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Discussion Starter #1
Just came in from plowing snow and my 570 Ranger leaked some coolant. The fan was running, and I let the engine run while I was doing something else, and then the engine died. I got back in it, cranked it and the temp light was on at 201 degrees and the fan started running. So, I thought I would get it back to the garage and it barely ran to go back. When I moved it, I noticed coolant on the snow, so when I got it back in the garage, I checked it and it had overflowed coolant around the radiator. I also noticed the top radiator line was hot/warm and the bottom radiator line was cold/cool. Is this the thermostat that is bad?
 

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That is strange Mt. 201 degrees is not extreme and that was on a restart when temps normally run higher.

"I checked it and it had overflowed coolant around the radiator. "

Are you saying it spewed from the cap ? from the recovery bottle ? from a seam on the radiator ?

The temp should be hot coming in the top and cooler (not cold) going out the bottom hose.

Depending on the answer to where it was spewing from, I am thinking you may have been a bit low on coolant and got some air in there and bubbled/ blocked & overheated OR , you could have dirty fins that are blocking the air flow ie : mud/weeds/seeds/snow either on the front or the backside of the radiator. I would fill it back up and let it run with CAP OFF with the radiator up as high as you can and let it purge. If you can stare into the cap hole long enough, you will be able to see that it has good circulation .....or not.. No other overheat history ??

One other thing, in all the years of working on Polaris engines, I have never seen a bad/nonworking thermostat.
 

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Discussion Starter #3
That is strange Mt. 201 degrees is not extreme and that was on a restart when temps normally run higher.

"I checked it and it had overflowed coolant around the radiator. "

Are you saying it spewed from the cap ? from the recovery bottle ? from a seam on the radiator ?

The temp should be hot coming in the top and cooler (not cold) going out the bottom hose.

Depending on the answer to where it was spewing from, I am thinking you may have been a bit low on coolant and got some air in there and bubbled/ blocked & overheated OR , you could have dirty fins that are blocking the air flow ie : mud/weeds/seeds/snow either on the front or the backside of the radiator. I would fill it back up and let it run with CAP OFF with the radiator up as high as you can and let it purge. If you can stare into the cap hole long enough, you will be able to see that it has good circulation .....or not.. No other overheat history ??

One other thing, in all the years of working on Polaris engines, I have never seen a bad/nonworking thermostat.
Jungleman, thanks for that feed back. The radiator is clean, fins are all clear. Perhaps it has overflowed in the past and I've not noticed, but I will try refill and allow to run to purge any air. Thanks again for the reply.
 

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Discussion Starter #4
Jungleman, thanks for that feed back. The radiator is clean, fins are all clear. Perhaps it has overflowed in the past and I've not noticed, but I will try refill and allow to run to purge any air. Thanks again for the reply.
That is strange Mt. 201 degrees is not extreme and that was on a restart when temps normally run higher.

"I checked it and it had overflowed coolant around the radiator. "

Are you saying it spewed from the cap ? from the recovery bottle ? from a seam on the radiator ?

The temp should be hot coming in the top and cooler (not cold) going out the bottom hose.

Depending on the answer to where it was spewing from, I am thinking you may have been a bit low on coolant and got some air in there and bubbled/ blocked & overheated OR , you could have dirty fins that are blocking the air flow ie : mud/weeds/seeds/snow either on the front or the backside of the radiator. I would fill it back up and let it run with CAP OFF with the radiator up as high as you can and let it purge. If you can stare into the cap hole long enough, you will be able to see that it has good circulation .....or not.. No other overheat history ??

One other thing, in all the years of working on Polaris engines, I have never seen a bad/nonworking thermostat.
When I noticed it was overheated was when the engine died with the fan running while I was busy with something else. I cranked it again, and pulled into the garage and it was running very rough with no power and the hot lamp was on. I hadn't check the temp at this point and stopped the engine and that's when i noticed the antifreeze on the snow. When I opened the hood, antifreeze had sprayed some of the inside of the hood. I went back and then cranked it and the temp showed 201, so it had cooled somewhat. As soon as I can get free, I will jack up the front end and put some antifreeze (Prestone 50/50)
 

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The cooling system is pretty simple. Check simple things first. Most likely you either have a bad radiator cap that will not hold the proper pressure to keep the coolant from boiling, and/or the coolant level is low, possibly due to previously unnoticed leakage, leaving air pockets in the system, a bad thermostat that won't allow coolant flow or a bad water pump.

