Expansion Tank Full
Discussion
It will become obvious that I am no mechanical wizard, in fact I know virtually nothing.
I have a Chimaera 4.5 and my problem is that I religously checked the water level in the cooling system and kept her topped up via the expansion tank as I can't get the top off the swirl tank, which I beleive is quite common.
I made sure the water level stayed at or above the line inside the expansion tank and this meant very lttle topping up in fact.
To get to the point I checked her yesterday and the header tank was full to the brim and I know I didn't fill her that much. I took her for a bit of a run and there was no evidence of any overheating, the temperature guage looked as it does normally and checking the level again after she had cooled down still showed the expansion tank being full to the brim.
The question is ...... does this sound like a problem and if so what is it likely to be.
Any advice would be greatly appreciated.
I have a Chimaera 4.5 and my problem is that I religously checked the water level in the cooling system and kept her topped up via the expansion tank as I can't get the top off the swirl tank, which I beleive is quite common.
I made sure the water level stayed at or above the line inside the expansion tank and this meant very lttle topping up in fact.
To get to the point I checked her yesterday and the header tank was full to the brim and I know I didn't fill her that much. I took her for a bit of a run and there was no evidence of any overheating, the temperature guage looked as it does normally and checking the level again after she had cooled down still showed the expansion tank being full to the brim.
The question is ...... does this sound like a problem and if so what is it likely to be.
Any advice would be greatly appreciated.
Just bleed the system to make sure you have to get the swirl pot screw off i have a special tool i made fits snug and got lots of leverage think you have to tackle that prob first! if you have the bible pages 138-139 has all the answers personally it should settle to a level after bleeding without the need to over check all the time
hope that helps
hope that helps
Seriously, I tried all manner of tools in the garage but in the end the blade of a pick axe was the perfect fit and it has enough leverage to remove it "gently".You must prime to the swirl pot now, there's air in the system and the only way to get it out is through the swirl pot lid. Even if you have to put a stilson wrench on it you must open it to prime the system properly. I bought a replacement swirl pot cap off Steve Heath, good quality product and easy to open.
In normal operation, gas that enters the cooling system will form fine bubbles in the coolant. The cooling system is designed to extract these bubbles by separating them in the swirl tank and transferring them to the header tank where they will gradually seep out past the pressure cap.
The transfer to the header tank relies on tidal flow between the swirl tank and the expansion tank which occurs when the air in the expansion tank compresses and expands due the pressure changes. If the expansion tank is too full there may be insufficient tidal flow for this transfer to occur, and you may find that the gas accumulates in the swirl tank and eventually this will cause cooling problems.
You need to be sure that the swirl tank is full of water. The only reliable way to do that is to take the cap off and look inside. The caps tend to seize on and may need a lot of torque to loosen. Look for a bar or piece of plate the that fits the slot so you can do this without damaging the cap. A smear of grease on the thread when you refit it helps prevent it seizing next time.
The transfer to the header tank relies on tidal flow between the swirl tank and the expansion tank which occurs when the air in the expansion tank compresses and expands due the pressure changes. If the expansion tank is too full there may be insufficient tidal flow for this transfer to occur, and you may find that the gas accumulates in the swirl tank and eventually this will cause cooling problems.
You need to be sure that the swirl tank is full of water. The only reliable way to do that is to take the cap off and look inside. The caps tend to seize on and may need a lot of torque to loosen. Look for a bar or piece of plate the that fits the slot so you can do this without damaging the cap. A smear of grease on the thread when you refit it helps prevent it seizing next time.
GreenV8S said:
Excellent description of what happens.
It's worth noting that because of the position of the Expansion Tank low down in the engine bay it isn't easy for air to be transported there. In my experience gravity tends to win and so some of the air stays at the highpoint in the Swirl Pot. The only way to overcome this is to top up at the Pot.tvrbob said:
GreenV8S said:
Excellent description of what happens.
It's worth noting that because of the position of the Expansion Tank low down in the engine bay it isn't easy for air to be transported there. In my experience gravity tends to win and so some of the air stays at the highpoint in the Swirl Pot. The only way to overcome this is to top up at the Pot.If you open the swirl, don't expect the water to brimming, it shouldn't. If it is, it means the expansion is totally full and won't accept any more. It's why ou should top up through the expansion and not the swirl.
