edwroy 138 #1 Posted October 18, 2014 Hi all, Have a '91 520H with 1300+ hours - back cylinder valve seat issues. Can the valve seats be repaired or do I need to this about repowering? thoughts appreciated. Edwroy Share this post Link to post Share on other sites
ericj 1,579 #2 Posted October 18, 2014 if you can pull the motor off and tear it down your self a machine shop should be able to redo the valve seat for about $ 100.00. or at least that's what my local napa machine shop charged me on 2 different times. i have 2 20 hp onans sitting here waiting for me to come up with the green stuff to get them done. the gasket set cost about $50.00 through onanparts.com. so it is salvageable if you want to go that route eric j Share this post Link to post Share on other sites
wh5208speed 646 #3 Posted October 18, 2014 Hi all, Have a '91 520H with 1300+ hours - back cylinder valve seat issues. Can the valve seats be repaired or do I need to this about repowering? thoughts appreciated. Edwroy You can reseat the valves...but it is just a temporary fix. There is endless scores of people of who have tried to repair the valve seats only leading the valve seats to fail again and eventually to succumb to repower or parting the tractor out. I have a few Onan motors and if/when I have a value seat issue.....I am going save my money and energy and just repower. Thad (Ohio) Share this post Link to post Share on other sites
546cowboy 302 #4 Posted October 18, 2014 A tear down of the engine is not neccesary but you will need to pull the engine and take it to a machine shop. They can get an oversized seat and install it for less than $150 usually. Share this post Link to post Share on other sites
ericj 1,579 #5 Posted October 18, 2014 i had to pull the intake and exhaust manifolds, pull the heads stater,coil and heads. basically take it down to a short block. an don't do like i did and forget to drain the oil lol eric j Share this post Link to post Share on other sites