Toro 522xi model 73561 sudden overheating

[Old CC 1]

A 1991 toro 522xi that has given good service for over 27 years, now suddenly overheating.  Was mowing high grass, higher secondary to excessive rainy days, but not too high. Realized I was running low on gas, stopped to refuel. Had a new gas can, not metal but these new ones, went to new gas station, not the usual.  Returned, fueled and started mowing..within 8-10 min..-pto engaged the temp gauge had reached the red zone and engine was loosing power.  Shut her down. Did a test the next clear day, normal drive around at power......slowly over 8-10min reached red zone. (Note did not let it run in red) no pto.

Any ideas, other than dumping the fuel tank, empty or change the fuel lines and filter.....checked oil, dirty will change.

[WVHillbilly520H 10,369]

2 hours ago, Old CC said:

A 1991 toro 522xi that has given good service for over 27 years, now suddenly overheating.  Was mowing high grass, higher secondary to excessive rainy days, but not too high. Realized I was running low on gas, stopped to refuel. Had a new gas can, not metal but these new ones, went to new gas station, not the usual.  Returned, fueled and started mowing..within 8-10 min..-pto engaged the temp gauge had reached the red zone and engine was loosing power.  Shut her down. Did a test the next clear day, normal drive around at power......slowly over 8-10min reached red zone. (Note did not let it run in red) no pto.

Any ideas, other than dumping the fuel tank, empty or change the fuel lines and filter.....checked oil, dirty will change.

I would check actual temps with a laser scan thermometer, then temp sensor/sending could have failed, or in the 27 years have you ever pulled the engine and removed the engine tins/shrouds and cleaned the chaffe/dirt and other debris? If not this may be your biggest issue.  I thought I was keeping my 520H clean until I had a trans temp light come on removed the fenders and found this...before pressure washing.

[shallowwatersailor 3,213]

It sounds as if you have some how blocked the airflow to the engine with cutting the tall grass. Actually in the Kohler engine manual it call for removing the shrouds and cleaning the cylinder heads of chaff. You can clean about 3/4 of the top end without pulling the engine going from the top, but a thorough job will require the engine to come out. 

[ZXT 2,394]

When you clean the cooling fins, don't just knock the top layer dirt and grass off and call it a day. That'll restore the airflow across the fins, but it won't account for the oil/dirt grime that will be cooked onto them. Clean them good enough that you see bare metal. The fins don't exchange heat nearly as well if they don't contact the air directly.

Edited July 9, 2019 by ZXT

[Old CC 1]

All good answers. Took tin off...check oil....found heavy grease and dirt on bottom fins...oil was very dark brown but within normal level (it never burned oil)..some minor dust and debris.

Decreases....scrubbed and blown..changed the oil, filter and air filter and pre-filter....still run hot without load or with, in about 15 minutes.according to gauge.  All this started as stated above, with a refuel.....immediately 8-15 min after restart.  Have not lost power...but don’t want to damage the engine.  Will use temp gun on engine next to get temp, thinking may have fuel issue, any more ideas would be helpful.

[WVHillbilly520H 10,369]

34 minutes ago, Old CC said:

All good answers. Took tin off...check oil....found heavy grease and dirt on bottom fins...oil was very dark brown but within normal level (it never burned oil)..some minor dust and debris.

Decreases....scrubbed and blown..changed the oil, filter and air filter and pre-filter....still run hot without load or with, in about 15 minutes.according to gauge.  All this started as stated above, with a refuel.....immediately 8-15 min after restart.  Have not lost power...but don’t want to damage the engine.  Will use temp gun on engine next to get temp, thinking may have fuel issue, any more ideas would be helpful.

@shallowwatersailor, don't these Kohlers have an issue with the temp sensor/gauges?

[Old CC 1]

Yes, I read that in researching this issue.....that’s why I am going with temp gun reading to see what the temp actually is, before I check fuel system including replacing the pump.

[Old CC 1]

These are all good thoughts. Engine was cleaned an serviced by dealer service center 2 years ago (full with removal). Will clean screens and remove tin this weekend. Oil is dirty so will change as well.  Will post results

Old CC

[Old CC 1]

I ran it 10 minutes into the red zone, cutting grass. Stop and immediately opened the hood and used heat gun. Exhaust pipe 500f, upper fins 189f, bottom fins 206f, engine body 302f. Began to have some hesitation, shut her down. Will pull the fuel filter and plugs next. 

[19richie66 16,933]

Sounds lean

[shallowwatersailor 3,213]

In your original post you mentioned going to a new gas station for fuel. I use to run 93 Octane on my two 5xi with Kohlers. I wonder if there is an issue with the fuel that you bought? My 520xi would always run hotter than my 518xi. The temp gauge does appear to have issues on some units and are not as reliable as could be. But the fact that yours changed all of a sudden is puzzling.

[Kurt-NEPA 755]

On 7/11/2019 at 6:58 PM, WVHillbilly520H said:

@shallowwatersailor, don't these Kohlers have an issue with the temp sensor/gauges?

 

That is the conclusion I came to on my 5xi's.  I am convinced it is the more the sensor than the gauge.  Unfortunately the sensor is NLA.  I'm thinking of replacing both the sensor and the gauge with an after market unit.  I have a 522xi that is fine, but a 520xi that is running marginally hot (at least by the gauge).  I guess this is the fun of older tractors.

 

I'm starting to take readings with an infra-red temp gun.  We'll see were that leads.  At this point, I am not sure the Kohler is running that hot.

 

One thing that I think helps is to use a blow gun after every mowing and blow through the intake with the engine running (carefully).  I am amazed at how much grass comes out.

[Old CC 1]

Does anyone know where I can adjust the mixture?  What bugs me is how sudden this occurred. Stumped for new ideas, great tractor and will keep looking for the answer. Thanks for all the great suggestions, please keep them coming..has anyone experience this same issue?

[katanski 2]

On 7/13/2019 at 3:27 PM, 19richie66 said:

Sounds lean

I had the same issue, changed the fuel pump. No more overheating.