Air in cooling system
Discussion
I had a problem where the car would empty the overflow bottle every so often (apparently randomly) ever since I bought my car. Earlier this year I discovered a leaking bottom main hose and decided to put a complete hose set on (from ACT).
On re-filling it took me a long time to clear the air out of the system but it still lost some water level in the expansion the other day so topped it up. I squeezed the top hose (from thermostat) yesterday morning and a lod of air bubbled out of the expansion so I kept at it until I could get no more out and drove it. This morning I squeezed it just to check and got a load more air out.
I'm guessing that air collects here as it is the highest point in the system but is this normal? It is possible that my original problem was due to an air lock. I'm having not pleasent thoughts about my head gasket at the moment. Certainly a classic head gasket failure on the Pug 205s is to push air into the cooling system. Any calming words would be welcome!!
Thanks
Rob
On re-filling it took me a long time to clear the air out of the system but it still lost some water level in the expansion the other day so topped it up. I squeezed the top hose (from thermostat) yesterday morning and a lod of air bubbled out of the expansion so I kept at it until I could get no more out and drove it. This morning I squeezed it just to check and got a load more air out.
I'm guessing that air collects here as it is the highest point in the system but is this normal? It is possible that my original problem was due to an air lock. I'm having not pleasent thoughts about my head gasket at the moment. Certainly a classic head gasket failure on the Pug 205s is to push air into the cooling system. Any calming words would be welcome!!
Thanks
Rob
What are the bubbles that are coming out?.. ie what gas?.. you could take it to a garage and have them insert the CO probe into your bottle and get the bubbles to come out.. see if it gives a reading. If it does then it's like you say, head gasket or 'other' issues!!.. But if not, then it's trapped air.
Last year with a 1.3 bar cap, my system ran about 25mm from the bottom of the tank... It held this but I always thought the pipes were hard at temp more so than I would have expected (obviously 1.3 bar hard)... early this year I re-filled the system and ensured I got all the air our of the heater matrix... I'm now holding over 50mm with a 1 bar cap..
Conclusion... I'd been running a year with trapped air in the heater (or somewhere)... This didn't come out at all or ever drop the level over time.. it just pressurised the system... so you could have similar issues.. My heater always ran hot so some water was getting through.. but having fully cleared it, it now runs mega hot!.. to the point where it's now too bl**dy hot in the car!!
Bottom line... Don't assume all the air is out even if it starts to hold a level. It may not be... even now my level is going down a tad... about 10mm every 1000 miles or so... but I also have a vented (both ways) cap so could be evaporation...
What level do you have in your expansion tank?.. and how hard are your pipes at temp??.. and what cap type are you running???
I also had the issue when running the 1.3 bar cap with 'out' vent only, that when cooling it would draw air into the system through pipe joints (these joint would not leak at pressure but would allow air in as it went negative)so may be a bit of this.
Also.. if you leave the cap off and run the engine.. do the bubble appear in the bottle then as it's running????
And I'd have the gas tested also...
Does it still dump the lot out having changed the hoses?.. I had that in a XR2 once.. it would go 2 months without a problem.. then dump the lot??.. got the head and block re-ground and never had the issue again?
good luck anyway
Last year with a 1.3 bar cap, my system ran about 25mm from the bottom of the tank... It held this but I always thought the pipes were hard at temp more so than I would have expected (obviously 1.3 bar hard)... early this year I re-filled the system and ensured I got all the air our of the heater matrix... I'm now holding over 50mm with a 1 bar cap..
Conclusion... I'd been running a year with trapped air in the heater (or somewhere)... This didn't come out at all or ever drop the level over time.. it just pressurised the system... so you could have similar issues.. My heater always ran hot so some water was getting through.. but having fully cleared it, it now runs mega hot!.. to the point where it's now too bl**dy hot in the car!!
Bottom line... Don't assume all the air is out even if it starts to hold a level. It may not be... even now my level is going down a tad... about 10mm every 1000 miles or so... but I also have a vented (both ways) cap so could be evaporation...
What level do you have in your expansion tank?.. and how hard are your pipes at temp??.. and what cap type are you running???
I also had the issue when running the 1.3 bar cap with 'out' vent only, that when cooling it would draw air into the system through pipe joints (these joint would not leak at pressure but would allow air in as it went negative)so may be a bit of this.
Also.. if you leave the cap off and run the engine.. do the bubble appear in the bottle then as it's running????
And I'd have the gas tested also...
Does it still dump the lot out having changed the hoses?.. I had that in a XR2 once.. it would go 2 months without a problem.. then dump the lot??.. got the head and block re-ground and never had the issue again?
good luck anyway
Edited by TVR Beaver on Wednesday 23 June 10:06
Now that sounds much like what the problems I'm having.
