need some help with air leak

[BRUISER]

so here is a question?

I got under bus to remove DD3 and I can not get to the one of the top bolts that holds the DD3 to chassis.

I can get all bolts off etc but the one bolt that is close to the tire I can not get off.

are you guys taking off your tires to remove the DD3?

thanks
ken C

[Purplewillie]

On my 4905 I was having air issues and after fixing the governor problems it still didn't always air up past 90 psi. Sometimes I could hear the leak under the the front, at other times it was quite. Turned out to be the push/pull parking valve right beside the driver, exhaust was plumbed straight down thru the floor. Sometimes leaking , sometimes not.  Replaced the parking brake valve , no problems since.
Mark



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[bevans6]

Yes, you need to pull off the tires to work on the DD-3's on an MCI.  Carefully inspect all the hoses - if you are going to do some rebuilding, may as well do them too if they need it.

Brian

[BRUISER]

well tires had to come off and pulled dd3, put new parking brake diaphragm in it and put it back on and the thing still leaked

so had to order a new one and replaced it and bam air leak fixed and bus now airs up to full pressure

[bevans6]

Did you replace the diaphragm with a second one, or get a new DD3?

Brian

[Cary and Don]

Why would you want to take the DD3 off?  We changed the diaphrams with it on. Taking hoses loose is just asking for more leaks to fix.

Don and Cary

[BRUISER]

Did you replace the diaphragm with a second one, or get a new DD3?

Brian

Could not get dd3 open easily on bus. And this was my first one so i took it off and replace the parking brake diaphragm. After putting it back on had more leaks. So I replaced entire dd3 with a new one. Had to also twist caps due to air lines not meeting up correctly on new one.

[bevans6]

MCI mounts have very little room to work, taking the can off is about the only possible way to do a quality job.  There is barely enough clearance to get them out.  Mine were very crusty and when I took them apart for inspection many little parts in the locking mechanism were failing, about to fail, or just plain broke on disassembly.  I put two brand new ones on.  Oddly, the old ones were still working perfectly but the rubber boots were missing, the shaft was a little pitted and the hoses were shot so I needed to service them at the very least.  As it turned out the aluminium castings were very corroded and were not even good as cores.  About the only parts that were good were the diaphragms...

Brian