Johno said:
It's why ou should top up through the expansion and not the swirl.
Correct for topping up, not for priming. Priming is not carried out via the expansion tank; it's done at the swirl pot. You'll never get the new coolant in fast enough through the expansion pot and you'll be at risk of causing cavitation in the pump that will stall the coolant flow. To get coolant in via the expansion tank the engine must be running and the coolant must be hot enough to have opened the thermostat. You really don't want to be doing this with substantial amounts of air in circulation. That is the whole purpose of there being a cap on the swirl pot. Hello Razorman,
Here is a reply I gave once before on this. Hope it helps. Don't forget the radiator bleed step - it is important to ensure the air is out of the system, just like you would bleed the central heating radiators in you house to get proper flow around the system:
You need to check & fill the system from the swirl tank but first you need to ensure there is no air in the system (as happens when there is a leak somewhere). It is explained in the handbook (if you got one with the car). The way I do it is:
1). Ensure coolant is cool and remove expansion tank cap.
2). Turn heater control to hot.
3). Fill expansion tank with coolant to about half way up.
4). Remove brass screw on top of swirl tank. Mine was stuck rigid when I first got the car and no matter how much leverage I tried applying, it wasn't going to shift before I would have distorted the can, so I (very carefully )applied a blowtorch to it (avoiding any hoses or plastic parts etc. with heat shields). It didn't take long to break the seal and then it unscrewed easily by inserting the tip of a large flat-bladed screwdriver sideways and applying leverage. It always opens easily now every time.
5). Fill swirl pot to the top with coolant.
6). Undo bleed plug on top of radiator (might be on either side!). See what comes out! If air comes out, wait until only coolant flows with no air. When all air has gone, retighten radiator bleed plug.
7). Refill swirl tank with coolant to the top. (The level will have dropped as the coolant comes out of the radiator bleed).
8). Replace swirl tank brass screw.
Basically, that is the process I use. You should then run the engine until the fans kick in, wait for it to cool and then repeat the process. This is to try & purge the system of any air that may have been trapped in the heater matrix etc.
If the car susequently dumps some coolant on the garage floor, don't worry, it is it's way of naturally finding it's own level in the expansion tank. Mine runs only about an inch fron the bottom with no problems. Excess coolant is evacuated via the blue expansion tank cap.
Cheers,
Mick
Here is a reply I gave once before on this. Hope it helps. Don't forget the radiator bleed step - it is important to ensure the air is out of the system, just like you would bleed the central heating radiators in you house to get proper flow around the system:
You need to check & fill the system from the swirl tank but first you need to ensure there is no air in the system (as happens when there is a leak somewhere). It is explained in the handbook (if you got one with the car). The way I do it is:
1). Ensure coolant is cool and remove expansion tank cap.
2). Turn heater control to hot.
3). Fill expansion tank with coolant to about half way up.
4). Remove brass screw on top of swirl tank. Mine was stuck rigid when I first got the car and no matter how much leverage I tried applying, it wasn't going to shift before I would have distorted the can, so I (very carefully )applied a blowtorch to it (avoiding any hoses or plastic parts etc. with heat shields). It didn't take long to break the seal and then it unscrewed easily by inserting the tip of a large flat-bladed screwdriver sideways and applying leverage. It always opens easily now every time.
5). Fill swirl pot to the top with coolant.
6). Undo bleed plug on top of radiator (might be on either side!). See what comes out! If air comes out, wait until only coolant flows with no air. When all air has gone, retighten radiator bleed plug.
7). Refill swirl tank with coolant to the top. (The level will have dropped as the coolant comes out of the radiator bleed).
8). Replace swirl tank brass screw.
Basically, that is the process I use. You should then run the engine until the fans kick in, wait for it to cool and then repeat the process. This is to try & purge the system of any air that may have been trapped in the heater matrix etc.
If the car susequently dumps some coolant on the garage floor, don't worry, it is it's way of naturally finding it's own level in the expansion tank. Mine runs only about an inch fron the bottom with no problems. Excess coolant is evacuated via the blue expansion tank cap.
