Any idea where the wet tank is on a GMC 5303 suburban? The tank behind the passenger rear wheel well is a dry tank, and the one under the driver is also a dry tank. Replacing drain valves with decent 1/4 turn valves, and there's some moisture in those supposed dry tanks. I suspect that there is an automatic purge on the wet tank. I also suspect that it's disconnected, as there is a flex line going to the air compressor governor that is disconnected and hanging. Fitting is plugged with a bolt on the governor side.
Simple-trace the output air line from the compressor to the wet tank. Mine had an air/water separator from the factory.
I agree, it just involves getting my head in some very low clearance spaces. Looking at the maintenance manual, it looks like there are 4 tanks. I think I may know where the wet and dry tanks are, tucked between the spare tire compartment (which is right in front of the drivers side rear tire) and the battery box. No outside access, only access from underneath. I still suspect that the moisture ejector is disconnected. I'm tempted to put some pressure on that line that's disconnected at the governor and see what it does.
This picture is from a transit but you can see the air dryer and the tank after is the wet tank.
I can see two round things between the batteries and spare tire on the drivers side. I'll take pictures and see.
Yes, that's the tanks. They are oriented vertically, with the wet tank on the outside. The dry tank has that drain valve that takes the special key. The wet tank has a line coming off the bottom of it, going into the spare tire compartment, and then going into the heat ductwork inside. Any idea where the ejector is? There are also two lines coming down, to drains. I suspect these are the outlets of the ejector. I'll pull the interior duct this afternoon and see if the ejector is right there inside the coach. I hope so. Any ideas? I want the air system fully functional, as it's a safety thing.
The book says the ejector can be triggered by the governor or the air brakes. Hopefully when I put my hands on it, i can verify which one it is.
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The tanks are between those two doors. Front is battery, rear is spare tire.
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Found the moisture ejector valve, it's in the heater duct on the drivers side. I'm 95% sure the disconnected line at the governor goes to this. Both exhaust lines were plugged with dirt dobbers.
I've got a trip to Lowes this afternoon for a faucet valve in the non-mobile house, so while I'm there I'll get a rubber tip for my blow gun to run some air down the control line at the governor and see if the valve activates. If not, I'll try it at the valve itself. Who knows how much water is in that wet tank.
Also, anyone have experience getting one of those turnkey valves out? I'd like to replace it with a 1/4 ball valve like I have everywhere else.
Shouldn't be too hard to remove.they should be brass or copper. The drain in tank could be plugged after removing valve. If so, you can probe with small screwdriver. Careful that you don't get a bath. If it has water and oil sludge, let it drain over night to get all the oil out. GM mentions this in their shop manuals.
I can't imagine what's in that wet tank. A mess, for sure. Good call on the point of not taking a nasty, nasty bath.
Pulled the line off the bottom of the wet tank. Great googley moogley. Looks like grey paint. 2 gallons, maybe more once the temp cycles today.
Quote from: j.m.jackson on September 08, 2017, 05:20:00 AM
Pulled the line off the bottom of the wet tank. Great googley moogley. Looks like grey paint. 2 gallons, maybe more once the temp cycles today.
That can't be good. :o
Quote from: muldoonman on September 08, 2017, 06:05:09 AMThat can't be good. :o
Agree. ILTM like you've got a combo of water and oil. Water happens (although if you have an air dryer and this is past it in the system, that's another thing to think about) but I think your biggest question now is "how much oil". Drain that tank as well as possible and air it up (maybe a few short drives at highway speeds with a drain after each?) and see if you're getting oil out of the tank once all the "old stuff" is out of there.
Just goes to show what can happen when tanks are never drained or moisture ejectors are disabled. Probably was disabled because of air leakage and couldn't find repair kit or rebuilt unit or didn't want to be bothered with proper repair. Makes you wonder about proper perotic maintenance or service being done prior.
Chessie,
Yes, that's why I'm touching every system to make sure they're roadworthy.
I'm looking forward to seeing what's up with the ejector valve.
What i'm thankful for is that this is gray, not brown (rust).
The oil mixed with water keep it from rusting as much as you might think. Would rust more with a good compressor that didn't pass any oil.
Ok, so here is what I found this evening. The drains on the ejector (it has 2) were clogged and kinked.
I disconnected abnd blew out the line from the bottom of the wet tank to the ejector wet input, reconnected the line on both ends, and then pulled the output lines and started the engine to fill the wet tank. I then activated the valve locally, after pulling off the control line ,with a rubber tipped nozzle on my air hose. When i block the output with my finger and a paper towel, water/oily air from the input blows out the vent hole in the valve body, meaning that the replaceable o-ring in the valve needs to be replaced, as documented in the service procedure. But it doesn't do this if the output lines aren't blocked.
So, in the end, a PO disconnected the automatic purge valve because the drains were blocked with dirt dobers and kinked. A symptom of this was what sounded like an air leak from the valve when it was trying to complete it's cycle, but couldn't, because the output lines were blocked.
I'll make the tool for the dry tank drain tomorrow if i can't unscrew it, and get a new fitting for the compressor governor line to the ejector valve to replace the one that was damaged/cross threaded with the bolt to plug it.
Made the tool to drain the dry tank. Painted it yellow so it'll be harder to lose.
About half a quart of black oil came out of that one. Better than the 2.5+ gallons that I got out of the wet.
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Quote from: j.m.jackson on September 12, 2017, 09:44:09 PMMade the tool to drain the dry tank. Painted it yellow so it'll be harder to lose.
About half a quart of black oil came out of that one. Better than the 2.5+ gallons that I got out of the wet.
Aww, that much oil is NOT a good sign. Of course, it looks like mostly oil but there's probably a good bit of water mixed with it. Still, it looks to me like you're getting a lot of oil from your compressor. Get that system clean and then drain your tanks every day and see how much oil is in the discharge.
I can't assess the current compressor health because of the previous drain situation. I don't know how long the moisture ejector was disconnected. Now that I have functioning drains on all 4 tanks, I can do the proper procedure and drain them after running for the day.
I think I got about 3.5 gallons of oil/water out of the wet tank. I just looked and my open top drain pan is a 5 gallon pan. I thought it was a 3 gallon.
The PO didn't have the tool to drain the dry tank, or he didn't mention that he had it. So, there's a chance it hasn't been drained since 2000.
Don't panic yet.
You have no way of knowing the order of things.
There may have been a compressor change in the past, after the oil.
Under "normal" conditions, it would take a VERY long time to accumulate that much goop.
I like your idea, run it, and watch the tank drainage closely to evaluate.
If you put male air fittings on the right style of quarter turn drain valves, it allows using a garden sprayer and the female fitting to introduce the liquid of your choice to help clean that goop out.
Trouble is, no matter what the compressor pumps in there, it will come out oily for awhile.
happy coaching!
buswarrior
It sounds like a great idea to clean a bit more on that tank when you can.
Just monitoring it seems the ideal thing to do Imo. If it can help Napa use to carry a blended
(not so hot) can of brake & electric cleaner. I sure used it a lot primarily because it was safer on rubber and paint etc..
Floyd
theproblem is this...that much oilhas to have gone beyond the tanks.
oil and diaphragms equal mush.
brakes hate it,
relay valves gum up and freeze tight as a drum in the cold
were i u i would find something to flush it out...