Coolant bubbles advice. Video

[Blueskai]

I recently drove down a particularly bumpy hill to a campsite (Biblins in Monmouth, if you know it) and at the bottom the engine saver showed I was overheating. I am guessing I had shaken the sh*t out of the radiator resulting in a blockage. The overheat only just knocked on the door of 100C before I turned it off and left it for a few days.

The result is that I cannot bleed the system as air continuously bubbles out of the bleed hose. The coolant also slowly rises in the expansion tank and overflows when the bleedhose it closed off. I hope it is a blockage, but cannot think where the air is coming from. I am prepared for the worst, but hope it can be fixed.

The bubbles only happen when I lower the funnel down to the foot well as far as I can. They stop when I raise it to about the glovebox height.

SEE MY VIDEO for idea of whats happening. http://www.youtube.com/watch?v=nLhfgddsQq0&feature=plcp

There is no oil visible in the coolant and no bubbles in the expansion tank.

I plan to change the radiator first and check the thermostat. I wonder whether the water pump, which is quite new, could be at fault. Anything but the headgasket would be nice.

[Velocette]

I recently drove down a particularly bumpy hill to a campsite (Biblins in Monmouth, if you know it) and at the bottom the engine saver showed I was overheating. I am guessing I had shaken the sh*t out of the radiator resulting in a blockage. The overheat only just knocked on the door of 100C before I turned it off and left it for a few days.

The result is that I cannot bleed the system as air continuously bubbles out of the bleed hose. The coolant also slowly rises in the expansion tank and overflows when the bleedhose it closed off. I hope it is a blockage, but cannot think where the air is coming from. I am prepared for the worst, but hope it can be fixed.

The bubbles only happen when I lower the funnel down to the foot well as far as I can. They stop when I raise it to about the glovebox height.

SEE MY VIDEO for idea of whats happening. http://www.youtube.com/watch?v=nLhfgddsQq0&feature=plcp
There is no oil visible in the coolant and no bubbles in the expansion tank.

I plan to change the radiator first and check the thermostat. I wonder whether the water pump, which is quite new, could be at fault. Anything but the headgasket would be nice.

Did you check the temperature a few minutes after you turned off as heat soak can make it rise. As I understand it 100 isn't technically overheating but abnormally hot if the engine isn't being worked terribly hard.

[Northern Bongolow]

the way i would go first with this one is to check for leaks with a pressure test of the system, there is no point in trying to bleed the bongo unless the system is proved airtight. you may find you have a pin hole or similar.
try a non engine running bleed first and see what appears at the funnel, if no air present then start the engine.

how long was the engine running when the vid was shot and what was the approx temp, it maybe that you just havnt continued long enough to open the stat and fully purge the air out. i find using the vid method that you have to push the motor hard to do a full job in under half an hour.

with the bleed pipe blocked off and the engine warming up the coolant will eventually come over the top of the expansion tank with the cap removed as there is no pressure in the system to raise the boiling point, so it boils early.

hope this helps.

[Blueskai]

Thank you, there is some reassurance from your responses. A few more facts.

After the event, I did spend a good while trying to bleed it at full temperature, but the bubbles kept coming.
When the RAC came, as the lanes were very narrow, I suggested driving behind them, monitoring the temperature and checking the expansion tank for leaking but the temperature did not rise above 86C in fact even after about 40 minutes of slow stop-go driving (The RAC truck got badly stuck on a tight bend!) it actually dropped to about 83. Which makes me think it is not terminal. I have not driven it for over a week and there are no leaks under the van where it has sat during this time.

The video is taken practically cold. But illustrates what happens even when up to temperature. ie No bubbles until the funnel is dropped to the footwell. When the engine is not running there are no bubbles.

With the bleed pipe capped, from cold it takes a couple of minutes for the coolant to spill out of the open expansion tank.

[Northern Bongolow]

i must admit it doesnt sound good. if the coolant is being shoved out so early on things are way out of wack. that deosnt ness mean its the head though. it could just be a hole in a pipe or hose.
as i said before you really need to see if there is a leak somewhere first, by pressure testing the system.

pm sent.

[Blueskai]

I spent the afternoon changing the rad and giving the coolant another go.

I have come to the conclusion that there is air somehow entering the system. I am unsure how, but I have a suspicion that it is somehow coming in through the air con system. I had a very promising result with the bleed, everything looking good. Engine up to temperature and so on. Then I test the air con and pretty soon I feel like I'm starting over again!
Quite late on in the process I am noticing something I have not encountered before; the coolant and bubbles pushing up through the bleed hose into the funnel. After a while it goes back to normal.

On my final attempt I got it to what appeared to be completion and took it for a drive, temp was hovering at about 80. Put on the air con and shortly after I stopped only to see the temperature rise and the dreaded gurgling sound from under the seat. I can hear the coolant bubbling inside the engine block. How can I locate any faults in such a complicated system?

[g8dhe]

The air con only controls the flow of air over the heating matrices, it doesn't control the flow of coolant thru them at all, so I can't see that has anything to do with it, just chance I suspect!

[haydn callow]

Sounds as though combustion gases are getting into the cooling system that = blown head I'm afraid. I am pretty sure you have bled it correctly.

[Blueskai]

Thanks Haydn.

I don't smell any exhaust gases from the coolant and I have been glued to the funnel all afternoon. Anyone local to us who can give me the absolute truth, I'm living near Glastonbury now
I was recommended Bell Hill by Ian when the problem first occurred. But that's 45 mins away..

[helen&tony]

Hi
It's worth looking in the local Yellow Pages / local rag / WHY...there's often someone who has a vehicle transporter....get it "trucked" to Bellhill...rates are often reasonable for transporting with the private guys
Cheers
Helen