grinchsr 647 #1 Posted April 17, 2020 Tractor is a 518H with unknown hours because the meter went to bed at 771 hours. Engine runs great at full throttle with a 48 " deck with PTO engaged. Runs great for 20 minutes then it will start to surge. Does engine temp effect the governor? I feel if it is a carb cleaning or a intake leak it won't wait 20 minutes to start surging. Share this post Link to post Share on other sites
oldlineman 1,537 #2 Posted April 17, 2020 Might be the gas tank cap vent clogged. Share this post Link to post Share on other sites
wallfish 18,108 #3 Posted April 17, 2020 If you can stop the surging by using the choke to "dial it in" I'd guess fuel related issue. Intake leak could be possible because of heat expanding the metal Engine heat shouldn't effect the operation of the governor but heat could effect the spring, maybe How about trying to reposition the spring in another hole to make the governor less sensitive? Share this post Link to post Share on other sites
lynnmor 7,822 #4 Posted April 17, 2020 You should define "surge" , does the engine speed up, does it appear to be missing or is it simply varying speed repeatedly? Do the tests mentioned above and report back. Share this post Link to post Share on other sites
grinchsr 647 #5 Posted April 17, 2020 I checked the vent looks good. The spring was in the factory hole which is the third hole from the pivot so I moved it one more hole away. Have not tried running a partial choke but I will try it. GOOD idea !! Will be testing tomorrow Share this post Link to post Share on other sites
grinchsr 647 #6 Posted April 17, 2020 It has done both but not at the same time. One time I had it out and the RPM's would increase then drop back then rev up again with no regularity. Today it was varying speed repeatedly. Share this post Link to post Share on other sites
lynnmor 7,822 #7 Posted April 18, 2020 If the engine over speeds, it's the governor. After a cold start, run the throttle up to full speed (3600 RPM), then see if it increases above that as it warms. If it only slows a bit, then comes back up repeatedly, I would pull the carburetor and clean it thoroughly. Share this post Link to post Share on other sites
grinchsr 647 #8 Posted April 18, 2020 Thanks Weather permitting I going to test it today and see where it goes. Will post results Share this post Link to post Share on other sites
grinchsr 647 #9 Posted April 19, 2020 (edited) Found it!!! Rear intake gasket at least it was. Can I reuse the exhaust gaskets? Edited April 19, 2020 by grinchsr Share this post Link to post Share on other sites
WildmanC120 613 #10 Posted April 20, 2020 16 hours ago, grinchsr said: Found it!!! Rear intake gasket at least it was. Can I reuse the exhaust gaskets? If both of my exhaust gaskets looked like that, I would give them a quick spray with copper coat or the like and reuse them. Glad you found your issue. Share this post Link to post Share on other sites
rmaynard 16,299 #11 Posted April 20, 2020 The exhaust gasket does not look too bad. If you don't have a new one to replace it, just make sure that you torque it to specs. Having said that, as long as you are getting a new intake gasket, why not get an exhaust as well? Share this post Link to post Share on other sites
grinchsr 647 #12 Posted April 20, 2020 I would have but I am not sure of the tractors future so I am trying to keep it a budget build Share this post Link to post Share on other sites
lynnmor 7,822 #13 Posted April 20, 2020 (edited) Do not buy after-market intake gaskets, they will look like that in a year. I know you want to keep the expense down, but this is an excellent opportunity to do some needed maintenance. The intake and exhaust bolts are easy to strip, do not over-tighten. The exhaust is off, so clean it up (glass beading is best) and paint it with Rustoleum High Temperature spray paint. Mufflers are high priced used, so preserve what you have. Get a pair of valve cover gaskets and adjust the valves, that probably was never done. Check all along intake manifold seam for possible leaks. There is a place that one of the heat shield tins cut into it, so cut some clearance on the tin. It would be a good time to open the carburetor and clean it properly, you may not need parts if you are careful with the gasket. Edited April 20, 2020 by lynnmor Share this post Link to post Share on other sites
grinchsr 647 #14 Posted April 20, 2020 Thanks for the good tips. I threw the carb in Berrymens last night and was going to order gaskets today. I will definitely take your advice on the gaskets. No sense doing it again Share this post Link to post Share on other sites
