‘Stormcloud’s cooling system had been neglected by the PO, and required remediation before being used as a daily driver for my piece of mind.
The radiator leaked, the temperature gauge was not operating, and the water pump bearings were shot.
Green coolant was seeping from the climate control servo, the block heater, and various hoses.

Since ‘Desert Rose’ recently developed a turbo bearing failure, I had to press ‘Stormcloud’ into daily service sooner than planned.
I was not able to complete the full cooling system rehabilitation.
I still need to replace the fan shroud, coolant reservoir, reservoir cap, various hoses, and also work on the cabin heating system (which is bypassed for now).

Below is what has been done to ‘Stormcloud’ prior to the failure of ‘Desert Rose’s turbo seals:
The temperature sender, on the block between cylinder number 2 and 3, had very high resistance and a used PNP sender took its place.
This restored the temperature gauge function.
The radiator, heater core, and transmission oil cooler were bypassed to allow for a thorough flush, de-oiling, and citric acid flush of the engine.


Next, the water pump housing, and thermostat housing were removed, and treated with a weeklong Evapo-Rust soak to remove corrosion.
Scrubbing with a nylon brush removed the converted aluminum oxides.
Repeated soaks of the parts in a citric acid solution softened the heavy scale buildup, allowing it to be removed with a nylon scraper
Not all of the scale dissolved even after one month of soaking.

Attached Thumbnails

         

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022