Discussion
now having taken iff the expansion tank cap ( blue one near the radiator) to check coolant level and fill up a bit, I noticed while hammariting the wishbones on sunday ( anyone know a good way to remove hammarite from hair??) the sound of gently escaping air comoing from somewhere, also sounded like the sligh electrical buzz you get when the ignition is on but the engine not running,
anyway as the car had not been driven for some hours, and had cooled down , and the ignition eas completely off, this seemed a little strange....
undid the cat , checked the water inside, all ok, warm but not hot,
put the cap back on, still the sound of escaping air.
now this may be a silly question but is it supposed to do this??
if not would some ptf tape be suitable to try to stop the hiss?
also read that the thread itself is a seperate part of the container but seems to be well on there, maybe some sort of sealant around that , if its coming from there....
any advise would be appreciated.... a little wary of driving with at the mo ...just in case...
thnx
S.
anyway as the car had not been driven for some hours, and had cooled down , and the ignition eas completely off, this seemed a little strange....
undid the cat , checked the water inside, all ok, warm but not hot,
put the cap back on, still the sound of escaping air.
now this may be a silly question but is it supposed to do this??
if not would some ptf tape be suitable to try to stop the hiss?
also read that the thread itself is a seperate part of the container but seems to be well on there, maybe some sort of sealant around that , if its coming from there....
any advise would be appreciated.... a little wary of driving with at the mo ...just in case...
thnx
S.
OK not sure if I can help but here goes.
How to remove Hammerite from hair = Scissors!
Or in my case glasspaper.
I don't think the expansion tank should vent. The cooling system as I understand with my limited knowledge is pressurised.
Could you tell if the escaping air was in blowing or sucking (oooh'er) mode.
To find a leak in blowing mode, use soapy water. Put some water in a cup with a shot of washing up liquid, just splash it on all over and look for bubbles.
Not sure about locating a leak in suck mode?
But not to worry your bound to get plenty of advise on that one, on P/H.
Hope this helps.
How to remove Hammerite from hair = Scissors!
Or in my case glasspaper.
I don't think the expansion tank should vent. The cooling system as I understand with my limited knowledge is pressurised.
Could you tell if the escaping air was in blowing or sucking (oooh'er) mode.
To find a leak in blowing mode, use soapy water. Put some water in a cup with a shot of washing up liquid, just splash it on all over and look for bubbles.
Not sure about locating a leak in suck mode?
But not to worry your bound to get plenty of advise on that one, on P/H.
Hope this helps.
Had a very similar problem on mine - hissing noise. As I understand, there will always be a little noise as the system is under pressure and the seal between the blue cap and thread will never be (and shodln't be) completely air/water tight. I'm working on the basis that if you can't hear it from about 12" away, then it is OK. On mine, I could hear it from 4'!!
Replaced the blue cap twice - no luck. Next step was to put liquid metal around the joint between the tank and thread - still no luck. Phone around a number of ali fabricators to ask about rewelding the joint - all said it should be able to be done, but since I had used liquid metal the joint was contaminated and it would cost quite a bit to grind it off!
Last week I fitted a new expansion tank and blue cap (£125!!!) so hope the problem is now sorted (a 2nd hand one was around £55+p&p+VAT)
Hope this helps
Alex
Replaced the blue cap twice - no luck. Next step was to put liquid metal around the joint between the tank and thread - still no luck. Phone around a number of ali fabricators to ask about rewelding the joint - all said it should be able to be done, but since I had used liquid metal the joint was contaminated and it would cost quite a bit to grind it off!
Last week I fitted a new expansion tank and blue cap (£125!!!) so hope the problem is now sorted (a 2nd hand one was around £55+p&p+VAT)
Hope this helps
Alex
I thihk its blowing out from around the cap somewhere, and I only noticed it when the bonnet was up and it was very faint... but if the system is pressurised and air is escaping what is replacing the air , assuming the sysytem is still pressurised?
might try some pft tape aroound the thread, and will also try the soapy water method ( good tip , thnx), just hope it wont come to needing a new tank..
where did you get the quote for the second hand one? do you think its worth the risk seeing as they seem to be a little delicate inthe first palce?
what about soem other sort of sealant it the air is escaping from around the joint between thread and bottle?
I notice that the thread on the cap is not a comtinuous one , is in about 5 parts at regular intervals around the inside of the cap, would this cause the air leak? is it supposed to?
might try some pft tape aroound the thread, and will also try the soapy water method ( good tip , thnx), just hope it wont come to needing a new tank..
where did you get the quote for the second hand one? do you think its worth the risk seeing as they seem to be a little delicate inthe first palce?
what about soem other sort of sealant it the air is escaping from around the joint between thread and bottle?
I notice that the thread on the cap is not a comtinuous one , is in about 5 parts at regular intervals around the inside of the cap, would this cause the air leak? is it supposed to?
If you're not losing any water, I wouldn't worry about it
The cap is designed to keep the water under pressure when it heats up, if the pressure gets to great then it lets first a bit of air, then water out (billows of steam) rather than keep all the hoses under high pressure (IIRC its about 14 PSI but I'm not sure) Obviously you dont see this until the temp gets ~100 but because it's under pressure the water dosent boil until you get ~105-110 (someone correct me if I'm wrong)
Anyway, when it all cools down air needs to get back in (as the coolant contracts), to my knowledge there isn't a pressure threshold for air coming in, so a gentle hiss until the car is the same temperature as the air would be OK
The cap is designed to keep the water under pressure when it heats up, if the pressure gets to great then it lets first a bit of air, then water out (billows of steam) rather than keep all the hoses under high pressure (IIRC its about 14 PSI but I'm not sure) Obviously you dont see this until the temp gets ~100 but because it's under pressure the water dosent boil until you get ~105-110 (someone correct me if I'm wrong)
Anyway, when it all cools down air needs to get back in (as the coolant contracts), to my knowledge there isn't a pressure threshold for air coming in, so a gentle hiss until the car is the same temperature as the air would be OK
that would explain it, as i didnt notice the hiss until the car had cooled down quite a lot and would also account for the missing thread in the cap.
no it doesnt seem to be losing too much water although did have to put about a litre in there last week but havnt checked it more a couple of months so that could be why.
so working on that premise any attempt to stop the hiss with tape or sealant would be a bad idea....exploding hises .....
thanks for that...
S.
no it doesnt seem to be losing too much water although did have to put about a litre in there last week but havnt checked it more a couple of months so that could be why.
so working on that premise any attempt to stop the hiss with tape or sealant would be a bad idea....exploding hises .....
thanks for that...
S.
the reason I replaced the expansion tank is that it was hissing quite loudly and was losing quite a bit of coolant. If you can hardly hear it and it's not losing coolant, don't worry.
I got a quote for the 2nd hand one from Douglas Valley Breakers, but decided that they are quite fragile and for an extra £50 I'd get a new one
I got a quote for the 2nd hand one from Douglas Valley Breakers, but decided that they are quite fragile and for an extra £50 I'd get a new one
Gassing Station | Chimaera | Top of Page | What's New | My Stuff