In need of a CCKA short block.

[metalguy]

Been a while, but I have the engine installed, and running pretty well. Sadly, it does smoke some, probably worn rings. It has .030 over pistons. Are rings readily available for this? At any rate the 646 runs, drives, stops, starts, and digs like only a 646 can. ------Metalguy

[DavidBarkey]

Been a while, but I have the engine installed, and running pretty well. Sadly, it does smoke some, probably worn rings. It has .030 over pistons. Are rings readily available for this? At any rate the 646 runs, drives, stops, starts, and digs like only a 646 can. ------Metalguy

That is great you have it running . Being .030 over . I assume it is stamped on the pistons . So you would have had a chance to see the cylinders . Was the a ware ridge at all ? I have seen where low grade parts were use to save money and the rings are soft and ware fast . Not a bad thing as it save the bore .https://onanparts.com/index.php?main_pa ... cts_id=828
Is just on option . There are many more . When in doubt contact Boomer Onan parts , he is the expert in all things Onan . boomersonanparts.com
One other thing . Onans will burn/ fill breather oil if the slightest bit over full . So I have learned

[metalguy]

Yes, when I decarboned the heads, I saw that the pistons were marked with .030 on top. There was no ridge.I may just pick up those pistons you linked to. Seems parts are often hard to find for these guys.------Metalguy

[ssmewing]

Here is a pic of why I need a new engine. The pitting in the cylinder is deep!

A guy brought me 2 tractors last year. Both were to be refurbished. One of the things I always do is open the engine up, that is taking the heads off along with the intake and exhaust. Both tractors had water damage just like the one in this post. That is so sad.

I bought a new old stock short block on eBay for $500 shipped. Boomer helped out with picking the one that would work in 1975 646 I have that I need to fix up. I got it in a trade deal. It was running and driving when I got it. But the engine smoked. I should get that project done. It will make a nice tractor for someone. And, it gets some money in my pocket.

That means I will have a previously running short block that could be rebuilt. I just have no idea when that will be. It is rather silly to be sitting on that 646 for years.

The priority of getting going on that changed when I bought a 648 that came loaded.

I started with a 644. That was my Project Basket Case. When I bought it it was literally in a basket crate completely disassembled. And, it was the first 600 series I had seen in person at the time. I loaded it in my trailer by hand, piece by piece. I had to both fix it and use the parts I got with it to put it back together. It went well and was a very nice tool to have. I ended up doing some more horse trading and got a freshly rebuilt Kohler for it that was a stator charge rather than a generator.

I sold the 644 after I got the 648. I had to take the 648 engine apart first. That all went well.

Both the 646 and the 648 are bypassing well below the stated psi of 2,400 or whatever it is. The 648 has my gauge on it and it bypasses at 1,800 psi. The 646 has be about the same as the way it squealed during moderate use.

I have some projects.

[metalguy]

This is my second 646. My first one was a complete basket case also. The loader had been cut off of it, and the arms were cut forward of the cylinder attach points, engine had pitting in the cylinders, much of the three point was missing, and the only two cylinders it had were the three point, and the belly cylinder. I put in loads of work, and money, and it is a fully functional, great tractor now. I plan on making this second one very nice as well, then selling one of them , as I really don't need two, but they are fun and handy to have! -----Metalguy