I have found that after fitting the Chris Spain cooling system header tank with the low level alarm there is a problem. When filling the cooling system to the correct level and venting the header tank all is fine and the alarm does not activate when driven for the first time. On subsequent drives it was found that the alarm bleeps constantly, and very annoyingly, till the system reaches working temperature, then all is well until you brake hard and it goes off again.
The problem is that with the initially full system the coolant heats up there is expansion. The header tank overflows as the pressure cap lifts and coolant is lost. Next time you go out the level in the header tank has dropped and the alarm activates.
The answer to this problem is to reinstate the original Stag idea of the plastic bottle overflow which has the pressure and back vent system, whereby any overflowing liquid is drawn back into the header tank when the engine cools.
To elaborate: Fill the system to the brim of the header tank. Obtain a blanking radiator cap and fit to the header tank. Connect an 8mm bore pressure hose from the overflow outlet (beneath the header tank blanking cap) to the bottom of the original Stag overflow bottle. Make sure that the original overflow bottle is in good order (mine wasn't as the brass neck leaked from the seal) Make sure you have the correct 20 psi bottle pressure cap (part no. GRC222) You now have a constantly full header tank and the alarm does not activate unless there is a real loss of coolant. I hope this makes sense, whatever, it works on my Stag!
Date: 15/06/2014
Having just returned from a 1000 mile holiday in France I thought all interested persons might like to know the following developments.
On arrival at Calais and parked up in the Ibis Hotel, I checked under bonnet and noticed that the level in the Stag overflow tank was low.
Giving the top rad hose a squeeze and noticing that there was no pressure in the system, I then gave it another squeeze. The resultant effect was to blow the low level float switch out of the end of the Chris Spain head tank. Further inspection revealed that the plastic boss had sheared off inside the tank and the float switch it's self was defective.
This switch was fitted by the maker and was "as received".
I managed to blank off the hoses to and from the head tank and reverted back to the Stag 'as fitted' system.
Needless to say I have now stripped out the whole system.
Thanks Chris!
The problem is that with the initially full system the coolant heats up there is expansion. The header tank overflows as the pressure cap lifts and coolant is lost. Next time you go out the level in the header tank has dropped and the alarm activates.
The answer to this problem is to reinstate the original Stag idea of the plastic bottle overflow which has the pressure and back vent system, whereby any overflowing liquid is drawn back into the header tank when the engine cools.
To elaborate: Fill the system to the brim of the header tank. Obtain a blanking radiator cap and fit to the header tank. Connect an 8mm bore pressure hose from the overflow outlet (beneath the header tank blanking cap) to the bottom of the original Stag overflow bottle. Make sure that the original overflow bottle is in good order (mine wasn't as the brass neck leaked from the seal) Make sure you have the correct 20 psi bottle pressure cap (part no. GRC222) You now have a constantly full header tank and the alarm does not activate unless there is a real loss of coolant. I hope this makes sense, whatever, it works on my Stag!
Date: 15/06/2014
Having just returned from a 1000 mile holiday in France I thought all interested persons might like to know the following developments.
On arrival at Calais and parked up in the Ibis Hotel, I checked under bonnet and noticed that the level in the Stag overflow tank was low.
Giving the top rad hose a squeeze and noticing that there was no pressure in the system, I then gave it another squeeze. The resultant effect was to blow the low level float switch out of the end of the Chris Spain head tank. Further inspection revealed that the plastic boss had sheared off inside the tank and the float switch it's self was defective.
This switch was fitted by the maker and was "as received".
I managed to blank off the hoses to and from the head tank and reverted back to the Stag 'as fitted' system.
Needless to say I have now stripped out the whole system.
Thanks Chris!
Martin.
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