155D Rebuild

[ym155dsask]

I'm in the process of rebuilding my '77 155d. My first engine rebuild. It was overheating, blow by, hard to start, low on power. I have it all pulled apart. It looks like the headgasket was blown. Piston rings are in tact. Some wear on the Pistons. Rod bearings worn out. I have all the replacement parts ordered. Sleeves. Rings. Pistons. Gaskets.

Should I try and polish the crank? What about the head...should I take it to a machine shop and get it checked?

Pics

 

[winston-HT]

I would check crankshaft for roundness and to specs. Looking at side of rod I would suggest you check crankshaft end thrust to specs. Sure looks like quite a bit of wear on rod sides.
You can take a "good" metal straight edge, lay it diagonally across head surface and check for warpage. If any doubt then take to machine shop.

I am assuming you have manual. https://www.tractorforum.com/threads/yanmar-ym135-ym155-service-manual.51613/

 

[ym155dsask]

Ok. Is it possible to check the crank without removing it? I can check the head with a straight edge. Other than checking for warpage would it make sense to check the valve seats or is that rarely an issue on these tractors.

Service manual is on its way with the parts order.

 

[used red MN]

Other than checking for warpage would it make sense to check the valve seats or is that rarely an issue on these tractors.

Have a machine shop check the head for cracks and the surface, have them grind the valves. It only makes sense to me if you are putting new sleeves and pistons in.
You can check the rod journals of the crank without removing it. You really need someone familiar with using micrometers to do it though in my opinion.
Edit: adding welcome to YT!

 

[bmaverick]

Have a machine shop check the head for cracks and the surface, have them grind the valves. It only makes sense to me if you are putting new sleeves and pistons in.
You can check the rod journals of the crank without removing it. You really need someone familiar with using micrometers to do it though in my opinion.
Edit: adding welcome to YT!

Add the service manuals for the YM135/YM155 are free on the YTOG in PDF download.

 

[bmaverick]

maybe here?