Daft question......................again...
Discussion
I would say that, as long as the expansion tank isn't completely empty when the engine is cold, leave it alone.
It's there for expansion - ie engine gets hot, pressure cap opens to allow steam out, steam goes to expansion tank and is collected, engine cools down, water in expansion tank gets drawn back in again...
if expansion tank is too full, there's nowhere for the steam to go, so it gets vented... then the engine cools down, water is drawn from expansion tank so level goes down, you top it up, etcetera etcetera...
It's there for expansion - ie engine gets hot, pressure cap opens to allow steam out, steam goes to expansion tank and is collected, engine cools down, water in expansion tank gets drawn back in again...
if expansion tank is too full, there's nowhere for the steam to go, so it gets vented... then the engine cools down, water is drawn from expansion tank so level goes down, you top it up, etcetera etcetera...
haggis where is this steam coming from. surely you wont get steam unless your cooling system exceeds 100degC, as the system pressurised surely it will need to get above 110degC before becoming steam and this can only happen once the system has depressurised
I think as you've filled the system with cold water the expansion forces excess water out once driving the system is full of hot water.When you stop the water cools and sucks some back from the expansion tank.
I think as you've filled the system with cold water the expansion forces excess water out once driving the system is full of hot water.When you stop the water cools and sucks some back from the expansion tank.
well strictly speaking you're right - as the cold water expands, it's forced past the pressure cap - when the engine gets hotter, once the water is de-pressurised, it turns to steam so bubbles along the pipe and into the expansion tank...
so it's not steam at the moment it leaves the radiator but it might be when it reaches the tank. Sometimes.
so it's not steam at the moment it leaves the radiator but it might be when it reaches the tank. Sometimes.
silverback mike said:
It keeps a suckin'
If it doesn't suck water back, you have a leak as it sucks air in as it cools instead.It took me ages to get my swirl pot full of water and some in the expansion tank,i was amazed at the amount (3 or 4) of tiny leaks which i couldn't see except by using a dentist mirror
Hi silverback, I see you now have a repaired radiator, you said your engine now runs cooler than before. Right, the cooler the water the lower the water pressure in the system, therefore the swirlpot cap shouldnt open to vent excess pressure into the expansion tank. If you are concerned, warm the engine to running temperature and look for leaks, that would account for water loss if you are sure you are losing it. My pressure cap on the swirlpot is rated at 15 psi,now I dont know if this is the correct cap as it was on the car when I got it and mine doesnt lose coolant. I hope this helps mate
SteveJ
SteveJ
steve j said:
Hi silverback, I see you now have a repaired radiator, you said your engine now runs cooler than before. Right, the cooler the water the lower the water pressure in the system, therefore the swirlpot cap shouldnt open to vent excess pressure into the expansion tank.
It will if the swirlpot is full before you start. It has to, there's nowhere else for the expanded hotter water to go.
tvrgit said:
Hi silverback, I see you now have a repaired radiator, you said your engine now runs cooler than before. Right, the cooler the water the lower the water pressure in the system, therefore the swirlpot cap shouldnt open to vent excess pressure into the expansion tank.
It will if the swirlpot is full before you start. It has to, there's nowhere else for the expanded hotter water to go.
The swirlpot is absolutely toppers when cold.
silverback mike said:
Hi silverback, I see you now have a repaired radiator, you said your engine now runs cooler than before. Right, the cooler the water the lower the water pressure in the system, therefore the swirlpot cap shouldnt open to vent excess pressure into the expansion tank.
It will if the swirlpot is full before you start. It has to, there's nowhere else for the expanded hotter water to go.
The swirlpot is absolutely toppers when cold.
I know, you said in your first post, that's what my advice was based on.
silverback mike said:
This is by far my daftest question.
Following my recent coolant loss, I am forever topping up my expansion tank, but the 'other' one with a pressurised cap is topped up.
Do I fill up the expansion tank to the recommended level? or what.
Sorry.
Not sure what your doing Mike.
Are you checking the levels after every trip (once cold) and topping up the ex tank?
Or is this a weekly check?
If its the former don't, stick a gallon in the boot and check the swirl pot after two trips.This gives the system a run from normal conditions.If the water level in the swirl pot has dropped further than befor i suspect you have a leak
>> Edited by Pies on Tuesday 13th September 21:18
tvrgit said:
tvrgit said:
steve j said:
Hi silverback, I see you now have a repaired radiator, you said your engine now runs cooler than before. Right, the cooler the water the lower the water pressure in the system, therefore the swirlpot cap shouldnt open to vent excess pressure into the expansion tank.
It will if the swirlpot is full before you start. It has to, there's nowhere else for the expanded hotter water to go.
The swirlpot is absolutely toppers when cold.
I know, you said in your first post, that's what my advice was based on.
All good advice to me, thanks.
Pies said:
This is by far my daftest question.
Following my recent coolant loss, I am forever topping up my expansion tank, but the 'other' one with a pressurised cap is topped up.
Do I fill up the expansion tank to the recommended level? or what.
Not sure what your doing Mike.
Are you checking the levels after every trip (once cold) and topping up the ex tank?
Or is this a weekly check?
If its the former don't, stick a gallon in the boot and check the swirl pot after two trips.This gives the system a run from normal conditions.If the water level in the swirl pot has dropped further than befor i suspect you have a leak
>> Edited by Pies on Tuesday 13th September 21:18
Checking periodically pies. I am using the car for the daily motorway trip to work and back (about 40 miles) so haven't checked it for a few days, but every time I check, it seems to have emptied itself.
But no obvious signs of leakage.Gassing Station | S Series | Top of Page | What's New | My Stuff