Very annoying!

[TV8]

I Pulled the car out of the garage today and found a reasonable sized puddle of coolant under the front of car. The valley under the radiator was soaked and looking in the bottom nearside corner, there are small coolant type stains.The coolant levels were also low and needed some topping up.

I topped up the coolant, then, running the car up to temperature, leaving ticking over etc, no leaks to be seen anywhere. Allow to cool and try again and nothing! The heat of the sun and standing there, fans cutting in and out, actually dried everything out!

Car is back in the garage and I have just had a look and still no leaks!!!

Beyond doubt, the radiator needs to come out but I am not sure how it can leak at least half a pint then nothing!

Any ideas please?

[EGB]

Came from expansion tank? Low coolant level got very hot and gave a hot releaving pressure squirt out of VW cap.

[TV8]

I will look at that but I am thinking that would be more off-side than nearside?

[Sardonicus]

It's the rad. soon as the same conditions occur ie temp it will weep away Graham.

[pb450]

Leaking joint at hose connection expands when hot and reseals again?

I've had this in the past on my MG but only over a period of time and probably not half a pint. All dries and reseals when everything heats up.

Shot in the dark really and not very likely.

[TV8]

I have just checked and it's totally dry. To use or not to use that is the question!

[TJC46]

TV8 said:

I have just checked and it's totally dry. To use or not to use that is the question!

Use it. Its ok to leave it ticking over and no leak, but take it for a spirited drive and really build the pressure up within the cooling system, then have a look for a leak.

My monies on the rad, they develop very tiny pin prick holes which leak as the rad heats up and expands.

i had the same problem as you describe, but mine was two fold.

I had a leak at the bottom hose joint which i sorted, and then thought all was well.

The car was fine for a few weeks, but the coolant level would slowly drop over this time period, and i could not visibly see any leak.

Finally bit the bullet and removed the rad and had it pressure tested. It failed, so had a re-core and 3 years on car has never been better.

Good luck.

[Bluebottle]

Leak, either the rad or the pipework to the rad...when running air was getting sucked into the system replacing the lost water.
When u parked it up and turned engine off the core temps rise, before it all starts to cool down, that air in the system expands with the elivated heat which presssurises the system, should vent through the expansion tank unless less pressure required for it to exit somewher else, ie leaking joint or rad.

[TV8]

Thanks everyone. Definitely getting a new rad and will try the car again today.