1955 D4 7U need help

It sounds like you're getting combustion pressure from the cylinder into the cooling system. It can come from a liner that's low in the block, a head gasket blown, or a from a leaking pre combustion chamber (which i would suspect first). Are there bubbles in the radiator when it's running? Does the exhaust blow a whitish color? Does the engine miss?

i didn't see any bubbles in the coolant, when its running it will puff white smoke every so often but doesn't seem to be missing. before this i could spray some starter fluid and it would fire right up, now spraying any in it doesn't even help it start at all. Thank you for your help

That starting fluid can have some pretty big consequences as I'm sure you know. It can cause stuff that leads to symptoms like this, but I'm only trying to put two and two together from what you've told us.

I would do a compression check first. I don't know the specs on it, but lots of people on here do.

You say that starting fluid doesn't try to start it, but can you pull start it? I'm assuming the tractor still runs?

Add clogged radiator to your list of things to check.

When this happened to me I'd just got the Pony motor back on and here's what I found.
When I filled the coolant with water, I didn't use the petcock on Pony motor to bleed air off
which resulted in airlock. As soon as I corrected this it stopped burping out radiator cap.
Thats my 2 cents....

From what you said in your last message ,it sounds like you had an air lock in the cylinder head,due to not bleeding it at the starting engine bleed cock . Watch it carefully as this condition can crack the cylinder head.

Ok, I thank you all for your help with this, here is what i have gotten to now, after checking everything i took the thermostat out and now i have bubbles in the coolant (i think the thermostat may have been stuck closed) and it still overflows, it will start and run and blows white smoke when i have the cap on, when i take the cap off it will clear up some. Before this started i would shot a shot or two of starter fluid and it would start right up, (i use the started fluid because i have put a electric starter on it because it did not have a starter or pony motor so no way to warm the cylinders without burning out the starter. but know the start fluid does not help it start at all, takes a bit of cranking to finally get it started. any help would be appreciated greatly and thank everyone again for all the help so far.

It sounds like you're getting combustion pressure from the cylinder into the cooling system. It can come from a liner that's low in the block, a head gasket blown, or a from a leaking pre combustion chamber (which i would suspect first). Are there bubbles in the radiator when it's running? Does the exhaust blow a whitish color? Does the engine miss?

You may have combustion pressure getting into the coolant system, maybe from a cracked or leaking pre com chamber, a liner that's low in the block, or a blown head gasket. It could also be a cracked head.

I had a D7E that did that. An idiot operator can cause it.