How can air get into the cooling system?
Discussion
Approx 170 mile run completed 2 weeks ago, and the following day when engine was stone cold had water coming out the top of the expansion tank when I released the cap to check the level.
AA came and suspected airlock, however he did also conduct a sniffer test for exhaust gases which was negative (head gaskets were fully repaired 2 years ago when diagnosed as faulty).
Airlock released last week and no more obvious signs or issues, however few miles completed since then and when checked tonight water was back to approx 3/4 up the expansion tank.
Any ideas where to start looking now? Appreciate any thoughts.
AA came and suspected airlock, however he did also conduct a sniffer test for exhaust gases which was negative (head gaskets were fully repaired 2 years ago when diagnosed as faulty).
Airlock released last week and no more obvious signs or issues, however few miles completed since then and when checked tonight water was back to approx 3/4 up the expansion tank.
Any ideas where to start looking now? Appreciate any thoughts.
You fill at the swirl pot
The expansion tank is for that they run at about a 1/3
Use the bit of pipe at the back of the dizzy to blead the rest of the air out
Or do the search for filling the coolant I think it's goaty who has a good wright up
It's the pipe you can see on the front of the manifold
The expansion tank is for that they run at about a 1/3
Use the bit of pipe at the back of the dizzy to blead the rest of the air out
Or do the search for filling the coolant I think it's goaty who has a good wright up
It's the pipe you can see on the front of the manifold
Edited by jojackson4 on Tuesday 29th April 20:02
Have you followed the procedure here see post by ChimpOfDarkness ?
You should be checking water level by checking that the Swirl Pot / Header Tank is full.
Not the expansion tank
The expansion tank I believe should be between 1/3 and 2/3 full dependent on the mood of your particular car.
And it really does vary from car to car.
ETA
Custom filler funnel that allows you to run the car to temperature without losing all your water.
You should be checking water level by checking that the Swirl Pot / Header Tank is full.
Not the expansion tank
The expansion tank I believe should be between 1/3 and 2/3 full dependent on the mood of your particular car.
And it really does vary from car to car.
ETA
Custom filler funnel that allows you to run the car to temperature without losing all your water.
Edited by Goaty Bill on Tuesday 29th April 20:18
Thanks for all the replies.
As mentioned system professionally bled and set up last week so I have no doubt it was done correctly.
Hoses must be at least 6 years (and probably a few years more) so could be a good place to start.
Rad also showing slight signs of breaking down / wear but as mentioned no signs of obvious leaks. Am reluctant to start changing bits in the hope of sorting it and would rather have a clear steer first.
As mentioned system professionally bled and set up last week so I have no doubt it was done correctly.
Hoses must be at least 6 years (and probably a few years more) so could be a good place to start.
Rad also showing slight signs of breaking down / wear but as mentioned no signs of obvious leaks. Am reluctant to start changing bits in the hope of sorting it and would rather have a clear steer first.
I wouldn't be certain its bled properly even if set up by professionals, air bubbles can be hard to fully remove, and when my coolant was changed by a specialist they couldn't do a proper job.
Did it myself a couple of weeks after after noticing loss of coolant signs but no obvious leaks.
Did it myself a couple of weeks after after noticing loss of coolant signs but no obvious leaks.
The Aardvark said:
Thanks for all the replies.
As mentioned system professionally bled and set up last week so I have no doubt it was done correctly.
Hoses must be at least 6 years (and probably a few years more) so could be a good place to start.
Rad also showing slight signs of breaking down / wear but as mentioned no signs of obvious leaks. Am reluctant to start changing bits in the hope of sorting it and would rather have a clear steer first.
I brought mine home after the engine rebuild and after the 800 or so initial break in miles, got another litre of water into it.As mentioned system professionally bled and set up last week so I have no doubt it was done correctly.
Hoses must be at least 6 years (and probably a few years more) so could be a good place to start.
Rad also showing slight signs of breaking down / wear but as mentioned no signs of obvious leaks. Am reluctant to start changing bits in the hope of sorting it and would rather have a clear steer first.
It was done correctly by a highly experienced TVR mechanic, but some bubbles can take a while to work their way through.
I had to change radiators a while later, filled it using the above method, a couple of hundred miles later, got another litre of water into it. No leaks though.
I changed my hoses for the first time about 3 years ago; all were originals.
While yours could be failing, 6 years is not a long time.
I would suggest a pressure test.
A lot of garages have the kit to do this.
