Community Forums

John_Canfield · 02-24-2008, 03:30 AM

>Last post has the resolution<

Anybody had trouble with their spitter spitting every few seconds for 30 minutes at a time? Freightliner said it might fix itself in time but it has done this for several days.

John_Canfield · 02-24-2008, 03:30 AM

>Last post has the resolution<

Anybody had trouble with their spitter spitting every few seconds for 30 minutes at a time? Freightliner said it might fix itself in time but it has done this for several days.

RRT2 · 02-24-2008, 05:36 AM

OK...I'll bite. What's a 'spitter spitting' ? (Just hate it when I don't know everything!!)

Rose

John_Canfield · 02-24-2008, 02:16 PM

Hi Rose - I suppose you didn't focus on the thread subject: "Moisture ejector..."

The spitter is spitting water, or at least I hope so

Problem is mine is a little too active.

lthrnk · 02-24-2008, 02:51 PM

John

Have you manually dumped the air tanks with the pull lanyards? Might be enough to force out whatever is causing the spitter to run.

RRT2 · 02-24-2008, 04:37 PM

Yes, John, I saw 'moisture ejector'... DH was the one that was wanting to know where/what. He STILL doesn't understand. (He's the mechanical/techie guru at this parking spot!)

R

jimandsue60 · 02-25-2008, 04:31 AM

Hi John, I may have had a similar situation but on a different component.

I had a problem where mine was spitting air out intermittently and then stayed open and wouldn't allow the airbags to air up. I found a faulty safety valve on the bottom of the air dryer behind the rear axle. There was a rubber seal that had failed. I was able to make a temporary repair to get the coach aired up. I was able to get a replacement at a FL dealer.

Jim

Moder2 · 02-26-2008, 03:53 PM

John,

I have had that happen on OTR trucks before. It is normally the spitter valve itself. It has always happened to me in cold weather where it would ice up or something like that.

Quick fix to get you back on the road, bypass your dryer. Should just need a #10 Aeroquip coupling and take the two big air lines off and join them to each other. That will get you to a repair shop or home. Not recommended to do long term since you putting "Wet" air in your system, and in any cold weather you might run into ice problems.

John

John_Canfield · 02-28-2008, 04:02 PM

Thanks everybody for the feedback

On our way back to our place from our trip the spitter was better behaved but still wasn't quite right.

Our weather is turning nice here so I'm going to see what I can see under the coach.

I need to dump the air in the ping tanks anyway, so perhaps that might help.

Cruzer · 02-29-2008, 05:58 AM

"Freightliner said it might fix itself"

Now that's what I call customer support.

Draining the ping tanks won't help. They are after the fact. Your air dryer is plumbed directly after the compressor and prior to the primary (ping) tank. The automatic drain valve in the air dryer is set to "spit" and dump any moisture settled in the base of the dryer whenever it receieves a trigger signal from your air compressor governor. The governor is mounted on the air compressor and controls the cut-in and cut-out pressures of the compressor. Once you reach the high cut-out pressure, the governor sends an air pressure signal to the compressor to hold the intake valves open to unload the air compressor. Once the air pressure drops below the cut-in setting the air pressure signal goes away and the valves close so that the compressor can pump again.

Whenever your governor reaches the cutout pressure it also sends a brief burst of air to the air dryer to make it spit out any moisture. If your air governor is sticking it may be sending that air pressure for too long of a time period, which holds the valve open too long.

So, you could have either bad valve in the air dryer or it may be the air compressor governor. Draining any of the tanks downstream from this won't affect anything. Fortunately both of these are Freightliner issues and hopefully you're still within the 3 year chassis warranty.

FleetMan · 02-29-2008, 07:23 AM

[QUOTE]Originally posted by Cruzer:
"Freightliner said it might fix itself"

Now that's what I call customer support.

Freightliner's advice would be appropriate if the leak was continuous, indicating a piece of debris stuck in the spitter valve and it might be blown out on a subsequent activation but that was not John's problem as he described it.

Cruzer's excellent description of the operation of that portion of the air brake system and conclusion are the most logical causes of the problem.

John_Canfield · 06-02-2008, 11:38 AM

Update Monday, June 2:

The problem was the "turbo valve" which is a little gizmo about 2" long and maybe 1/2" in diameter that sits in the bottom of the dryer. The valve came apart when the tech unscrewed it. Tech and the service manager said they have seen several of these fail recently.

As Fleetman stated, FTL's advice was appropriate - it might be debris but it it doesn't stop, it needs service.

chasfm11 · 06-02-2008, 12:54 PM

I'm curious. Was the "turbo valve" inside the bottom of the dryer or external? The reason that I ask is that the time before last when I replaced my dryer filters, I bought a "kit". That kit included the valve on the outside of the dryer and a new cover for the input heater coil in addition to the two filters. Since I had the parts, I went ahead and replaced both. The last time that I replaced my filters, just bought the filters alone.

Does it make sense to go the kit route say every other filter replacement (about 4 years?). I'm all about replacing things to prevent problems but am not certain that there is any value in the kit.

John_Canfield · 06-02-2008, 02:52 PM

It is my understanding it is external on the bottom of the air dryer - I was trying to assimilate a lot of information from the tech and I might have missed the exact scenario.

Freightliner only replaces the filter element at the M3 maintenance - apparently the valve is not a routine maintenance item (but I could be wrong.)

I'm not sure I'd be too concerned about replacing this valve on a proactive basis. Ours has acted up for about 1,000 miles of driving with no obvious negative effects that I can tell. It's just something to deal with when it breaks.