GK IV PLUS ISSUE Cancel The title field is required!

1. James Smith

   

   113 posts
   
   1/12/2015 10:01 AM

   We have an old GK IV tee mower that has developed a problem with the rear reel not wanting to drop when it is hot. If we bring it to a hose and cool it down through the radiator it starts working again. This has been going on for about 6 months and since it is now winter time we would like to get to the bottom of the problem and fix it if possible.
   
   To me it appears to be having an issue that seems heat related but not sure how that would work out. you would think as the oil heated up it would get thinner which would allow the reel to drop faster and not stop dropping. does anyone have any idea as to what may be causing this?
   
   thanks in advance for any advice given.

   
   
   
   
2. David Brandenburg

   

   3 posts
   
   1/14/2015 7:01 AM

   We have a bunch of GKIV from 83 to current and all of ours are gas air cooled so I have never had a overheat problem. Is there a temperature gauge and is it showing the mower is hotter than normal?
   
   I would agree the mower should drop easier when the oil is thin and warm. Could it be the rear cylinder bypasses the oil when it is hot? Does the reel pick up normal?
   
   It is a pretty simple system and the only adjustment we have ever made is to the shims in the sequence valve to control the speed the rear reel drops.

   
   
   
   
3. Henry Heinz

   

   0 posts
   
   1/14/2015 8:01 AM

   When it gets hot and starts acting up, remove your cylinder from the lift arm and make sure the arm and reel still move freely. The with it unhooked run it and see if the cylinder operates properly. The engine getting hot and needing to cool it shouldn't have anything to do with the hydraulics working, as long as the engine is running and turning the pump hydraulics should work no matter what the engine temp is. I believe the new sequence valves are non-adjustable, but in most cases that is where the problem is for that center unit. My guess would be without digging in to it, is that when the metal parts heat up and expand there could be some wear in there that's causing something to stick. It could also be in the relief side as it builds pressure it may be just running over the relief. Do you hear any squealing noise when you raise the units?
   
   Regards,

   
   
   
   
4. James Smith

   

   113 posts
   
   1/14/2015 2:01 PM

   The reel or the lift cylinder makes no noise when in operation. Using common sense, I have to think that something inside the lift cylinder is getting hot and expanding causing the unit to get slow or stop working, or oil may be bypassing something but in my thoughts that may cause it to drop without enough pressure to hold up the weight of the reel. It could be a seal that is bad and helping it to jamb or something. We had another older unit in our scrap area of our shop that I had my guy swap out lift cylinders on yesterday. we will see next time we get to use it.

   
   
   
   
5. Henry Heinz

   

   0 posts
   
   1/15/2015 6:01 AM

   In most cases when you hit the pedal to raise it and hold it you should hear a squealing noise, that would be relief opening and fluid running over the relief. In some cases relief valves get weak and don't hold, open to soon, or stick allowing the bypass of hydraulic fluid leading to similar issues. When hot and dropping, you can raise the center unit, quickly blocked it up so it wont drop and unhook your lines, cap the cylinder ports and remove blocks, if the reel drops all the way down you have bad seals, as the oil passed from one side of the piston to the other.
   
   I have also seen cylinders so badly worn that when pressure is applied the ram gets cocked in the cylinder and it wont move, and in other cases will just drop. In most cases people will rebuild cylinders with a seal kit and never take bore readings of the cylinder, and use a micrometer on the piston, so only a very small portion of the job gets done, but the problem is still there.
   
   
   Regards,