Coolant leak - any ideas?

[Jonty5speed]

Good morning all,

When I got home from work last night I noticed a trail of coolant on the road outside leading directly to my car. This morning I looked underneath the car and in the engine bay, checked hoses and connections but there was no sign of a leak or where it may have come from. I topped the radiator up with about 1 litre of water, drove to work and checked the level, which was fine. The engine has been running very well and when up to temperature shows a steady 85 degrees on the gauge.
Has anyone experienced anything similar? Could it be a symptom of something serious developing or should I not worry about it too much?

Thanks in advance,

Jon

p.s. I've posted a picture showing the coolant trail behind the car, it follows the line of the boot lid (how exciting is that!)

[cliveyboy]

Did you check the expansion bottle level is not tooo high. Mine slowly fills up over time

A real long shot is when you parked it on the road had the car before you being running its air conditioning. It was a hot day yesterday.

Clive

[Jonty5speed]

Thanks Clive,

I've just had a quick look and it would appear that I don't have an expansion bottle. There is a small breather tube connected to the top of the radiator (just beneath the filler cap) which is in the right sort of area and is slightly damp. Do you think yesterdays temperatures would explain why the car decided to evacuate the radiator, in which case do I have one of the very few 'winter only' cars?

[types26/36]

I dont want to alarm you so I wont start talking about water pumps but why dont you just take it to your friendly garage and have the cooling system and radiator cap pressure tested, if the cap is defective it would also dump the water out of the overflow.
Brian

[elans3]

I would agree with the previous answer. Most probable culprit is a goofed radiator cap. People tend to forget them as the cars don't do many miles, but I would change mine every two years as a matter of course, especially a they're relatively inexpensive.

[poiuyt]

Get an expansion bottle (or make one) and run the overflow hose from the radiator cap into the bottle so the end of the hose is near the bottom, and fill it with antifreeze about 1/3 full. When the cap releases pressure you will find the expansion level goes up and as it cools it will suck the antifreeze back into the radiator.

Steve B
1969 S4

[ElliottN]

If you fit an expansion bottle, make sure your radiator cap is a "recovery cap" (to allow the coolant to move back and forth according to temp./pressure). If you already have a recovery cap, and no expansion bottle - it could explain the trail of coolant.