2015 RT radiator... Where's the Juice?

[landev]

I'm in the process of replacing the antifreeze in my RT. I'm following the instructions in the Clymer's manual... did the drain of cylinders, both radiators, and reservoir. I'm in the process of refilling. Tipped the bike on the side stand, waggled it back and forth, poured in coolant very slowly. The manual say's it take 1.75 liter... it will only take 1.25 thus far. As per instructions, I ran the bike up to operating temp, shut it down and added perhaps another .1 liter. Ran it again... still not taking anymore.

Feeling the left radiator... it's cool whereas the right is warm, so it seems no coolant is getting to the left side. I tried burping again, squeezed the lines, nope... can't get any any more fluid in.

Has anyone run into this? Seems like there's an airlock but I don't know how to remedy it other than draining the system (at least the left side) again...

Thanks for your experience and wisdom in advance!

-l-

 

[52184]

I don’t have an RT, but I use this tool for changing coolant on all three of my water-cooled bikes. Vacuum filling the system pretty much eliminates the chance of an airlock.

Best,
DeVern

 

[Boxflyer]

Here's the entire system.
The coolant must go thru the LH side before it gets to the RH side.

Are you touching the radiator tanks, or feeling discharge air from the shrouds?

When I'm riding in the winter, I warm my left hand in the discharge chute, but on the right side, it's mostly just cool air by the time it gets over there.

 

[landev]

Cool looking solution... and affordable... I'll order one of those! I have to do a more extensive service on my 2015 GSW (K52) and it also includes a coolant change. I changed coolant on the Adventure ~ 3 years ago and didn't run into this issue, so thought change on the K51 would be a piece of cake... nope!
In the meantime, in an attempt of getting this bike off the lift asap, my thought was to remove the smaller hose connected to the top of the left radiator (see photo) and try to bleed through there. I'm assuming it's an overflow for the left side, though that's just a stab in the dark.
I'm guessing your recommendation would be just to wait for delivery of a vacuum bleeder, no? I'm sure it'd be less messy!

Thanks for that tip. Can you ever have too many tools?

Best!

-l-

 

[landev]

Boxflyer,

Now I'm even more confused. That's an awesome diagram... but if the coolant must first go through the left side (I was feeling the radiator itself) then that radiator being cool makes no sense to me. The right side was definitely warm... the left side, not at all.

 

[Boxflyer]

The path of the "red/hot" coolant thru the radiators is not really back and forth as depicted…the tubes are vertical and all/any fluid in the LH lower radiator holding tank can travel up any tube it finds a low resistance path, and likewise down from the top tank on the RH side.
In theory, you could have most of the coolant going up the LH radiator in just a few tubes and the RH side filled….but that's just theory!

I'm thinking that in a few heat/cool cycles any trapped air will find it's way to the holding tank and you will be just fine.

Here's where the temp sensor is circled in green. It is at the hottest collected point of coolant just before the thermostat and if you don't show an overheat with the bars on your dash and the fan in the RH shroud runs, then things are OK.

 

[landev]

Thanks for that detail, but my head still hurts on this one.

I did a warm up of the bike twice. Both times just idling and a few revs (it's currently snowing.) The first time, felt the left radiator when I shut off the bike... it was distinctly cool. I mistakenly thought the lower line running to that radiator was the output... it was cool as well. The right side radiator was warm as was the lower line (output according to the diagram.)

I did a second warming of the bike to operating temp when my first attempt only added ~ .1 liter of fluid. This time I left the radiator cap off as it warmed. At operating temperature, the coolant on the right side was steaming in the right radiator and the lower line leading to the engine was very warm... the left was still cool... upper and lower lines. I don't understand why my observations seem completely bass-ackwards from what I expect having viewed the diagram!