Topic

Probably a simple answer for the technical boffins here, but long story short, a friend recently bought a nice cheap TF, he bought it to show me and after a 10 min drive the coolant bottle was full to the top and bubbling, my TF bottle stays roughly at max hot or cold, is this likely to be a airlock somewhere or could it be the start oh head gasket failure? I also have a freelander that did exactly the same just before the head gasket failed, any ideas boffins type people??? To answer a couple of questions before people ask

The heaters work fine, hot and cold
The temp gauge is staying at halfway
And the rad is getting hot

I suppose it could be that there is too much coolant in the car, although I have only seen the car when hot so can't confirm the amount in the bottle from cold

Thanks in advance
Stuart

Assuming the correct mix of 50/50 coolant is in use - Air's getting in somewhere or the cap's not holding the pressure. So it boils because the boiling point temp is lowered due to the lack of pressure. Mine was a split seal in the expansion tank. Check underneath for drips.

Coolant Pipe, hose size diagram & leaks

I'd be checking the cap first. They're one of the usual suspects.

I also had an airlock in the engine bleed point area.

Obviously check the oil for mayo too.

It may not be HGF ......yet.


FIND the leak and FIX it. (it may be a dodgy cap, a split hose, an inlet manifold gasket, a shot radiator, or even a ropey waterpump.....)

Bleed the system to remove ALL air, topping up as necessary.

..... drive cautiously and monitor for further leaks, airlocks and signs of HGF.

.... allow the engine to cool and rebleed the system.


Cross fingers and drive.

Rad getting hot means your thermostat is working properly.
Temp gauge staying at halfway point means temp is within range.
Heaters still blowing hot usually means the coolant system is ok.

Full or empty the coolant in the expansion bottle really shouldn't be bubbling to the extent that you can hear it.

As its a new purchase I would put a dishwasher tablet in the expansion bottle, start the car and let it circulate but monitor the colour of the coolant, if its starting to go murky it means its clearing oil out of somewhere, heater matrix/radiator or other restrictive places.
Drop the whole lot, flush thoroughly with plenty of fresh water and refill with fresh coolant, might even be prudent to disconnect the hose to the jiggle valve and use a nail to ensure that its free.

Replace the expansion cap as they are a known weak point and a few batches were made that failed within a very short space of time.

As has been said, if there is something, anything wrong with the coolant system it can lead on to bigger things very easily.

It just sounds as though the system isn't retaining the pressure. As said, the easiest check is the expansion bottle cap.

cjj wrote: wrote:

It just sounds as though the system isn't retaining the pressure. As said, the easiest check is the expansion bottle cap.

I agree, have advised all our Epsom MG club members to replace their caps if unsure of age (we have about 50 Fs & TFs in the club) I have obtained a small stock of caps (OEM ones) and have supplied a few already.