Deposit/scaling in raw water cooling

[friz]

So is this normal? New to me BMW D190 (mid 80's) diesel engine. Have not run the engine yet. I removed the thermostat cover to discover no thermostats. The white scaling concerns me. At first I thought it was a coating of some kind but although hard it crumbles away. Is this salt deposit? I believe I am looking at the sea water side of the cooling system. The fresh water side appears clean. I have not pulled the heat exchanger or the sea water pump yet but will now. If this is salt I am going to guess the engine/boat spent some time sitting in salt water without being flushed. My 28' trawler is on a trailer so going forward the motor will be flushed after each use. Any comments/advice appreciated.
Thanks, Friz

 

[Ski in NC]

No expert here on that motor, but it sure looks like the fresh water (coolant) side.

You need to find the parts break down drawing to find out if the t-stats go there.

 

[sbman]

The raw water side would not normally have a thermostat. The thermostat would go in the fresh water side of the system. I know zero about BMW marine engines and it's possible they do things differently.

 

[friz]

No expert here on that motor, but it sure looks like the fresh water (coolant) side.
You need to find the parts break down drawing to find out if the t-stats go there.

I have the parts catalog and a service manual. The service manual shows the thermostats in the "cooling system" and not the "seawater system" so I now tend to believe you. And by the drawings the thermostats set in the two large holes. But the white scale is confusing me. The tank under the radiator cap is clean gray metal inside. I am going to pull the heat exchanger and have a look. What is the white scaling from?

 

[friz]

The raw water side would not normally have a thermostat. The thermostat would go in the fresh water side of the system. I know zero about BMW marine engines and it's possible they do things differently.

I think you are right - thanks. But what is the white scaling?

 

[Lepke]

Scaling is probably from using water with impurities. Maybe the po was using salt water. The scaling is probably why the engine has no thermostats. The engine was probably overheating. Scaling is like insulation, it keeps the coolant from easily absorbing engine heat or the heat exchanger from transferring heat to the salt water.

 

[bogranjac1]

Fritz, I found exactly the same white scale in my Yanmar raw water pump when opening it to replace the impeller.
I didn't ever encounter any problem regarding this deposit
Lepke, I think he is referring to the salt water side,therefore impurities would not be an issue as it's seawater.