coolant sounds like it\'s boiling after drive?

[Juz]

after a trouble-free first 3 months of ownership i think i might have my first problem, had to happen sooner or later lol.

i did a long drive (160miles) on sunday evening and when i got back, i left the turbo timer running for 6mins and once the engine had switched off i heard the sound of something boiling coming from the very front of the engine bay. (i.e. could hear it bubbling). i switched the ignition and a/c on to run the fan for a couple of minutes and it stopped it.

the next morning i topped up the coolant and oil levels, and did a couple of shorter journeys (about 20miles each) within a few of hours of each other. after the first one the car seemed normal so i thought maybe the coolant level had just been low and the lack of it caused it to boil, and topping it up had fixed it. then after the second i parked in a car park, when returning to the car something had leaked slightly from the very front drivers side of the engine bay (where the coolant filler neck is) but not enough to put me off driving home. on the drive back i kept an eye on the guages and everything seemed fine. however, once i got back after the turbo timer had switched off, again i could hear a boiling noise which i had to bring the fan on to stop.

then this morning i checked the levels again and oil is fine, but the coolant was right down and took a lot of water to fill the tank. i also found that once i fill past the level of the tank into the filler neck it leaks from the base of the neck. so i\'m thinking that the leak before in the car park was if it had boiled and the excess that was bubbling out of the tank got out that way.

what do you guys reckon i should do? i\'ve filled water back up but don\'t really want to drive it unless absolutely necessary until i know it\'s ok, so what could be causing the coolant to boil?

oh and one other question too - when i\'ve been talking about the coolant i mean the plastic cap in the bottom left corner (when facing engine bay from front of car) which says "radiator coolant only" on it and has the long plastic measure attached. what is the other coolant filler neck for which is further across towards the middle and has a metal cap? i took this off and the level is right up to the top so that particular one is fine, just wondering what it\'s for?

cheers guys! oh and by the way i will be joining up as a paid member as soon as possible so please don\'t think i\'m just trying to leech your help for free!

[Oedipus Rex]

What you are calling the filler neck is actually the expansion bottle. You don;t fill your coolant from there. As far as I\'m concerened, and I may be shot down by others, the expansion bottle is about a useful as a condom in the vatican to tell where your coolant level is. The reason you have found water on the floor is because you filled the expansion bottle not the coolant filler neck. By the sound of it your actual filler neck has been full to the brim so you have no problem there

I always use the filler neck, which is the one in the middle of the engine bay to check the coolant level. If you coolant buzzer hasn\'t come on then you\'re not low on coolant. It doesn\'t have to drop far for the alert to come on.

On the bubbling noise issue. I\'ve noticed it after really getting my car well hot. I asked some questions on here and was told it is not that unusual to hear a bit of a bubbling noise from the cooling system after switching off.


Sounds to me like you have no real problem.

[Juz]

ahhh thank god for that i filled the expansion bottle back up this morning and it\'s pretty much ****ed it all back out again, but the actual neck in the middle with the metal cap is still up to the brim. i\'ve been and bought a new metal filler cap though anyway which i will put on just in case, as i did a bit of searching and read that it was worth replacing those every once in a while. the coolant/temperature guage is showing normal too, i just got a bit freaked by the bubbling noise and that\'s what prompted me to fill the expansion tank up
puts my mind at ease now anyway, i\'ll keep an eye on things but feel ok to drive it now lol.

[Oedipus Rex]

Originally posted by Juz
ahhh thank god for that i filled the expansion bottle back up this morning and it\'s pretty much ****ed it all back out again, but the actual neck in the middle with the metal cap is still up to the brim. i\'ve been and bought a new metal filler cap though anyway which i will put on just in case, as i did a bit of searching and read that it was worth replacing those every once in a while. the coolant/temperature guage is showing normal too, i just got a bit freaked by the bubbling noise and that\'s what prompted me to fill the expansion tank up
puts my mind at ease now anyway, i\'ll keep an eye on things but feel ok to drive it now lol.

yeah basically you put coolant in the expansion tank, then the system dumps more in after a drive and it just overflows the tank. Nothing to worry about, it really isn\'t for filling, it really is just an overflow bottle. The only place you fill from is the cap in the centre, if thats full you don;t need any more. That one shouldn;t need replacing but the sprung loaded on the AST does sometimes (thats the one that says to never ever open on pain of death or something similar.

