hmmm hot day, coolant leak!

[Jovic82]

Hi all,

was driving the car today for a reasonable distance and when i turned the car off i could hear a hissing from both caps (filler and ast) and coolant was being pushed out of the filler cap. it then sounded like they were sucking back air into the system through the same too places. ive also noticed that the expansion tank is very full so would i be right in thinking this is all related???  :mmmm

nick

[nikp]

How old are the two caps - first thing to do would be to replace these if they haven\'t been done in a while

[M@r]{]

 Mine Expansion tank got full, then started coming out of the overflow then I got a £6k bill    

[Jovic82]

ah oh now im worried!?!?!?  two caps are probably quite old as they were on the car when i got it imported. Forgot to mention that i constantly watch the pfc for water temp and they have never exceeded 98oc the whole time i have owned it.

i have seen on a few other threads that the hissing has happened to a few other people in the hot weather. is it common?

will get some new caps and try them and hopefully (fingers crossed) will sort the problem!.

nick

[M@r]{]

you may be ok mate.  But the temp thing doesnt mean its ok either though.  Mine didnt overheat at all at first.  I used to park it up, come back to it 20mins later and find a pool of water under it - it had been coming out of the expansion tank.  changeed the cap on the AST first off. Seemed to fix it for a week but it started again.  It did eventually start overheating - Water Seal failure.    I was given a tip that gives a good idea if a seal has gone:

Take the rad cap off, let the car run and warm up - if the water starts spurting out its not lookng good - suppose that shows the system is pressuring up

[nikp]

^ Ditto.

I found that eventually it proved difficult cooling the temps even whilst travelling along the motorway. But all is not lost yet.

[Adriansturgess]

{\']
Take the rad cap off, let the car run and warm up - if the water starts spurting out its not lookng good - suppose that shows the system is pressuring up

When you say \'spurting out\' do you mean like a fountain? If I start my car up with the rad cap off, the water level slowly starts to rise and would eventually overflow if I didn\'t put the cap back on, but I would have thought this is what you would expect as the water  is starting to heat up and expand and the water pump is starting to pump the water.....I hope it\'s normal anyway!!!!

[banned advertiser]

Change your caps as first port of call, it has cured some, and not others. If it does not cure, get pressure test done, and you\'ll have 2 new caps for your rebuild.
http://www.rotaryart.uk.com/acatalog/New_3rd_gen_engine_perf_tuning.html

[Jovic82]

mine is definately not coming out of the expansion tank at the moment only out of the caps but i will keep a very close eye on it.


mark - on your little test mate, do you mean remove the filler rad cap or the ast rad cap?
and in follow up to adrian\'s question, would it spurt out a lot or just overflow as i would have thought this was normal too.

[rx7veilside]

leave the ast cap and only fill the middle cap (thermostat housing)..the level will rise with the cntre cap off as water pump is running and the thermo does have a small hole in it..but it shouldnt ise fast and spurt out until warm when it starts to expand

[M@r]{]

AST cap on, Fller cap off.  Its ok just overflowing, its if it starts spurting out, volcano stylee I think that means you have \'issues\'!!  

mark - on your little test mate, do you mean remove the filler rad cap or the ast rad cap?
and in follow up to adrian\'s question, would it spurt out a lot or just overflow as i would have thought this was normal too.

[Jovic82]

okay thanks for that chaps. i will get some new caps and try

here are some pictures of my caps. they both seem to be pressure caps and i thought that only one should be (the ast)??

tthere are very slight differences. on the one on the right hand side, it looks like the larger rubber has come away from something. what you guys think? this was the one that was leaking!

anyone know what the part numbers for the two caps so i can order up from mazda?

Cheers
Nick

[Adriansturgess]

That doesn\'t look right....the normal filler cap doesn\'t have a spring but the AST does....looks like somebody\'s fitted the wrong cap.

[banned advertiser]

Yes def wrong, fit the ast with the pressure cap (spring) does it say what pressure it is, if someone has got it wrong on the caps they may also have it wrong on the pressure of the cap. It should be 0.9 bar on the cap with the spring. The place were you fill it should have no spring.

[Jovic82]

update, got the new caps and everythings looks to have sorted itself out! pheww!

i burped the system and let it settle and topped it up to the correct levels.
The expansion tank was very overfull so i removed the excess and left it inbetween full and low when cold. was it okay to do this?

Cheers