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  #1  
Old 10-17-2011, 01:53 PM
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cooling system trouble 1984 300 SD

I still cannot get the air out of the cooling system. I replaced the heater core and drained the radiator. All the coolant hoses are hot except for the lower radiator hose from the thermostat to the bottom of the radiator. The heat is toasty.

I've tried putting it up. I've also tried crimping the expansion tank line and pumping the top radiator hose to generate vacuum. I've also tried revving it up pretty good for 20-30 seconds. Still no luck. The needle keeps creeping up.

Any advice on how to get that air out of there without damaging the engine would be appreciated.

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Last edited by vstech; 10-17-2011 at 02:21 PM.
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Old 10-17-2011, 02:04 PM
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That lower radiator hose should not be hot. It's sending coolant cooled from the radiator back to the engine.
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  #3  
Old 10-17-2011, 02:26 PM
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are you thinking that there must be an air bubble in your cooling system because the temp climbs?
more likely you either have a stuck thermostat, or a leaking head gasket/cracked head...
the fact you have cool lower radiator hose, points to a working radiator, so non flowing coolant would be stuck thermostat.
the turbo 617's do not usually have issues with air bubbles in the coolant. the naturally balanced radiator/engine block prevent air from remaining in the system.
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Old 10-17-2011, 03:51 PM
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No not just because the temp climbs. Before I emptied system to replace heater core it was perfect. Emptied radiator and heater core. Replaced heater core. Refilled. Got coolant to heater core by revving engine. Temp still climbing though. I don't know what would cause the thermostat or the head to be damaged. It would be an odd coincidence that either of these things would happen while the car was out of service for a few weeks.
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Last edited by mbzjag8090; 10-17-2011 at 04:14 PM.
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  #5  
Old 10-17-2011, 06:18 PM
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You posted the identical situation yesterday:

Lower radiator hose not hot after coolant flush.


Kindly close this thread and keep all your questions on a single thread.
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  #6  
Old 10-19-2011, 05:17 PM
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I didn't start this thread. Someone else did because it was initially part of another thread dealing with a no-start condition.

For the benefit of a future user:

The problem had nothing to do with air bubbles and it was not overheating. The dash is out so I also had the instrument cluster out. I plugged in the leftmost electrical connection to the instrument cluster and the temp. gauge seemed to be working.

But without the electrical connection in the center of the instrument cluster that controls the speedometer, the temp. gauge isn't grounded. That means that even though the temp. needle goes up as the car warms up, the needle isn't registering properly since it isn't grounded. I figured that because the needle was going up at a speed similar to that as when the car warms up that the unit was properly connected. So as it turns out the car was okay all along.

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