[eyedee]

From a previous thread involving a similar topic debating where coolant should go, I think there may be a miss understanding as to what fluid goes where under the bonnet?!?  I believe (and please correct me if I am wrong) that the filler neck in the front left hand corner of the engine bay (when standing in front of and facing the vehicle) that Juz refers to is the black Radiator coolant cap (which says "Radiator Coolant" in yellow text).  This "coolant" is the mixture of anti freeze solution and water which feeds the radiator.  The expansion tank and secondary coolant reservoir that keeps being referred to is for the intercooler fluids (typically green or blue).

With regards to your post, I believe that it is relatively common for the water to boil in this way in summers heated temperatures whilst on long journeys.  However, check that both of your fans are operating correctly, that nothing is obstructing air from getting through the vented sections of the bumper.  Someone else may know more than me (quite likely!) and will be able to help further.

cheers  :wave

[eyedee]

It seems from having read the two replies sent whilst I was writin mine that what I\'ve writen is in fact more confusing and that I may have got the wrong end of the stick with regards to the question!  :rollin   Please ignore...  :p   :o  

[Oedipus Rex]

Originally posted by eyedee
From a previous thread involving a similar topic debating where coolant should go, I think there may be a miss understanding as to what fluid goes where under the bonnet?!?  I believe (and please correct me if I am wrong) that the filler neck in the front left hand corner of the engine bay (when standing in front of and facing the vehicle) that Juz refers to is the black Radiator coolant cap (which says "Radiator Coolant" in yellow text).  This "coolant" is the mixture of anti freeze solution and water which feeds the radiator.  The expansion tank and secondary coolant reservoir that keeps being referred to is for the intercooler fluids (typically green or blue).

With regards to your post, I believe that it is relatively common for the water to boil in this way in summers heated temperatures whilst on long journeys.  However, check that both of your fans are operating correctly, that nothing is obstructing air from getting through the vented sections of the bumper.  Someone else may know more than me (quite likely!) and will be able to help further.

cheers  :wave

There is only one cooling system.  The plastic bottle is merely an expansion bottle.

[eyedee]

I know I\'m going to look thick asking this question (which everyone else seems to naturally know), but...  please can someone explain how the three coolant inputs link up to one another and explain exactly what they are for (why there are three)?  The Rex is my first turbo\'d car so I have never had to deal with coolant in this form before, so I\'m a bit confused!!!  Equally confused, as the garage I visited recently put anti freeze down (what I now know to be called) the expansion tank! - is this okay?!?

Sorry for the \'ABC\' question! :rolleyes:

[Oedipus Rex]

Originally posted by eyedee
I know I\'m going to look thick asking this question (which everyone else seems to naturally know), but...  please can someone explain how the three coolant inputs link up to one another and explain exactly what they are for (why there are three)?  The Rex is my first turbo\'d car so I have never had to deal with coolant in this form before, so I\'m a bit confused!!!  Equally confused, as the garage I visited recently put anti freeze down (what I now know to be called) the expansion tank! - is this okay?!?

Sorry for the \'ABC\' question! :rolleyes:

ok I\'ll explain but go to //www.iluvmyrx7.com for a diagram.

First there is only one input and that is the filler neck with the yellow sticker in the middle of the engine bay. This feeds the entire cooling system, which goes to the rad, the engine and the turbos. When you start the engine it pumps the liquid around the system, including through the rad, past the fans.

Then there is the AST, which is the Air Seperator Tank, which is used to draw out any air that may get caught up in the coolant system.

Third there is the expansion tank, which the coolant system draws liquid out of as it pressurises the system, allowing more liquid in the system under pressure than not under pressure, therefore in effect increasing the capacity of the cooling system.

It\'s not acutally a very complicated system at all.

[Oedipus Rex]

see attached pic.

[eyedee]

Thank you for that mate.  So, I guess putting anti freeze in will not have done any harm?  I\'ll read into it further tonight and get to halfords to buy some decent coolant asap!

Cheers very much  

[JL1978]

AST does sometimes (thats the one that says to never ever open on pain of death or something similar.

  what happens if we open this? as when  i did my coolant change the other day i opened it to have a look and it is full to the brim:confused:

[Oedipus Rex]

Originally posted by JL1978
what happens if we open this? as when  i did my coolant change the other day i opened it to have a look and it is full to the brim:confused:

I believe it initiates the inbuilt self destruct feature on the 7

[JL1978]

I believe it initiates the inbuilt self destruct feature on the 7

   how many days do i have left:D   i was always tolkd to look with the eyes and not with the fingers but hey i was never one for listening:D

[spagram]

I had the same boiling problem with mine, it turned out that the seal on the AST cap (black plastic tank) had gone so the system wasnt pressurising properly, worth checking. The cap is a main dealer part so you cant get one from halfrauds unfortunatly.