Farmall H 1940 Rings or Valves

jrtaylor71 · Jan 17, 2021

So I have been going through the tractor that I bought and I have some engine questions. The engine runs fine has 25lbs of oil at any engine speed or temp. The compression is 90lbs on all cylinders. Had a chance to scope all 4 cylinders and the pistons look new but the head was never done. The head is casting #8043-DC so gas head. I am thinking that the lower cylinder pressure is valves not ring. I did a bit of oil in one and I get 135lbs. So what do you think?

used red MN · Jan 17, 2021

The compression raising after you retest it after adding oil to the cylinder is an indication of poor ring seal and
not valves. The reason you think the pistons look new is because oil is coming up past the rings washing the
carbon off the top of the pistons around the outer edge.

jrtaylor71 · Jan 17, 2021

It does not smoke at all. Even under a load.

So if that's the case then just rings or just get an in frame engine kit?

old · Jan 17, 2021

Whats the history of it?? Has it maybe sat a year or more with out running?? If it has good chance the rings are sticking so compression is low. Run into that many times and a good ATF treatment fix the low compression

rustred · Jan 17, 2021

from what i see and what u have there is it could use an engine job. i dont know how you know the head has never been touched, but i can see
the valves and seats are worn quite wide meaning need a valve job.i always hear this the " engine dont smoke" well you will not see the smoke
unless it is just pouring the oil out the exhaust pipe. u need to monitor the oil consumption. how much oil do u use in a days work. ir u are
going through 1/2 a gallon in a day yes its burning oil and that dont mean you will see the smoke either. and before even thinking of
ordering parts you do a tear down and examine whats needed make your list then order your parts. also it looks like somthing has been
bouncing around inside that engines with those pistons looking like that. is the air cleaner installed and have oil in it?

used red MN · Jan 17, 2021

I do agree with rustred, since it is new to you I would do as he says an monitor the actual oil usage. The smoking will be most pronounced after a period of higher rpm then 20 seconds of idle and then the smoke will show up if you raise the rpm back up above idle. I see you are possibly using it to move snow, getting some time running it will be good for it. You may want to put card board or paper grocery bag covering the radiator screen on the front grill to keep the engine temp up. Even if it is 50 degrees out the engine will likely not overheat.

Janicholson · Jan 17, 2021

Were it mine I would run it for at least mid summer before doing anything but use it. Once it it has proven to be an oil burner, or fouls plugs all the
time, then tear it down. It is a distillate tractor it has a compression ratio of 4.5:1 if it is high altitude, maybe 5:1. Do not expect more
compression (really) You probably don't know for sure your gauge is accurate. Was the throttle open? Did you crank it 6 compression strokes per hole?
Was the battery nice and charged? Putting a teaspoon of oil in it will raise the compression by taking up space. Unless you decide you want to tinker
more than drive, run it. Jim

jrtaylor71 · Jan 17, 2021

(quoted from post at 21:33:29 01/17/21) Were it mine I would run it for at least mid summer before doing anything but use it. Once it it has proven to be an oil burner, or fouls plugs all the
time, then tear it down. It is a distillate tractor it has a compression ratio of 4.5:1 if it is high altitude, maybe 5:1. Do not expect more
compression (really) You probably don't know for sure your gauge is accurate. Was the throttle open? Did you crank it 6 compression strokes per hole?
Was the battery nice and charged? Putting a teaspoon of oil in it will raise the compression by taking up space. Unless you decide you want to tinker
more than drive, run it. Jim

Yes the throttle was wide open and it made at least 6 compression strokes. The battery is fully charged. It has flat top pistons and 8043dc gas head.

jrtaylor71 · Jan 17, 2021

Thank you used red mn and rustred. The guy I got the tractor from clearly did not know how to take care of it. Oil bath air cleaner was full of water and oil. The trans and final drive had water in it. The radiator and antifreeze was full of rust and it had no thermostat in it. The only that was clean was the engine oil. As for oil usage I have not had to add any oil. I pulled the valve cover today and it was very clean. Going to pull the pan and see how much sludge is in it and check the oil pump just to be safe.

I am retired and have lots of time to tinker.

James Williams · Jan 18, 2021

90 lbs on a used tractor thats been sitting is good.Run it,I doubt your going to use it hard.Being a new owner you want everything perfect.If
it starts good and no smoke thats all you can expect

BarnyardEngineering · Jan 18, 2021

Some people just want to do it for the experience and if that's your goal, then go for it. You could start with a simple "hone and ring" job for science. If you have to go back and do sleeves and pistons later, all you're out is the cost of a set of rings, and your time.

Thing is 25PSI really isn't that great of oil pressure. It's adequate, and indicative of worn bearings. So you probably want to do a full overhaul if you do end up doing more than rings.

What are your intentions for the tractor? Unless you're going to be plowing for 10 hours a day all spring and grinding feed all winter, there's really no need to do anything to the engine given what you've told us so far.

jrtaylor71 · Jan 18, 2021

(quoted from post at 19:32:33 01/18/21) Some people just want to do it for the experience and if that's your goal, then go for it. You could start with a simple "hone and ring" job for science. If you have to go back and do sleeves and pistons later, all you're out is the cost of a set of rings, and your time.

Thing is 25PSI really isn't that great of oil pressure. It's adequate, and indicative of worn bearings. So you probably want to do a full overhaul if you do end up doing more than rings.

What are your intentions for the tractor? Unless you're going to be plowing for 10 hours a day all spring and grinding feed all winter, there's really no need to do anything to the engine given what you've told us so far.

Pulling tree's and stumps in the spring, cutting pasture in the summer with a sickle mower and pulling and running a feed wagon year round.

As for the oil pressure I am going to pull the pan and check the oil pump and bearings.

Question: Is it normal for all the oil to drain out of the oil filter?

ss55 · Jan 19, 2021

A leak down tester can show where compression is being lost on each cylinder: rings; intake valve; exhaust valve; or head gasket. If a teaspoon of oil increased compression by 50 percent, that sounds like worn rings unless you dumped a whole lot of oil into that cylinder.

Most H's don't get run a lot of hours any more, it may still work a long time as-is. Use it as-is for a while before deciding to overhaul it.

jrtaylor71 · Jan 19, 2021

I am pretty sure I need a new oil pump spring. It's not broken but it's only 3.43 long.

jrtaylor71 · Jan 19, 2021

Bottom end. Did not pull any of the caps.

jrtaylor71 · Jan 19, 2021

Plunger and plunger seat.

jrtaylor71 · Jan 19, 2021

jrtaylor71 · Jan 22, 2021

Just as a follow-up to this in regards to the oil pressure. I replaced the spring and gasket and now have about 62lbs of oil pressure.

Farmall H 1940 Rings or Valves

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