I have an International 4900 fire truck that is suddenly not building air pressure above 20 psi. Is there a fuse or something that could have blown? Thanks,
Is a drain valve on a tank open?
It was fine yesterday. Don’t hear anything leaking. Gets to about 20psi and that’s it.
Get a spray bottle with soapy water, fire the truck up, start at the air compressor spraying discharge line and working your way back looking for bubbles. Not building past 20 makes me think 3 possibilities. Governor, dryer purge valve or a relay valve dumping air out of the exhaust. 20 psi won’t make a ton of noise so the soapy bubbles will help you. It’s gonna be a good size leak. What engine is in it? You can also remove the inlet to the compressor and see if it builds air like it should. They sometimes get plugged up. If it can’t take air in it can’t make air. I used to make quite a few trips to Boyd when I took care of drill rigs. West side of town not far from the school.
Either the dryer purge is stuck open or a discharge line is ruptured. You might have a relay valve purging out exhaust, at 20 psi, gonna be hard to hear. I would remove the wet tank drain and screw in a quick fitting. Run shop air to tank regulated at 125-130 psi. That way you can hear what's leaking. Good luck.
It has an air inlet to keep the pressure up, that is my next move. As you cant hear anything with it running.
What year is the truck?
X2 on the shop air and the bubbles.
2001
Thanks, guys, Dryer purge was stuck open just a little bit and it’s sticking. Now the dash gauges are intermittent.
Is this the instrument cluster you have?
Yes, worked fine and then stopped today.
My 8100 has that same dash and it's always been intermittent. Early on you could bang it and get them to come on, but it doesn't any more. There are a couple places listed online that you can send the gauge cluster off for repair. Just search for international instrument cluster repair. They are known for going bad. 1992-2000's
I have fixed quite a few intermittent or dead clusters. Its pretty easy a few tools and a soldering iron and some fine electrical solder. Here is a thread from a couple years ago on one I repaired. Older International Instrument Cluster Repair
Great I will look it up will be great if I could solder it.
That is awesome, shouldnt be too difficult, great write up. When you mention moving the gauges back, should I move the tach and speedo back down to zero as well?
Don't worry about the needle positions. The gauges have pins that fit into sockets on the circuit board. When you push the circuit board back in place a couple of the gauges may push out of place in the plastic housing. Lay the instrument on its back and push them back in. Here is a link to the manual for the instrument panel: instruments 2001.pdf drive.google.com
Great thanks