[GMCnet] Probably a silly question but...why drop tanks?

[Shawn Harris via Gmclist]

I understand why a person buying a coach that has been sitting for sometime would want to change the fuel lines and many other things but I don't
understand why we would drop the tanks unless there is a specific issue or reason to. Is it not easier to just add an inline filter and change it
often until any contaminants would be caught by the filter? Obviously if there was water in the fuel or the unit is not running well and all other
things seems to check out then, yeah, i get it, but it seems in my research that it's just an automatic "must do". Can you guys shed some light on
what I'm missing? Pardon my ignorance.
--
Shawn Harris
1977 Palm Beach 403
Bone stock - gutted interior
North Vancouver,
Canada

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[Tom Lins via Gmclist]

Green machine wrote on Fri, 20 September 2019 22:25

> I understand why a person buying a coach that has been sitting for sometime would want to change the fuel lines and many other things but I don't
> understand why we would drop the tanks unless there is a specific issue or reason to. Is it not easier to just add an inline filter and change it
> often until any contaminants would be caught by the filter? Obviously if there was water in the fuel or the unit is not running well and all other
> things seems to check out then, yeah, i get it, but it seems in my research that it's just an automatic "must do". Can you guys shed some light on
> what I'm missing? Pardon my ignorance.

Unless you can prove without any doubt (receipt, you helped do it, hose is labeled) that the hoses have been changed you are risking at the least
being on the side of the road or at worst the coach goes up in flames. Old hoses do not like ethanol.

--
Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, FI-Tech EFI, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
GMC Dealer Training Tapes
http://www.bdub.net/tomlins/

[Charles Boyd via Gmclist]

Sir, dropping the tanks is required to replace the rubber gas lines from pickups and from vent lines on the top of the tanks. While they are down you
should remove the pick ups to visually check the condition of tubes and filter socks and replace the rubber O ring sealing it. Use a rubber lubricant
or tire soap to lubricate to keep from pinching O ring. Also the gen fuel line on the GM outfitted coaches is located about 1/4 way up on rear of
tank and hard to get to without dropping tank. You also have to remove the front one to get to the rear bolts. When you put them back in you can
replace the rubber fill line connectors. Some advise to replace the rubber lines on top of tanks with steel or copper-nickel so they never have to
drop them again, but they usually have to anyway for something. They really aren't hard to do after 3 or so times..

Green machine wrote on Fri, 20 September 2019 22:25

> I understand why a person buying a coach that has been sitting for sometime would want to change the fuel lines and many other things but I don't
> understand why we would drop the tanks unless there is a specific issue or reason to. Is it not easier to just add an inline filter and change it
> often until any contaminants would be caught by the filter? Obviously if there was water in the fuel or the unit is not running well and all other
> things seems to check out then, yeah, i get it, but it seems in my research that it's just an automatic "must do". Can you guys shed some light on
> what I'm missing? Pardon my ignorance.


--

C. Boyd
76 Crestmont
East Tennessee

[Shawn Harris via Gmclist]

Perfect. This is the answer I was looking for. Makes total sense to me now. I didn't realize it was necessary to drop the tanks to get at all the fuel
lines. I spoke with Jim B and he gave me all the lengths of each size hose I will need to replace and they are on order.

Thank you kindly fine sir!


C Boyd wrote on Fri, 20 September 2019 21:49

> Sir, dropping the tanks is required to replace the rubber gas lines from pickups and from vent lines on the top of the tanks. While they are down
> you should remove the pick ups to visually check the condition of tubes and filter socks and replace the rubber O ring sealing it. Use a rubber
> lubricant or tire soap to lubricate to keep from pinching O ring. Also the gen fuel line on the GM outfitted coaches is located about 1/4 way up on
> rear of tank and hard to get to without dropping tank. You also have to remove the front one to get to the rear bolts. When you put them back in
> you can replace the rubber fill line connectors. Some advise to replace the rubber lines on top of tanks with steel or copper-nickel so they never
> have to drop them again, but they usually have to anyway for something. They really aren't hard to do after 3 or so times..
>
>
>
>
>
>
> Green machine wrote on Fri, 20 September 2019 22:25
> > I understand why a person buying a coach that has been sitting for sometime would want to change the fuel lines and many other things but I
> > don't understand why we would drop the tanks unless there is a specific issue or reason to. Is it not easier to just add an inline filter and
> > change it often until any contaminants would be caught by the filter? Obviously if there was water in the fuel or the unit is not running well and
> > all other things seems to check out then, yeah, i get it, but it seems in my research that it's just an automatic "must do". Can you guys shed
> > some light on what I'm missing? Pardon my ignorance.

--

Shawn Harris
1977 Palm Beach 403
Bone stock - gutted interior
North Vancouver,
Canada

[Charles Boyd via Gmclist]

Having said all that my fuel Lines had been replaced and were in fairly good shape and I got a few inline filters and an inline electric pump and
pumped the gas from in front of the switching valve thru filters back into tank till filters were running clean from both tanks. Took about a half a
day. Bout same time as dropping tanks and cleaning and replacing lines. I was having filter clogging issues and each time I would change a filter I
would blow shop air back thru tank and pump some more. I still have to Change filters a couple times a year but I consider this normal. I did
permanently install the fuel pump on the reserve tank and wired it to reserve switch on dash.
It's your coach and your choice..





