Toro Groundsmaster 4000's overheating Cancel The title field is required!

1. Krueger Casey

   
   3/13/2013 4:03 PM

   We are currently having problems with two of our GM 4000's overheating. Once mowing for about 15 to 20 min the mowers start to go into the red. We have taken out thermostats, taken radiators down to get tanked and kept them clean with air since the service. We have also changed all hydraulic filters and sharpened the blades and even replaced the heat gauge. We are in central Washington with little grass out of dormancy yet so not much load on the mowers yet.
   
   If there are any thoughts on this problem we are all ears!!!

   
   
   
   
2. Douglas Eggert

   

   1 posts
   
   3/13/2013 4:03 PM

   We had the same issue and did all you did, but changed the thermostat last season and did the water pump and fan clutch this season. We didn't take the radiator out last winter, but did do it this year and quite frankly surprised how much debris was packed in it. I personally think it was the clutch, seemed weaker than the new one just spinning it in your hand.
   
   So we're hoping the water pump/ clutch combos is doing the trick. If not, all that is left is the gauge.
   
   Good luck.

   
   
   
   
3. Witthuhn Toby R

   
   3/14/2013 2:03 PM

   We have two 4000's that both developed overheating problems. Both times it was the head gasket.

   
   
   
   
4. Krueger Casey

   
   3/15/2013 12:03 PM

   With your problem being the head gaskets were you loosing alot of coolant or a little at a time. We are not really seeing any coolant loss?

   
   
   
   
5. Dinger Greg

   
   3/16/2013 11:03 AM

   Depending on the leak you might not lose any or very little. You can get a "sniffer" at Napa that will test for combustion gasses in the rad. It's not very expensive and a good tool to have around. It's a test vial and some fluid that changes color depending on gas presence and engine combustion type.
   
   It will at least help in the diagnosis process.
   
   Just a side note. Pulling a tstat CAN make an engine overheat as fast as anything. A true test for them is to put them in a pan of boiling water and a thermometer to verify their operation. In twenty years I've seen exactly one thermostat actually fail. I've replace many, but that was either preventative, or throwing darts.
   
   Some good reading.
   
   http://mtiservice.blogspot.com/2012/09/ ... e.html?m=1

   
   
   
   
6. Jennings Dustin T

   
   3/18/2013 11:03 AM

   had the same problem with ours last summer. replaced thermostat, replaced temp gauge, replaced water pump, still overheated. Turns out it was the fan clutch. We didn't notice it at first but the fan clutch was never kicking in high gear when the engine got hot, it was running only at idle speed and wasn't able to cool the engine as it was meant to do. Replaced the clutch and everything has been fine since. They aren't cheap, but nothing is really...

   
   
   
   
7. Robert Shetter

   

   3 posts
   
   3/18/2013 3:03 PM

   Take a broom handle to stop the fan from moving. Start the unit. If the fan hesitates to turn even for a second it is the fan clutch. Also you need a minimum of 100 psi to effectively blow out the radiator.

   
   
   
   
8. Witthuhn Toby R

   
   3/18/2013 3:03 PM

   We didn't really see a loss of coolant with the head gasket problem. We did see a buildup of pressure and excess coolant in the overflow tank even when the engine was cool though.