Cheers,
Mick
AlexanderV8 said:
If the car susequently dumps some coolant on the garage floor, don't worry, it is it's way of naturally finding it's own level in the expansion tank. Mine runs only about an inch fron the bottom with no problems. Excess coolant is evacuated via the blue expansion tank cap.
Cheers,
Mick
This is important too; the expansion tank is rather small for the duty so filling more than 1/3 full may result in overflow when the engine is at its hottest. All that hot water needs a space to expand into. My experience is that 1/2 full does not leave enough expansion space for proper hot work like trackdays. I keep mine at 1/3 and that works well.Cheers,
Mick
Thanks everyone for the (as usual) invaluable input.
Just for information I have managed to removed the swirl pot cap. I did it by using the blade on a coal chisel (just the right width for the slot) and a large adjustable spanner on the chisel for good leverage.
One question now though is that in the advice given here and in the bible it says half fill the expansion tank when you start bleeding the system. I first noticed this problem because the expansion tank was full to the brim and it still is having removed the swirl pot cap. By the way, I could not see the coolant level in the swirl pot, so it must be well down.
Is the level of coolant in the expansion tank going to affect bleeding the system?
and so do I need to try and remove some coolant from the expansion tank before I start?
Just for information I have managed to removed the swirl pot cap. I did it by using the blade on a coal chisel (just the right width for the slot) and a large adjustable spanner on the chisel for good leverage.
One question now though is that in the advice given here and in the bible it says half fill the expansion tank when you start bleeding the system. I first noticed this problem because the expansion tank was full to the brim and it still is having removed the swirl pot cap. By the way, I could not see the coolant level in the swirl pot, so it must be well down.
Is the level of coolant in the expansion tank going to affect bleeding the system?
and so do I need to try and remove some coolant from the expansion tank before I start?
Edited by Razorman on Sunday 23 March 13:37
Edited by Razorman on Sunday 23 March 13:38
My reading of your symptoms is this.
At some point your expansion tank has become empty and next time the system cooled the contraction of the coolant has drawn in air because there was no water left in the expansion tank. At sometime later when the engine was hot the pocket of air has been drawn into the pump thereby stalling coolant flow. When this happens hot spots occur on the block casing localised boiling. The boiling coolant then forces the expansion tank relief cap open and coolant is forced outward through the tank. This accounts for the full expansion tank and the lack of water in the swirl pot.
The normal cause of this is a small leak somewhere in the system that has allowed the expansion tank to run dry. Once there has been a cold/hot/cold cycle you will have drawn air in. The only way to solve this is to prime the system at the swirl pot.
With the system cold fill the expansion pot 1/3 to 1/2 full and then fill the swirl pot. Put all caps back on then massage the top hose to agitate the coolant. After doing this you will find a new air space has formed in the swirl pot. Refill and repeat until massaging no longer creates air in the swirl pot.
Now you are primed. Start the engine and take it through a heat cycle. When cold recheck the swirl pot and fill as required. A little air is OK but anything more than an inch is too much. When you're sorted you need to find where the coolant is being lost from.
At some point your expansion tank has become empty and next time the system cooled the contraction of the coolant has drawn in air because there was no water left in the expansion tank. At sometime later when the engine was hot the pocket of air has been drawn into the pump thereby stalling coolant flow. When this happens hot spots occur on the block casing localised boiling. The boiling coolant then forces the expansion tank relief cap open and coolant is forced outward through the tank. This accounts for the full expansion tank and the lack of water in the swirl pot.
The normal cause of this is a small leak somewhere in the system that has allowed the expansion tank to run dry. Once there has been a cold/hot/cold cycle you will have drawn air in. The only way to solve this is to prime the system at the swirl pot.
With the system cold fill the expansion pot 1/3 to 1/2 full and then fill the swirl pot. Put all caps back on then massage the top hose to agitate the coolant. After doing this you will find a new air space has formed in the swirl pot. Refill and repeat until massaging no longer creates air in the swirl pot.
