SAlt deposits on block

[Tom Glennon]

Gentlemen: Help me solve my mystery!

As I look at my engine (M25XP) from inside the cabin, facing aft, there has what appeared to be white residue in streaks on the starboard side of the block.  I thoroughly checked the raw water pump and hoses, the impeller gasket, and all possible suspects, to no avail.  I took a small wire brush to the area, removing any noticeable flaking engine paint.  I then ran the engine up to temperature with no apparent leaks.  I then pushed the throttle up to about 2500 R.P.M. for about 5 minutes or so, and still all remained dry.

After washing the block , etc. with a light detergent and rinsing/drying, I sprayed the exposed metal with an engine paint.

The next time I looked, a couple of days later, there appeared to be a couple of drops of salty-tasting water in the engine well under the  block, yet when I ran the engine, no leaking.  I am stumped.

My engine runs like a top, and the impeller has been changed yearly.

Any clue as to what could be the cause?  I must say, the Sherwood impeller cover has taken on a lovely verdigris patina.... perhaps an earlier leak that has sealed?

Thanks in advance.

[Ron Hill]

Tom : From what you've said the only salty items you haven't mentioned are the inlet and outlet raw water hoses!!  You might have a pin hole leak in one, probably the output to the heat exchanger.    

[Tom Glennon]

Thanks Ron... "Pin hole" could possibly be the culprit, as there is no evident water when I have the engine running, and I am observing the system.