It's much easier to find leaks on a parked car with the engine off and cool/warm, rather than sitting on the drive with the hot engine clattering in your ears and water from tiny leaks evaporating before you can see them.
As an update on this -
New rad was installed approx 6 weeks ago, and all seemed ok. Having monitored the water level in the expansion tank for the next couple of weeks it seemed to settle at about 0.5 inches below halfway - all seemed good, car was running cooler (approx 80 degrees), fans kicking in at around 83 degrees.
However, after a run of approx 90 miles the weekend before last which involved higher speed and higher average revs, water level in the expansion tank had risen back up to approx 1.5 inches from the top of the expansion tank when checked on a cold engine. Small release of pressure / bubbling as well when the cap was released.
Now having consulted mechanic, and before he starts taking the engine apart, are there any other areas to perhaps focus on?
To summarise -
Head gaskets repaired 2 years ago.
New rad just fitted, system bled and checked.
Higher miles / higher speeds / higher revs appear to cause rising water in the expansion tank.
I'm trying to stay positive and realise that this is very basic info given here - just have the feeling that this is not going to be easy or a quick fix.
Appreciate any possible ideas.
Thanks
New rad was installed approx 6 weeks ago, and all seemed ok. Having monitored the water level in the expansion tank for the next couple of weeks it seemed to settle at about 0.5 inches below halfway - all seemed good, car was running cooler (approx 80 degrees), fans kicking in at around 83 degrees.
However, after a run of approx 90 miles the weekend before last which involved higher speed and higher average revs, water level in the expansion tank had risen back up to approx 1.5 inches from the top of the expansion tank when checked on a cold engine. Small release of pressure / bubbling as well when the cap was released.
Now having consulted mechanic, and before he starts taking the engine apart, are there any other areas to perhaps focus on?
To summarise -
Head gaskets repaired 2 years ago.
New rad just fitted, system bled and checked.
Higher miles / higher speeds / higher revs appear to cause rising water in the expansion tank.
I'm trying to stay positive and realise that this is very basic info given here - just have the feeling that this is not going to be easy or a quick fix.
Appreciate any possible ideas.
Thanks
have you checked the small pipe from the bottom of the expansion tank to the swirl pot?.. if it's restricted / crushed / blocked in any way it could be acting as a one way valve.. allowing fluid in when hot... but not allowing it back when cold... They do suffer from this...
That said, unless it's causing a vacume in the block, you must have a small air leak somewhere to allow the pressure to equalise once cold ... Have a look
That said, unless it's causing a vacume in the block, you must have a small air leak somewhere to allow the pressure to equalise once cold ... Have a look
V8 GRF said:
Has the heater been open during this process?
If the system is filled and bled with the heater off then when you switch the heater on there is often air trapped in the heater pipes that then needs to be removed.
It has unfortunately - system was filled on hot. Has been set to hot and cold since the issue started again with no difference, ie water risen in the expansion tank.If the system is filled and bled with the heater off then when you switch the heater on there is often air trapped in the heater pipes that then needs to be removed.
Seemed to be fine for a few weeks on journeys to work and back that are A and B roads with a total of approx 40 miles, but does seem to be the higher mileage journeys with higher speeds and engine revs that highlight this problem. Reluctant to take engine apart due to likely final cost but looking increasingly likely that it may have to be done.
I'd check your radiator before taking the engine apart.
I had a new alloy radiator fitted after my accident last year and it started leaking within a few months and less than 1000 miles. I wonder if you have perhaps got a small pinhole leak that only opens up on higher temperatures and leaks small amounts of water over an extended period?
ETA Just reading the details of this thread closely. Why do you suspect air in the system,is the car overheating? Filling up the expansion tank without leaking can just be simple overfilling?
I had a new alloy radiator fitted after my accident last year and it started leaking within a few months and less than 1000 miles. I wonder if you have perhaps got a small pinhole leak that only opens up on higher temperatures and leaks small amounts of water over an extended period?
ETA Just reading the details of this thread closely. Why do you suspect air in the system,is the car overheating? Filling up the expansion tank without leaking can just be simple overfilling?
