Coolant Leaking From The Cap

[ribinsons]

Hi, just recently replaced the water pump un 55reg C4 hatch. Yesterday noticed that after I've parked car coolant is leaking from under the expansion tank cap. No other leaks. Today - after short drive - the same. Engine is going fine, no overheating; nothing unusual.

Could that be case of dodgy cap as garage replaced to different?

Any ideas?

 

 

Thanks

[Johndouglas]

Maybe the tank has been overfilled.   Space must be left to allow for expansion when the coolant gets hot.   When the coolant is cold, the level must be quite a bit below the neck of the tank.   Check it when the engine is cold.   Also are you sure that the system has been bled correctly.   It's easy to get an airlock when filling.

[paul.h]

Depending on the above checks and if the cap was on tight, then take it off and give it a clean in case dirt is stopping it sealing (or check when the engine is warm, just undo the cap very slightly to see if there is an escape of gas showing it is sealing and then do it back up). If none of these, then probably you need a new one although it does seem odd it would fail during a water pump change.

 

Also does the engine fan come on when the engine gets hot ? - test by letting the engine run whilst stationary, although this check is usually done when the coolant has been replaced. This is to check the engine temp sensor and fan are ok, having had a car that were not ok and the tank cap released the boiling coolant when it overheated.

[paul.h]

The following may help a bit. It is for a 1.6 hdi 110hp. You do not appear to have given your engine in this or your posts on the rear lights (which your last post was to let us know how the garage fixed it - we are still in suspense). Shows the fan should start at about 97°C so the temp gauge would not be much different to normal. 1.4 barg steam is 126°C so if the cap is lifting due to high temp and pressure (and not overfilling) the fan should be on and the high temp warning should be on before the cap lifts.

 

Cooling circuit with or without air conditioning

Capacity of the cooling circuit 6,5 litres

Surface area of the cooling radiator 21 dm2

Pressurisation Cap with 1,4 bar rating

Opening of thermostatic regulator 83 °C

Fan Triggering threshold 97 °C (stops at 94 °C)

Number x electrical power 1 x 130 Watts

Air conditioning cut-off 115 °C

Warning 118 °C

Post-cooling 105 °C (for 6 minutes)

[ribinsons]

Its 1.4 petrol. The brake light is still of - wiring broken (where wires go from the body to the boot lid; in the rubery casing). Citroen quoted £350 to fix it. It will wait.

 

The odd thing is that it was fine for two months since water pump was replaced until this Sunday I decided to check coolant level and too the cap off (did few times before since it's been fixed-never had probs). Had a short trip to the shop (20min in total) and since then coolant is just shooting from under the cap!

 

Took the cap off this morning and there is like black plastic "cover" inside with which looks like two little valves (dont know the technical name for it :) ). The black "thingy" is very wobly inside the cup.

 

Temp gauge rarely gets into three bars - most of the time stays in two.

Edited June 19, 2013 by ribinsons

[paul.h]

I have read elsewhere that the 1.4 petrol may be prone to head gasket failure so I hope it is not that.

 

First thing though will be to see if the coolant radiator hoses feel under pressure and if not, swill the cap out under a tap to clean the valves and seal and tank neck and if that does not work consider a new cap. Those little valves are to let air out as the coolant heats up and expands or air in when the coolant cools. So if it is blowing coolant out it must not be holding pressure at up to 1.4 bar or the pressure is going above this if the head gasket has failed.

 

If you do suspect the head gasket has failed, I would be reluctant to use the car much in case the head becomes warped due to overheating.

 

Apart from the current problems, how have you found the car and engine - is the performance ok. Only asking as a possible replacement for our C3.

[paul.h]

I would also check the radiator top hose is hot, showing the thermostat is opening as the engine heats up.

[ribinsons]

Car is in the garage. Awaiting the verdict :( I do suspect its gasket now. Seems that some sort of thermostat failed first by not kicking the fan in time to cool the engine that resulted in gasket failure cause now its spiting tiny bit of water the oil cap (when the cap is off). Not been lucky with C4. Just had it for a year. Wife's done just around 3000 miles but already starter and water pump replaced. O2 sensor needs changing. Third brake light went busted. And now the cooling sistem and whole engine is caput. Had C5 (52 reg 1.8 petrol) before and never had problems. Grrrrrr.

Will let you know what the garage said.