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Jay Lutz would be proud of me, I've got water + water wetter in my Scirocco cooling system.

But this leads to a problem - at least maybe. The car has started using some water, maybe a pint in a session. And seemingly leaving no trace - I realize now that ethylene glycol makes a pretty good leak detector by not evaporating very well!

Engine is running well and not overheating, spark plugs and piston tops look about the same, oil is not milky so I don't think it's a head gasket?? Water pump is old so I suppose changing it is an obvious first step, I did have an instance on my street '84 GTI of the water pump seal leaking at revs but not at idle....

I guess my real fear is head gasket, but I don't think symptoms really support that?? I hate to take apart a happy engine.....

After several trips to garage during last winter's cold snaps to put a drop light under the hood to ward off ice, I'm tempted to go back to a low % ethylene glycol mix anyway - don't tell Jay!

Hi Al,

You can get those dye test kits that use black lights at most auto parts stores. They work very well for straight forward leaks.

Also, I fill the engine with antifreeze during the winter. When it's warm enough, I flush the system back to water and water wetter.

-Kyle

Not sure if you solved the problem but I thought I'd share a past experience.

I had an almost invisible hairline crack on the back of the fill neck, it allowed steam to escape and barely left a trace. After about 10 sessions, I noticed some discoloration on the underside of the hood and eventually tracked it down. Didn't drip and left almost no trace but was going through almost a pint every session.

Good luck

It was the water pump - I was initially thrown off by the lack of telltale ethylene glycol.

Al