I changed the hoses after I sprang a leak around the bottom hose, which I initially heard as air bubbles being drawn into the system when squeezing and releasing the top hose. I have no idea what type of cap I have at the moment, it is the one that came on the car, so I think this should be checked. It is pretty obvious to identify the different types?
Heater sounds correct as well. I'd heard people talking about the super hot heaters in the Griff but mine has never been that impressive so I suspect I do have air in the heater. Any clues on how to bleed that would be appreciated, I see the pipes going into the front wing but no obvious way of bleeding it there but I've not yet dug down the back of the engine to see where they come from.
I feel much more hopeful that it is not the head afterall as what you are describing sounds so much like what I have
I've not spotted any air bubbling when the engine is cold but will check again later just in case. Test I used on the Pug was to see if the system pressurised when cold so will try that as well, logic being that if the gasket is gone then the air pumped in will pressureise the system.
Thanks alot
Rob
Edit: just been out to the car park...
Pressure cap is a VW/Audi part No. 443121 321
And it is drawing air in, still! If I squeeze the top hose and let go suddenly you can hear the air coming in. Comes from the area of the lower connection to the rad, same as before the hose change, grrrr (but at least it now looks pretty!).
I changed the hoses after I sprang a leak around the bottom hose, which I initially heard as air bubbles being drawn into the system when squeezing and releasing the top hose. I have no idea what type of cap I have at the moment, it is the one that came on the car, so I think this should be checked. It is pretty obvious to identify the different types?
Heater sounds correct as well. I'd heard people talking about the super hot heaters in the Griff but mine has never been that impressive so I suspect I do have air in the heater. Any clues on how to bleed that would be appreciated, I see the pipes going into the front wing but no obvious way of bleeding it there but I've not yet dug down the back of the engine to see where they come from.
I feel much more hopeful that it is not the head afterall as what you are describing sounds so much like what I have
I've not spotted any air bubbling when the engine is cold but will check again later just in case. Test I used on the Pug was to see if the system pressurised when cold so will try that as well, logic being that if the gasket is gone then the air pumped in will pressureise the system.Thanks alot
Rob
Edit: just been out to the car park...
Pressure cap is a VW/Audi part No. 443121 321
And it is drawing air in, still! If I squeeze the top hose and let go suddenly you can hear the air coming in. Comes from the area of the lower connection to the rad, same as before the hose change, grrrr (but at least it now looks pretty!).
Edited by Rob_the_Sparky on Wednesday 23 June 13:20
Silicone hoses require a bit more work to get a good seal...
I use a soft non-setting sealant to assemble, and proper hose clamps, I hate jubilee clips TBH. Many like Mikalor clamps?
Getting a pressure tester makes the identification of leaks a lot easier, tiny holes in the rad can also result in HGF paranoia
As mentioned a test on the coolant can quickly confirm that.
I use a soft non-setting sealant to assemble, and proper hose clamps, I hate jubilee clips TBH. Many like Mikalor clamps?
Getting a pressure tester makes the identification of leaks a lot easier, tiny holes in the rad can also result in HGF paranoia
As mentioned a test on the coolant can quickly confirm that.Sorry for the topic hijack, but does anyone know you tell if your heater valve is open or closed?
The electronics on mine packed up a while ago (read never worked) but I'm not sure if it's stuck open or closed?? I'm going to test the switch and motor when I take off the Whale tail to change the blower switch at the weekend.
I'm going to try and bleed the system tonight, by fixing a head of water above the swirl pot and running the car.
I may try moving the valve manually tonight and see if there is any difference??
The electronics on mine packed up a while ago (read never worked) but I'm not sure if it's stuck open or closed?? I'm going to test the switch and motor when I take off the Whale tail to change the blower switch at the weekend.
I'm going to try and bleed the system tonight, by fixing a head of water above the swirl pot and running the car.
I may try moving the valve manually tonight and see if there is any difference??
if you take the cap off and look at the underside... If it's a vent only cap it will have one valve or lump... if it's a vent and allow air in when cooling type.. it will have two valves or bumps...
I got my system fully sealed in the end to the point where I could remove the cap and had air rush into the bottle (think some people confuse this with air escaping but in my instance it wasn't... you can also tell as the pipes grow a bit when you do this)
The reason for this negative pressure is that the expansion pushes up the tank expelling air to the 1 bar or 1.3 bar of the cap... It then cools and drops back beyond the 1 bar to atmospheric mark creating a partial vaccume (or at least pressure less than atmostphere).. at this point it will draw in air from any joints that will allow it to pass.. however these joint may not leak water at pressure... just let air in when negative.
Audi cap's are also 1.3 bar I think and not the 1 bar as specified by TVR.
.
