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Buddy, Technician
Category: Heavy Equipment
Satisfied Customers: 730
Experience:  25 years experience
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Century: with a Red top cummins n14 it has 1,080,000 miles..hose..cap

Customer Question

I have a 1999 Freightliner Century with a Red top Cummins N14 it has 1,080,000 miles. I am having problems with the cooling system some time the antifreeze comes out from the antifreeze tank outlet hose were air is suppose to come out. I replaced the antifreeze tank about two months ago, the cap is a 15lbs. The oil pressure and engine temperture is great. The oil cap is clean. When the temperture is about 200 and the fan is on when I shift from a Higger gear to a lower gear and when I press the gas pedal in between the gears the water pump belt squeaks, I replaced the water pump about 400,000 miles ago. I replaced all of the hoses in the cooling system about 2,500 miles ago. When the tempeture is abount 180 you can feel that the cooling system hoses are under pressure, when the truck is off, you can feel the pressure in the cooling system starting to go down and it feels like there is no pressure left in the system. When I rev the engine the antifreeze level goes down. What is the prob
Submitted: 7 years ago.
Category: Heavy Equipment
Expert:  Buddy replied 7 years ago.

HiCustomer Welcome to JA. I am Buddy, and i will try and help you out. How much coolant loss are you getting out of overflow hose?Did this problem just start or has it been getting worse over time?



Customer: replied 7 years ago.

It losses 1and1/2 gallons on 4,000 miles. The hoses that go to the radiator were hard so i changed them.

Expert:  Buddy replied 7 years ago.

If coolant temp is normal it sounds like you are possibly getting compression in your cooling system. If you have a radiator pressure tester with adaptors ,you can pressure test the radiator cap and make sure it is opening up at correct pressure. Then you could hook it to your surge tank and run your engine to operating temp and monitor pressure.If pressure is getting above 15 psi, you are getting pressure in there from somewhere. First you would need to bypass the air compressor and see if it is causing the problem. You could remove discharge line from air compressor and bleed air down. Run engine again and see if pressure rises above specs. If it does, then you more then likely have a head gasket blown or head issue. If head gasket is blown i would check liner protrusion and make sure it is between .004 and .007 . You can also do most of these checks without a pressure tester. You can get a clear bottle of water and put your over flow hose in it from surge tank and run engine up to operating temp on fast idle and see if you are getting air bubbles in bottle. If you are getting bubbles, you are getting pressure in cooling system. I hope this helps you out.If you have anymore questions, just ask.



Customer: replied 7 years ago.
Thank you for your help i cant do anything right now i have to wait till tommarow. I will let you know if i have any more questions.
Expert:  Buddy replied 7 years ago.

You are welcome. Let me know what you come up with. If you have anymore questions, just ask.




Edited by Buddy on 10/16/2009 at 4:31 AM EST

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