Detecting miniscule coolant leaks with a cold Uno

method
With the engine fully cooled, remove the coolant cap.

Place the driptray of mat under the engine.

Depressurise the ball.

Place the rad cap centrally over the ball’s valve, and draw around it. This helps cutting, and later location.

Cut the ball leaving lots of overrun. You can always take more off if needed .


It just happened the ball’s valve is the same size as the filler neck (arrowed) .

[I cut the ball in half first. Now I have a basketball cap :rollyeyes:]………..

this is the kit as I used it:-

Clean the filler off with a rag.

Just to clarify, the Uno Turbo’s filler neck is located differently to most other Unos.


Disconnect the battery negative lead, and cover the battery with something which won’t conduce electricity. We don’t want any fires / explosions now do we? .

Place the pump on top of the covered battery, taking care not to scratch your paint .

I intended to use the jubilee clip to seal the ball’s valve to the filler neck. It turned out that the material is too thick. A tyre or ball inner tube may have been better. The pressure needed is low enough to hold in place by hand .

Moisten the ball’s valve underneath to aid sealing (I used spit ).


Fix or hold the contraption to the filler and get pumping (slowly). Take care not to over pressurise as you can easily do more damage. Listen for a hissing, indicating air loss. It took me a few goes to get it to seal. Would be easier to have an assistant pump or hold.


Check the drip tray / matt for leakage. I had some in two locations . You might not see any. In this case, it could be the radiator cap at fault, or an internal leak (eg head gasket).

I suppose you could have both an internal and external leak at the same time, especially if you have run the engine dry and warped your head.

If you see drips, get under the car with your eye protection on, and trace the drips. – sorted leak found Tad Darrrrrrrrrrr .

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