Edited by V8 GRF on Tuesday 24th June 15:08
i had, let's say so, the same Problem after my small accident....
no CO was measured in the swirlpot...but nevertheless -> head gaskets caused it!!
solution: surface grinding of the heads, new gaskets....done!
it was MINIMAL leakage and just hairline crack from combustion chamber to coolant ...
and the best way to fill swirlpot to about max was always mentioned -> take off the hose on the top of the left cylinder head..that is the TOP of the coolant System!!
no CO was measured in the swirlpot...but nevertheless -> head gaskets caused it!!
solution: surface grinding of the heads, new gaskets....done!
it was MINIMAL leakage and just hairline crack from combustion chamber to coolant ...
and the best way to fill swirlpot to about max was always mentioned -> take off the hose on the top of the left cylinder head..that is the TOP of the coolant System!!
hififreak said:
i had, let's say so, the same Problem after my small accident....
no CO was measured in the swirlpot...but nevertheless -> head gaskets caused it!!
solution: surface grinding of the heads, new gaskets....done!
it was MINIMAL leakage and just hairline crack from combustion chamber to coolant ...
and the best way to fill swirlpot to about max was always mentioned -> take off the hose on the top of the left cylinder head..that is the TOP of the coolant System!!
Heads machined flat and gaskets done 2 years ago - so possible I guess, but unlikely? I'm assumimng something else and, thinking negatively, something major!!no CO was measured in the swirlpot...but nevertheless -> head gaskets caused it!!
solution: surface grinding of the heads, new gaskets....done!
it was MINIMAL leakage and just hairline crack from combustion chamber to coolant ...
and the best way to fill swirlpot to about max was always mentioned -> take off the hose on the top of the left cylinder head..that is the TOP of the coolant System!!
i have had my share of cooling system problems over the past few years. Similar to what you describe in a rising level within the expansion tank.
Tried all the usual, air in the system, faulty thermostat etc, etc.
Finally resorted to flushing everything out, reconditioned the rad which had a very tiny pinhole in it,and every thing seemed fine, until as you say, higher revs, higher engine temp, and a returning expansion tank problem.
Again after methodically checking everything over again,i traced a small leak on the valley gasket. This was not visible when cold . The coolant would run down the valley gasket and onto the gearbox bell housing and eventually evaporate, so no signs of coolant loss under the car.
Car would run fine, no overheating, but when it was cold, the expansion tank was nearly always full.
I would then bleed all the system, and set all the correct levels, but slowly over a period of time it would do it again.
Its worth checking as any coolant loss could cause your problem.
The expansion tank level should rise as the engine temp increases, thats what its designed to do. When the engine cools it draws some of this back into the engine. Maybe worth renewing the small bore hose from the swirl pot to expansion tank, incase it somehow is blocked and is not letting coolant return to the swirl pot as the engine cools.
Im sure every ones car is slightly different but for what its worth the following day after a spirited drive,and with the engine cold, i still have to release the pressure cap on the expansion tank slowly. If you release it quickly, this sudden release of pressure can draw coolant out of the swirl pot and into the expansion tank, giving you a false high level.
Tried all the usual, air in the system, faulty thermostat etc, etc.
Finally resorted to flushing everything out, reconditioned the rad which had a very tiny pinhole in it,and every thing seemed fine, until as you say, higher revs, higher engine temp, and a returning expansion tank problem.
Again after methodically checking everything over again,i traced a small leak on the valley gasket. This was not visible when cold . The coolant would run down the valley gasket and onto the gearbox bell housing and eventually evaporate, so no signs of coolant loss under the car.
Car would run fine, no overheating, but when it was cold, the expansion tank was nearly always full.
I would then bleed all the system, and set all the correct levels, but slowly over a period of time it would do it again.
Its worth checking as any coolant loss could cause your problem.
The expansion tank level should rise as the engine temp increases, thats what its designed to do. When the engine cools it draws some of this back into the engine. Maybe worth renewing the small bore hose from the swirl pot to expansion tank, incase it somehow is blocked and is not letting coolant return to the swirl pot as the engine cools.
Im sure every ones car is slightly different but for what its worth the following day after a spirited drive,and with the engine cold, i still have to release the pressure cap on the expansion tank slowly. If you release it quickly, this sudden release of pressure can draw coolant out of the swirl pot and into the expansion tank, giving you a false high level.
ETA Just reading the details of this thread closely. Why do you suspect air in the system,is the car overheating? Filling up the expansion tank without leaking can just be simple overfilling?
Edited by V8 GRF on Tuesday 24th June 15:08
[/quote]
No signs of overheating, car behaving normally. Just that water level in the expansion tank is rising when engine is stone cold so assuming that it's being pressured somehow forcing the water to rise.
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