Engine Guards and Coolant Bottle Relocation

How did you know you had air bubbles?

What I did, is make sure that my radiator was topped off. I also filled my coolant overflow can to the top; under the seat in the airbox. When the engine got to temperature, the excess coolant from the engine pushed the coolant out of the overflow bottle's vent line.

My assumption is that the hose from the radiator to the coolant overflow would now be full of hot coolant (without air bubbles); and stay that way until the radiator and motor cooled off, and pulled the coolant back into the radiator from the overflow bottle. Since the hose is attached to the bottom of the overflow bottle; it's not going to draw any air.

My overflow bottle has only spewed coolant once. It hasn't done it since. I assume it is working as designed.
 

I used clear hose and could easily see the bubbles. There's a lot more air than you think. The coolant never truly pushes the air out of the line. If there is enough flow out during a particularly long heat cycle, it is likely that it sucked air back into the radiator during cool down. At least that is what I observed.
 

Hmmmmm...... interesting. That line needs to be bled of air then.

I may have to consider mounting a overflow bottle closer to the radiator. ****....

I'm going to pop off the radiator cap this morning, and see what the coolant level is. If it's still at the top of the radiator filler neck; I'm golden. However, I'll have to refill the overflow bottle again since I've broken the coolant suction state between the radiator and the hose to the overflow bottle.
 
Last edited by a moderator:


One hose on top & another at the bottom.
 
Whilst the R3 is my first W/C bike - I have had "experience" of air in car cooling systems (all men should learn on Land Rovers).

Bubbles mean reduced efficiency - But also accelerate corrosion - especially on gaskets. ONE objective of that overflow tank is to auto bleed air OUT. If the coolant level in the tank is below the radiator top then you WILL get an air pocket in the rad. And when that gets TOO big and the rad pressure builds - I'd want to be a long way from the rad.

I had a bleed cap fracture last year. It's like a steam&grit blaster - will burr it's way through paint/leather/anything pretty much if there's enough of it and it's VERY hot. Just saying!
 

I have to admit this has me a bit puzzled. Assuming the radiator is completely full, and the coolant level is at the Min Cold line, then wouldn't the air in the line be pushed into the overflow bottle and since its fed from the bottom, bubble to the top? And if so, then as the engine cools and draws coolant back from the bottom of the overflow bottle, how does the air get back into the system?

I've had my overflow bottle below the top of the radiator through a couple of Phoenix summers and have not had an overheating problem or a loss of coolant.

Not trying to be a smart ass, I just don't understand how the air stays in the system, assuming the overflow bottle level rises to the Max Hot line, as mine does.
 
GPM said:
I just don't understand how the air stays in the system, assuming the overflow bottle level rises to the Max Hot line, as mine does.
Click to expand...
It's easy - bubbles go UP and can/will get stuck in crevices etc during filling - the tinyest mark and that's where they'll cling. Over time they get shifted about and will follow the law's of nature and go UP. If the radiator is the highest point of the circuit - That's where they'll eventually stay.

Over time the air bubbles CAN collect in pockets and when hot begin to do what you don't want - expand. This pushes more liquid out (not air) and reduces the efficiency - as the engine cools so does the air and the fluid cames back into the circuit. But you want liquid in the circuit when the brute runs really. The idea is to get the air out of the active circuit. If they're able to move out of the pressure cap upwards - good - If not they stay in the circuit - bad.

If you look at systems where the expansion reservoir is below the radiator top - There are always bleed valves at the TOP of the circuit.
 
You must log in or register to reply here.

Similar threads

LED Headlights and Indicator install
Replies
0
Views
133
BigBri81
Coolant flush
Replies
3
Views
999
atomsplitter
alarm system and the idiot that fitted it
Replies
1
Views
712
RocketSteve
new to forum/map for triples and tors on 2007 with bypass cat
Replies
2
Views
494
pastorg
how to fit front engine bars
Replies
6
Views
479
Blastedbones
Menu
Log in
Register