High pitch "buzzer" sound coming from driver side middle hub from CTIS

[Steelreaper80]

Hey guys,

I have a 1991 M925A2 with "functional" CTIS. While driving it today I noticed a loud buzzing sound coming from the drivers side middle hub while the tires were inflating. I stopped and crawled under the truck. It was so loud that I actually had trouble finding it. It closely sounds like the low air pressure or parking brake buzzer in the cab. That is the best way I can describe it. Does anyone know what it is? My CTIS controller then started flashing all the lights and the CTIS stopped working. My CTIS is at best temperamental and usually just a pain in the rear. I would like to know what was causing the buzzer sound though.

 

[gimpyrobb]

Hard to say. Could be a kinked line or a failed gasket/seal.

 

[Jbulach]

... a loud buzzing sound coming from the drivers side middle hub while the tires were inflating....

If I'm understanding you correctly, this is the front axle on the rear tandem?
If so, and you think it's coming from the outside of the wheel, your wheel valve has likely popped off the adapter nipple. You can usually feel the air coming out around the wheel valve guard.
You can use heater hose to replace the seal if necessary. The biggest issue is, corrosion of the aluminum threads on the wheel valve end up ruining it. I just recently bought all new ones off big internet action site for $25 each (typically $75-100).

If the wheel valve not leaking, it's most likely your hub seals.

 

[M35A2-AZ]

I had that on my M932A2 and it turned out to be an oil seal in the axle had moved and was letting air by it. Hard to track down, start by taking the big supply hose off one axle at a time. it is the big hose that goes to the valve about each axle.

 

[peker aaron]

Hi,
I have a 1989 M932A2 wrecker - I was using the crane and then when I turned off the PTO I cant' get the truck to drive
as soon as I put it into drive - 1-5 the motor stalls
can you help out?

 

[gimpyrobb]

Hi,
I have a 1989 M932A2 wrecker - I was using the crane and then when I turned off the PTO I cant' get the truck to drive
as soon as I put it into drive - 1-5 the motor stalls
can you help out?

You probably should start your own thread about that. Its not related to this thread at all.

932 or 936?

 

[fuzzytoaster]

Hi,
I have a 1989 M932A2 wrecker - I was using the crane and then when I turned off the PTO I cant' get the truck to drive
as soon as I put it into drive - 1-5 the motor stalls
can you help out?

Gimpy is right, also your PTO is still engaged. That's why.

 

[Steelreaper80]

Thanks for the info. When it warms up a bit I will take a look further at the hose and possibly oil seal. Too **** cold right now!

 

[Jbulach]

Just noticed your from Indy, what part? Some good guys up around there! I'm about 1-1/2hr SE of down town, near Cincy.


Sent from my iPhone using Tapatalk

 

[Steelreaper80]

SE side of Indy. You will always know it is me, bought my 5 ton to pull my new Case tractor.

 

[Steelreaper80]

https://youtu.be/aY9VA2fpslc

Another member posted this video of his truck. Mine is doing the exact same thing with the same noise. Apparently it is a bad hub seal??? Now my question is, can I just disable the CTIS and still drive the truck or does it need immediate attention? If so, what parts do I need to order and where can I get it fixed? Will a truck shop be able to handle it? Thanks guys!

 

[Jbulach]

That's an awesome looking combination!

It will be fine to drive as is, some will suggest that you unplug the connector from your ctis control box.
Check and keep an eye on your tire pressure, If they leak down fairly quickly you can put valve cores in the stem where your wheel valve hose screws on. This will help if you have leaking wheel valves, but not leaking wheel o-rings.
You could also isolate your leaking seal by unhooking and plugging the airline for that wheel. This would allow the ctis to function for the other 5 tires, until you get your seal fixed.

Any heavy truck shop should be able to handle the repair. It would likely be best if you did get the seals in advance. I think most of the bigger MV parts vendors would have them in stock.

 

[Steelreaper80]

Awesome. Thank you for the info. Ordering the seals now.