If you've had severe overheating problems previously it's possible to have warped a head or blown a head gasket which would allow coolant loss via the engine cylinder. If no prior overheating issues, I'd scratch that concern off the list, for now.

It's normal for the top of the radiator to be hotter than the bottom. Hot coolant from the engine returns through the upper hose to the top of the radiator. As the coolant circulates through the radiator the heat is removed (transferred to the air) and the cooler liquid exits the radiator through the bottom hose to return to the engine and remove more heat.
You may be able to check off a couple of possible problems by running the engine until normal temperature (over 180 F) and looking into the radiator cap hole to see of coolant is flowing with the engine running at 3000 - 4000 RPM. IF coolant is seen flowing then the thermostat and water pump are working. If not, the thermostat is stuck closed, the water pump impeller is bad, or the radiator is internally clogged. (helpful hint: in my experience once an engine overheats the thermostat isn't long for this world even if it wasn't the cause of overheating. Thermostats contain a wax pellet which expands to open the thermostat. When overheating occurs something happens to that pellet and more often than not the thermostat will fail in the near future)

If you are unable to see coolant flow due to poor lighting or inaccessibility, with the engine cool, remove the thermostat and take it to the kitchen. Place it in a pan of water hanging from a piece of wire and off the bottom or sides of the pan, along with a thermometer. When the water reaches the temperature imprinted upon the thermostat the thermostat should begin to open. I won't fully open until a higher temperature is reached, perhaps 10 F higher.

If the thermostat checks out, start the engine and see if coolant is pumped out of the thermostat opening in the block. DON"T RUN IT LONG LIKE THIS! If it is, the pump is OK. either take a chance that the original thermostat won't fail shortly (since you did overheat at least once) or just replace the thermostat. There is no paper gasket to seal the thermostat housing to the block. The thermostat itself incorporates a rubber gasket that can be reused if in good condition.

A radiator (cooling system) pressure tester can pressurize the radiator and test for system leaks as well as help pinpoint them. With the engine cool use the tester to pressurize the system and watch for leaks. Also watch the gauge. If it holds steady the system should not have any leaks. That same tester can test radiator caps. Radiator caps usually are not very expensive so replacing it may be an option in lieu of a test. Parts changing diagnosis of radiator caps is one of the few "parts changer mechanic" themes I am not opposed to.

A system that isn't full leaves air pockets. Since centrifugal pumps (your water pump) can't pump air the coolant won't circulate if there is air in the pump. In addition air pockets create hot spots within the engine. It's very important that no air pockets are in the system. The Service Manual provides a procedure for bleeding air from the system using the bleeder screw on top of the thermostat housing.

If when you pressure test the system you find no leaks, have replaced the radiator cap and still have coolant loss it's time to suspect a head gasket, warped head, internal crack from the water jacket to the cylinder or bad seal between the water pump and crankcase. It wouldn't hurt to check your oil to see if it's turned milky, a sure sign of water in the oil and a bad sign for your wallet.
 

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Discussion Starter #6
The cooling system is pretty simple. Check simple things first. Most likely you either have a bad radiator cap that will not hold the proper pressure to keep the coolant from boiling, and/or the coolant level is low, possibly due to previously unnoticed leakage, leaving air pockets in the system, a bad thermostat that won't allow coolant flow or a bad water pump.

If you've had severe overheating problems previously it's possible to have warped a head or blown a head gasket which would allow coolant loss via the engine cylinder. If no prior overheating issues, I'd scratch that concern off the list, for now.

