My Coolant level

[davegttph1]

Unsure now on what Im checking for :rolleyes: its only been a year with the car and Im still unsure eh, anyway, going for a long spirited drive later so thought Id check all the fluids etc.

Coolant, the exapnsion tank behind the drivers headlight seems to be reading full. The filler cap, took that off and its not full but I can see coolant in there, and the AST seems to be running almost empty. Now IIRC the filler car and AST should be full to the brim? no/yes?

Obviously I fill it at the filler cap, is that right? what about the AST? do I just pop some more coolant in there?

Cars running fine (least it was on its last run) no buzzers or warnings, no overheatings either with it but want to be sure. Going out in an hour.

Thanks guys

[RAW]

i asked the guys at RE:WORKS about this a while ago. i have had the car several months and have never topped up the coolant-it is always just under the level of the metal cap.  they said that most people make the mistake of constantly worrying about it and topping it up with a cup here and a cup there whenever it changes my a few mil. they said if it looks alright then just leave it alone!

[davegttph1]

yes but I do recall when I had the car at first the AST was full as was the filler cap level.  Now Im not too fussed about the filler cap level as theres only half a cup full down and I can see it but the AST is almost running empty, and from my vague knowledge the AST is there so the coolant system pushes trapped air into it and pulls in coolant to top it all up automatically, now Im worried that if theres no coolant in the AST to draw in then Im going to have a problem in the near future. The thing for me to remember is I dont have 3k to rebuild it if it goes wrong so I want to make sure I know the car is running well.

[MillSpeed]

Yeah, the AST should be full. Has your expansion tank started overflowing at all? The fact that the expansion tank is full and the AST isn\'t might suggest the AST cap is faulty. Have a good look at the seals and also make sure the return valve opens easily.

[davegttph1]

thought it should be full, do I just add more coolant to top it? nothing else? The AST is an Alloy one if that makes any difference.

The return valve? on what? where? lol sorry. not heard that brought up before.

Thanks

[MillSpeed]

On the bottom of the AST cap there\'s a little \'flap\' (for want of a better description!) which opens downwards. When the coolant cools down and contracts, the flap opens and allows coolant to be drawn back from the expansion tank. If this isn\'t happeneing and the coolant is only travelling in one direction to the expansion tank, then the expansion tank will overflow as your engine is emptied of coolant. Pop your AST cap off and have a look, it should be there.....I think!

[davegttph1]

On the bottom of the AST cap I can push the valve towards the cap with the spring pushing back outwards, I presume this is the flap you talk about....

Ive just topped the AST to the top and the filler cap neck pretty much to the top too. Hope Ive done correctly.

[MillSpeed]

In the centre of the spring loaded bit that pushes towards the cap itself is a small circular flap that opens in the opposite direction, away from the cap. It should open easily.

[davegttph1]

how does it open? its flush with the metal so cant grip it with my fingers, when I push the rest of the flap that goes inwards with it... you think the cap is knackered and the coolant is leaking from the filler neck then? When does it do this? when the car is switched off and cooled down or whilst running?

[MillSpeed]

Hope this works, attached an image of a rad cap. The bit in the centre should open towards you (away from the cap), should be able to get your fingernails behind it.

http://s30.photobucket.com/albums/c321/MillSpeed/?action=view¤t=radcap.jpg

If this isn\'t opening then that could explain why your AST is empty and your expansion tank is filling up. When the coolant heats up it expands and pushes against the spring loaded bit. When the coolant pressure exceeds 0.9bar, the spring begins to yield and coolant flows down towards the expansion tank. When the engine is shut down and begins to cool, the coolant in the engine contracts and draws the coolant forced out into the expansion tank back into the engine via that little return valve.

EDIT: Didn\'t work so I\'ve posted the link instead!

[davegttph1]

Ahhh sorry I was looking at the AST cap not the rad cap... maybe where Im going wrong then.

Ive just been out in it and its ran fine and the temps have behaved as theyve always done in the past, seemed fine, only problem is Im not going out now as the drivers side front tyre is flat and wont go up, damn valve is fooked

[MillSpeed]

Sorry mate, it is the AST you\'re looking at....it\'s just I posted a pic of some generic rad cap off the net. Same thing tho, the AST cap is the RX7\'s equivalent of a rad cap. I\'ve got an after market AST cap on mine so I can\'t remember exactly what the Mazda cap was like, but the operating principal should be the same.