Overheating woes....still.
Discussion
Okay, getting dis-illusioned now. Had the head gaskets replaced, heads checked out and new thermostat fitted. Ran the car a while, checked the fan worked etc, all seemed fine for about a week. This weekend got stuck in traffic and noticed the water getting too hot along with a sound like a kettle whistling from under the bonnet, luckily was just getting to my home when this occured, so switched off for cool down. Checked the swirl tank and found about a litre of coolant missing even though it was showing full just a day or so earlier.(No signs of any leaks).
Started the car next day from cold, turned the heater on full and topped up the coolant level at the swirl tank and left to run for about 10 minutes.
Two things i noticed, firstly the fan never came on in that time (checked fuses all seem okay and fan had worked on earlier run) and secondly, the hose that goes from the swirl tank to the radiator stayed cold.
Hot air did come from the heater vents okay.
Also my temperature gauge has stopped working since new thermostat added.
Any ideas guys on any possible solutions/symptoms ?
Car is S2.
Started the car next day from cold, turned the heater on full and topped up the coolant level at the swirl tank and left to run for about 10 minutes.
Two things i noticed, firstly the fan never came on in that time (checked fuses all seem okay and fan had worked on earlier run) and secondly, the hose that goes from the swirl tank to the radiator stayed cold.
Hot air did come from the heater vents okay.
Also my temperature gauge has stopped working since new thermostat added.
Any ideas guys on any possible solutions/symptoms ?
Car is S2.
Hard to make sense of all that without seeing the car in the flesh. Check the fan comes on when you short out the otter switch - without that, all bets are off. Check the otter switch turns the fan on when you leave the car idling long enough to get hot enough to need it. Check that when the engine gets up to temperature, the top hose, radiator and bottom hose all get hot. Check the cabin heater pumps out hot air. Check your pressure cap holds pressure. Check that you don't have any water leaks when the system is up to temperature (tell tale signs are wisps of steam and antifreeze stains, but small leaks aren't always obvious unless you look carefully).
I had a similar sounding problem at the beginning of this year. Normally, I dont use the car very much over winter and this last winter I had parts of the engine in bits and so couldn`t run it on a regular basis. Once all the engine was back together I noticed that somehow I had lost loads of coolant (no idea where it went). I topped up the coolant (it took a fair bit too) and ran the engine for a while and noticed neither the fan was comming on nor was the radiator top hose getting hot. I figured it must have been down to an airlock in the system (if coolant is not passing by the otter switch, it will not get hot enough to switch on the fan). On rechecking the swirl pot the coolant level was low again so more coolant was put in. I must have done this a couple times before the top hose began to heat up. Now everything is fine!!
Perhaps you have a similar problem. How often to you check your swirl pot coolant level?
Roy.
Perhaps you have a similar problem. How often to you check your swirl pot coolant level?
Roy.
When I drained and refilled my cooling system a while back it took a few cycles are filling, running, cooling, refilling, running, cooling etc. before all the appropriate pipes got hot and the fan kicked in. 
If you can't see where the water is getting out, its either going out the exhaust ( which it won't on your car if the heads been done, hopefuly ! ) or getting out as a vapour. Now I don't want to get involved in this cap thing again, but its an OVERFLOW TANK and not an expansion tank. The water on an expansion tank will refill the rad when it cools, IT WON'Y ON YOUR S.
So, if you have the pressure cap on the OVERFLOW TANK, go to the swirl pot and put it on there! check the spring tension is nice and tight, if it ain't put a additional rubber ring on it to bolster it up.
My car kept overheating and as soon as I did this all the problems dissapeared.
I think the reason some people have no problem with the cap on the overflow is that it seals better on there and provided the pipes are in good order it will maintain the pressure and hence no overheating.
The main problem with the swirl pot is very poor fit with the cap, and the car will boil if the pressure is not maintained. Worth a try ?
good luck.
gadgit.
So, if you have the pressure cap on the OVERFLOW TANK, go to the swirl pot and put it on there! check the spring tension is nice and tight, if it ain't put a additional rubber ring on it to bolster it up.
My car kept overheating and as soon as I did this all the problems dissapeared.
I think the reason some people have no problem with the cap on the overflow is that it seals better on there and provided the pipes are in good order it will maintain the pressure and hence no overheating.
The main problem with the swirl pot is very poor fit with the cap, and the car will boil if the pressure is not maintained. Worth a try ?
good luck.
gadgit.
Check the rad was bled properly, there is a bleed valve to the top left corner. As has been said check the fan is working properly, next time it does it stop the car, make sure the fans are working etc, don’t try and ‘just get it home’ or you may end with another gasket problem, if need be stop wait for it too cool then carry on home.
Next to check is the fan relay, mine played up a few times, in the end it turn out to be the fuse box that was causing the problem, the connection had become corroded in the box, it over heated causing the relay to repeatedly fail, I the end I took the relay connections out of the box trimmed the wires back to good wire and crimped normal connections on, after that the car never had a problem.
You could also check the water pump to make sure it’s not leaking.
Next to check is the fan relay, mine played up a few times, in the end it turn out to be the fuse box that was causing the problem, the connection had become corroded in the box, it over heated causing the relay to repeatedly fail, I the end I took the relay connections out of the box trimmed the wires back to good wire and crimped normal connections on, after that the car never had a problem.
You could also check the water pump to make sure it’s not leaking.
Thanks for the tips guys.
Few answers:-
1) the pressure cap IS on the swirl tank (always has been) but i think i will get a new cap to make sure its working okay.
