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TRex
New Member

7 Posts

Posted - 08/12/2019 :  08:24:59 AM  Show Profile  Visit TRex's Homepage  Reply with Quote
2010 Thomas on a Freightliner conv chassis.VIN AL8755. Complaint is steady loss of coolant. New EGR cooler. No external signs of leakage and oil report shows no coolant. Doing a pop bottle test gives me a small marble sized bubble every 10 secs or so. No steady stream. When put under pressure it will leak down slowly. Been tested twice for combustion gas in coolant. Combustion gas indicated both times. I am not real confident about that test. Pulling the head is the next step. I want to be sure I am not missing something. BTW does the doghouse come out on these. It doesn't look like it. TIA

baptistbusman1
Senior Member

USA
165 Posts

Posted - 08/12/2019 :  2:03:39 PM  Show Profile  Reply with Quote
Have you pressure tested the new egr? I've gotten bad ones from Freightliner before. Also, when you replaced it did you use an airlift coolant filler to get all the air out of the system? I have heard having air pockets in the egr can cause it to burn through.
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TRex
New Member

7 Posts

Posted - 08/13/2019 :  10:05:20 AM  Show Profile  Visit TRex's Homepage  Reply with Quote
We did airlift fill. Did not test the new one, but the old one showed no signs of coolant in it.
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Bluenozer
Senior Member

Canada
194 Posts

Posted - 08/14/2019 :  04:23:23 AM  Show Profile  Reply with Quote
Just changed an air compressor for this condition , would push it out under load on the road only, this was an ISB it would pop the 16 psi check at the back of coolant reservoir and without a bottle hooked up the only sign of wet was inside of the hose from fitting was wet but with the bottle hooked up it would catch coolant

OEM trained in wiring and all engine platforms for 20 years
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TRex
New Member

7 Posts

Posted - 08/19/2019 :  04:16:19 AM  Show Profile  Visit TRex's Homepage  Reply with Quote
Thank you. I will check that. I thought about the compressor but ruled it out because I never heard the air dryer cycle while testing. But the oil report shows no signs of coolant. I did notice that pressure relief valve. Not sure I am understanding how that recovery system works. Next time I have an old tank I am going to cut it open. Thanks!
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