Coolant no pressure - Thoughts please along with suggestion what to check please.

delmel · 1 Dec 2021

Hello, Have an I10 which appears to have no pressure within the coolant system. Heating works fine, engine not showing as overheating, inside radiator cover and reservoir tank are small bubbles like a foam appearance which goes away soon after turning off and cooling.
I have noticed a drop in coolant, but not sure over how long. No apparent leaks visible or showing under the car or anywhere.
Car starts and runs first time, no white smoke when car is warm or engine revving. I am not entirely sure but the acceleration from pedal does seem a little under performing only on the top end, so acceleration when fully pressed seems less responding on the last third of pressing pedal.
Oil is fine and clear. No leaks anywhere apparent.

Thoughts please along with suggestion what to check please.

Burnerman · 1 Dec 2021

Maybe the coolant temperature really isn't high enough to pressurise the system.....ideally the normal temperature is around 90deg C.
Feel the rubber hoses after a run- they should be really hot and difficult to squeeze.
Do observe the coolant level for a while.
John

delmel · 2 Dec 2021

Hose at top was hot but soft enough to squeeze. I will try a further distance, but sure this was after driving over 10 miles. My thought were poss Rad cap change, or could it be thermostat not open or closing correctly, or a failed water pump, not sure how to check either or are these a poss reason, and I think the thermostat is in a bad position on these.

Old Salt · 2 Dec 2021

You can check the thermostat by dropping into a pan of water and then heat it up and see if it opens. Rad caps are cheap enough to replace anyway but at this time of year I wouldn't think 10 miles was long enough to really get the system working at or near to operating temperatures.

If you are really concerned look for loose hose clamps, expansion tank leaks or loose cap or dirt on the sealing faces. When was it last checked and did you put the cap back on properly?

As the interior is warm the thermostat is obviously open but may not be closing properly. If its hard to get at I would leave it until other issues have been checked.

Mottie · 2 Dec 2021

If you give the top hose a good squeeze, can you hear any hissing near the expansion tank cap? Might be worth changing it anyway for what they cost.

delmel · 2 Dec 2021

I will check, but do not recall any hissing when squeezing hose. I did take the cap off and could see small bubbling like fairy liquid but it isnt anything as it goes quickly when engine stopped.

Mottie · 2 Dec 2021

Was there any pressure when you removed the cap? Was the engine warm?

delmel · 2 Dec 2021

Engine and water was warm not overheated, heating working and blowing as expected warm, and no pressure when cap removed at that time. I have not yet took it on a longer run to check again.

Burnerman · 3 Dec 2021

With a low ambient temperature, some engines will not achieve their normal running level......small diesels for example when they are up to their normal running temperature will actually start to cool if left on tickover.
A reasonable thermostat check on the vehicle is to start the engine, run it at around 2000 RPM and when the thermostat opens there will be a rush of heat through the radiator and hoses. If this doesn't happen or the coolant temperature just increases slowly then the stat may be stuck open.
John

Diver Fred · 3 Dec 2021

Switch the AirCon off. run the car for at least 20 minutes to get the engine throughly warm (operating temperature) and then check to see if the AirCon drain is dripping water. If it is then the Heater matrix has failed.

Might be cheaper to replace the car

delmel · 3 Dec 2021

Aircon is not used as it does not cool. Heater works fine

sxturbo · 3 Dec 2021

I would say there is nothing wrong if there is no other symptoms

delmel · 7 Dec 2021

Done a fair run and no overheating, was a little pressure but not as I would expect. Still bubbles that clear once engine is off and begins to cool. Still have to monitor the cooant for dropping again.

Diver Fred · 7 Dec 2021

delmel said:
Aircon is not used as it does not cool. Heater works fine

If the heater matrix is leaking the heater will still produce heat. Just might produce lots of mist on the windows in very cold weather.

delmel · 7 Dec 2021

I think its ok, if matrix was leaking that would have wet footwell in passenger seat wouldn't it also smell (which it has no coolant smell). Not sure how to check but will try

Coolant no pressure - Thoughts please along with suggestion what to check please.

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