50 hour rebuild report

[SailorBob]

Some of you may remember my story about overheating my YM1700 which resulted in having to rebuild my engine this past summer. I decided to tackle the rebuild myself. So, I pulled the head took it to a machine shop had it magnafluxed, resurfaced, and pressure tested. I purchased new valves, stem seals, springs, and keepers. Also, I replaced the cylinder liners, pistons, rings, rod bearings, and, wrist pins. I was very pleased especially since it fired right up on the first try. After a few hours I broke a valve spring. I replaced it and ran it a few more hours and broke another. I believe that I got a bad batch of springs. Anyway, I ordered some genuine Yanmar OEM springs. That was about 40 hours ago and have had no further problems since. I also installed a water pump kit on the tractor as well.

I am happy to report that it runs great. There is no smoking or using of oil. It starts easily and has plenty of power. It runs cool even with a rotary cutter in 98 degree heat. I should be good to go now for a few thousand hours more now

I just wanted to give encouragement to anyone else out there to not be afraid to work on these tractors yourself. They are pretty simple. I am not a mechanic (I am a computer systems analyst) but, I did my research on this forum, Hoye's website, and I sure I have read the shop manual thru 4 times or more.

Thanks to everyone that helped me and answered my questions.

 

[kenmac]

glad to hear all is going well for you. To bad about the broken valve springs. Were they after market springs ?

 

[SailorBob]

glad to hear all is going well for you. To bad about the broken valve springs. Were they after market springs ?

Yes. The springs were after market. After that I got some Yanmar OEM springs from Danny Parker and replaced them all and have not had any more problems.

 

[E_Sanborn]

Sailor_Bob,I suspected there may be more than a few geeks who dabble in Grays. Cool that you found the support and confidence to complete a very intensive overhaul. Question raised by the OEM valve springs? Were these the only OEM parts you were able to install, or were there other OEM parts available on the market? Thanks, Ed

 

[SailorBob]

I think there are lots of OEM parts still available. When I bought the parts I did not realize that they were after market parts since I bought them over the web. They looked just like the original equipment. I believe that they are good parts for the most part. I don't why the valve springs were defective though.