Ford 641 issues

BILLBENDER

New User
New to the forum. I just bought a 641 that starts great idles fine but under load loses power and starts smoking. I tested a bushhog behind it and smoke started rolling out of the oil fill. There had been some white smoke from the breather but I figured that was normal. Now I ran a compression test and my numbers were 1-4 125,100,118,120. I already had it in my head it was rings but now I'm confused and don't want to tear it down if I don't have to. Could this be carb related? This is all new to me so any suggestion would be great Thanks.
 
First test the spark at the plugs and the center wire of the cap and make sure it is a good blue/white that will jump a 1/4 inch gap or more.
Next pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in under 3 minutes.
Does choking it hurt or help?? what color is the smoke?? If black carb is set to rich or the air cleaner need to be serviced. Does choking it hurt or help?? What do the spark plugs look like?? You may need new plugs. I use NGK3112 plugs in all my fords
 
Haven't checked spark yet but will later tonight. The smoke from the breather was whote but the smoke from the oil fill was black. Choking didn't seem to do much. Spark plugs that were put in last wk 1&4 were good and 2&3 were black. When testing spark do you have plugs in or out? Dumb question I know but I forgot.


(quoted from post at 15:07:37 06/09/17) First test the spark at the plugs and the center wire of the cap and make sure it is a good blue/white that will jump a 1/4 inch gap or more.
Next pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in under 3 minutes.
Does choking it hurt or help?? what color is the smoke?? If black carb is set to rich or the air cleaner need to be serviced. Does choking it hurt or help?? What do the spark plugs look like?? You may need new plugs. I use NGK3112 plugs in all my fords
 
Plugs black and oily or black and suety SP if oily bad rings or valve guide. But if suety then those cylinders are running to rich which could also be a air cleaner that needs to be serviced. As for checking for spark plug in or out does not matter.
 
You might also try turning the main jet adjustment in a tad bit and see if that helps any
 
Just checked spark. Good from coil but pretty much weak on all plugs, like had to hold on block to get a spark.. Changed distributor cap and wires and nothing changed. Bad dist? I plan on messing with the carb a little tomorrow need to go get some gas.


 
Is it really steam, not smoke? Is it getting hot?

As for plugs, you ought to change them as a matter of course if you don't
know when they were last changed.
 
I just changed plugs last wk and then put a bush hog behind it and when I made first turn to go up a slight grade it lost power, oil pressure, and was smoking black from oil fill tube.


 
BILLBENDER- "I tested a bushhog behind it and smoke
started rolling out of the oil fill."

I'm confused by what you said. 'Smoke rolling' out of the
oil filler tube sounds strange. Please describe what/where
is the oil filler tube.

Surely, you're not pouring oil down the exhaust pipe
(thinking it is the oil filler tube)....wink.
 
"Just checked spark. Good from coil but pretty much weak on all plugs, like had to hold on block to get a spark.
I plan on messing with the carb a little tomorrow need to go get some gas. "

If you've identified weak spark at the plugs, I would not mess with the carb yet.
Take care of the weak spark first.
 
This tube is on the front right side as you look down from the steering wheel beside the distributor. The one where you unscrew the nut take cap off with small metal screen and put oil in when you change the oil. No I am not putting oil in the exhaust. When is started losing power black smoke started l coming from this tube.


 
You should not be taking the nut off that to fill with oil you simply pull the whole part up and off to have an open tube to pour the oil in and by doing what you have you may cause more problems since that is a breather for the crank case and by pouring oil into the mesh it can cause it to clog up and cause back pressure in the crank case
 
Changed cap and wires did you use TRUE wire core plug wires or ones made for a car or truck which are carbon and do not work well on a tractor. Did you also change the rotor if not and you have a new cap then yes spark can be bad because the rotor do go bad
 
I didn't pour the oil thru the mesh I pulled the whole piece out. Cap, mesh, as metal piece mesh is around. Nothing but a tube for the oil to be put in.


 
I bought a set of wires from this site designed for the tractor. When I changed the cap out I changed the rotor as well. Next thing I would assume would be to replace condenser and check point gap.


 
I would not replace the condenser since now days you have a 50/50 chance a new one will be any good. point gap yes and do so on all 4 lobes and set them to 0.025. Also make sure the points are good and clean by running a piece of cardboard like the flap form the box the point came in between the points
 
(quoted from post at 14:47:12 06/10/17) I would not replace the condenser since now days you have a 50/50 chance a new one will be any good. point gap yes and do so on all 4 lobes and set them to 0.025. Also make sure the points are good and clean by running a piece of cardboard like the flap form the box the point came in between the points

Smoke out the oil breather/fill...

ok.. its either compression leaking, or steam or water getting in there.

your compression tests... indicate normally its not leaking into the crank case... but I would check the compression cold... and then check it after running.. sometimes after running it will show low or failed then as the heat will make a cracked head show up..

but if still good.. then..

I would full the radiator to the top.. start the tractor, while keeping the radiator full to the top.. looks for bubble coming up every few seconds.. if continues to show bubble, you have a leakage to the compression area.. check water to make sure no oil residue... check oil the make sure its now white, or light brown greyish due to water getting into the oil..

you could have a blown head gasket, cracked head or warped head/block.. or other problem...

but good compression cold and then hot will help tell us whats going on... should be very little smoke coming from breather, and if it is, there is a problem!! either blowby (low compression) or crack or blown gasket, etc etc etc.. and color of water and oil are important.
 
Didn't have a lot of time today but I did check my point gap and it was .010 so I changed it to .025. I will put some new plugs in tomorrow and run it then do a compression again. Thanks for the help. The test I ran was cold.



 
Points set at 0.010 throws the timing off a good bit so that could be a lot of the problem
 
Ok so I got it started ran for about 20 mins. Ran compression again and got the same numbers. No smoke from oil tube but still smoke/steam from breather vent. Open up valve cover and found out that one of my valve spring had somehow gotten into the oil line. The one that between number 1&2 that has an open end. Could this be the cause of my breather smoke? I didn't put engine under load yet. Also I could see some bubbling on top of tapper cover. Any suggestions.


(quoted from post at 21:23:11 06/10/17) Points set at 0.010 throws the timing off a good bit so that could be a lot of the problem
 
Not likely the spring got into the oil line but more then likely the oil line got into the spring. The oil line in the spring can cause compression problems but not the smoke. As for bubbling if the engine is still good and warm that is pretty normal since it could still be warm enough to boil a little oil or water
 
So got a chance to ride the tractor around my house this evening. Ran good just cruising around, found a small hill to kind of out a little stress on it and it seemed to power up it decent in 1st and 2nd. Still has some valve cover smoke but that seemed to subside a little the longer I went. I put it in 4th to drive down the road and oil pressure dropped to about 25-30. Is this normal. I did find when . I got to the garage that my oil pan gasket seems to be leaking, will this cause a drop in oil pressure enough to be noticed? Still need to fine tune the carb I think it would sputter and pop every now and then. What should my oil pressure be running under idle it stays between 30-40 leaning more towards 40?





(quoted from post at 12:15:53 06/11/17) Not likely the spring got into the oil line but more then likely the oil line got into the spring. The oil line in the spring can cause compression problems but not the smoke. As for bubbling if the engine is still good and warm that is pretty normal since it could still be warm enough to boil a little oil or water
 

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