Swirl Tank overflowing - why suddenly now?
Discussion
For several months now no problems then on a 20 mile run I noticed a puddle of water under the car - quick finger dip and confirmed as anti-freeze!!
Changed the Pressure cap on the swirl tank for a new one, QH 15psi, and for good measure a new cap on the expansion tank. (non pressurised).
Now after 2 miles I notice that the water is leaking from around the swirl cap as if it doesn't fit properly but it feels very secure,it also overflows into the expansion tank and finally out of the overflow pipe.
The temperature gauge so far reads normal but that's not real proof of anything!
Reluctant to drive too far in case it all pumps out - any suggestions of the likely cause would be much appreciated.
Changed the Pressure cap on the swirl tank for a new one, QH 15psi, and for good measure a new cap on the expansion tank. (non pressurised).
Now after 2 miles I notice that the water is leaking from around the swirl cap as if it doesn't fit properly but it feels very secure,it also overflows into the expansion tank and finally out of the overflow pipe.
The temperature gauge so far reads normal but that's not real proof of anything!
Reluctant to drive too far in case it all pumps out - any suggestions of the likely cause would be much appreciated.
Is the reach of the swirl tank pressure cap long enough? It may feel secure when you twist it on but if the rubber seal isn't pressing down on the inner lip of the swirl tank it won't be doing any good and it'll leak. You should have to push the cap down slightly against the spring to be able to engage the locking mechanism.
Mark
>> Edited by dern on Friday 30th May 13:12
Mark
>> Edited by dern on Friday 30th May 13:12
Could be a blown head gasket and exhaust gases are pressurising the system. A simple check for carbons in the coolent should reveal all. Get a self test kit from Frosts or most TVR places should be able to do it for you.
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
Thanks for the comments.
Being hopeful its not the head gasket, I have looked at the replacement Quinton Hazell FC57 replacement radiator cap and note that it does not have a rubber seating washer high up inside it, where it would bed down onto the top of the swirl tank. The old one had one, the new cap simply has a thin metal"washer"in lieu.Iv'e cut one and put it in and will see if this makes any difference. I also noted that the bottom sealing washer is slightly smaller in diameter than the original. I recall earlier threads when people had to chop and change to get the correct one to fit - we shall see.
Thanks again
Being hopeful its not the head gasket, I have looked at the replacement Quinton Hazell FC57 replacement radiator cap and note that it does not have a rubber seating washer high up inside it, where it would bed down onto the top of the swirl tank. The old one had one, the new cap simply has a thin metal"washer"in lieu.Iv'e cut one and put it in and will see if this makes any difference. I also noted that the bottom sealing washer is slightly smaller in diameter than the original. I recall earlier threads when people had to chop and change to get the correct one to fit - we shall see.
Thanks again
Try the Quiton Hazel FC49, it has a longer reach and will hold the pressure.(See 'Swirl Tank Tank' topic in March)
Although it is rated at only 10lbs pressure you were never getting anywhere near that with the shorter reach cap which will leak and not build up to anywhere near the 15 lbs rating.
I had similar problems and now all is ok.
Another way is to add an extra rubber washer to the existing cap.
The problem was worsened in my case because I needed to regularlly check the water level which invcreased the chance of a poor seal every tinme it was replaced.
This is all behind me now I use the longer reach cap even if it is only available to 10lbs rating this has proved to be enough.
The Quinton Hazel caps are acailable at most component centres.
Although it is rated at only 10lbs pressure you were never getting anywhere near that with the shorter reach cap which will leak and not build up to anywhere near the 15 lbs rating.
I had similar problems and now all is ok.
Another way is to add an extra rubber washer to the existing cap.
The problem was worsened in my case because I needed to regularlly check the water level which invcreased the chance of a poor seal every tinme it was replaced.
This is all behind me now I use the longer reach cap even if it is only available to 10lbs rating this has proved to be enough.
The Quinton Hazel caps are acailable at most component centres.
Problem now seems to be cured having fitted the rubber washer to the inside of the cap. I take your point on the longer reach QH radiator cap and think it would be a good idea for me to fit one.
An interesting "oddity" was also resolved - several times after a run I noticed a small puddle of water had gathered on the "bulkhead" near the brake servo, I thought this was the problem swirl tank water but its not.Sampling it (ie finger dip!)it had no anti-freeze in it and it turns out to be water from the windscreen bottle washer. I believe what happens is that the air pressure under the bonnet when the car is on the move "squeezes" the plastic feed pipe to the windscreen spray nipple and pressures the water to dribble out and back in under the bonnet - I could actually see where it had happened. Another simple what I thought was a problem solved.
An interesting "oddity" was also resolved - several times after a run I noticed a small puddle of water had gathered on the "bulkhead" near the brake servo, I thought this was the problem swirl tank water but its not.Sampling it (ie finger dip!)it had no anti-freeze in it and it turns out to be water from the windscreen bottle washer. I believe what happens is that the air pressure under the bonnet when the car is on the move "squeezes" the plastic feed pipe to the windscreen spray nipple and pressures the water to dribble out and back in under the bonnet - I could actually see where it had happened. Another simple what I thought was a problem solved.
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