The heater pipes go through the bulkhead on the passanger side... I removed the rubber pipe from where it joinst to the engine metal pipes at the drivers side bulk head area.. and got a hose pipe and blew it through.. Try it on both to ensure it's fully flushed out.. also do this with the heater turned onto Hot so the valve is open....
.
Using an old cap I also made a tester.. filled the system to 1.5 bar and left it overnight... this will also show leaks if you have any... and should show up a HG if blown...
See how you get on.... Hope that's all it is!!
I got my system fully sealed in the end to the point where I could remove the cap and had air rush into the bottle (think some people confuse this with air escaping but in my instance it wasn't... you can also tell as the pipes grow a bit when you do this)
The reason for this negative pressure is that the expansion pushes up the tank expelling air to the 1 bar or 1.3 bar of the cap... It then cools and drops back beyond the 1 bar to atmospheric mark creating a partial vaccume (or at least pressure less than atmostphere).. at this point it will draw in air from any joints that will allow it to pass.. however these joint may not leak water at pressure... just let air in when negative.
Audi cap's are also 1.3 bar I think and not the 1 bar as specified by TVR.
.
The heater pipes go through the bulkhead on the passanger side... I removed the rubber pipe from where it joinst to the engine metal pipes at the drivers side bulk head area.. and got a hose pipe and blew it through.. Try it on both to ensure it's fully flushed out.. also do this with the heater turned onto Hot so the valve is open....
.
Using an old cap I also made a tester.. filled the system to 1.5 bar and left it overnight... this will also show leaks if you have any... and should show up a HG if blown...
See how you get on.... Hope that's all it is!!
Edited by TVR Beaver on Wednesday 23 June 13:51
Wildfire said:
Sorry for the topic hijack, but does anyone know you tell if your heater valve is open or closed?
The electronics on mine packed up a while ago (read never worked) but I'm not sure if it's stuck open or closed?? I'm going to test the switch and motor when I take off the Whale tail to change the blower switch at the weekend.
I'm going to try and bleed the system tonight, by fixing a head of water above the swirl pot and running the car.
I may try moving the valve manually tonight and see if there is any difference??
When you have the system dry you can take the pipe off the valve and take a look - I did this to cure the paranoia. Oddly mine is hot when control is cold and vica versa but I can cope with that so didn't fiddle!The electronics on mine packed up a while ago (read never worked) but I'm not sure if it's stuck open or closed?? I'm going to test the switch and motor when I take off the Whale tail to change the blower switch at the weekend.
I'm going to try and bleed the system tonight, by fixing a head of water above the swirl pot and running the car.
I may try moving the valve manually tonight and see if there is any difference??
Colin RedGriff said:
Don't forget to bleed the rad, air gets trapped in the top. Top the system and then loosen the nut on the top offside of the rad and let out the air
Yeah I couldn't find a bleed screw (or drain) on the rad I have fitted but pretty sure I got the bulk of the air out. Then ran the car multiple times stationary until I thought I'd got all the air out (clearly not managed it though!).Had a poke round this morning and got a turn or more on all the jubliee clips on the new hoses plus a load of air out of the top hose. After tightening it I could no longer hear it drawing in air, so that is a good start. Have to see how it progresses...
Oh and only one valve in the pressure cap so it certainly could produce a negative pressure in the system.
Had a go at bleeding the system last night. I used the following equipment.
Radiatior/Swirl pot cap with a large hole drilled in it and a bottle siliconed on top of it and a rubber seal siliconed on the inside. Popped this on top of the swirl pot, put a little water in it and ran the car until it was up to temp and the fans cycled.
I got quite a bit of air out of it that didn't come out of it with just the swirl pot open.
The rad bleed screw/nut is on the driver's side top corner of my rad and is like a big nut with a groove in it.
Unortunately I think my car is still running hot, so it's a new 'stat this weekend, then if that doesn't work a new rad.
Radiatior/Swirl pot cap with a large hole drilled in it and a bottle siliconed on top of it and a rubber seal siliconed on the inside. Popped this on top of the swirl pot, put a little water in it and ran the car until it was up to temp and the fans cycled.
I got quite a bit of air out of it that didn't come out of it with just the swirl pot open.
The rad bleed screw/nut is on the driver's side top corner of my rad and is like a big nut with a groove in it.
Unortunately I think my car is still running hot, so it's a new 'stat this weekend, then if that doesn't work a new rad.
Steve Heath does a marvellous piece of kit so you can pressure the system while cold.. Basically a valve that that screws on the Ali tank and you can put a pump to it. I found a few jubille clips that weren't quite tight enough this way.
A simple cheap bit of kit tgat can save no end if headaches and well worth having in the toolbox imho.
BB
A simple cheap bit of kit tgat can save no end if headaches and well worth having in the toolbox imho.
BB
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