Cooling - best way?
Posted: Sat Oct 29, 2016 7:28 pm
I have a few issues with the coolant in my car , and wondered if anyone could offer some advice as to what course of action would be best to take, to improve it?
It started when I took the car for its first decent run - 300 miles each way, but found I'd used (or lost) about a pint of coolant in the process !
I must admit my passenger and I could both smell what seemed to be boiling coolant / steam and burnt oil / petrol smells during the trip.
The oil leaks at the front of the car were causing the oil smells - (needs more gasket sealant - to be addressed later!)
But as for the water loss - upon inspection, It turned out that the radiator cap used on the thermostat extension conversion didn't fit that well, so the top seal was leaking coolant when it got upto temprature / pressure.
I pinched the little lock tab ears slightly on the rad cap and this seemed to seal a little better, but endeavouring to ensure a full seal, I also applied a smear of non-setting Hylomar Blue gasket sealant to the mating surfaces of the upper rubber seal of the rad cap and the thermostat extension housing rim.
At the same time, I removed the rubber sealing grommet from around the rubber overflow tube in the Tudor overflow bottle top, (still positioned the nose of the car) - I was advised that atmospheric pressure was required to refill, when cooling had taken place - was not being helped by a vacuum in the Tudor bottle, when the radiator cooled down and sucked coolant back into to top up the system - this seemed logical ? (although the Lotus Workshop manual says it should be an air tight seal ?)
On the return journey the oil / petrol smells were still there slightly, but hardly any water was lost - about an egg cup full needed to fill the system, (I noted there was still a small air gap when I removed the rad cap and looked into the thermostat extension housing).
Not too bad it seemed - but still not completely full !
So, I have had some thoughts about trying to make it completely air tight / full of coolant, I list them out for your thoughts and comments please :-
1) Modern cars always, always, have header / expansion tanks - fact?
2) They are generally positioned above the highest point of the cooling system and usually nearly always incorporate a 'gravity assisted' refill when cooling down to refill.
3) my plan is to mount an expansion vessel against the bulkhead, as high as possible, with hopefully a gravity feed back to the system? - I'll still use a 'Twin Seal' 10lb pressure cap - but on the expansion vessel only - not the stat extension ( another 'blank cap' ?
4) My S3 wide rad conversion still has a filler cap, but it is fitted with a 'blank' rad cap.
2) Reduce the length of the overflow pipe - making it as close as possible to the return fill point - (there must be a meter and half at present, going from extension housing to nose of car) - is there a recommended sensible length / internal bore size required, as this seems an awfully long way, for any coolant to be sucked back ?
3) My thoughts are that it must make a hell of a vacuum to lift the 'refill' coolant out of the bottle in the nose, along a meter or so long pipe and back into the thermostat housing, whilst attempting to refill the system completely - I'm thinking it's almost impossible for the temprature generated cooling down vacuum / suction, to pull it that far - is nearer better?
So, Summarising: Fit Gravity expansion tank, short overflow hose using specified / suitable / small bore pipe, twin seal rad cap on expansion vessel, blank cap on extended stat housing ?
FYI: Engine presently fitted with a 74 degree stat. When coolant is 'full'' the engine temp ranges from 74 - 80 degrees.
Fitted with S3 Wide rad, twin electric cooling fans controlled by a stat in the extension housing.
It started when I took the car for its first decent run - 300 miles each way, but found I'd used (or lost) about a pint of coolant in the process !
I must admit my passenger and I could both smell what seemed to be boiling coolant / steam and burnt oil / petrol smells during the trip.
The oil leaks at the front of the car were causing the oil smells - (needs more gasket sealant - to be addressed later!)
But as for the water loss - upon inspection, It turned out that the radiator cap used on the thermostat extension conversion didn't fit that well, so the top seal was leaking coolant when it got upto temprature / pressure.
I pinched the little lock tab ears slightly on the rad cap and this seemed to seal a little better, but endeavouring to ensure a full seal, I also applied a smear of non-setting Hylomar Blue gasket sealant to the mating surfaces of the upper rubber seal of the rad cap and the thermostat extension housing rim.
At the same time, I removed the rubber sealing grommet from around the rubber overflow tube in the Tudor overflow bottle top, (still positioned the nose of the car) - I was advised that atmospheric pressure was required to refill, when cooling had taken place - was not being helped by a vacuum in the Tudor bottle, when the radiator cooled down and sucked coolant back into to top up the system - this seemed logical ? (although the Lotus Workshop manual says it should be an air tight seal ?)
On the return journey the oil / petrol smells were still there slightly, but hardly any water was lost - about an egg cup full needed to fill the system, (I noted there was still a small air gap when I removed the rad cap and looked into the thermostat extension housing).
Not too bad it seemed - but still not completely full !
So, I have had some thoughts about trying to make it completely air tight / full of coolant, I list them out for your thoughts and comments please :-
1) Modern cars always, always, have header / expansion tanks - fact?
2) They are generally positioned above the highest point of the cooling system and usually nearly always incorporate a 'gravity assisted' refill when cooling down to refill.
3) my plan is to mount an expansion vessel against the bulkhead, as high as possible, with hopefully a gravity feed back to the system? - I'll still use a 'Twin Seal' 10lb pressure cap - but on the expansion vessel only - not the stat extension ( another 'blank cap' ?
4) My S3 wide rad conversion still has a filler cap, but it is fitted with a 'blank' rad cap.
2) Reduce the length of the overflow pipe - making it as close as possible to the return fill point - (there must be a meter and half at present, going from extension housing to nose of car) - is there a recommended sensible length / internal bore size required, as this seems an awfully long way, for any coolant to be sucked back ?
3) My thoughts are that it must make a hell of a vacuum to lift the 'refill' coolant out of the bottle in the nose, along a meter or so long pipe and back into the thermostat housing, whilst attempting to refill the system completely - I'm thinking it's almost impossible for the temprature generated cooling down vacuum / suction, to pull it that far - is nearer better?
So, Summarising: Fit Gravity expansion tank, short overflow hose using specified / suitable / small bore pipe, twin seal rad cap on expansion vessel, blank cap on extended stat housing ?
FYI: Engine presently fitted with a 74 degree stat. When coolant is 'full'' the engine temp ranges from 74 - 80 degrees.
Fitted with S3 Wide rad, twin electric cooling fans controlled by a stat in the extension housing.