Community Forums

Corley · 11-03-2021, 10:32 AM

I have a 2003 Discovery, 38u. It has a Freightliner chassis with air bag suspension. Let's assume I am camping, and have lowered the airbags. Let's the assume I am ready to leave the camp, but for some reason the engine will not function. I then call for a wrecker to tow the motorhome. However, because the engine won't run, I have no air pressure to pump up the bags.

So, the issue is: How do I insert air into the suspension air system in order to lift it up off the stops?

First, I assume that the wrecker will have onboard air, so if his air can be used to fill my air bags, we are good to go. Can his air be injected into my system, and assuming "YES", where is it connected? I have an air outlet in the front of the motorhome for airing up tires and such, will that point work OK? If " YES", will the wrecker have hose connections that will be compatible? Or, should I be carrying something to allow the connection o be made?

My outlet port in a female quick connect, but as you may be aware, there are about a thousand different quick connects, and no standard. Likelihood of his hose fitting my connection point are like 1%. Plus, his connection point will also be female, so a hose with two male fittings will likely be needed. Who supplies this stuff?

Or perhaps there is a different connection point that I am not aware of??? Anyone have experience with this?

bentjm · 11-03-2021, 11:06 AM

They will have to provide air to your coach to release the air brakes.

CountryB · 11-03-2021, 11:33 AM

Any good tow truck operator will have an assortment of fittings to connect to your air system. Sometimes the quick disconnect air port (you use to air your tires) will work, sometimes they will just remove a plug on the air tank.

The Coach can only be towed from the front (a flat bed tow is best). If towing from the front they will need to disconnect the driveshaft or remove the drive axles so the transmission is not damaged.
As mentioned, the parking brake needs to be released. it can be done with air (if airing up the coach is an option) or it can be manually "caged" using a caging tool (looks like a threaded rod with a nut and t-shaped end).

twinboat · 11-03-2021, 11:39 AM

The quick connect fittings are all screwed to pipe thread. If the wrecker doesn't have the correct fitting he will change it to one he has.

We have, on ocassion, removed a tank drain to connect a fitting to air up the system. The hose is then zip tied up to the wrecker, it's not that big a deal.

With air from the tow, suspension lifts up and the parking brake can be released.

The drive shaft or both axles will need to be removed if towing more then 3 or 4 miles otherwise the transmission can be damaged.

wolfe10 · 11-03-2021, 11:43 AM

I would STRONGLY suggest that towing be your very last option.

Most issues can be addressed in place-- either by a knowledgeable owner or by a mobile tech.

JaminSamin · 11-03-2021, 12:50 PM

On my 2002 Freightliner XC chassis there is a fitting plumbed into the air dryer supply line to fill the air system from an outside source. You may have one too.

Crasher · 11-03-2021, 08:13 PM

It's not a problem for the experienced tow truck operator. Even if the suspension was up, they will keep the air system pressurized from the tow truck to keep the brakes released. I had the air compressor fail on my 99 39Z Bounder years ago while parked overnight in an I80 RV rest stop in Ohio. Tow truck came to my site, hooked up, removed the DS, plugged into the air system and towed me 60 miles to Cleveland. Just another day for the driver.

Ray,IN · 11-04-2021, 08:43 PM

When my MH had to be towed the wrecker driver removed an automatic air drain, screwed his extension hose into the tank and supplied compressed air to the complete air system. It took him longer to raise the MH enough to slide underneath than connect his air system to mine.

gnvrvin · 11-05-2021, 09:23 PM

If not on a flat bed.....watch out for generator exhaust pipe many have had the pipe crushed

Just a warning
Greg

Domo · 11-07-2021, 01:11 PM

Quote:

Originally Posted by CountryB

Any good tow truck operator will have an assortment of fittings to connect to your air system. Sometimes the quick disconnect air port (you use to air your tires) will work, sometimes they will just remove a plug on the air tank.

The Coach can only be towed from the front (a flat bed tow is best). If towing from the front they will need to disconnect the driveshaft or remove the drive axles so the transmission is not damaged.
As mentioned, the parking brake needs to be released. it can be done with air (if airing up the coach is an option) or it can be manually "caged" using a caging tool (looks like a threaded rod with a nut and t-shaped end).

No. On a Freightliner the convenience air chuck that is commonly used to fill tires is NOT used to add air to the system. It has a one way valve and only would give air to the secondary tank - not the primary.

Plus, by adding unfiltered/undried air via the convenience chuck, you are "polluting" your system.

More importantly, you need to cage your brakes and the only way to have reliable (rather than residual) air pressure is to add air at the Schrader valve (looks like tire stem) located on the air dryer under the chassis - any other location is not correct and NOT recommended by Freightliner and can result in damage to your coach.

When in doubt, grab your VIN and call Freightliner 1-800-FTL-HELP. They are fast and helpful.

EDIT: I see others have mentioned the Schrader valve on the air dryer.