Originally Posted by bismic

I was just re-reading a TSB and noticed the following:

Engine coolant quality can be affected by combustion gases, operation at low system pressure, or exposure to excessive system temperatures.


Engine coolant degradation characteristics include:

• silicate drop out (clouding)
• reduced corrosion protection

NOTE: Rust flakes and silicate that combine in the system might collect in the oil cooler and be mistaken as casting sand.


Seems like to me you either need a coolant filter OR you need to flush your coolant system any time you:

• overheat
• over pressure
• under pressure (failed coolant reservoir cap)
• possibly if you used the wrong coolant or used the wrong additive (additives are not needed w/ Motorcraft Gold Coolant)
• allow combustion gasses to enter the coolant (EGR cooler OR headgasket failure)
• use hard water for dilution
• incorrect dilution
• heavy commercial use that includes excessive idling or sustained high speed driving at excessive GVWR load

Recommend checking coolant anticorrosion strength. Check the anticorrosion strength (nitrite level) of the coolant using the Rotunda 3-Way HD Antifreeze Test Strip Kit part number 328-00001 , 1-800-Rotunda (768-8632) option 2
or equivalent. Perform coolant anticorrosion strength at the frequencies recommended.

NOTE:
FAILURE TO FOLLOW THE SERVICE PROCEDURE AS INDICATED CAN RESULT IN INACCURATE TEST RESULTS.

DO NOT COLLECT FROM THE COOLANT RECOVERY OR OVERFLOW SYSTEM. COOLANT MUST BE BETWEEN 50 °F AND 130 °F (10 °C 54 °C) WHEN TESTED. ROOM TEMPERATURE IS PREFERRED.

Start with clean, dry hands and utensils.
Collect coolant sample from the radiator or petcock.
Remove one strip from the bottle. Do not touch the pads on the end of the strip.
Discard strip if nitrite test pad has turned brown.
Dip strip in coolant sample for one second, remove, and shake strip briskly to remove excess liquid.

FOR BEST RESULTS FOLLOW TEST TIMES CAREFULLY. USE A STOPWATCH OR CLOCK WITH A SWEEP SECOND HAND.

Wait 45 seconds but no longer than 75 seconds after dipping strip to compare and record results in the following order:
(1) Compare FREEZEPOINT (end pad) to color chart on bottle and record result.
(2) Compare NITRITE (end pad closest to handle) test to color chart on bottle.
(3) The middle pad is for MOLYBDATE which is not a performance measurement used in determining maintenance requirements for these applications.

It is okay to estimate a value between color blocks, but if uncertain about the color match, pick the lower numbered block, for example if nitrite color is between F and E, use column E.

Coolant test results:
If the nitrite level exceeds 800 parts per million (PPM), no action is required, anticorrosion strength meets specification.
If the nitrite level is between 300 PPM and 800 PPM, anticorrosion strength is low. Add 32 fluid ounces of Motorcraft iesel Cooling System Additive.
If nitrite level is less than 300 PPM, anticorrosion strength is very low and cannot be restored refer to Step 6.

Flush the cooling system with Motorcraft Engine Cooling System Iron Cleaner and refill with 50/50 mix of Motorcraftâ Premium Gold Engine Coolant with Bittering Agent and distilled water. A 50/50 mix of the Motorcraft Premium Gold
Engine Coolant with Bittering Agent and distilled water provides the proper cooling system protection and nitrite level for operating temperatures to -34 °F (-36 °C).

CAUTION
DO NOT ADD MOTORCRAFT DIESEL COOLING SYSTEM ADDITIVE WHEN REFILLING THE COOLING SYSTEM AFTER A COOLING SYSTEM FLUSH WITH MOTORCRAFT ENGINE COOLING SYSTEM IRON CLEANER. THIS MAY LEAD TO
POSSIBLE ENGINE DAMAGE DUE TO VERY HIGH NITRITE LEVEL CONCENTRATIONS.

PART NUMBER PART NAME
VC-8 Motorcraft Diesel Cooling System Additive
VC-9 Motorcraft Engine Cooling System Iron Cleaner
VC-7-B Motorcraft Premium Gold Engine Coolant with Bittering Agent
9C3Z-8101-A Pressure Relief Cap
328-00001 Rotunda 3-Way HD Antifreeze Test
Strip Kit (1-800-Rotunda (768-8632)

Refill capacity is 27.5 quarts. Install a 50/50 mix. In extremely cold environments, never excede 60%. In hot climates still maintain 50%. NEVER drop below 40%. Service at 105k miles and then every 45k miles thereafter.