twinreds

I keep finding coolant on the valleys below the thermostat and the upper radiator hoses. I repositioned the clamps on the hoses and tightened well. I do not see evidence of wetness on the hoses. I did have the thermostat fixed last fall, and they had left the small upper radiator hose loose with massive loss of coolant, but I fixed that connection too.
I know that the overwhelming opinion is to use a leak tester, but what are the suspects, so I can try to look and identify without having to remove the intake tube?

Mrmerlin

has the water bridge ever been off the engine? the head to WB connections can leak.
have the WB hoses ever been replaced? all 3 of them can leak from old age.

worf928

There's big-a$$ed o-ring (~3" diameter) that seals the water bridge to the block. After 15 or-so years it's plastic and doesn't seal. Coolant will seep through the gap and fill the valleys on either side of the block/bridge junction.

I find this to be the most common non-hose related coolant leak at the front of the engine.

davek9

Just went through this and it was the Water bridge to head.

As Dave said the big 'O' ring will leak w/ age too, usually there will be signs at that connection as it is higher and will capture the fluid around the seal.

Good news is the water bridge is replaceable on an S3 and some S4's w/o removing the Intake.

Dave K