4630 blow by

hurleyjd

Member
I have a 4630 Ford Tractor with a lot of blow by. I am thinking of just honing the cylinders and installing new rings. Have been told will not work as the cylinders are egg shaped from use. Question can I re-ring or will I have to strip the engine and have the cylinders bored and over size rings and pistons installed. What are the results from mechanics on this board.
 
Is the engine already apart, or are others merely speculating as to the condition of the cylinders? I've worked on a lot of Fords in my day, and don't recall seeing any that were egg shaped. Tapered, yes, but not elliptical.

If the engine is not apart yet, let me start with a question: What makes you think the blowby is excessive? Don't go just by looks out of the blowby tube. If the engine starts good in cold weather, I wouldn't touch it!

If you do decide to go into the engine, Ford allows a maximum of .005" before calling for a re-bore. Remove the pistons, run a bore gauge (or similar) through the bores to assess the true condition of the cylinder walls. Unless that engine has been dusted or severely overheated, odds are good that glaze busting and new rings will be all you need.
 
The tractor starts reasonable well. The breather tube has smoke or vapor and oil deposits on the engine around the tube. Does start slower when the weather is cold. It is not stored in a shed or building when not in use.
 
If it starts "reasonably well" in cold weather unassisted (i.e. you're not using ether or a block heater), I wouldn't give it a second thought. Some smoke and oil vapor near the blowby tube is perfectly normal.

Blowby "readings" are very subjective if it's simply a visual observation. In the right angle of sunlight, normal blowby can look very bad. The only accurate way to test blowby is with a manometer and the engine under full load on a dyno. However, one example of where a visual look is worthwhile is if you can see or feel pulsing out of the tube like an old train, that is a sign that you have a weak cylinder.

As for slow cranking, you could either have a weak battery and/or excessive voltage drop in your starter connections. I have a TW in my shop right now - one of the complaints was slow, hard cranking. Turned out I had over a 1 volt drop just on the various connections on the starter. Cleaned those up and she cranks good now.
 

What 4630 do you have ?
Some have a 201 non turbo engine and others have a 192 with turbo.
Turbo engines normally have a little more blow by than non turbo engines.

If it starts good and doesn't use much oil keep using it.

My 6610 appears to have more blow by than my other tractors, some times it looks really bad, but it starts fine and uses very little oil.
When it becomes to start from being low on compression or goes to using a fair amount of oil I'll tear it down.
 
Agree with Bern... If it's starting OK cold, unassisted.. leave well enough alone. The position of the tube on those things tends to magnify the amount of blow-by as the fan tosses it around pretty good.. and as Bern noted, in the right amount of light it looks like an awful lot.
All I can tell you is that when they get really bad...... the amount coming out the bottom is probably equal in volume to what comes out the top. It will look like it's on fire.
So from what you describe I wouldn't worry about it.

Rod
 

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