostat. On the side of the block is a block drain plug. With it cool so as not to burn your self put a pan under the tractor and pull that drain plug out and watch and see the color of the coolant that comes out if it will even come out. Seen more then one block that was clogged up so bad pulling that drain would not let it drain

 

[Dean]

It"s not ignition timing.

Thermostat, collapsed lower hose, low coolant, worn water pump impeller....

Dean

 

[flyingace]

The temp of my lower rad hose tends to be luke warm at the hottest. Much cooler than the upper return hose. This seems to speak to a blocked/corroded radiator or maybe incomplete opening of the thermostat. Or just not enough air getting pulled thru the rad.

Does the engine seem to be hot? Have you measured the coolant temp with a meat thermometer? Does it boil over? It's possible the temp gauge is bad or lost it's ground - that's what it turned out to be in my case.

 

[Jerry/MT]

While cooling system issues (stuck thermostat, clogged air side on the radiator, clogged coolant passages in radiator, collapsed lower hose, incorrect or non-working pressure cap, slipping belt, etc) are the usual cause of overheating, retarded timing and lean mixtures can also contribute to overheating.
You"re seeing the cool down while going down hill because the throttle plate is almost fully closed so the rate of heat output of the engine is drastically reduced so for the coolant flow available and the cooling capability of your radiator it"s able to reject the lower heat out put to the atmosphere and your coolant temperature drops. When you command more power from the engine, the heat input must increase but your cooling sytem, being limited by either low coolant flow or restricted air side flow, orboth, is unable to reject enough heat so the coolant temperature rises.

By all mean chek the timing and the mixture, and adjust as appropriate. You"ll also need to do a thorough check of the cooling system to look for problems there.

 

[Gaspump]

Waterpump?