Coolant magically disappears and engine overheats?

[Gazmus]

Hiya,

I know nothing about cars, but have googled this problem and I think found a solution. Hope you dont mind me spamming the board up just double checking its not going to explode my car?

Ive a 05 1.6 petrol cheap little up until this point lovely runaround of a car. 

After the crazy snow its started overheating and going low on power...not sure if over revving it because its low on power makes it overheat or if overheating can make power go away. 

Its doing a weird thing where I park up after a decent sized drive and it sounds like the whole engine is still running but its just the radiator fan going absolutely mental. Today on the M5 it started flashing the really bad red warning light *other ones always on keeping me company* and the temperature needle was darting up to the red end, then it comes back down for a bit and darts up dramatically again for no obvious reason (i was hiding in the left lane behind a lorry doing 57 after it came on first time.)

I did fill up the oil (tiny bit) and the coolant (tiny bit) at the weekend and there seems to be plenty still in there. The coolant does a weird thing though, when I open the bonnet it looks completely empty, then I open the cap to pour it in and it looks like the water in there is boiling and it just magically refills itself. Which is no doubt a terrible symptom of my dead car and not a delightful Ford based trick :(

Anywho...fan staying on and car overheating is what I told a girl at work. She said it is definitely that the coolant thingy has air inside of it and its stopping it work as this happens a lot in the cold? I googled it and the easiest solution I found was to unscrew the cap for the coolant hole, fill it right over the fill line to the brim, switch the engine on and wait for a load of air to come out.

Is this true or one of those internet tricks? I cant imagine filling it over the max line or running the car when the cap is off is a good thing. 

Any ideas? Im an absolute moron with this sort of thing but working away pretty much all the week so not sure when I can get it in to a garage to fix...and I hate walking to the train station every morning. 

Sorry for my idiocy, if you can help that would be great, if this makes no sense at all I apologise. 

[FatHead1979]

7 minutes ago, Gazmus said:

Hiya,

I know nothing about cars, but have googled this problem and I think found a solution. Hope you dont mind me spamming the board up just double checking its not going to explode my car?

Ive a 05 1.6 petrol cheap little up until this point lovely runaround of a car. 

After the crazy snow its started overheating and going low on power...not sure if over revving it because its low on power makes it overheat or if overheating can make power go away. 

Its doing a weird thing where I park up after a decent sized drive and it sounds like the whole engine is still running but its just the radiator fan going absolutely mental. Today on the M5 it started flashing the really bad red warning light *other ones always on keeping me company* and the temperature needle was darting up to the red end, then it comes back down for a bit and darts up dramatically again for no obvious reason (i was hiding in the left lane behind a lorry doing 57 after it came on first time.)

I did fill up the oil (tiny bit) and the coolant (tiny bit) at the weekend and there seems to be plenty still in there. The coolant does a weird thing though, when I open the bonnet it looks completely empty, then I open the cap to pour it in and it looks like the water in there is boiling and it just magically refills itself. Which is no doubt a terrible symptom of my dead car and not a delightful Ford based trick :(

Anywho...fan staying on and car overheating is what I told a girl at work. She said it is definitely that the coolant thingy has air inside of it and its stopping it work as this happens a lot in the cold? I googled it and the easiest solution I found was to unscrew the cap for the coolant hole, fill it right over the fill line to the brim, switch the engine on and wait for a load of air to come out.

Is this true or one of those internet tricks? I cant imagine filling it over the max line or running the car when the cap is off is a good thing. 

Any ideas? Im an absolute moron with this sort of thing but working away pretty much all the week so not sure when I can get it in to a garage to fix...and I hate walking to the train station every morning. 

Sorry for my idiocy, if you can help that would be great, if this makes no sense at all I apologise. 

Running the engine for a bit with the coolant tank cap off won't do any harm, in addition what you posted you also need the heater setting on max heat to ensure the full coolant including the heater matrix is in use.

Once the engine is up to temp, check if the top hose for the radiator is also warm, if not it might be that you have a sizeable air lock in the radiator.  If you've tried the steps you mentioned in your post, I'd say try it and see if it fixes it.

If not post back as we go from there.

[Gazmus]

Thanks dude, I shall give it a go after work tomorrow to save the engine noise keeping the neighbours up tonight :)

I have just learned from my dad that what I know as the coolant hole is actually the expansion tank if that makes my post any easier to understand. 

[doggsbody]

@Gazmus l do believe that @1979Damian will be right with what he said as if it was the head you wouldn't have any coolant left and the temperature gauge wouldn't rise back up, you just need to squeeze the top fattest pipe on the radiator while it's running to help push any air out faster 👍