2)Hot air IS coming from the heater.
3) Didn't know about the bleed valve on rad, will give that a try.
4) I know the fan has been working throughout the week but not sure if it came on during the day it started overheating again..i dont remember that distinctive 'whir' when sitting in traffic. Being that the fan fuses are okay, could this be an intermittent relay problem (do they do that?) causing the fan to come on some day, not on others? or a dodgy earth?
Questions:-
1) How do i 'short' the otter switch? I take it the otter switch is the one attached to the top pipe to rad?
2) Can the sender unit? for the temp gauge (the bit that goes in the block) be faulty or would it have to be the wiring/fuse to it?
Thanks again, i really want to sort this out as theres not too much left of summer !
Few answers:-
1) the pressure cap IS on the swirl tank (always has been) but i think i will get a new cap to make sure its working okay.
2)Hot air IS coming from the heater.
3) Didn't know about the bleed valve on rad, will give that a try.
4) I know the fan has been working throughout the week but not sure if it came on during the day it started overheating again..i dont remember that distinctive 'whir' when sitting in traffic. Being that the fan fuses are okay, could this be an intermittent relay problem (do they do that?) causing the fan to come on some day, not on others? or a dodgy earth?
Questions:-
1) How do i 'short' the otter switch? I take it the otter switch is the one attached to the top pipe to rad?
2) Can the sender unit? for the temp gauge (the bit that goes in the block) be faulty or would it have to be the wiring/fuse to it?
Thanks again, i really want to sort this out as theres not too much left of summer !
To short the otter switch just pull the plugs off (yes its the thing on the top pipe to the rad) you need to connect the 2 wires together so either use a wire with 2 male spade connectors at either end or a fuse, this will turn the fan on when the ignition is on, if it doesn’t then re-check the fuses and if still nothing swap the headlight relay and the fan relay over, if this works you know the relay is the problem.
I could probably pop round in the week again, won’t be till late next week though as I’m rather busy as just about to start an engine change tonight.
I could probably pop round in the week again, won’t be till late next week though as I’m rather busy as just about to start an engine change tonight.
From your original description it sounds like the thermostat may not be opening if the hose from the Swirl tant to the radiator is not getting hot.
That would indicate that the water is not flowing through the rad so not getting any cooling and also that is why the fan isn't coming on because the otter switch is on the pipe from the rad.
Colin
That would indicate that the water is not flowing through the rad so not getting any cooling and also that is why the fan isn't coming on because the otter switch is on the pipe from the rad.
Colin
My S3 used to send the needle into the upper regions while in traffic, it seemed the fan would cut in too late , so then struggled to cool. I changed the otter switch and still had the same result. In the end I fitted a Knenlowe variable thermostat switch. Its a bit of a bugger to fit the caphillary (sp) under the hose and get a seal but now I can now adjust the stat for winter and summer ( I had it coming on before it was mid way on the gauge in hot weather) You can twiddle it to come on when you please.
As Jonzo said make sure the pressure cap is in place properly, if not you will not get the full pressure and water will be pushed out hence your problems.
To help put an extra rubber washer cut from old inner tube at the the bottom of the cap totightrn the fit or better still get the longer reach cap.
This will allow a higher pressure which will raise the boiling point and stop the premature boiling which is pushing out your water.
Where are you, if you are within reasonable distance of Nottingham I would be only to pleased to have a looksee.
best of luck Bill
To help put an extra rubber washer cut from old inner tube at the the bottom of the cap totightrn the fit or better still get the longer reach cap.
This will allow a higher pressure which will raise the boiling point and stop the premature boiling which is pushing out your water.
Where are you, if you are within reasonable distance of Nottingham I would be only to pleased to have a looksee.
best of luck Bill
Okay, fixed my temp gauge, the wire had got cut somehow between two small resistors near the sender unit. Anyone know what these resistors do?..at present i have used ordinary cable and the gauge seems to be working fine.
Changed the pressure cap for a new 15lb one.
The overheating problem still seems to exist and i am now wondering whether its the thermostatic 'otter' switch as the fan does work but seems to come in too late ie it waits till the car gets hot then comes on rather than stabilising it at 90 degrees. The fluid level is remaining constant and seems to be circulating properly now.
Does anyone know the part number for the otter switch and/or what car it comes off of? My local car parts place had no match for it.Also, are these swtiches likely/able to fail or am i chasing shadows? it just seems to point to that with the fan coming on too late.
Changed the pressure cap for a new 15lb one.
The overheating problem still seems to exist and i am now wondering whether its the thermostatic 'otter' switch as the fan does work but seems to come in too late ie it waits till the car gets hot then comes on rather than stabilising it at 90 degrees. The fluid level is remaining constant and seems to be circulating properly now.
Does anyone know the part number for the otter switch and/or what car it comes off of? My local car parts place had no match for it.Also, are these swtiches likely/able to fail or am i chasing shadows? it just seems to point to that with the fan coming on too late.
If the pipe between radiator and swirl tank stays cold the otter switch won't turn on the fan.
If it stays cold it means there is no coolant flow through it. This could be due to a defective waterpump or to a radiator not letting the coolant pass.
I think you should have the radiator checked, perhaps there is too much resistance to let the coolant pass.
If it stays cold it means there is no coolant flow through it. This could be due to a defective waterpump or to a radiator not letting the coolant pass.
I think you should have the radiator checked, perhaps there is too much resistance to let the coolant pass.
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