This doesn\'t look good....

[Steve-A]

On the way home from rotorstock yesterday (which was awesome fun my mx5 with 13b from an n/a FC broke down.

On the a45 I suddenly noticed the temp had jumped off the scale. I was right by an exit so cut the engine and coasted off the road. Turns out a radiator hose had popped off and it had dumped all the coolant.

A very nice passer by volunteered to go to his home and bring me enough water to fill her back up, which he did and I drove it home very gently, keeping revs as low as possible. Probably didn\'t go over 2.5k. It made it the 90 miles home, and the level in the expansion tank hadn\'t changed.

This morning when I checked it the expansion tank was empty and the cooling system itself had lost some. The radiator was still full but the filler neck wasn\'t. I couldn\'t spot any leaks externally.

So I did the champagne test.

http://www.youtube.com/watch?v=yazP38SAeKc

Watch in HD and you can see more.

I started the car from fully cold. The water stayed totally bubble free till it get upto temp, then it started to bubble as shown in the video. Rate of bubbling increased with revs.

Can someone please confirm its f**ked?

I\'m not sure why the radiator hose popped off, I\'d run for 1000 miles or so since I built the car with no problems. The hose that popped was the only join that wasn\'t beaded, so I know its my lazy fault, it was on the list of things to do but it hadn\'t seemed a problem as it had held water fine. I don\'t know if the seal went which pressurised the system and blew the hose off, or if the hose worked its way loose, dumped the coolant that overheated it and killed the seals.

If it is dead as I think I\'m gonna have to have a long think about where to go next with it. I had been talking about getting a 4 port bridge built up for it for the future but currently working with £0 budget

[Prof]

It\'s still possible that it\'s air in the system - if the air is circulating around the coolant system, you may see more bubbles with increased revs.
 
If the expansion tank had emptied (drawn back into the rad under slight vacuum when it cools), then it sounds like the system is reasonably well sealed.  Try jackng the car up at the front, if you still have the heater matrix in the car, put the in car heating on full, and run the engine for a few minutes - making sure it\'s come to temperature - if you\'re rad has a bleed screw, gently open it and let the air out as it warms up.
 
If it is water seal failure, there\'s a good chance coolant will get into the engine - and you may see a lot of whitish smoke from the rear when you first start up.

[Steve-A]

Thank you Prof.

I will try those things and report back I don\'t recollect seeing any smoke.

[TiddlesRX7]

Ah mate sorry about your troubles. If it gives you any relief I had mine spitting lots of water out at Cadwell last year. I let it cool down properly and topped it up and its been fine since. The temp guage was up high too. I thought I\'d broke it but its still good Touch wood!

[TiddlesRX7]

These things can be a right PITA to bleed properly so it may have a few little air locks in it at the moment.

[Steve-A]

I\'ve just been running it for a while on the drive way. I jacked the front up and bled the rad.

No smoke at all, it did spit water from the exhaust for a while, didn\'t start spitting till I\'d run it for a minute. AFAIK I think it was just normal condensation level spitting rather than any extra

Once again very few bubbles/no bubbles till the thermostat opened, then quite a stream. This time if anything if i revved it up it gave one big bubble as i pushed accelerator then maybe a few less bubbles than idle, then back to same sortta bubbles as in the video.

That said I think they started to stop/slow down towards the end of running it, but then as I stopped it it let out quite a few big bubbles and continued to let out one largeish bubble every 30 secs or so. It had only got water in it right now, so I wonder if it was starting to boil once the engine stopped and coolant stopped flowing.

Will let it cool and then go check again later/tomorrow morning.

[shaunwil]

Hope it isn\'t anything serious. Had a good look on the stand and the workmanship is excellent

Shaun

[Prof]

What he said - excellent job of work.
 
As for the bubbles - it could well be boling, as with no antifreeze and no pressure the water will boil at 100 - and you\'ll hit that once the engine is shutdown for sure.

[Steve-A]

Third time\'s the charm!

Ran the engine up for a third time and maybe 1 or 2 tiny bubbles came out for the whole time the engine ran (good 10 mins). Yaaaaay!

Best sort the cooling system out properly now. Think I\'ll hook up a buzzer to Megasquirt that goes off if the coolant gets over 105 or something so I shan\'t be able to not notice the gauge moving.

Thanks for the tips guys, and for the complements on the car. Couldn\'t have done it without MRC

[TiddlesRX7]

Good neews mate. Really happy for you. They are a ..... to bleed properly arn\'t they