why wont my 03 freightliner build secondary air
Engine: detroit series 60
i have taken every line off air tank checked for restrictions it will only build 50 psi and that takes foreever primary builds to 120 doesnt have any air pressure on red supply line at foot valve someone has drier bypassed does this have anything to do with my secondary air problem
Hello Welcome to JA!
If one tank is filling to governor set pressure and the other is not, there is a double check valve between tanks that prevents loss of air from the primary tank if the secondary blows and visa versa, it is likely stuck, drain all tanks then rebuild air, If this does not salve it lets first check the
air into the primary tank see if we have good flow from the hose to the tank
with the dryer not connected you can have watter and oil in the tanks this will keep the air from building
It should not pass a inspection if its not connected.
The other option is
With the tractor off
after the tanks are drained fill the tanks with a air hose at the tanks you might have a brake chamber on the spring brake bleeding back threw the system you canhear it better if the truck is off and you fill the tanks with a air hose with the tractor running its hard to hear air leaks
ive already removed the tank drains and blew compressed air into tanks until nothing comes out does that tank have a baffle with a orfice or check valve inside thats not allowing air to transfer to the other half
yea icharged the tanks and found small leaks at fire wall and along frame repaired but still no pressure at secondary supply
Yes all the tanks have a baffle/valve so the air cant transfer to a different tank in case one blows out.
Did you check the load check valve at the head of the compressor see if it is letting air pass when the primary fills.
yea i even put anew governor on it
Ok next would be there is a 4 way valve this will between the tanks and compressor, Are we close to the truck to check this?
no its twenty miles from me
With the dryer being disconnected i would say we have carbon/oil and watter build up between the tanks and the compressor
Lets disconnect the line IN at the tanks and the OUT line at the compressor see if we get good air like this
Blow air backwards from the tanks lines and then from the compressor to the tanks
im going over to work on the truck some more is that four way valve right above the driver air tank? im open for any suggestions or help you can give me to check before i go out because i dont have access to computer out there
You should be able to disconnect the line out at the compressor and fill the tanks with a air hose if we can there it it between the tanks and compressor
yea idid that it filled the front half of the tank but nothing in the rear thats what has me stumped
Yes ok now lets trace the line back between the tank not filling and the compressor there is something between these 2 point blocking air,, it can be a spliced fitting full of carbon or a kinked line or the 4 way valve, There can be a T or something too between that line and the air compressor.
theres ared line that goes to foot valve and ablack line on rear half of that tank but im not real sure where it goes do es the black line charge that half of the tank
The air come out of the compressor to the air dryer from the air dryer it then splits up to the 4 way valve then to the tanks black line would supply the cab accessories back up to the primary for reserve when the primary fails
ok seems like every thing points to the four way valve im going to go out and see if i can fix this problem i greatly appreciate all your help and suggestions hopefully the problem will be in the four way valve
Im thinking the same with the dryer not being used this would be where the problems will start I would invest in a dryer
yea i ordered one yesterday but i have to have this truck moving by in the morning to get the load off again thanks so much !
20 YEARS OF HEAVY EQUIPMENT REPAIRS/ HEAVY EQUIPMENT MENTOR