It's normal for the top of the radiator to be hotter than the bottom. Hot coolant from the engine returns through the upper hose to the top of the radiator. As the coolant circulates through the radiator the heat is removed (transferred to the air) and the cooler liquid exits the radiator through the bottom hose to return to the engine and remove more heat.
You may be able to check off a couple of possible problems by running the engine until normal temperature (over 180 F) and looking into the radiator cap hole to see of coolant is flowing with the engine running at 3000 - 4000 RPM. IF coolant is seen flowing then the thermostat and water pump are working. If not, the thermostat is stuck closed, the water pump impeller is bad, or the radiator is internally clogged. (helpful hint: in my experience once an engine overheats the thermostat isn't long for this world even if it wasn't the cause of overheating. Thermostats contain a wax pellet which expands to open the thermostat. When overheating occurs something happens to that pellet and more often than not the thermostat will fail in the near future)

If you are unable to see coolant flow due to poor lighting or inaccessibility, with the engine cool, remove the thermostat and take it to the kitchen. Place it in a pan of water hanging from a piece of wire and off the bottom or sides of the pan, along with a thermometer. When the water reaches the temperature imprinted upon the thermostat the thermostat should begin to open. I won't fully open until a higher temperature is reached, perhaps 10 F higher.

If the thermostat checks out, start the engine and see if coolant is pumped out of the thermostat opening in the block. DON"T RUN IT LONG LIKE THIS! If it is, the pump is OK. either take a chance that the original thermostat won't fail shortly (since you did overheat at least once) or just replace the thermostat. There is no paper gasket to seal the thermostat housing to the block. The thermostat itself incorporates a rubber gasket that can be reused if in good condition.

A radiator (cooling system) pressure tester can pressurize the radiator and test for system leaks as well as help pinpoint them. With the engine cool use the tester to pressurize the system and watch for leaks. Also watch the gauge. If it holds steady the system should not have any leaks. That same tester can test radiator caps. Radiator caps usually are not very expensive so replacing it may be an option in lieu of a test. Parts changing diagnosis of radiator caps is one of the few "parts changer mechanic" themes I am not opposed to.

A system that isn't full leaves air pockets. Since centrifugal pumps (your water pump) can't pump air the coolant won't circulate if there is air in the pump. In addition air pockets create hot spots within the engine. It's very important that no air pockets are in the system. The Service Manual provides a procedure for bleeding air from the system using the bleeder screw on top of the thermostat housing.

If when you pressure test the system you find no leaks, have replaced the radiator cap and still have coolant loss it's time to suspect a head gasket, warped head, internal crack from the water jacket to the cylinder or bad seal between the water pump and crankcase. It wouldn't hurt to check your oil to see if it's turned milky, a sure sign of water in the oil and a bad sign for your wallet.
Pyromedic, thanks for that thorough troubleshooting outline. I've never over heated in the past and still not certain why it blew some antifreeze under the hood (I assume either from the overflow tank or the radiator cap). I've never had the radiator cap off. I will check it out tomorrow and hoping it is a minor issue.
 

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That would be a spew from the overflow. Pressure builds and pushes radiator cap seal up and coolant into the reservoir. As stated before, take cap off and run it up to temp watching the flow into radiator.
 

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I just came in from snow plowing and let my 570 mid idle for awhile with the heater on, so I offer this as a point of reference. It was about 32F degrees outside. The engine temp starts out about 172 degrees. After idling 20 minutes it rises to 201. At 200+ the fan comes on and the temp immediately drops. Fan shuts down about 185 and the temp continues to drop back to 172 degrees very quickly, in about 30-40 seconds. If I continue to let it idle this cycle repeats.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #9
That would be a spew from the overflow. Pressure builds and pushes radiator cap seal up and coolant into the reservoir. As stated before, take cap off and run it up to temp watching the flow into radiator.
I'm hoping that is all it is and will be testing tomorrow.
 

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I just came in from snow plowing and let my 570 mid idle for awhile with the heater on, so I offer this as a point of reference. It was about 32F degrees outside. The engine temp starts out about 172 degrees. After idling 20 minutes it rises to 201. At 200+ the fan comes on and the temp immediately drops. Fan shuts down about 185 and the temp continues to drop back to 172 degrees very quickly, in about 30-40 seconds. If I continue to let it idle this cycle repeats.


