Raw water cooling - removing scale

[Tomaz]

Hi,
I have a raw water cooled diesel engine in my boat. By changing zinc, I noticed a lot of scale inside. Is it any way to remove it without disassemble the engine?
I had a liquid in mind, which would be put into engine instead of raw water for a few hours to dissolve it. I got many suggestions from vinegard on, but I had a fear to damaga gaskets, impeller pump etc. Have anyone any suggestion how to do it?

[RichH]

Vinegar, dilute acids will all work .... however they will also remove metal. Better to use products: Mar-Solv or Ryd Lyme to dissolve the scale but not the metal componentry.
Take a good look at the engine''s thermostat..... a raw water cooled engine should have a thermostat that opens at 135 degress and not 180 degrees. If you find a 180 thermostat, the internal passages of the engine are probably also severly ''salted'' and you will definitely need to ''pickle'' the engine. Check the Thermostat .... or the engine temperature gage.
;-)

[kymatthegulf]

Originally Posted by RichH

Vinegar, dilute acids will all work .... however they will also remove metal. Better to use products: Mar-Solv or Ryd Lyme to dissolve the scale but not the metal componentry.
Take a good look at the engine''s thermostat..... a raw water cooled engine should have a thermostat that opens at 135 degress and not 180 degrees. ;-)

Hello, I have heard that dilute vinegar works well for mild case. Also I have read that thermostats open at 135 but ... why ??? any one know ?


cheeers

[Rockter]

The lower operating temperature for the raw water cooled thermoststs is because salt water really does scale very aggressively if it is allowed to run at the temperature common in heat-exchanged motors.... perhaps 90 degC, 194 degF.

Raw water motors really must be a bit overcooled.... they cannot be allowed to run so hot.

Cast iron is a common material. I am surprised you have zincs. They must blast away quickly, do they not?

[sailingdog]

Actually, the salt starts to precipitate out at about 150˚ or so, which is why the thermostat is set for 140˚. Might want to try Barnacle Buster...

[CapnHand]

The thread was posted 4 1/2 years ago.

[sailingdog]

Good point CapnHand... I checked the dates on the two posts above mine, but not on the rest of the thread...