Car (MKII 16 Valve) is going in on Friday to have a few things looked at, there is a coolant leak from the top outlet on the radiator, think I will need to top the coolant up on route to the garage as it is quite a distance, is it ok to put cold coolant into the header tank when the engine is up to temp? Pete
no, bad idea mate - its a pressurised system and taking the cap off when the engine is hot could scauld you. only ever top up the coolant when the engine is cold.
Its prob not a good idea, a/ you might burn yourself taking the header tank cap off and risk the rest of the coolant spirting out b/Cold water in a hot engine!! could end up cracking something Exactly how much water are you loosing?
Yer I have done this once, without thinking about it as I was on a trip and the water light had come on and I just naturally pulled over to put some water in when...... lovely hot engine water went all over me. It smelt great!
Cheers fellas I'm ok taking the cap off if you open it very gingerly the pressure is released slowly It’s the cold coolant part I’m concerned about I know it’s not good to put cold water into a system which is topped up directly into the radiator but with a plastic header tank I'm unsure whether it will have time to warm up sufficiently before it is drawn into the engine / radiator losing quite a lot really, drove it the other day and within twenty minutes the light was flashing Pete
If you're losing it that quickly then frankly I wouldn't worry about adding cool water\coolant I'd be more worried about it over heating. You'll be fine opening the coolant cap once the engine is up to temp so long as you open it slowly like you stated but sling an old cloth over it first so any steam is caught by that. I had to do this in my valver when the matrix was leaking severly. Pulled into Tesco's car park with the bonnet up filling the header tank with value mineral water.... Was the only water they had available! I'd assume that you'll be flushing and replacing the coolant once the leak is cured anyway so don't worry about it.
personaly mate and this is only my expirience so if you damage your car im not to blame ive filled my car up from a bottle at the side of the road at least 1 million times lol honestly ive had more water leaks over the years that have been rectified by a room temp bottle of tap water to get me home if the red light is on on your dash, its unlikely there is much water left to scald you just turn the cap very slowly you will hear the pressure release slowly turn more and maybe some water will come out, once the pressure has gone you will be able to top up
Cheers fellas Its the cold water going into a hot engine that I am worried about i.e. cracking something with the sudden temp change
Its leaking from where I can see around the top return outlet I've changed the top hose as I first thought that was to blame also tried to bleed the system neither fixed the leak, unfortunately I'm really busy with house stuff and work to spend the time investigating further so I'm going to drop it off at the garage tomorrow morning and see if they can cure it pete
