scottw99
New member
Hello, this thread will document my attempt at rebuilding the 2T73A found in the Yanmar 135.
I purchased the tractor with a replacement motor, another YM 2cyl diesel. Due to the fact that the hydraulic pump would not be easily integrated, and the engine dimensions being smaller (this could cause structural issues) I've decided to start measuring up the old engine to see what's usable and if a rebuild is viable.
When I got the tractor the block was stripped, but the head was still intact. Just yesterday I disassembled the head. The exhaust valves and seats look reasonable. Guides are good.
The intake valves were stuck in the head, and inside of the intake and valve chambers there is a ton of corrosion.. I'll have some pics up of yesterdays work shortly but it was pretty rough in there. I'm not sure if I split the valve guide tapping out the intake valve, but one of the intake valve guides has a hairline crack on the top that doesn't extend through the full length. I imagine that needs to be replaced. Both intake valves had to be tapped out and I'm thinking either the valves are bent slightly or the corrosion in and around the valve guide has somehow compressed it or altered it.
I need to do some more reading/research on replacing these guides, I was hoping to reuse them and only need to do valve lapping but from what I've read if you replace the guide you should have the new valve seat cut in.
Anyhow this is the first post of probably many, for the next while I'll be inspecting and measuring, taking pictures, and posting here. I need to pick up some more measuring tools to see what's in spec - still need a straight edge to check the head and block, bore gauge to check the cylinder sleeves, dial gauge, and some larger micrometers.
I purchased the tractor with a replacement motor, another YM 2cyl diesel. Due to the fact that the hydraulic pump would not be easily integrated, and the engine dimensions being smaller (this could cause structural issues) I've decided to start measuring up the old engine to see what's usable and if a rebuild is viable.
When I got the tractor the block was stripped, but the head was still intact. Just yesterday I disassembled the head. The exhaust valves and seats look reasonable. Guides are good.
The intake valves were stuck in the head, and inside of the intake and valve chambers there is a ton of corrosion.. I'll have some pics up of yesterdays work shortly but it was pretty rough in there. I'm not sure if I split the valve guide tapping out the intake valve, but one of the intake valve guides has a hairline crack on the top that doesn't extend through the full length. I imagine that needs to be replaced. Both intake valves had to be tapped out and I'm thinking either the valves are bent slightly or the corrosion in and around the valve guide has somehow compressed it or altered it.
I need to do some more reading/research on replacing these guides, I was hoping to reuse them and only need to do valve lapping but from what I've read if you replace the guide you should have the new valve seat cut in.
Anyhow this is the first post of probably many, for the next while I'll be inspecting and measuring, taking pictures, and posting here. I need to pick up some more measuring tools to see what's in spec - still need a straight edge to check the head and block, bore gauge to check the cylinder sleeves, dial gauge, and some larger micrometers.
