Confused - doesn’t seem to be head gasket but air bubbles like champagne?

[Firkhamhall]

Hello!  First post, be gentle and know early I am a DIY dunce!  :)

I have tried to search but couldn’t find my mix of problem (and searching for coolant and/or bubbles brings up masses of other topics)

Bike runs well enough but when it comes to a stop after a run, there are bubbles flowing into the reservoir like champagne, a constant fast flow and then, WHOOSH, the tank overflows.

Clues/things I’ve done.

1. I think I’ve correctly ruled out a head gasket issue, no white smoke, no sweet smell, rad cap is clean, no gunge at all, coolant isn’t oily.
2. Pumps seems to be working as I topped up the now empty reservoir with “orange” coolant and that has mixed and recirculated.
3. I can manually squeeze bubbles into the reservoir from the lowest pump pipe and seemingly squeeze all air out (when cold).
4. The water pump pipe always seems soft even when hot, the other pipes do seem to go hard with pressure.

So, I assume air is getting in when hot, can’t figure out where.

Where to start first?

Pipes (somewhere), rad cap (try a new gasket), could it be a water pump seal needed?

All advice appreciated.

[frankenduck]

It's probably the radiator cap. Part 17111464720. (That includes gaskets.)

[Firkhamhall]

OK, I’ll try that first then! 👍. Thanks for the P/N

[Laitch]

Bike runs well enough but when it comes to a stop after a run, there are bubbles flowing into the reservoir like champagne, a constant fast flow and then, WHOOSH, the tank overflows.

Before or during this chaos did the temperature lamp in the instrument cluster light up? How long have you owned this Brick and how many miles are on it?

[Firkhamhall]

Before or during this chaos did the temperature lamp in the instrument cluster light up? How long have you owned this Brick and how many miles are on it?

Hi Laitch.  Didn’t notice a warning lamp but it’s a custom build so not sure it even has one!  There’s a red light in the cluster that goes off after starting, takes a moment or two, presuming it’s that - either way it shows no warning for this issue, just the large spit of reservoir water.

Weirdly, the coolant level doesn’t go down, just seemingly just what’s in the reservoir and that is on MIN, no higher, as the neck fill hasn’t dropped. (I thought trapped air, but the bubbles are escaping past that to get to the reservoir. 🤷‍♂️)

I’ve owned it 4 days (!) buyer beware, cheap and no recourse. Miles unknown, except for what it has done after the build, under 500.

[Laitch]

The red light goes off after starting is likely the charging indicator light. Seems like that's working anyway.  All is not lost. When you get a replacement cap, follow coolant replacement instructions explicitly and we can all assess the outcome. A K1100 service manual is downloadable from the Service Manual section of this site's technical directory.

[Firkhamhall]

The red light goes off after starting is likely the charging indicator light. Seems like that's working anyway.  All is not lost. When you get a replacement cap, follow coolant replacement instructions explicitly and we can all assess the outcome. A K1100 service manual is downloadable from the Service Manual section of this site's technical directory.

Thanks!  I bought a used Clymers book too, determined to do some stuff myself

[Scott_]

You say it's a custom build?... some pictures wouldn't hurt.
In addition to what the other have noted:
Is the cooling fan coming on at all?
I'd be curious of what condition the thermostat is in.
As you are replacing the coolant, don't forget only mix it with distilled water---not tap water.(Tap water has minerals in it that build up in the radiator core, on the thermostat and on the water pump impeller)

[Firkhamhall]

You say it's a custom build?... some pictures wouldn't hurt.
In addition to what the other have noted:
Is the cooling fan coming on at all?
I'd be curious of what condition the thermostat is in.
As you are replacing the coolant, don't forget only mix it with distilled water---not tap water.(Tap water has minerals in it that build up in the radiator core, on the thermostat and on the water pump impeller)

Hi Scott,

I have heard the fan kick in, yes. (Once) it spins quite freely too.
I’ve ordered a new thermostat with the cap seeing as I’m draining it anyway, I might as well do both.
Distilled, check, got some.

