YM1700 heavy blue grey smoke at crank up steam from air cleaner

[Car Doc]

Once you get the head off and see how much ridge there is and how scratched up the cyl walls are that's when you will know better how far to go. Just me but I would do the rings and rod bearings also and check the ring grooves for side clearance before ordering parts.

At that point a new set of pistons may well be necessary and a good idea anyway.

 

[puresol]

I found a local shop to check the head for cracks, do a valve job for $120- resurface head if needed for +$60. Do I need a valve job? How will I know if I need a valve job? Does that sound reasonable? Everything else depends on the condition of the head. I talked to the guys at Hoye and they recommended rings, rod bearings, and gaskets. The shop that will work on the head recommended valve guides, and valve stem seals. Cash is limited, I dont want to just throw money into the tractor, I would like to strategically (as possible) put money into the tractor.

 

[Car Doc]

Absolutely grind the seats and valves and new seals the heads are the key to a smooth running engine dont scrimp on that whatever it needs done do it. I would have them show you the guides how much wear they have rather than simply replace them if they are worn the valve stems will be also and need valves replaced as well.

I would also advise the water pump kit if you can swing the money if not it will be like it was designed but a wp would be better imho.

Like I mentioned the condition of the cyl walls will give an idea how sound the rest of the engine is. If the walls are scratched and has a ridge you can catch a finger nail on shes needing some parts and a ridge reamer run on the cyl tops. If the cyls are shinny and no ridge you can more than likely get by with just the head work. my .002

 

[California]

I think you're really asking the question of whether to just get it back in service, or renovate to have a few thousand troublefree hours. Of course it depends on what you find when you open it up, but if it were mine I would be hopeful that I could just throw a new head gasket in it and get back to work.

More extensive (expensive) repairs would depend on what you find. Once you have the head off, try pouring solvent into the manifolds and see if it leaks out the valves. If the valves pass this test, and you don't see a burned channel on the head or block surface where compression escaped, then I wouldn't bother with the head planing and valve/guide/seal work. A little oil going down the stems and making smoke is a minor nuisance but I don't think that alone justifies major work at this time. Wait until there is real wear to remedy.

But look closely for more serious damage such as scuffed cylinder walls from shattered rings. This could turn into a major overhaul, but lets hope that isn't needed.

Edit -
Bah. I see CarDoc just answered your question better. He does this stuff for a living, my experience is gambling and mostly winning on buying thrashed looking vehicles and equipment that don't take much to put back in service. Give CarDoc's answer more credence!

 

[Car Doc]

I have a little trick I use on heads when I am checking the valves how well they seat or not. I set the head upside down on a bench and spray some dawn soapy water in the combustion chambers and then blow shop air into the ports and you will see just how good or bad they are seating.

Oh and thanks California all the advice givin on here is good advice as far as I have seen we all do what we can.