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Old 08-27-2013, 09:40 PM
ngoma ngoma is offline
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Join Date: Nov 2009
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See my comments in bold italics:

Quote:
Originally Posted by jbg View Post
  1. Drain.
  2. Fill with two cups of detergent and the rest water.
    Undo the top small hose from top port of the IP thermostatic actuator, keep filling reservoir until coolant (no bubbles) runs from that top port of the TA. This will help avoid trapped air bubbles. Reattach the hose.
  3. Start the engine with the coolant cap off.
  4. Let it idle until the water level in the overflow tank drops. I assumed this to mean the thermostat opened and is pulling water/detergent into the block.
  5. Top-off the overflow tank and allow the engine to continue idling. Monitor for engine temperature.
  6. Repeat.

Is my process flawed? Silly question, but if I keep my expansion tank cap off will the thermostat ever open?
Yes, but might not open for a long time just by idling (diesels in general).
Does the thermostat need both temperature and pressure to function properly? I've never thought to think about this until now.
Tstat does not need pressure to operate. Pressure helps raise the boiling point of the coolant. The cap allows the system to build pressure, up to its release point. Many like to use the 75 kPa caps to lessen the risk of blowing old heater cores, coolant hoses, radiators, etc.
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1985 744 gle d24t
1985 745 gle d24t
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