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Discussion Starter #1
Have recurring problem of overheating with the flashing notification.
The fan is running, but the coolant is cool and not circulating when I take off the radiator cap. It's also topped off.
What could be the problem? Thermostat?
Thinking of removing the thermostat for the summer.
 

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Yes I would take the thermostat out as a test and/or replace it.
 

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rd, NEVER run an engine without a thermostat. An EFI engine needs to be up to temp to work properly. You could have a plugged radiator or a bad pump impellar or a big air pocket . Although minutely possible that the stat is bad, not very likely . Carefully remove the stat and remove the rubber gasket and drop the stat into a pan of boiling water and check for it to open. Not that it would keep the coolant from circulating but when did you last install a new cap ? They go bad every few years and then boil over begins.
 

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rd, NEVER run an engine without a thermostat. An EFI engine needs to be up to temp to work properly. You could have a plugged radiator or a bad pump impeller or a big air pocket . Although minutely possible that the stat is bad, not very likely . Carefully remove the stat and remove the rubber gasket and drop the stat into a pan of boiling water and check for it to open. Not that it would keep the coolant from circulating but when did you last install a new cap ? They go bad every few years and then boil over begins.
Jungle, he has cool coolant and no boil over. Your right about almost all newer ecm controlled engines have block sensors and now exhaust sensors to control fuel flows and help with keeping emissions low.
I would remove and test the thermostat. Its simple, and the cost is zero.
 

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Yeah sum , I got that. I covered the usually non circulating bs............. air pocket/ bad impellar/plugged radiator stuff and then started on the cap spiel. My point is/was that I have worked on dozens of 700's that have overheated and I NEVER ONCE had a bad thermostat when there was no circulation. Not one.
 

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Don't know about the 700 Polaris engine but some engines run hot when there is no thermostat becaue the coolant passes through the radiator too quickly to shed heat. Ford 289 was bad about that.
 

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Pyro, With the 700 engine with two little cylinders you end up with a oil pan full of gas because it never warms up enough to burn it off. A V-8 will get hot like you said because , like you said, the coolant passes thru to fast and doesn't cool.
 

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Yeah sum , I got that. I covered the usually non circulating bs............. air pocket/ bad impellar/plugged radiator stuff and then started on the cap spiel. My point is/was that I have worked on dozens of 700's that have overheated and I NEVER ONCE had a bad thermostat when there was no circulation. Not one.
Plugged radiator not the symptoms. Maga!
 

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Discussion Starter #13
Oil level high!

Pyro, With the 700 engine with two little cylinders you end up with a oil pan full of gas because it never warms up enough to burn it off. A V-8 will get hot like you said because , like you said, the coolant passes thru to fast and doesn't cool.
Maybe that's why my oil level is so high! Thought maybe I had somehow added too much oil.
Could that also effect cooling?
 

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Discussion Starter #14
Air Pocket? How would I troubleshoot that?
I have a very steep hill to go to/from my dock. Could the result in creation of an air pocket? How would fix that?
 

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Maybe that's why my oil level is so high! Thought maybe I had somehow added too much oil.
Could that also effect cooling?
rd, mega short trips that do not allow the engine to get up to temp will result in excessive gas in the oil.Sometimes alot of it. More frequent oil & filter changes are going to be necessary.

Gas n oil not really having any effect on the cooling.
 

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Air Pocket? How would I troubleshoot that?
I have a very steep hill to go to/from my dock. Could the result in creation of an air pocket? How would fix that?
Elevate the front end , start and run , open the bleeder on top of the thermostat housing to let air out. Remove the floor access panel and squeeze the coolant hoses to move coolant and air thru them . Watch for bubbles in the radiator neck. When coolant streams out the bleeder ........Close the bleeder. Keep the radiator topped up with coolant thru out this process.

No on the steep hill thingy . rd, how long have you had this Ranger ?
 

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There was a thread about the issue and the use of a vacuum pump to suck the system full to avoid the issue. Pyro was the one with the link to the tool set I believe. I have a Nissan Xterra thats a pain to refill as it likes to trap air. I have a medical evacuator for the purpose of changing oil on small engines and fluid of brake systems that was a flea market find.
 

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There was a thread about the issue and the use of a vacuum pump to suck the system full to avoid the issue. Pyro was the one with the link to the tool set I believe. I have a Nissan Xterra thats a pain to refill as it likes to trap air. I have a medical evacuator for the purpose of changing oil on small engines and fluid of brake systems that was a flea market find.
I purchased one of those cooling system vacuums that pyro shared with us. I've only been able to use it once and it was on a Mule. It collapsed all the hoses and seemed to work well. The one bad thing about it is there has to be sufficient room around the radiator cap area as the gauge/connection part of the tool is kind of bulky. I'll give a review when I'm able to use it on a Ranger. It won't be long before I have a 2010-12 800 in here, it was 100 on Sunday.
 

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I have a 1/4 inch tube that I just need to go to the local wine brewing supply and get the proper sized bottle stopper to adapt to whatever size the radiator fill hole is.
.They have the stoppers setup with hole in them for use with air lock. Supposed to be another toasty weekend in TX. Near perfect in MN at mid to upper 70's. Canadians forgot the fridge door open today, 63
 

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Discussion Starter #20
UPDATE: I found a sneaky leak that dropped the radiator levels so low that it finally caused the engine overheating.

Just below the thermostat housing is a round plug on the block. I finally caught it peeing a pin size jet stream of coolant from a single point on the periphery of the plug! Over time, it dropped the coolant level so low the engine was overheating.

How to stop that leak without pulling the engine?!! How about some high heat resistant epoxy applied direction on the leak?

My lesson: Don't ever buy a "beater" ATV from a son-in-law. All sorts of problems to sort out. :)
 
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