Ford 640 running hot

[Doug (OH)]

Hi everyone, I mow with an old Woods 5' brush hog and my ford 640 has been running hot. It was about 80 deg. today in western ny. I've already flushed the radiator and core with vinegar water. The old anti freeze didn't look all that bad. It was brown like tea but no sludge. The thermostat is not that old and pops at about 170 deg. on the gauge. Looking down the top of the radiator I see pretty good fluid movement from the pump. The new anti-freeze solution is supposed to have a boiling point of 236 deg. and that's about how hot it will get unless I stop mowing and give it a chance to cool down. I cross-checked the fluid temp with a small meat thermometer and it reads fairly close to the NEW temperature gauge and capillary tube. The new gauge indicates hotter than the old one. When I replaced the gauge is when I became concerned about the high temperature reading. In other words, I've probably been running it hot for years without realizing it. I do get a lot of weed chaff in the radiator, but I clean the fins regularly. The tractor doesn't complain or bog down if I keep the revs on the tach at about 640-700 rpm while keeping the cutter set high. I also checked and readjusted the timing today, which was off. It is now set at 8 deg. tdc at 400 rpm. Took it out and mowed--no difference, except now when i throttle down it backfires through the exhaust. The only thing left that I can think of is to pull the water pump and check the impeller. Does anyone have any thoughts or ideas on this? I'm just about out of ideas, myself.
Thanks,
Doug (OH)

 

[old]

Did you back flush the cooling system by way of the block drain?? If you didn't good chance you left a lot of rust and lime in the block it self which will cause poor circulation of coolant and overheating

 

[NoNewParts]

(quoted from post at 22:00:17 09/17/17) Hi everyone, I mow with an old Woods 5' brush hog and my ford 640 has been running hot. It was about 80 deg. today in western ny. I've already flushed the radiator and core with vinegar water. The old anti freeze didn't look all that bad. It was brown like tea but no sludge. The thermostat is not that old and pops at about 170 deg. on the gauge. Looking down the top of the radiator I see pretty good fluid movement from the pump. The new anti-freeze solution is supposed to have a boiling point of 236 deg. and that's about how hot it will get unless I stop mowing and give it a chance to cool down. I cross-checked the fluid temp with a small meat thermometer and it reads fairly close to the NEW temperature gauge and capillary tube. The new gauge indicates hotter than the old one. When I replaced the gauge is when I became concerned about the high temperature reading. In other words, I've probably been running it hot for years without realizing it. I do get a lot of weed chaff in the radiator, but I clean the fins regularly. The tractor doesn't complain or bog down if I keep the revs on the tach at about 640-700 rpm while keeping the cutter set high. I also checked and readjusted the timing today, which was off. It is now set at 8 deg. tdc at 400 rpm. Took it out and mowed--no difference, except now when i throttle down it backfires through the exhaust. The only thing left that I can think of is to pull the water pump and check the impeller. Does anyone have any thoughts or ideas on this? I'm just about out of ideas, myself.
Thanks,
Doug (OH)

like Old said, backflush, front flush, every way flush that block. I disconnect the hoses, pull the thermostat, pull the block drain completely and put a high pressure nozzle on my garden hose against the block drain, while pounding a little with a fiber hammer on the block.
Make a mess, get wet, and don't stop until you get crystal clear water out of every opening.
I backflush the radiator too...be gentle here..garden hose, no nozzle, wrap a rag around it and stick it in the bottom outlet....makes a huge foul mess...great fun lol.
I don't trust thermostats, especially modern ones, so I do all cleaning and testing with it removed. After I'm sure the cooling system is ok, I put it back in. (a quick test putt with the thermostat removed will let you look in the neck with it running, and erase all doubts on the condition of the waterpump)

When checking your timing, don't forget to check the specs, and with your light, make sure the mechanical advance is working properly. Stuck/rusted advance weights will have the engine running very retarded at speed = hot.

...very high percentage of tractors I buy, opening the block drain gets..nothing, sediment is higher.
And distributor advance weights are rusted/gummed/stuck....

 

[Doug (OH)]

Thanks a bunch for the advice, guys! I did not flush the block as you described. I pretty much just ran water with a hose through the radiator and let it come out the bottom of the block, then filled with vinegar solution, heated it up, let it sit and "flushed" again.I will try flushing through the petcock hole in the block as you described. Would a pressure washer be too hard on it or does a hose fitting work well enough? Also, I'll take a look at the weights on the distributor. The mark was quite jumpy under the timing light. Is that an indication that the weights are sticking? Thanks again for the tips and advice!
Doug (OH)