[70mower]

I've currently got my VH70 torn down for rebuild. Its my first attempt at rebuilding an engine, so I'm learning while I go. I noted that the oil pump doesn't operate smoothly by hand, even after cleaning and re-oiling. Is this normal or should I replace it?

 

[bltee]

Is the piston itself and/or the bore scratched or scored?

 

[Toyguy]

Dave- Don't have an answer for you but I'm curious as to your reason for needing to rebuild your VH70 in the first place. I'm asking because it's almost, if not impossible to find rebuild parts for this engine if it should require oversize piston & rings. What is your situation with this. Do you have a parts source. Sorry for pulling you away from your original question.

 

[70mower]

Bob, I'd call the pump piston uniformly lightly scratched. The bore isn't very easy to see but don't see heavy scoring.

Gerald, I took the engine apart because of several issues, first it was very hard to start. It would only start with the throttle almost all the way closed. Second, it had always smoked a little under load and lacked power to mow through heavier grass. The smoking had recently gotten much worse and third the governor had not controlled engine speed on another occasion. It had been my only mower for about five years until I got a GT262 last year so I could now afford some down time on the 70.

Here's what I found after opening it up. The cylinder bore has virtually no wear but has some rust pitting at the very top, down to about where the middle ring is when the piston is TDC. The ring end gap is about twice the upper limit. I also found the rings have uneven wear. The width is a couple thousandths different at each end. Could this be due to operating over the pitted areas? Also looks like the head gasket was leaking around the area that is supposed to have the Belleville washers. My engine didn't have any. The crank and camshaft look good. Valve springs were both 1/8 shorter than spec but I've read not to worry about that.

My plan is to install standard rings, probably replace the oil pump, lap the valves and replace all the seals and the governor post.

I only plan to use it for occasional mowing. I just didn't want to see a nice old mower die and wanted to learn something about engines.

I've already ordered the rings. Supposed to be NOS Tecumseh parts, and have found the other parts that I think I'll need. I haven't looked into the electrical components yet. By the way I'm pretty sure I've seen oversized pistons & rings available. Let me know if you want to know where I've seen them. I'd have to look but am sure I could find them again.