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Air dryer started purging every minute and a half or so. No…

Air dryer started purging...

Air dryer started purging every minute and a half or so. No loss in pressure. Swapped the air dryer and new governor. Started doing that I’m very cold weather. Still doing the same thing after new parts. Next morning pressure gauges were reading MAX air pressure. Stopped and drained the tanks. Added anti freeze to the lines and built pressure back up again. Now it’s pirgkng every 3 minutes or so. Pressure saying around 130.

Mechanic's Assistant: What is the complete model and serial number of your machine?

Hmm not sure. Truck is freight liner cascadia with Detroit series 60

Mechanic's Assistant: Anything else you want the equipment mechanic to know before I connect you?

The old and new air dryer make “rattle snake” noise before it purges. This new one does it for about 10 seconds or so

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Answered in 31 minutes by:
1/19/2018
Don
Don, Journeyman
Category: Medium and Heavy Trucks
Satisfied Customers: 1,746
Experience: journeyman mechanic over 40 years experience
Verified

hi there my name is don i will try to help you on this

did you have a look at the old dryer to see if there was a lot of oil build up on the purge valve

did you get a lot of moisture out of the tank ?

purging at 130 is normal how about the exhaust ports on the quick release valve and the ABS valve ? what year is your freightliner ? did you put air brake antifreeze from the compressor

is your model dryer a adip model

during the question period you will not be charged anything until i press the answer on my end and you see the rate me pop up at your end

don

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Customer reply replied 7 months ago
Didn’t get a chance to look at the old air dryer. It’s a 2009 cascadia. It was -4 or so when this started happening. Hard to say if a lot of moisture came out due to weather. From what I read on few sites it could be the unloaded valve. Or anything else that I could look at before that?

hi there thanks for that information

if your talking about the compressor unloader valve it is working normal from what your saying

the purge valve on the dryer could be sticking but its new correct and you plugged in the heater right ?

but you changed the whole dryer right or just the canister ?

don

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do your brakes hang up a bit or release normally ?

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Customer reply replied 7 months ago
Yeah it’s a brand new air dryer and new governor. Seems like the compressor is just always working. Pressure stays put at 130. And about every 3 minutes i hear the rattle snake noise from the dryer and then the “sneeze”. Breaks seem to release normally.

hi there thanks for that great information

have you tried a leak down test yet to see if you have an air leak

is the truck empty of air when you pick it up or shut it off for awhile ?

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Customer reply replied 7 months ago
Usually empty overnight.

hmm thanks for that information

have you tried a leak down test ?

build pressure up to 100 lbs release the brakes make a brake application shut the truck off and maintain brake application for three minutes and see if the pressure drops more that 10 lbs

can you do that and let me know

how long does it take the compressor to build air between 50 and 90 lbs should be under 2 minutes

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Customer reply replied 7 months ago
Not able to do it right now. Is it possible to continue in the morning ? I’ll do the leak down text first thing

hi there sure thing

however i live in western canada so i am on mountain time

right now its 10:16 pm

i do have an appointment at 1:00 pm tomorrow afternoon till about 3 pm

so in the morning untill 12:00 noon or after 3 pm mountain time what ever works good for you

by the way i am a red seal Canadian government licenced mechanic and air systems are one on my specialties

Don

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Customer reply replied 7 months ago
Sounds good thank you!

Have a great night

Don

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Customer reply replied 7 months ago
Good morning. Ok so while holding the breaks down it lost about 25lbs in the 3 minutes and took about 2:15 mins to build it up from 50-90psi

hi there thanks for that great information

compressor build time is a little long ( thats at 1200 rpm correct ?)

the pressure drop of 25 lbs means that there is a leak somewhere in the system could be the reason that the compressor is working to keep up pressure

did you check the the hose off the discharge of the compressor and the fitting in that is goes to for carbon build up sometimes the carbon build up on the compressor head holds the valve open

take the fitting of the compressor when the hose goes from the compressor to the air dryer and have a look at the fitting see if there is a lot of carbon build up and also look at the hose to see if it has lots of carbon

my feeling is this that you still have moisture in the system and it might be freezing up one of the Valves

or on the tank its self you have a 90 lb protection valve on the tank and small plastic lines coming off it

if you do not have a air system alcohol (air brake antifreeze ) injector i would put one in the cost is $ 90.00 and an easy install you fill it with air brake antifreeze and it injects it into the air system just after the air-dryer . so the line that comes off the air dryer going to the primary tank goes to the injector then the line comes out the other side of the injector to the air system

this keeps the system clean and keeps ice from forming . i put them on all our trucks because they see such a drastic change in temperature hauling freight

as for your air leak make sure the air is up to max make sure you block the wheels

shut the truck off and see if you can hear an air leak if not it may be in the brake application system

release the brakes ,either have some one push on the brake peddle and hold it or pull the spike down

make a spray bottle with soap and water mix of if it cold fill with windshield washer fluid

spray all the air line connections on the valves and air tanks also spray around the clamps of the brake pots if there is a leak it will indeed bubble up if nothing from the cab back then open the hood and do the same there the leak will show

make sure you maintain over 100 lbs or air pressure in the system this may require starting the truck a couple of times if it is a good leak

it will take about 1/2 hour to check all the lines ,

to install the injector is about the same amount of time

that is what the injector looks like

https://www.haldex.com/en/na/air-dryerair-line/alcohol-evaporator-/

https://www.haldex.com/en/na/air-dryerair-line/alcohol-evaporator-/a72420/

this will give you an idea of the price

https://www.ebay.com/i/302606397389?rt=nc

installation instructions

http://tycrop.com/wp-content/uploads/2015/07/alcohol_evaporator.pdf

if you have a problem installing let me know

have a great day

Don

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Customer reply replied 7 months ago
I’m in warmer climate now. I’ll check the discharge valves tomorrow and replace them. I did read a post earlier that recommended to replace the unloaded valve. I did that this morning it def purges less often. But not the issue. Thanks

sounds good

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Customer reply replied 7 months ago
I have another question. So only leak I found was at the fittings to the air tanks. My pressure gauges show 140 psi. Never had it this high. Still purging every 3 mins or so while driving. Could those leaking fittings be the culprit of this unusual behavior
Customer reply replied 7 months ago
Also building up pressure at 1200 rpms from 50-90 took only 1-minuet

Hi there thanks for that great information

the normal pressure is between 135 and 145 so your good there at 140 the only way you can adjust the pressure is at the governor you unscrew the little black cap and you will see a stud and nut in there you would have to adjust it there .

build time is perfect nothing wrong with the compressor

the leaks depending how bad they are it will definitely effect the cycle of the compressor

did you repair them ?

Don and as far as the pressure and purging all is good there not to worry about that

also remember that if the trailer your pulling has leaks and so on that also will effect the compressor cut in and out

Don
Don, Journeyman
Category: Medium and Heavy Trucks
Satisfied Customers: 1,746
Experience: journeyman mechanic over 40 years experience
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