Now you are primed. Start the engine and take it through a heat cycle. When cold recheck the swirl pot and fill as required. A little air is OK but anything more than an inch is too much. When you're sorted you need to find where the coolant is being lost from.
All the advice here is very good, but the simplest thing to do would be to take the expansion pressure cap off, and let the engine run up to temperature, you'll be able to see any air coming out through the expansion, and then it'll suck the coolant back in to the swirl when it needs it.
Keep an eye to the temp gauge and don't put your head over the hole and all the other h&s advice etc . . .
The system will work out the air pretty quickly. If there isn't enough coolant it'll soon be sucked clean out the expansion as well and you can top up as it's running.
I'm going to get my flame proof jacket on now as many will tell me I'm talking nonsense, but how many of you have watched your TVR being serviced, I can assure you that if you think they've all got pressurised systems for this then you are mistaken and this is very often how they get the air worked out of the system.
Keep an eye to the temp gauge and don't put your head over the hole and all the other h&s advice etc . . .
The system will work out the air pretty quickly. If there isn't enough coolant it'll soon be sucked clean out the expansion as well and you can top up as it's running.
I'm going to get my flame proof jacket on now as many will tell me I'm talking nonsense, but how many of you have watched your TVR being serviced, I can assure you that if you think they've all got pressurised systems for this then you are mistaken and this is very often how they get the air worked out of the system.
Johno said:
All the advice here is very good, but the simplest thing to do would be to take the expansion pressure cap off, and let the engine run up to temperature, you'll be able to see any air coming out through the expansion, and then it'll suck the coolant back in to the swirl when it needs it.
There appears to be a misunderstanding here. The instructions for priming these coolant systems are quite straightforward. Running the engine to force the system to clear itself will only work if there is a small amount of air in the system. If there is a large amount of air then that method won't be able to clear before being drawn into the pump. Once air gets into the pump then circulation stalls and the coolant starts to boil. I assure you what you have seen is the removal of small amounts of air. Priming is a very different operation, ask your service engineer. Hot engine and stalled coolant flow is not a good combination, I would advise anyone trying it to keep well away from the engine bay. If circulation stalls the first you'll know about it is when you see hot water and steam being ejected from the open expansion tank.From what I read here there is no way of knowing how much air has entered the system.
As I've said before, that is the reason there is a cap on the swirl pot.
Edited by tvrbob on Sunday 23 March 15:44
tvrbob said:
Johno said:
All the advice here is very good, but the simplest thing to do would be to take the expansion pressure cap off, and let the engine run up to temperature, you'll be able to see any air coming out through the expansion, and then it'll suck the coolant back in to the swirl when it needs it.
There appears to be a misunderstanding here. The instructions for priming these coolant systems are quite straightforward. Running the engine to force the system to clear itself will only work if there is a small amount of air in the system. If there is a large amount of air then that method won't be able to clear before being drawn into the pump. Once air gets into the pump then circulation stalls and the coolant starts to boil. I assure you what you have seen is the removal of small amounts of air. Priming is a very different operation, ask your service engineer. Hot engine and stalled coolant flow is not a good combination, I would advise anyone trying it to keep well away from the engine bay. If circulation stalls the first you'll know about it is when you see hot water and steam being ejected from the open expansion tank.From what I read here there is no way of knowing how much air has entered the system.
As I've said before, that is the reason there is a cap on the swirl pot.
Edited by tvrbob on Sunday 23 March 15:44
Hi there
I need to change out my temp gauge sender. While I am at it the intention was to drain and refill the coolant system and anti-freeze. Sounds like a bit of a nightmare if I get that much air into the system. No real reason to do this, just thought I have never even topped it up since I got it, and the opportunity was there to fill it so I know it's correct.
What is the advice. Should I go ahead, or simply replace the sender and top the system up.
Rgds
Phil
I need to change out my temp gauge sender. While I am at it the intention was to drain and refill the coolant system and anti-freeze. Sounds like a bit of a nightmare if I get that much air into the system. No real reason to do this, just thought I have never even topped it up since I got it, and the opportunity was there to fill it so I know it's correct.
What is the advice. Should I go ahead, or simply replace the sender and top the system up.
Rgds
Phil
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