Radiator Question

[Juan_Banjovy]

Not really a problem but I'm curious if others have seen this. The overflow tank won't stay at the upper line. It fills up to the top of the tank. I filled up the radiator to the top & syphoned out the overflow tank until it was at the "upper" line. Rode it awhile, came home & let it sit a few hours. Overflow tank was filled to the top & radiator coolant level was 1.5" lower. Should that matter? Leave it alone or maybe have something checked?

 

[DSMMECHANIC]

Could be a bad thermostat/radiator cap, water pump or coolant fan not working. But with the radiator down that much coolant I believe the next may be the unfortunate problem. You are blowing coolant out through the overflow. You are getting exhaust gasses in your radiator which pushes the coolant out of the bike. I would have a mechanic run the needed tests to see if you have exhaust gasses in the radiator. Or a compression test and look for a drop in pressure. If there is, pop the radiator cap and see if you see air bubbles coming to the top. This could be a bad head gasket or cracked cylinder and or head itself. This should help you get going in the right direction. I hope this helps and good luck. Pray for a faulty thermostat or radiator cap!!!!!!!

 

[Alias]

Not really a problem but I'm curious if others have seen this. The overflow tank won't stay at the upper line. It fills up to the top of the tank. I filled up the radiator to the top & syphoned out the overflow tank until it was at the "upper" line. Rode it awhile, came home & let it sit a few hours. Overflow tank was filled to the top & radiator coolant level was 1.5" lower. Should that matter? Leave it alone or maybe have something checked?

Check the hose running between the radiator and the overflow tank. If it has the slightest air leak, it will suck up air instead of the fluid when the radiator cools down.

 

[Deleted member 1183]

Not really a problem but I'm curious if others have seen this. The overflow tank won't stay at the upper line. It fills up to the top of the tank. I filled up the radiator to the top & syphoned out the overflow tank until it was at the "upper" line. Rode it awhile, came home & let it sit a few hours. Overflow tank was filled to the top & radiator coolant level was 1.5" lower. Should that matter? Leave it alone or maybe have something checked?

Not unusual if the coolant was recently changed. There will be residual air in nooks and crannies in the system that will need removing and might show these symptoms for a while. However if the coolant wasn't changed then there might be an issue.
If You fill to the max line on the overflow when the engine is cold then expansion will occur when the motor is fully up to operating temp. That will result in the level raising above the max line. However when cold again the level should drop back to the max line. I have seen issues where the return valve is not allowing coolant back tho and that would be my first port of call.

 

[dduelin]

Is this an ongoing issue or a one time thing that happened yesterday?

There is a procedure to filling the radiator. It's done with the engine cold. Top off the radiator and start the engine. Leave off the radiator cap, don't install it. Let the engine warm up about 3-5 minutes. With the engine warm and idling, snap the throttle open and shut 3 or 4 times to "burp" air out of the system. Turn off the engine. Top off the radiator as necessary to the neck. Replace the cap. Check the overflow tank and fill to the high mark.

If the system was not burped and purged of air it makes the coolant level artificially high when cold and when hot the air expands and pushes coolant out and possibly fills the tank.

Now if it's doing what you describe every time you ride it then check for more serious issues but I doubt you have any. These are very robust engines with a small amount of coolant. If you are loosing coolant while riding the engine will overheat in short order and trigger the check engine light.

 

[MZ5]

Follow dduelin’s instructions and check as Griff describes. Personally, I doubt there’s a head gasket problem.

If the radiator coolant level declines even after following the instructions and checks, if it was my bike I’d next replace the radiator cap (assuming you don’t have any drips anywhere). If it’s not sealing and thus the system isn’t coming up to design pressure, coolant _could_ boil off without a head gasket leak. A failed rad cap seal could also prevent the system pulling coolant in from the expansion tank (as could a cracked hose between rad and tank). Follow the other instructions first, though.

 

[Juan_Banjovy]

Is this an ongoing issue or a one time thing that happened yesterday?

There is a procedure to filling the radiator. It's done with the engine cold. Top off the radiator and start the engine. Leave off the radiator cap, don't install it. Let the engine warm up about 3-5 minutes. With the engine warm and idling, snap the throttle open and shut 3 or 4 times to "burp" air out of the system. Turn off the engine. Top off the radiator as necessary to the neck. Replace the cap. Check the overflow tank and fill to the high mark.

If the system was not burped and purged of air it makes the coolant level artificially high when cold and when hot the air expands and pushes coolant out and possibly fills the tank.

Now if it's doing what you describe every time you ride it then check for more serious issues but I doubt you have any. These are very robust engines with a small amount of coolant. If you are loosing coolant while riding the engine will overheat in short order and trigger the check engine light.

It just recently happened. Last week I noticed white spray along the right side of the bike that lead to the radiator cap. I removed the cap & it was 1 1/2" low so I topped it off with coolant & wiped off the white stuff. Rode it again & the white stuff returned. It overflowed out the radiator cap & spewed all over the right side of the bike again. It was 1 1/2" low again. I didn't top it off again. That's when I noticed the overflow tank was full instead of at the line. I ordered a new radiator cap & it should be here in a week. I'll check the clamps on all the hoses & make sure they're tight.

 

[Juan_Banjovy]

Update: Ordered a new radiator cap July 17 & it's not here! UPS says they got it to the U.S. Postal Service. USPS says they never got it. Meaning, it's lost. I'll give them a week to find it & order another radiator cap. From my dealer, not Partszilla. Anyway I checked all hose connections & they're on tight.

 

[Juan_Banjovy]

Update: USPS found my radiator cap & got it to me today. I compared it to the old radiator cap & learned why it leaked. I always had to fight this cap to get it on or off & the 2 metal tabs were bent meaning it wasn't sealing fully. I topped off the radiator, installed the new cap & went for a ride then parked it for several hours. Fixed. Overflow tank is at the line now, not to the top. Radiator is still full. Getting the new cap off was a fight as usual. I bent the tabs again but this time I straightened them with pliers. Getting it back on again was also a fight. Took 30 minutes to check my coolant level. That cap isn't coming off again until I change coolant in a few years. What a PITA. Here's a pic of the bike after a ride with the old radiator cap.

 

[MZ5]

Glad you got it fixed!

I found it relatively easy to bend those tabs on the caps, too. It’s tight and tricky or fiddly to get the cap off until you get the knack of it (and it’s still less easy than most cars).

 

[GregC]

reminds me of an expression an old mech engr I knew used: "if it jams, force it. If it breaks, you probably needed a new one anyway."

I had a wee leak on my 2015 ... due to the Dealer not reattaching the overflow hose to the overflow tank after the 16,000 service. I noticed it as soon as I got home because I had coolant sprayed down the right side of the bike. That was the last time the dealer has seen my bike (took it there because I did not want to tackle the valve inspection and the bike was still under warranty).