Cooling trouble after water pump rebuild.

[n4cer26]

Just finished replacing water pump seals and impeller on my 97 Magnum 425 due to oil leak out of the weep hole. Haven't owned it very long and have only riden around the yard a couple times because I only recently got it. I installed a new bullet aluminum impeller and made sure the nut was tight and that thebimpeller was not spinning on the shaft. My oil leak is now fixed.

 

I filled the radiator and let it run. The motor seemed to be getting hot and the radiator fan never came on. Looking into the radiator its hard to tell if the coolant is circulating due to the vibration of the quad. Never looked down the radiator prior to pump rebuild so not sure how it compares now.

 

Think it could be a bad thermostat or air in the system? Is there a refill procedure? Any advise is appreciated!

 

Sent from my SM-F926U using Tapatalk

 

 

[Mech]

I'm not familiar with polaris at all but it's possible there might be a bleed bung or something to get the air out.. The manual will say.

Other than that you can often tell if the pump is working by giving the engine a rev and the fluid level in the radiator will drop a bit then come back up as the fluid starts to circulate.

Then, it's possible the thermostat's stuck. It can and does happen that once a thermostat has been in use, in antifreeze, and then allowed to dry out, they get sticky. You know how antifreeze feels a bit claagy(is that a word?), sort of grippy on your finger, well that's the effect it has on the thermostat. Mostly after a bit they do open and then come right again.. but you have to be monitoring the temp very carefully waiting for it to open. Sometimes they get just slightly hotter than they should before opening that first time, and then after that they work as intended. If you are sitting watching it and it gets too hot turn it off and leave it and then try it again. Sometimes they come right on the second run.

Most thermostats are fully open about 85-96 degrees C, and most, (car fans anyway), come on about 104-106 degrees C, and then turn off at about 4 degrees below starting temp.. That's your leeway.  Don't let it get hotter than about 104 and it should be fine.. 

[Gwbarm]

Good job getting the seals in with no problem! It sounds like you may have an air pocket inside the cooling chamber in your engine, there should be a rogue screw that looks like it does nothing on the engine, screw it out until coolant starts coming out and close it back, then you have bleed all the air in the system out. It's also possible you could have air in the radiator also, it will eventually work itself out run it a little with the cap off, and sure its possible the thermostat stuck from getting dry after being in coolant so many years.

[johniii]

Sounds like air in the cooling system. The thermostat should be changed if your doing the cooling system. 

Edited July 18, 2023 by johniii

[n4cer26]

Good job getting the seals in with no problem! It sounds like you may have an air pocket inside the cooling chamber in your engine, there should be a rogue screw that looks like it does nothing on the engine, screw it out until coolant starts coming out and close it back, then you have bleed all the air in the system out. It's also possible you could have air in the radiator also, it will eventually work itself out run it a little with the cap off, and sure its possible the thermostat stuck from getting dry after being in coolant so many years.

Thanks for your reply! Any idea where this "rogue screw" is located on the engine? I wouldn't begin to know where to look.

Sent from my SM-F926U using Tapatalk

[Gwbarm]

Not sure! Im not that familiar with these older Polaris engines, but check around where the hose and water pump connect and follow the cooling chamber, I know you can't really know exactly , but somewhere in the vicinity of how you think the cooling chamber might run and see if you see one. I will also see if I can find a manual and take a look also.

[n4cer26]

Not sure! Im not that familiar with these older Polaris engines, but check around where the hose and water pump connect and follow the cooling chamber, I know you can't really know exactly , but somewhere in the vicinity of how you think the cooling chamber might run and see if you see one. I will also see if I can find a manual and take a look also.

Will do. Thank you for your time and assistance with this. I really appreciate it!

Sent from my SM-F926U using Tapatalk

[johniii]

Check this out. Free manuals are online. Hope this helps.

[n4cer26]

Check this out. Free manuals are online. Hope this helps.

Thanks a million!

Sent from my SM-F926U using Tapatalk

[johniii]

No problem, good luck!!

[Mech]

If there is a bleed screw it will be in the highest point on the engine's cooling passages.

I looked for the thermo opening but in the several manuals I looked in they didn't quote a figure. I did notice the fan on temp is a bit lower than I suggested it will be.

The manuals all said that there is a small bleed hole in the radiator filler neck and to check it's not blocked. There's a bigger hole going to the overflow pipe, and then straight below that, below where the cap seals, on a tube going down, there is a small hole.

[n4cer26]

If there is a bleed screw it will be in the highest point on the engine's cooling passages.
I looked for the thermo opening but in the several manuals I looked in they didn't quote a figure. I did notice the fan on temp is a bit lower than I suggested it will be.
The manuals all said that there is a small bleed hole in the radiator filler neck and to check it's not blocked. There's a bigger hole going to the overflow pipe, and then straight below that, below where the cap seals, on a tube going down, there is a small hole.

Thank you! Turns out the thermostat is opening and the water is circulating to the radiator. The fan would not come one at all. I made a jump wire for the connector on the thermal switch and the fan powers on and runs fine. The engine cools appropriately with the fan running. Ordered a new thermal switch and will leave the jump wire in place until then. Thanks

Sent from my SM-F926U using Tapatalk

[Mech]

Good one.

I'm glad someone in here bothers to test and diagnose things before buying parts !

[n4cer26]

Good one.
I'm glad someone in here bothers to test and diagnose things before buying parts !

Yeah, I try to but sometimes I jump the gun and buy stuff I don't end up needing. I'm getting better. Boy that water pump was a job in the Magnum but I now have zero oil leaking! Worth it!

Sent from my SM-F926U using Tapatalk

[johniii]

Great news. If you go to manuals lib.com they have the manual. Good to have a copy.

[Gwbarm]

From the manual posted it said the bleed screw was at the top of the cylinder head.

[n4cer26]

From the manual posted it said the bleed screw was at the top of the cylinder head.

Yeah, if it has one I would think it would have to be in the cylinder head somewhere!

Sent from my SM-F926U using Tapatalk