Coolant buzzer again!

[RemarkLima]

Hi all, bit of a long one, but I\'ll try and describe the situation as much as possible!

Very occassionally I get the coolant buzzer go off. Now it\'s not done it for ages but I went to Silverstone a couple of weeks back and got there fine, had a day out ragging over peoples cars around! Then end of the day I start up the RX and the coolant buzzer goes off but only for 30 seconds if that! Then fine all the way home.

Since then it\'s done it pretty much 90% of the time after I first start up and then goes... I have no trouble starting at all (always on both rotors now, I think that was bad plugs!), hot or cold and there\'s no white coolant smoke out of the exhaust when it starts, I\'m yet to do the ol champagne test but don\'t feel it\'s water seals (*tocuh wood*) as the oil is mayo free and the coolant is still clear and clean (only changed it start of the year).

There\'s no obvious signs of a leak anywhere, and while it\'s hard to tell the level on the expansion bottle, that always seems to have enough in!

So any ideas? It\'s got a standard plastic AST and a .9 bar cap on that with the usual solid cap on the filler neck. The rubber seals look good on both caps, but I was thniking of replacing the AST (keep it plastic for now), and both caps.

Anything it could be or that I can try?

Cheers,
Mark

[Laeeq]

There is a small clip just like the one for the coollant level sensor under the oil filler neck or behind power steering pump (one small wire comming out of the loom).  It can either be rusty or not connected so you can check that as that did sorted mine...

[RemarkLima]

Cool! Cheers, I\'ll take a look!

[RemarkLima]

Hey Laeeq... I can\'t find that... It\'s pretty budy around that whole engine bay!

Also, I\'ve been topping up a few times before I\'ve been setting of, got to a friends today and look down to see coolant coming out near the front offside wheel, where the expansion bottle is, so I\'m assuming that\'s it overflowing, where does the overflow go?

So what happens when the engine cools? should it draw coolant back in from the expansion bottle right? By what path?

Cheers,
Mark

[RobbieRX-7]

That is usually like a typical coolant seal failure. Water coming out by the drivers side wheel. It can also be a faulty ast cap letting too much water into the overflow tank!

[RemarkLima]

Don\'t say bad things like that!

So, really change the AST cap... May as well swap out the AST as well while I\'m at it right?

[RobbieRX-7]

You can eliminate it by getting an fc3s filler neck. This simply bolts on where your old filer cap goes and is much cheaper than buying an ast. Personally i decided to keep the ast, upgraded to a petit alu ast from the states. If it still dumps water into your expansion tank after a alu ast, then your water seals are gone. heppened to me 2 months back. All rebuilt by me now and running mint!

[RemarkLima]

Hmm, I don\'t fancy removing it TBH, I\'ve read the arguments for and against and basically as it\'s not a bad thing to have then I\'ll be keeping it!

Yeah, heard mixed things about ali AST\'s as well, as the Mazda item has baffles inside which mean other stuff "happens", can\'t remember what, but it\'s lasted 13 odd years, so a new one should last again I\'d hope! I\'m also running the later 0.9 bar pressure cap on the AST, so the system shouldn\'t be under massive pressure....

Would the champagne test proove if it\'s water seals?

[RobbieRX-7]

The champagne test is a good indicator but not 100%. Try it for yourself. The water will overflow naturally, even on a good engine, but if there are air bubbles, it\'s fooked

[RemarkLima]

Cheers Robbie, I\'ll try it tomorrow evening.

[RobbieRX-7]

Forgot to say that a couple of bubbles is ok, prob just air escaping but if there are loads of tiny tiny bubbles ( champagne fizz) it\'s all over mate.

[Lum]

sounds like exactly the same syptoms as i had! A new AST cap sorted it for about 3 weeks! Affraid the coolant seals were finished though and a new cap just masked the problem.
Hope yours is something simple though!

[RemarkLima]

Good to know... I\'ll try that tonight but I get a clean exhaust when starting up, it never has any problems firing up hot or cold, no puffs of white smoke... But I assume the expansion bottle must have an overflow so if you filled up all parts of the system it would have to go somewhere right?

Otherwise if it\'s terminal, then I did read that you can use a rad weld type of stuff, while not great can mean you\'ll survive on borrowed time for a bit... At least until I move house!

[teabagger]

If you suspect water seal problems, get it to any half-reasonable garage and get them to test your coolant for hydrocarbons. You could also get the system pressure tested to make sure you\'ve not got a small spit or hose not seated quite right that\'s causing you problems.

[RemarkLima]

Cool, I\'ll try that as well... All got to be worth ago before needing to "replace the headgasket"