hd6 repair or sell

I have an hd6b that I bought a couple of years ago.  It had been setting for several years.  It fiired up easy enough but I did not get to use it much - had to fix the clutch and the radiator.  I recently tried it again and noticed it smoking.  First I thought it was a fuel problem but it is oil smoke and it is getting rid of some oil.  I am guessing I have a scored sleeve or broke or stuck rings.  Seems to be related to #3 cylinder - when I make it miss by loosening injector line, it smokes much less.  Any suggestions?  Can I get one sleeve if one is corroded?  How much are gaskets gonna cost me?  I have the 6000 motor instead of the 344(motor no is 6000 HD6 serial 15547, machine no is HD6B 15350 serial 16647, if I am reading right).  Another problem is super slow hydraulics.  I took to valve assembly apart and found some broke springs - tried to find substitutes.  Did not help.  I thought the pump was good, but I am beginning to think otherwise.  Anything I should look specifically at?  Any easy way to test the pump and rule out a weak pump?  This thing has great undercarriage and steers easy, all gears are intact, etc.  Starts good.  What is it worth to sell it outright as is?  I prefer to have it operation because I need to build a big pond, but I want to size this job up before I commit.  Thanks, Andy.

With the pump off, if you can turn the shaft easily by hand, its likely to be well worn. New pumps are difficult to turn by hand. The rotary distributor type control valves also wear and begin to bypass oil, giving you the impression the pump is shot. Some guys build up the bores with bronze weld then hone them to spec. On tractors I want to keep, I prefer to throw those valves on the scrap heap and fit stackable conventional spool valves and a large oil reservoir where the right side battery box was

The jacks are not leaking off.  The blade will hold for several days in the up or down position.  I am wondering if the is some way to trouble shoot whether it is the pump or the valve.  Seems like if it is in the valve it must be in the pressure relief.  Thanks everyone for suggestions  on the motor.  I think I will check the price of a gasket set and tear her down and look for myself.  Keep the suggestions coming though because it will be a while before I have time to tear it down and fix it.

Merv is on the mark with the hydraulics being normaly slow. Even with good pump and valve, after a couple hours hard work the oil gets very hot because the tank capacity is not enough for the pump capacity. Bypassing in a valve that has some wear is then magnafied with the oil thinning from heat. When you put a big tank up on the right fender with spool control valves, you eliminate that problem, and provide auxillary hydraulics to run towed scraper and towed implements and hydraulic blade tilt

fix it. they are great machines and i agree with all post. thay are easy to work on.

Part number for the hydraulics book is 70644308. Someone said you can veiw them through Minnpars site. I dont have the knowhow to display the pages here

one thing i can say the 6g hydrolics were faster than that old 955 we had