801 won't start when hot...

jjstager2

New User
Hey everyone. I purchased a '58 Ford 801 last Spring. Since then I've replaced points, plugs, wires, distributor cap, rotor, radiator, water pump, thermostat, and carburetor. After doing all of that, the tractor cranks right up at idle, runs smoothly, and only starts to get too hot when I allow too much debris to collect on the radiator screen.

When it starts to run hot, I shut down the tractor and brush off the debris from the radiator screen (I've been shredding a pasture that has gone too long between mows and has really high weeds). If I can get it restarted, this solves the "too hot" issue. But Sometimes it won't restart until I let it cool down for a while.

Does anyone have any advice on how I can get it restarted when it is hot? Again - it starts beautifully when it is cold (no choke).
 
(quoted from post at 11:28:03 10/10/19) Hey everyone. I purchased a '58 Ford 801 last Spring. Since then I've replaced points, plugs, wires, distributor cap, rotor, radiator, water pump, thermostat, and carburetor. After doing all of that, the tractor cranks right up at idle, runs smoothly, and only starts to get too hot when I allow too much debris to collect on the radiator screen.

When it starts to run hot, I shut down the tractor and brush off the debris from the radiator screen (I've been shredding a pasture that has gone too long between mows and has really high weeds). If I can get it restarted, this solves the "too hot" issue. But Sometimes it won't restart until I let it cool down for a while.

Does anyone have any advice on how I can get it restarted when it is hot? Again - it starts beautifully when it is cold (no choke).

6 volt system?
 
Your problem might be clogged radiator fins if you're loading up the front like that it will suck the fine trash into the fins. Don't wash
it as that tends to stick the "mud" to the fins, blow them out from behind with air. You can tie a sisal croker sack to the front grille by
tying to the headlights or upper hood and tying the bottom or just let it hang loose. When it starts heating up shut it off and shake the
sack free of junk. A front bumper guard always helps, original is best as it's further out front. You might want to drain and disconnect
radiator hoses and backflush with a good amount of pressure ( you need to pull your thermostat for that I think) in case you have rust around
water jackets from a previous owner. A good thing to always have is one of those cheap heat sensor guns, it will tell you where the hot spots
are.
 
Failure to start only when hot (assuming not flooded) is classic symptom of weak ignition and/or low compression.

Dean
 

Thanks Dean. The battery is new and the starter cranks normally when its hot. How do I determine if I have a weak ignition?
 
Normally on those fords when you start your tractor the temp will increase to around 180 then you should see it drop quickly which indicates your thermostat is working properly. if it were mine I would completely flush out your radiator and block. if your tractor runs over 190 then you have a restriction or thermostat problem assuming you have a temp gauge to tell you the temp. power washing your radiator will help. to do it right will require removing the radiator to flush out the block as you can stick a hose into the top outlet and let it flush back to the bottom. you can drain your radiator and flush it will water and vinegar, mean green or what ever you have. just remember when your finished to add antifreeze and test for temp freeze. I just flushed out my 961 --4 times--but never could get it to stay below 225 so I bought a new radiator on ebay. now it doesn't go above 170 with a new thermostat and radiator cap. I do believe the previous owner had used a lot of stop leak in it. when a motor gets hot you may be losing some compression due to maybe valves not seating properly. you just need to solve your temp problem first.
 
The spark should jump a 1/4" gap with a sharp snap during cranking and it should be a bluish white color.

I would recommend a compression test if spark appears good.

Dean
 

Starts beautifully when cold with no choke???

If you mean what you say, its running too rich. If you mean after its been run a bit, then its still a bit rich.

Gas fumes are heavier than air, and updraft carbs should take a quick bit of choke to help the heavy fumes get sucked up into the engine. Down draft carbs dont have this problem.


however still could be a lot of other things... ignition switch has a high resistance contact, coil is failing, condenser weak, points burnt or dirty, especially if Chinese points. Bad battery cables or connections, at starter and coil,, bad solenoid ignition bypass...
 
I noticed recommendation to flush the radiator,that isn't necessary unless you saw something akin to mud when you installed the new radiator. Make sure fan blade isn't mounted backwards and that the fan shroud is on the tractor. Putting a screen in front of radiator isn't a good idea. If an engine is on the border of overheating,a screen will finish the job of making it overheat.
You are much better off temporarly installing something out front to push weeds down and hold them down until they go beneath tractor and are past radiator.
 
it starts beautifully when it is cold (no choke)

That sounds like the carb is adjusted too lean An updraft system like that should need the choke to start cold, even in warm weather. Running too lean could be contributing to the overheating problem as well. Have you checked for a good spark when it's hot and won't start? If it doesn't have a good strong blue/white spark that will jump at least a 1/4" gap to ground then it's most likely the coil starting to go bad, as they exhibit problems when hot at first and then gradually at lower and lower temperatures until they won't provide a good spark even when cold.
 
Did you change the coil? If so, put the old one back in.
When you change a bunch of parts the same time, hard to diagnose. Lots of older parts built better than some of the new ones.
 
(quoted from post at 07:54:01 10/11/19) Insure coil polarity was changed when you went to 12v neg ground.

The coil is one thing I did not touch. I assume it's polarity is correct - but I do not know for sure. I will check.

Thank you all for all of your suggestions. I really appreciate the advice.
 
If you changed from 6V positive ground to 12V negative and did not reverse the coil, it is incorrect.

That said, check spark (see below) and perform proper compression test if spark is good.

Dean
 

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