Overheating after coolant flush and change

After flushing and changing the coolant last week, the bike started getting hot (230) around town. I read about burping the system, so I tried that today. I removed the radiator cap and allowed the engine to come up to temp. There appeared to be good flow, but when the engine reached ~220, it started spitting coolant out of the radiator. I let it continue for a minute or two with the thought that it was just air "burping". When I shut it down (225) I checked the coolant level and the radiator appeared to have lost quite a bit of coolant. I revved it a couple of times during the spitting phase and it caused a definite increase in the amount of coolant coming out.

Am I F(*^*&%^ED ????


I refilled the radiator afterwards. Overflow tank was at the low mark.


When I initially opened the radiator, it was full. Overflow reservoir was at low mark.


Exhaust does not smell of coolant. No external leaks noted.

There was no overheat issue prior to flush and change. Even during low speed parking lot maneuver practice for 45 minutes and highway speed cruising for ~75 minutes.

 

My interpritation of burping the system:

(starting with room temp coolant, never open the cap when that stuff is hot.)
open the cap
start the bike
let it idle till the temp reaches 170 deg F
rev the engine (no need to redline it, but get it past 7K) a couple times (two or three times)
shut it down, and let it cool to room temp
refill coolant as needed

When you checked the coolant while it was hot, the system would have pulled from the overflow resivor, prolly why it was low.

Yes, when coolant was spitting out of the cap I would bet some air went with it.

You should be fine, but wait till someone who knows a little more than me chimes in.

 

Did I let it get too hot?

 

Yea, that is what caused the spitting, that and you rev'ed it while it was that hot.

 

Phew!!! Hope that is the case! I'll report back when I try it again. Thanks!!!

 

I'll bet you have air in the system------
No big deal but it's a pain in the ass to get it out and you do need to get it out.
Try squeezing the hoses while it's running and then let it sit on the sidestand overnight with the cap off.
Just keep working with it and be careful, hot coolant is nasty!

 

AS described, you need to check/top up the radiator (not just the overflow) once or twice AFTER it has cooled down after a short ride.

ALWAYS helps to state your bike's year and mileage !!

 

2001 and 45k miles Thanks!

 

Burped the system as described. Rode to work and temps hit 240. A little bit of coolant came out of the oerflow tank. I rode home after work and heard boiling in the radiator after shutdown. Bad radiator cap ?

 

That could easily be your problem !! Caps don't last forever as rubber gasket may crack or harden, spring weaken over time. It's amazing that replacing the cap wasn't the FIRST thing people here recommended !

 

Air in the system, OR more likely, Bad thermostat that is not opening...

 

Did you happen to disconnect the fan connector when flushing and if so forget to plug it back. I did that once. So figured it 's worth mentioning. Do you hear the fan coming on when it gets hot?

If not the fan and the system is free of air I am guessing its the T-stat.

 

Fan is on at 220.

 

My guess is the cap then. If the coolant level in the in the overflow resivor changed than the thermostat is functioning, it could be on its way out, but caps are cheap and easy to try.

 

Have a day off today, so this is my plan: Bought new radiator cap: Murray Ultra 7516. Looks and fits identically and has same 1.1 bar/16psi rating. Siphoned off ~3 oz of coolant and added water wetter. Will report back after 1 hour ride.

 

Well got back from highway cruise, parking lot low speed practice and a little suburban riding. Temp hit 220, fan kicked on and hovered between 210-220 during practice and in traffic. 183 on the highway cruising at 80 indicated in 5th and 6th gear. No boiling sounds when I returned home. So far the rad cap replacement seems to have done the trick. Will update as I ride more. Thanks VFRWorld!

 

That is exactly how it is suppose to act. Looks like you got it!

One thing to check your thermostat. First thing in the morning, start the bike and let it idle. Watch your temp guage. When it hits somewhere around 170/175 the thermostat should start to open. Because the coolant in the radiators is still cold the temp gauge should fall back a few degrees when the thermostat opens. When you see this drop in temp you know the thermostat has started to open. This is an indication that the thermostat is fine.

 

I kind is tried a variation of this before I took off. I let it idle and felt the left side radiator. It stayed cool until about 180 then warmed rapidly. I *think* that means the thermostat is ok.

 

You are Correct!

 

1998 47k

Glad to see this thread, did a coolant change last weekend and have rode twice since with near overheat temps observed.
Today on commute to work 233-235F at 65 on interstate, 64F ambient with 94% humidity
When I parked at work, crept up to 254F, I shut it down then in my parking spot to head into work.
I will try removing more air tonight and stop to find a radiator cap for the bike as well.