Pics, hopefully it works…


F6AC0E47-D4B7-4BBA-ACE1-9D4AF369DFA9.jpeg (133.15 kB . 768x576 - viewed 359 times)

[frankenduck]

If you've only had it for 4 days:

http://bit.ly/new2kbikes
http://bit.ly/kbikemandm

[Firkhamhall]

If you've only had it for 4 days:

http://bit.ly/new2kbikes
http://bit.ly/kbikemandm

Thanks!

[The Mighty Gryphon]

4 days?  How many times did you ride, how many miles before it puked the coolant?

Do you know if the bike had a fresh coolant change just before they sold it to you? 

It isn't unusual to have an air bubble in the system that takes a couple heat/cool down cycles to get out.

[Jethroww]

Hi, from your pictures are the radiator fins painted red?
That could effect your cooling.

[Firkhamhall]

4 days?  How many times did you ride, how many miles before it puked the coolant?

Do you know if the bike had a fresh coolant change just before they sold it to you? 

It isn't unusual to have an air bubble in the system that takes a couple heat/cool down cycles to get out.

2 x 30-40 miles rides and a puke at the end of each ride.  I’ve certainly made the most of buyer beware! LOL
I took the side panel off and you can see the champagne effect rushing into the reservoir, no airflow and it gushes.
All service items are to be done, the coolant defo doesn’t look fresh.

[Firkhamhall]

Hi, from your pictures are the radiator fins painted red?
That could effect your cooling.

It’s a plastic grid in front, like a rad guard, underneath is a clean and in order rad (fin-wise, at least)

[Jethroww]

Sorry didn't see that from the pics.

[Laitch]

Some elements of your Brick are not K1100 OEM; they appear to be from the earlier 2-Valve models or the first 4-valve models. The front brake calipers, brake discs, and front/rear wheels are what the earlier 2-V models used; they aren't an improvement over the original k1100 equipment. The foot peg plates look like they're from an early 4-V Brick. Find the VIN on the frame and run the last seven digits through this VIN-checker. Tell us what comes up.
Here are what K1100 front discs and calipers should look like. Below them are the 2-V y-spoke wheels from early Bricks

[Firkhamhall]

Some elements of your Brick are not K1100 OEM; they appear to be from the earlier 2-Valve models or the first 4-valve models. The front brake calipers, brake discs, and front/rear wheels are what the earlier 2-V models used; they aren't an improvement over the original k1100 equipment. The foot peg plates look like they're from an early 4-V Brick. Find the VIN on the frame and run the last seven digits through this VIN-checker. Tell us what comes up.
Here are what K1100 front discs and calipers should look like. Below them are the 2-V y-spoke wheels from early Bricks

Interesting - the frame is a K100RS, the engine is 114EA from 1991, must be a bit of a mutt.
Explains why the brakes are poor, not spongy as in need bleeding, just poor, but I’m comparing that to the Brembos on my 2018 S1KR - so very different.

[frankenduck]

Why oh doG's green earth would someone put 2V forks/brakes/wheels on that? Yikes!

(Yeah, I'd guess that they probably did it to use Y-spoke wheels but putting the crappier 2V forks and BRAKES on a 4V is something that I'd never do.)

[Firkhamhall]

Why oh doG's green earth would someone put 2V forks/brakes/wheels on that? Yikes!

(Yeah, I'd guess that they probably did it to use Y-spoke wheels but putting the crappier 2V forks and BRAKES on a 4V is something that I'd never do.)

I’m not overly bothered, it hardly looks like an original bike :)
ETTO and all that, for me it’s just a summer toy. 👍

[Firkhamhall]

It's probably the radiator cap. Part 17111464720. (That includes gaskets.)

Thanks Mr Frankenduck!  It does seem to be the radiator cap in the main!

Installed the new one today, the old gasket was starkly indented and a bit crusty in comparison.
What transpired was a slight leak from the pipe under the cap fitting, the one to the RH side of the radiator. It had not leaked before with a faulty cap, presume not enough pressure to show that failure.

Both sorted, no champagne bubbles, no whoosh of coolant, fan kicks in and all seems settled.

Thanks again!