Sent from my iPhone using Tapatalk
Assuming you refilled (with coolant) and then purged the air from the system as those are normal temps while cycling . Being it is a 2015, the chances of it being a bad cap are pretty unlikely but a defective fan circuit breaker can cause intermittent interruptions in the normal fan cycle that will cause it to overheat. Like I mentioned before, I have never seen a bad thermostat even on ten-to twelve year old machines that were the cause of a overheating episode . If you have never had the cap off before, I am thinking you have probably lost some coolant over time and accumulated some air that disrupted the flow.
As far as it running a bit poorly during the overheating episode, when was the last time you replaced the spark plug ? One lungers have a habit of fouling a lot easier after they get some age on them.
 

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I don't have a service manual, but am trying to order one today. I filled the radiator up with coolant and cranked it. It runs fine and I keep watching to see if the coolant was being circulated. The only thing I saw was intermittent bubbles rising to the top and a gradual rise in coolant level to overflow just a little out of the radiator cap opening. I ran it until the temperature went from about 40 degrees to 165 degrees. The top radiator hose was cool and when I squeezed it, it pushed coolant out of the top of the radiator cap opening. So, it doesn't appear to be moving the coolant into the engine as far as I can tell.
 

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Assuming you refilled (with coolant) and then purged the air from the system as those are normal temps while cycling . Being it is a 2015, the chances of it being a bad cap are pretty unlikely but a defective fan circuit breaker can cause intermittent interruptions in the normal fan cycle that will cause it to overheat. Like I mentioned before, I have never seen a bad thermostat even on ten-to twelve year old machines that were the cause of a overheating episode . If you have never had the cap off before, I am thinking you have probably lost some coolant over time and accumulated some air that disrupted the flow.
As far as it running a bit poorly during the overheating episode, when was the last time you replaced the spark plug ? One lungers have a habit of fouling a lot easier after they get some age on them.
I cranked it and it runs fine, but doesn't seem to be circulating the coolant at this point.
 

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The thermostat will not be open yet at that temp to allow circulation.

"I ran it until the temperature went from about 40 degrees to 165 degrees "
 

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You need to let it run so the stat fully opens and then squeeze the radiator hoses while keeping the radiator topped off to PURGE the air. Get the cap as high in the air as you can and.............be patient, this takes a while.
 

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Discussion Starter #15
Assuming you refilled (with coolant) and then purged the air from the system as those are normal temps while cycling . Being it is a 2015, the chances of it being a bad cap are pretty unlikely but a defective fan circuit breaker can cause intermittent interruptions in the normal fan cycle that will cause it to overheat. Like I mentioned before, I have never seen a bad thermostat even on ten-to twelve year old machines that were the cause of a overheating episode . If you have never had the cap off before, I am thinking you have probably lost some coolant over time and accumulated some air that disrupted the flow.
As far as it running a bit poorly during the overheating episode, when was the last time you replaced the spark plug ? One lungers have a habit of fouling a lot easier after they get some age on them.
I don't have a manual and don't know where to find the purge screw. Is it on the engine where the hose running to the radiator is located? If I can find it, is it a matter of just loosening the screw while the engine is running to allow some fluid and air to escape?
 

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You need to let it run so the stat fully opens and then squeeze the radiator hoses while keeping the radiator topped off to PURGE the air. Get the cap as high in the air as you can and.............be patient, this takes a while.
Ok, I have it running again with the cap off. I assume it will have to get above 200 with the fan running to see if it is cycling coolant. Thanks for the help.
 

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Ok, I have it running again with the cap off. I assume it will have to get above 200 with the fan running to see if it is cycling coolant. Thanks for the help.
 

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Ok, I have it running again with the cap off. I assume it will have to get above 200 with the fan running to see if it is cycling coolant. Thanks for the help.
temp is 174 and coolant is running pulsing up and down and running over slightly
 

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Ok, I have it running again with the cap off. I assume it will have to get above 200 with the fan running to see if it is cycling coolant. Thanks for the help.
temps is now 215 with fan running. Coolant was being pushed out of cap. so I put cap on. Is that ok?
 

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Discussion Starter #20
took cap back off and coolant went down into radiator...temp is 242
 
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