Where does this tube go and do i need it?

Gordie Allen · June 26, 2013, 08:20:03 AM

There is a 1/4" copper tube that comes out the top of the coolant reservoir (with a pickup extending to the bottom of the tank). It has a flair fitting on the other end that ends at the front of the engine at about crankshaft level. I don't recall unhooking this when reinstalling the over-sized radiator from PO after raising it to get adequate ground clearance. Anyway, after pressure develops in the reservoir, this tube siphons the tank dry. I have no engine antifreeze leaks. When I added distilled water to the tank today, I noticed clear water leaking, and discovered the tube. No mention of this tube in the Maintenance Manual and not in any illustrations. My only option is to pull the radiator - unless I don't need it. Hoping I don't need it.

luvrbus · June 26, 2013, 09:16:35 AM

Sounds to me like part of a recovery system that has been added some where down the line

Gordie Allen · June 26, 2013, 09:37:36 AM

I can't believe a tube that small, that is not pressurized by the water pump could be of any primary importance. Since I don't have any antifreeze leaking from the engine or components, don't even think there is a place to hook it up. Any other opinions out there? Seems like these DD's had all kinds of special features as add-ons. Like, I discovered in the manual some had a water filter/conditioner. Of course it has a illustration of THAT in the Manual.

luvrbus · June 26, 2013, 09:43:06 AM

I just peeked at some old manuals for GM it shows that line to be a self bleeder to remove air ties into the top of T housing or cross over pipe on the V engines it was a add on

Gordie Allen · June 26, 2013, 09:54:45 AM

Interesting since this is a 671. Maybe the tank came out of a bus with a V engine. That's a big issue with these old buses, you don't know what's been added, or subtracted, or modified, and I'm still at DD-101 course level. Thanks for your research and quick reply. If I don't get any news to the contrary, I'll plug it.

luvrbus · June 26, 2013, 10:03:38 AM

I also see a 1/4 inch line going to the shutter valve if one was equipped with shutters but I never saw a GM with shutters before

viento1 · June 26, 2013, 11:55:45 AM

I have a 1/4 inch line with a valve at the end. I beleive it is a coolant level indicator as it goes up into the resevoir. If when the valve is open and no fluid comes out, the system is low... So I have been told anyway.

dellisor · June 26, 2013, 12:05:42 PM

I do have a 4104 with shutters on it if you need any pics let me know

Gordie Allen · June 26, 2013, 01:35:52 PM

Mine doesn't have shutters, but did at one time. The air valve is still mounted on the watter outlet housing.

Ed Hackenbruch · June 26, 2013, 02:37:44 PM

My 5A has the same setup as Randy's, (viento1). i don't have a sight glass on the surge/reservoir tank as some do. Mine is frozen up and i haven't bothered to free it up yet as i also have another line that is an overflow line. Too much water in and it will drain the excess to the ground by the back corner of the bus.

Gordie Allen · June 26, 2013, 08:33:27 PM

Yeah, I have a 1/2" overflow tube in addition to this 1/4' one. But the 1/4" line will empty the tank once it starts to siphon. So I fill the reservoir, and as soon as there's enough pressure to push water over the top, it empties the tank again. Apparently this has always happened when I was going down the road, cause this is the first time I saw where exactly the water was going. The bus hasn't gone over 20 miles since I drove it home from FL 16 mo ago.

JohnVickrey · June 27, 2013, 03:05:24 AM

The line might go into the heater lines. My theory is to not worry about what it was or did, is it needed now. You can eliminate most of the old wiring and a whole lot of the plumbing if you stick to he "is it needed now theory". Of course if you are a purest you may not be able to.

Gordie Allen · June 27, 2013, 06:24:28 AM

John,
I'm with you; I'm not a purest. I pulled ALL the wiring except for the heavy cables. All new relays, fuse panels, switches, sending units, everything. Rebuilt the OTR heater replacing the copper lines with 80' of 1" heater hose and new cores. I'm going to clip and solder the line today.
Thanks to all. This is a great community.
Gordie

JohnVickrey · June 27, 2013, 08:15:30 AM

Them old copper heater lines make a great raceway for the new wires and air lines that need to go from the front of the bus to the back.

Gordie Allen · June 27, 2013, 11:35:56 AM

I built a 4"x6" raceway down the driver's side from the front panel to the back and then across to the back electrical panel. Ran 1"heater hose and all the AC and DC wiring in it. Most of it is hidden behind front couch and kitchen counter. In the bathroom I put a rounded cover on it. Not really obtrusive anywhere, but easy access inside the bus. Gave all the copper (25#) and aluminum (250#) to a friend who scraps for getting out of my way.