Coolant frothing.

[Justmike]

Hi, I am new to the forum and have only had my GL1000 K3 for a year.
It starts and runs absolutely great. Good turn of speed and fuel consumption varies as expected depending on how I ride it. Last week I was getting 50mpg and yesterday I didn`t check but it was a lot less.
Anyway, I did the timing belts 3 weeks back as I have no idea when they were last changed. But I started losing water which I found was down to the top hose clamp not being on right. In the meantime I fitted a new radiator cap because the system wasn`t pressurising. I think this was actually due to the clamp issue.
The water seemed to settle and all was well on a run of about 120 miles.
Yesterday I took the bike out for a quick run and when parking after 30 miles I noticed frothy water under the bike. On checking the expansion bottle it was full to the top. I left it for now to see if it would settle. Further up the road another 20 miles it was the same again. This time I opened the side cover and I could see the coolant was frothing in the expansion bottle and this was then making its way out on to the road. On checking the radiator I could see no water. So why was it all in the exp bottle. To be on the safe side I bought a bottle of water and filled the radiator, it took 1/2 litre/1 pint. We headed back home and again stopped after 20 miles and still some leakage. On checking the radiator it was still full.
Again after arriving home I still had leakage and on checking the exp bottle it was full once again. I left the engine to cool for a while and then fired it up. By this time the coolant had settled back down and was sitting at the full mark. I left the engine running until the fan kicked in and let it come on and off about 3 times. The coolant level never shifted during this time and there was not frothing of any kind.
I have read elsewhere people saying that frothing is down to head gaskets leaking. But taking into account that the bike is running well and starting easily. I see no tell tale white smoke/steam from the exhaust, and then while running it up to temperature while parked all is well.
So I ask the more experienced owners on here, what do you guys think?
Your help on this will be appreciated.
Mike

[raven41951]

It sounds like trapped air. When you had the loose hose you lost coolant and it was replaced by air. When hot, air expands a lot more than water and it was probably "pushing" the water out of its way and ended up in the expansion tank along with coolant. From your description the situation has resolved since the trapped air found its way out and you replaced the lost coolant.

If the coolant level sinks to the point you can't see it, the best way to refill is to add coolant gradually with the engine running while you watch for trapped air which may "push " coolant up to the fill area. When the surging stops, the air is all out.

[Justmike]

I found where the original leak was and fixed it. The wire clamp wasn`t properly on the top hose and when I moved the radiator to replace the timing belts I must have disturbed the fitting causing it to leak. Anyway I managed to get both hoops of the clamp onto the pipe (one wasn`t on properly) and it was fine after that. I thought everything was fine after that until yesterday when the coolant started frothing. I just found it strange that the exp bottle filled all the way up, yet the radiator was full of air. As I mentioned the radiator was still full when I got home and water was circulating in it. And once again the exp bottle was full. Once the engine had cooled the level dropped to the full mark.
Maybe there had been an air lock, but i`ve no idea where. I`ll be taking it out again and i`ll keep an eye on things to see what happens.

[newday777]

Most likely the problem is the head gaskets. It sounds like one or both have blown. That introduces compressed exhaust gasses into the cooling system.
Check you spark plugs for one that looks steam cleaned.
While the plugs are out, cover the plug holes with rags, hit starter button and spin over the motor. Did anything shoot out the plug holes?(it will shoot far if you don't cover the plug holes)
This is typical of 4 cylinder wings that have set sleeping for years and brought back to life, especially when the head bolts were not retorqued before starting the motor after it's long nap.

[Justmike]

Thanks Newday777.
After the initial frothing problem I looked everything over and took her out again for another 35 mile each way run to a mates house, and it behaved with no frothing.
I took it out again the other day and it was baking hot. Like running with a heater blowing in your face. Running between 60 and 80 I kept a watch on the temperature and it stayed constant, just touching the white indicator line on the gauge. When I got to my daughters place a 35 mile run I checked the coolant and silly me, I hadn`t tightened the cap on the expansion bottle properly so of course I was losing pressure and some coolant had come out of the bottle. The bottle had filled but no sign of frothing. I returned home several hours later and this time temperatures were fluctuating. But as they were not too high I just ignored it (sort of) until I got home.
I immediately checked the expansion bottle and found it still full but no frothing. This time because of the fluctuating temps I checked the radiator to find it low. So I put some water in, but it only took about a 1/2 pint, so it would seem I had lost very little water and pretty much what was missing from the radiator was in fact up in the expansion bottle. I started the bike up and ran it until the radiator fan had been on 4 or 5 times, I did see some bubbles in the exp bottle but just the normal fluid transfer type. On leaving everything to cool down the water level had returned to a little above the full line. Probably due to me putting in that 1/2 pint. I hoped to get her out for another run but i`ve had the path in front of the shed dug up and recemented. But with all the heat we`ve had it is more than dry enough to get back out again.
Hopefully that last hiccup was my fault and not the bike. I will be keeping a close watch and if any doubts I will just get new head gaskets and be done with it.

Mike

[newday777]

Did you burp the radiator before putting the cap on when filling it?

[Justmike]

Hmmmm, I didn`t actually. I didn`t think I would need to since I had put in so little.

Mike

[raven41951]

It sounds like it was just trapped air. I am concerned a little that the coolant is not returning to the radiator from the expansion bottle. You should probably check the expansion system for leaks as the parts can get brittle over the years. Include the radiator cap in the inspection.

I installed Evans waterless engine coolant in my new DCT and I have not had a bit of trouble although I only have 4,000 miles on it so far. The Evans coolant has a higher boiling point (375F) so it does not expand as much therefore producing LOWER pressures (and strain) in the cooling system. A plus for older cooling systems.

[Justmike]

Ok I thought I would leave an update.
I haven`t had much chance to get the bike out, long story.
Anyway I had it out and it behaved pretty much but still had a problem with coolant filling the expansion bottle and the radiator being low but still pressurised.
Something was niggling at me about the expansion bottle, so once I had finished sorting out some wiring and waiting for a replacement rectifier under warranty, I finally got her fired up tonight and watched what was happening with the exp bottle.
I removed the exp bottle cap and pulled it apart. It never really seemed to tighten properly, and now I had found why. The seal had started to perish and break up and this was stopping the cap from sealing.
After doing some research I found reference to exp bottles filling up and the coolant not returning to the radiator when the engine cooled. And of course the problem was being traced back to either a leaky return pipe or a badly sealing bottle cap.
After removing the seal it was obvious where that problem was. The part of the seal that went inside the bottle neck was falling apart and stopping the cap from screwing on fully home allowing the bottle to lose pressure which cased the radiator to suck air down into it instead of the coolant.
After trimming off all the broken parts of the seal I was left with the flat part which fits inside the cap. I greased this up with a little vaselene and managed to bottom out the cap and create a seal.
On running the engine through a few cycles of the cooling fan coming on I switched off to see what would happen as the engine cooled.
About an hour later the levels were still the same, but within 2 hours as the engine cooled the levels in the exp bottle started coming back down to where they should be. So things are looking good.
Tomorrow I plan on going for a day out with a round trip of about 200 miles.
Keep all your fingers crossed that I have found the problem.

Mike