John1957 5 #1 Posted May 30, 2016 Just purchased a GT 550 with 360 hours. Has the air cooled Koller 20hp gas engine. It is a beast and with the 48 inch recycle deck it does an unbelievable job mowing. However, after about twenty to thirty minutes mowing the oil temp gauge starts rising going to red. The engine continues to run fine. The engine starts fine and does not smoke that I can tell. The oil I believe is fresh but per the dipstick it was low so I added some as part of the first use check and grease. Air filter cleaned along with foam filter. The fan compartment was very dirty so I blew it all clean. Still running hot. Took the side panels off today and the temp sensor area was packed with grass and dirt. Blew it clean but still running hot. When it heats up the low oil pressure light DOESN'T come on. I am thinking a bad sensor or Guage but perhaps it is the oil pump. I would like to think it is something minor but with my luck the engine is probably shot... Debating whether to take it to the shop but wanted to hear from the experts first!! Any suggestions would be appreciated. Thanks, John. 2 Share this post Link to post Share on other sites
953 nut 51,486 #2 Posted May 30, 2016 Two thoughts; #1,with the tins off take a garden hose and really flush out all of those cooling fins, #2 borrow or buy a non contact thermometer and see what the real temperatures are. (lots of AC contractors use them) 1 Share this post Link to post Share on other sites
JERSEYHAWG / Glenn 4,487 #3 Posted May 31, 2016 The problem with removing the tins, is pulling the engine to do so completely. That's a huge design flaw IMHO. Others will chime in. I tried the high pressure air trick, never took the tins off yet. Would like to though. One day. Glenn Share this post Link to post Share on other sites
ferguson65 71 #4 Posted June 1, 2016 Mine used to run up near the red all the time in the summer. Never in the red, but damn close. It would get to that point and never get any hotter. This winter I pulled the engine and removed all tinwork and blew it out. It was disgusting. My tractor has 740 hours on it. So far the gauge hovers right around the halfway point or maybe a bit higher on even the hottest of days. It's not a 5 minute job, but it's not that tough either to get the engine out and cleaned up. 2 Share this post Link to post Share on other sites
