Club 80-90 Forums

Hi all,

I have T25 1.9 litre petrol. I seem to have a problem with the coolant level dropping in the header tank. The expansion tank is topped to max and that stays constant but header tank looses around a litre very quickly and from there on it stays around at that level. I cannot seem to spot any leaks around the engine bay. Could this be a issue with air lock in the system?

I recently drained out and cleaned the expansion tank, could this have caused more air to enter the system? Please advice.

Thanks,
Desmond.

Hi did you bleed The system after you clean out the tank.
Also how many times are you adding fluid to the system i.e. how often are you topping up a litre.
Is there any water in your oil?

Hi,

Thanks for your response. No, I haven't bled the system as I am not if I am supposed to do that after cleaning?

I have topped it 2.5 weeks ago - lost a litre. I topped it up again yesterday and today when I checked its lost a litre again.

I dont know how to find out if there is water in the oil?

Thanks,
Desmond.

If you only emptied and cleaner the header tank then no need to bleed, unless you took it off the van?

It’s quite common for a small leak from a pipe junction to seep under pressure and evaporate leaving no trace , and just as common for a pipe junction to suck in air thus stopping the coolant being returned from the top up tank to the header tank as the engine cools


The system is very simple....
The headertank ( the one in the engine bay ) should always be full to the brim, and the top up tank ( behind the number plate flap) should be full to the max mark when cold. When the engine is up to normal running temp the coolant expands and is pushed into the top up tank, when the engine cools down the coolant is sucked back into the header tank

Get a super bright torch and check front to rear for any white/pink deposits anywhere to indicate any problem areas.
David.

You need to find the leak obviously, I would start in the engine bay and move forward, check where the plastic piping connects to the rubber hose at the front of the vehicle before it enters the radiator, these are known to fail over time (that is if your system has the plastic pipes).  Reference checking water in the oil as mentioned earlier, have look in the oil filler cap for a milky substance. Does the red light come on warning you of low coolant level, the engine needs to be up to temperature and under pressure to check for leaks.

Thanks all for the responses.

I have not taken the expansion tank off the van when cleaning so will assume I dont need to bleed the system.

Will take a bright torch and try and spot and leaks. Thanks for the tip on the plastic piping connects at the front of the vehicle - will take a look at it as well.

The red light does come on when the coolant level is low

Thanks!
Desmond.

You may not even have a leak , it could be a faulty pressure cap on the header tank or faulty hose between the pressure cap and the top up tank , meaning it pushes coolant to the top up tank , but cannot suck it back as the engine cools . Is the top up tank over full after you stop the engine and it cooled ?

Hi,

Yes that is true - I did notice that the top up tank seems fuller than what I have filled it.

Thanks,
Desmond.

You don’t at a any point say what age you van is or which cooling system , so hard to point you further

It’s much easier if you add those details along with your van age ect in your signature on here ( hover your mouse on your username on the top right and it will show user control panel profile ) , so everytime you post the info is there for all to respond to .....

Thanks for letting me know. I've updated my signature now. 

Thanks,
Desmond

So you maybe have a bayonet pressure cap , rather than a blue "Darlek" cap ?

Image: https://ibb.co/xFKCzxr

Yes thats right - its a bayonet pressure cap

I took the washer out to take a closer look and the cap seems to be damaged.

Could this be a reason for the coolant level dropping off?

Image of cap: https://imgur.com/pe6FkM2

Thanks,
Desmond.

Bin it and buy a new one.
David.