CB650F Coolant change after repair

[Goblin]

Need some advice with a coolant change. I helped a friend with his CB650F (2016) that had a coolant leak coming from the thermostat case. So I replaced the rubber O-ring and tried to fill her up with fresh coolant.

I know about air pockets that can trapped in the system, so I gently put the first liter coolant in and gave the system time to let the air escape. Following the service manual (bleeding the radiator bleed bolt) tried to fill the second liter coolant in, but the radiator was full after I put in the next half liter. So I started the bike to bleed the system, but the coolant is coming straight out of the radiator. Long story short, I can’t get more than a liter coolant in her (I must overlooked something). This is not the first coolant change I did in my life but this bike is giving me a headache ☹️

 

[miweber929]

I don't have a service manual in front of me but is there a bleed screw on the front of the engine block? Usually that will get stuff flowing. Sounds like you have a classic air lock behind the thermostat. I’d try to find something on the other side to get things flowing; I usually tip the bike from side to side and pinch hoses which sometimes gets them flowing.

Good luck!!!!

 

[Brammers]

Do a full drain and go again.

J

 

[Goblin]

There is only a bleed screw on the side of the radiator. I did tip the bike from side to side and pinch the hoses. Yeah I think I have a air lock behind the thermostat. I did a full drain and tried it again but with the same result, what the heck am I missing 🧐 (a coolant change isn’t rocket science)

 

[Goblin]

Update on the coolant change for the CB650F. For some reason the air wouldn’t escape from the system doing it the traditional way. So I used the airlift way, pulling a vacuum in the system With the vacuum purge tool. All is fine now, all coolant is in and the bike is running again 👍

 

[WinCB]

I'm experiencing a similar issue to that described by Goblin in the original post when trying to replace my coolant.

I've drained and refilled it as per the instructions and the manual states 2.5 litre capacity but I'm only able to get approximately 1.9 litres back in.

I've tried twice now with the same result and do not have access to any vacuum purge equipment mentioned earlier in this thread so I would very much appreciate it if anyone could offer any additional advice as to how I might remove any air locks that may be in the system, please.

I was about to say that I cannot keep draining and refilling in the hope that eventually it accepts the full capacity because that could get expensive, but I guess I could capture the new stuff that I'm draining and simply keep retrying with that instead of keep using brand new stuff out of a container each time... unless of course someone tells me that would not be a good idea.

What are the implications of running with less than the specified amount of coolant in the system?

Thanks in advance.

 

[Brammers]

I've gotten more out by disconnecting a hose at the front of the engine.

To your other point, you will not be running less coolant, if you followed the top up procedure correctly... You will just have swapped out less old coolant. The 650 manual is very good at getting rid of air locks etc.

I've done it by the book and drained a bit more by releasing a hose... Neither had a negative impact if you're changing the coolant every 3 years.

J

 

[WinCB]

Apologies for the delayed response - I haven't been around much over the past few weeks.

Thanks for taking the time to reply, however, I'm still a little concerned because I tried to measure what I took out when I drained it and I'm pretty sure that I got more than 1.9 litres out.

Maybe I'll just have to try draining and refilling again and see what happens. Is there any reason why I should not capture what I take out and simply refill using that, given that it was new coolant when I tried the first time?

Thanks.

 

[Brammers]

If you can be sure it isn't contaminated, then reuse is possible.

But anything close to 2L as a change is fine. Honestly I've done that for years.

You've swapped the fluid twice... That's more than good enough.

Just make sure the radiator is full (check after a run once it's cooled) and there's an inch or two in the bottom of the coolant tank when cold. It'll be fine.

Don't want to come across as patronising but you're overthinking it.

J