Recent Posts

11

Technical Support / Re: Coolant temp gauge doesn't show any movement

« Last post by Eric Maclean Co-Admin on April 10, 2026, 10:20:14 PM »

Roger
It sounds like it's time for new thermostats.
That would also account for the low gauge readings.
You might want to take your engine serial number and check with the Cat online parts menu to see exactly what temperature thermostat or ( regulator) in Cat terms that C9 should have in it .
If I'm not mistaken the thermostat on a C9 should be in the 180* to 190* temperature range .
Running the engine with faulty thermostats will prevent the engine from reaching proper operating temperature which contributes to poor fuel mileage and a greater possibility of wet stacking at idle not to mention poor cab heater performance in cold weather.

Hope this helps
Eric

12

Technical Support / Re: No Air Pressure??

« Last post by Richard Davis on April 10, 2026, 05:03:59 PM »

Roger
Considering the age of your coach, I suspect your air dryer is a Wabco 1200 series.  Be aware that there are LOTS of generic after-market knock-offs of this dryer that sell very cheap ($50 to $100).  Some have had success with them, others have been disappointed.  The actual Wabco dryer is very expensive.  So, be forwarned when you are shopping.

13

Technical Support / Re: Coolant temp gauge doesn't show any movement

« Last post by Roger Milne on April 10, 2026, 01:36:22 PM »

So just a follow up on this in case it helps others.

So we just drove 2000 miles from AZ to SC. As I was a little skeptical of the gauge and it's accuracy, I was able to get in on the Aladdin system this RV has installed and actually has a sensor page much like modern cars have with temps and pressures from various components.

Thankfully this one had both Coolant and Transmission temps and the actual readings were exactly where I'd expect the temps to operate at under driving conditions.
What I will say is this. The CAT and Allison analog gauges work, but at slightly different values compared to the digital ones on the Aladdin. But they did show readings and the Allison more closely that the CAT.
The other thing I did notice is the CAT engine itself, seems to run very cool and it was only during extended hill climbs in the AZ and NM hills that it climbed to what I'd expect them to run normally. But even during continuous road driving they CAT ran about 130-150* digitally and about 1/4 the way off the peg to halfway on the analog.

This is my first experience driving a big diesel and this type of transmission and I can say it is really cool to just watch these rigs, just pull and pull, when going up hill. A very different experience from driving conventional vehicles where the RPM increases dramatically going up hills.

Can't wait to drive it more.

14

Technical Support / Re: No Air Pressure??

« Last post by Roger Milne on April 10, 2026, 01:26:06 PM »

Roger
With your air drier it is often cheaper to buy a complete rebuilt unit than it is to buy individual parts to repair one.
Do you know which model and make the air dryer is.
If you have a haldex pure air plus like the one in the link below and decide to change the filter cartridge try to get it loosened before you remove the unit from the vehicle chassis as they can be seized on and take a lot of torque to get them to come loose.

Hey Eric,

Thanks for the reply.
Yeah we only reached or new RV home base yesterday and will be here for at least the next couple months while we search for a home. But to answer your question, No that doesn't seem to be the same style. I'll take a pic of it in a little bit and post it but it is at least accessible as it's right in the rear engine compartment by the door and I will remove the cartridge before hand as I agree trying to remove that after the body is off would be troublesome. I can't for the life of me figure out why the body would just start to leak, but removal will hopefully reveal what failed and then the search for the replacement will begin.

15

Technical Support / Re: No Air Pressure??

« Last post by Eric Maclean Co-Admin on April 10, 2026, 12:15:22 PM »

Roger
With your air drier it is often cheaper to buy a complete rebuilt unit than it is to buy individual parts to repair one.
Do you know which model and make the air dryer is.
If you have a haldex pure air plus like the one in the link below and decide to change the filter cartridge try to get it loosened before you remove the unit from the vehicle chassis as they can be seized on and take a lot of torque to get them to come loose.



https://www.anythingtruck.com/product/052-170DA33100.html

Hope this helps
Eric

16

Technical Support / Re: No Air Pressure??

« Last post by Roger Milne on April 10, 2026, 11:42:55 AM »

Sorry for the delay in replying been a busy few days driving.

But wanted to update the situation and get some feedback. So managed to find a mechanic to come out on Easter Sunday and trouble shoot the air system. We found a substantial leak on the back of the air dryer body and we cobbled together a bypass for that and immediately started building pressure again. The only side effect was the air hammering the supply tank as it charged but stops when it hit max pressure. Sounds like someone tapping on the tank with a metal hammer but it does the job.

So now we have reached our destination and I can get some tools I’m gonna pull the air dryer body off and see where the leak is coming from. Then track down a replacement.
But doing this has uncovered another issue. So it appears I have a line leak in the rear right somewhere else as the tanks fill and discharge and as soon as I shut off the engine the back rear bleeds the tanks to zero over night. So that’ll have to be investigated as well.

So I appreciate everyone’s advice and videos etc. and will post another update when I get the air dryer off and see what’s up with that.

17

Technical Support / Re: Vorad

« Last post by Michael Hammer on April 10, 2026, 07:24:09 AM »

Yes, could you post the company that did board repairs. Thanks.

18

Technical Support / Re: No Air Pressure??

« Last post by Eric Maclean Co-Admin on April 07, 2026, 04:44:36 PM »

Roger
This might help you understand and troubleshoot the governor, compressor and air drier.

https://youtu.be/bmgSwSeLk_o?si=Whx7W1D9RPOiNeEP

Eric

19

Technical Support / Re: No Air Pressure??

« Last post by Roger Milne on April 05, 2026, 03:36:27 PM »

Ok. Good to know. Apparently the local NAPA store here in Van Horn has one but is closed until tomorrow. Will go that route first thing in the morning.

20

Technical Support / Re: No Air Pressure??

« Last post by Frank Bergamo on April 05, 2026, 03:17:27 PM »

I would look at the air governor first. They are cheap and can be found at any NAPA or truck place.
https://www.napaonline.com/en/p/BNDBENOR275491X?srsltid=AfmBOopTf_e_N9aDErTU0dxEAmegEjE49t_dqFghb9TdQ5ydIgb8_MLPBeA
Good luck, hope this helps.