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Evening- At issue: 2005 freightliner with an MB4000 diesel…

Customer Question
Evening- At issue: 2005 freightliner with...
Evening- At issue:
2005 freightliner with an MB4000 diesel engine. The truck is not producing sufficient air pressure .
at an idle it might get to 20 lbs. must be rev-ed to 1500 rpm for several minutes to get the buzzer to go off. will not hold pressure if the rpm is reduced.
I checked air inlet to the compressor - clear and there is suction. checked pump air at the dryer. Air in but no air out - no water or oil present.
I changed the dryer - complete unit. No change. No air to the tanks .
What gives?
Submitted: 7 months ago.Category: Medium and Heavy Trucks
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Answered in 49 minutes by:
11/29/2017
Technician: Jeremy, Certified Truck/Bus Technician replied 7 months ago
Jeremy
Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3,784
Experience: ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

First off, check the governor. Pull the line off for the unloader valve and see if there is air pushing through that air line while the pressure is low. If so, then there is a fault in the air dryer or that governor. The governor is cheap, replace it. If no air coming out of the line from the governor, then the air dryer needs to be checked. See if you are getting air out of the purge while filling. If so, the air dryer purge needs to be replaced.

If there is neither of those issues, then bypass the air drier with the hose going to the tank directly and not to the air dryer. Then see if it builds air. If it does, replace the air dryer.

If all is good, then check the first tank and see if you have air coming from it. If so, the tank internal valve is stuck shut and the tank needs to be replaced.

_______________________________________________________________________________

You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see, touch, smell, hear the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.

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Jeremy

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Technician: Jeremy, Certified Truck/Bus Technician replied 6 months ago

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Jeremy
Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3,784
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