Help - air in cooling system? Overheats quickly

[Ptaaty]

I just did a cooling flush and change...and when checking afterward, after a minute it will suddenly heat up quickly.

I've never done a coolant change before so I might have messed something up. When I did the water flush through it didn't have this problem...

System was completely drained...after the normal radiator cap removal and drain plug, I put the cap back on then pressurized the venting hose (the one that comes off the overflow tank and goes to the ground) to remove all fluid from the overflow tank.

Not sure what to do, I removed the radiator cap and let it warm and after a minute or two I can hear the gurgling and coolant will start to sputter out, I assume driven by boiling down on the radiator or cooling sleeve. Also tried rocking bike back and forth.

 

[MrZappo]

Is their fluid in the reservoir?

 

[Ptaaty]

Is their fluid in the reservoir?

Yes, fluid in reservoir and in the radiator. Three times I let it partially cool with cap off then ran it a bit (bubbling, but steamy). After it cooled down, I added more to the radiator, cap on this time, then ran until fans ran again.

 

[ahchiu]

Keep the radiator cap on and to fill to the Full line, after a couple of heat cycle it will purge out all the air by heat expansion and cooling contracting of the coolant it will draw from the over flow, after it stabilized fill the over flow up to the full line, do not romove the cap.

 

[MadRussian]

Also, with bike running, lean bike left and right, as far as you can without dropping it.

That will help get any air out as well.

 

[Fred W]

Keep the radiator cap on and to fill to the Full line, after a couple of heat cycle it will purge out all the air by heat expansion and cooling contracting of the coolant it will draw from the over flow, after it stabilized fill the over flow up to the full line, do not romove the cap.

Yes this ^

Every time that you remove the cap you are allowing air into the radiator. What's supposed to happen is the air bubbles to the neck of the radiator and the pressure blows them out into the recovery tank. Then (if you leave the cap on) as it cools down the partial vacuum will draw coolant from the tank back into the radiator. It takes several heat /cool cycles to get all the air out for good.

Do not pay much attention to the fast changes in the temp display during this time. The sensor is plugged into the end of the pipe over the valve cover. It is a display of coolant (or air bubble) temp at that point, not of the engine.

By the way, if you never go through the completely unnecessary steps of flushing with water and blowing it out, you will never have this issue again. Just drain the coolant from the coolant drain screw and then refill it at the radiator cap with 50/50 coolant and you get very little air in the system. The vast majority of the coolant is replaced with new, and what is left is in no way harmful to the engine.

 

[08FJR4ME]

Where is the coolant drain screw? I believe the last time I did this I pulled the hose off the pump and refilled. Makes a mess but worked.

Dave

 

[Ptaaty]

Where is the coolant drain screw? I believe the last time I did this I pulled the hose off the pump and refilled. Makes a mess but worked.
Dave

It's the bottom screw on the pump face itself. It has a copper washer around it and hex head.

 

[Ptaaty]

Keep the radiator cap on and to fill to the Full line, after a couple of heat cycle it will purge out all the air by heat expansion and cooling contracting of the coolant it will draw from the over flow, after it stabilized fill the over flow up to the full line, do not romove the cap.

Yes this ^

Every time that you remove the cap you are allowing air into the radiator. What's supposed to happen is the air bubbles to the neck of the radiator and the pressure blows them out into the recovery tank. Then (if you leave the cap on) as it cools down the partial vacuum will draw coolant from the tank back into the radiator. It takes several heat /cool cycles to get all the air out for good.

Do not pay much attention to the fast changes in the temp display during this time. The sensor is plugged into the end of the pipe over the valve cover. It is a display of coolant (or air bubble) temp at that point, not of the engine.

By the way, if you never go through the completely unnecessary steps of flushing with water and blowing it out, you will never have this issue again. Just drain the coolant from the coolant drain screw and then refill it at the radiator cap with 50/50 coolant and you get very little air in the system. The vast majority of the coolant is replaced with new, and what is left is in no way harmful to the engine.

Thanks for the inputs. It was taking the cap off that I think caused the issue to not resolve...this is backward of most cars so it threw me.

FYI - I agree with your statements about flushing for the most part. I suppose it is likely you would never have to flush and fully empty (including reservoir). However, I am the second owner and had no idea what was in there before, and was switching from the blue stuff that was in there, to Peak orange (no silicate, etc).

I think I might make a "BJ II" post in tech to show Gen 2 newbs (like me) how to change coolant with minimal effort and have an *optional* step when you potentially change coolant type (owners first or for whatever other reason). There was tons of Gen 1 info and lots of conflicting Gen 2 stuff. For example, Gen 2 doesn't even have a drain on the overflow res...you need to pressurize the little tube hanging under the bike.

 

[08FJR4ME]

Where is the coolant drain screw? I believe the last time I did this I pulled the hose off the pump and refilled. Makes a mess but worked.
Dave

It's the bottom screw on the pump face itself. It has a copper washer around it and hex head.

Thanks, I will try that next time which will be soon. Gotta love this forum.

Dave

 

[Ptaaty]

Keep the radiator cap on and to fill to the Full line, after a couple of heat cycle it will purge out all the air by heat expansion and cooling contracting of the coolant it will draw from the over flow, after it stabilized fill the over flow up to the full line, do not romove the cap.

Thanks, this was exactly it. I refilled both reservoir and radiator again to full, ran it to temp system closed (cap on). Refilled reservoir again, kept radiator cap on, ran it again to temp. This morning the reservoir was down to the bottom line (went from full to low line last night when it contracted / filled in). This morning it worked like a champ, no issues with quick heating....in fact fans wouldn't even kick in after 10 minutes at idle so it's all good.

 

[Ptaaty]

Where is the coolant drain screw? I believe the last time I did this I pulled the hose off the pump and refilled. Makes a mess but worked.
Dave

It's the bottom screw on the pump face itself. It has a copper washer around it and hex head.

Thanks, I will try that next time which will be soon. Gotta love this forum.

Dave

FYI - I think the easiest way to change is just remove the single bottom/rear fairing bolt (right side of the bike version of the one you remove for oil changes), then set up a shield, like thin flexible plastic (I used my daughters old 3 ring binder cover) to direct flow down (fluid comes out fast!). I think you need a shield like that regardless.

On the left side, all you really need to do is expose the rad cap...just remove the black plastic around the glove box, aft section only. Buy a flexible tube funnel with handle and shutoff (<$5 at walmart) and you can easily refill both rez and rad with no mess and no need to remove more fairing.