C Boyd wrote on Fri, 20 September 2019 22:49

[Johnny Bridges via Gmclist]

Shawn, as the laziest person on this forum, skipping taking the tanks down saves a bit of time, but reminds me of an old country song: "You'll be
glad and I'll be gladder settin' the woods on fire...".
The pia factor is actually draining the gas down to the point that the tanks aren't very heavy. They're cumbersome because they're large but easy
enough to get out. A couple of ratchet straps from Freight, Harbor makes it easy to click them back up when you're done. Remember, the PO may well
of had your outlook and mine, and replaced all the hoses EXCEPT the ones atop the tank. If you didn't see it done, it probably wasn't done is a good
mantra. I might add, the smoking lamp is OUT during this procedure.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell

[Matt Colie via Gmclist]

Shawn,

As Johnny said, ignorance can be corrected. (Of course, we were all born knowing all about GMC coaches.)

Attached below are two things I wrote years ago just because I had a lot of experience with TZE tanks. What I did not include, because the first is
about lifting the tanks back into place, was that once you think you have the tanks drained try to remove the drain plugs in both tanks. That seems
to be a 50/50 bet. Another thing that I made practice of and failed to mention is that things are simpler if you remove the fill piping first and put
it back last. There is a caution here. The rubber coupling for this are probably hardened and may not want to come off. If this is the case, I
suggest that you take a break and order all new from JimK. You will need them and they are probably not available locally. They were not for me and
I live next to Detroit.

There is a second piece that you might read and profit from about the fill vent lines that cause many people much grief.

Matt - Finally out from under his coach and looking forward to Mansfield

Lifting Fuel Tanks when working alone.

From GMCnet forum Wed, 27 June 2012 10:06

I have learned how to lift GMC fuel tanks into place alone and without even hard work.

As a result of a strange set of circumstances, I have had to have the fuel tanks down more than I might have liked. The tanks are not heavy, but they
are quite unmanageable.
Remember to mark the fuel and fill vent connections as they are the same size and are easily confused.

I lift my coach with a combination of a 7k# car lift and a floor jack and support it with jack stands. Problem - My barn only has a 10' ceiling and so
the amount I can lift is limited. But what I have worked out will work anywhere and is particularly good if you are working alone. Getting the tanks
down is easy, gravity is on your side. The biggest problem I had there was getting out from between the tank and the creeper so I could get your's
truly and the tank both out from under the coach.

I tried the floor jack to lift tanks: Problem - the floor jack ends up where you need to be.
I tried combinations of three and four scissor jacks (talk about slow)and stacks of wood but it only took hitting one with the creeper to make me
abandon that plan.

As a sailor, I am used to rigging lines to do things and was hoping I could rig to lift the tank from overhead. But, sailors do lots of things that
the rest of the world has no need to understand. This is an operation called a load hammock.

To lift a fuel tank, you need a pair of cargo straps. Look at Harbor Fright 90984. The set is 4 ea 15' straps with ratchet tensioners. You just need
two of the long straps. You don't need the ratchet parts at all. They are usually on sale for 10$. Get a set if you plan to change out you rubber fuel
lines. Actually, get a set unless you plan to pay someone to change your rubber fuel lines because all information is that you will soon be doing it.

We are going to lift the rear (main) tank first, so, slide under the coach and look. You see the J-bolts hanging down. Put the hook through the hole
outboard of the J-bolt and take it forward to the matching hole in the next floor beam. Now take it one more floor beam forward trough the matching
hole. Pull the loose strap down so it is on the floor for most of the tank length. Put the other strap in the same way, but leave it tight for now.

Drop your main tank onto the creeper and roll it under the coach. You will need a long something like a broom handle (or got around to the other side)
to make the hanging strap get under the tank, but that will not be difficult. Pull down the near strap and do the same.

Now, because you used the creeper to move the tank, you have to slide in on your back just forward of the tank. Pull either strap tight and hitch it
off to the standing part of the strap.

Definition time:
Standing part - a piece of straight line than may even be under some tension.
Hitch - to wrap a line around something and under itself so it is held.
Bight - the middle of a piece of line worked without getting to an end.

OK - You have tension in one strap and an hitch holding it until you let go. If you take the bight of that strap and use it to make another hitch
tight to the first, it won't let go. You use the bight here so that all you have to do is pull the free end to release the locking hitch.

Now do the same for the other strap. Both are tight and locked.
Take either strap and pull out the locking hitch. Pull down on the middle of standing part over you. The tank will lift. Slide the hitch back and lock
it up again and do the same at the other. The tank should lift off the creeper.

You should be able to reclaim the creeper at this point. The tank is hanging somewhat rear down, but it is hanging under the coach. Slide under the
rear edge and push that up. It will roll in the straps but stay where you left it.

Now you can roll in on the creeper and connect the electrical (2), fuel line and fill vent both at the sender, the vapor vent off to the side and fuel
line for the APU (genset) and you can do it without juggling the tank and/or straining any of the lines.

Take the tank up, just like you lifted it off the creeper. You can stop any time you feel like it (or need to). You will have to go the the rear
(J-bolt end) and roll the tank to get the rear up first. when it gets close, fiddle with the J-bolts enough to get them through the holes in the strap
and a nut in each a thread or two only at this time.

Pull up the straps enough more to get both of the tank straps to hook over the frame. Now, go pull once more so the angle at the tank front is up
against that frame. If you did not take the fill pipe down, this is the time to pull the tank sideways enough to get the fill connected to the tank
side. Now you have to mussel it up the rest of the way, but it is not real tough, and if you have to let go, it won't go far. The straps won't quite
lift the tank so the bolts go into the angle. But, one bolt is all it takes to hold the empty tank.

Swap the washers onto the J-bolts and run them up, put in the other two front bolts in the angle iron and you are done with the rear tank.

Don't bother taking the lifting straps out yet, you have to do the same for auxiliary (front) tank. Same drill, but you have to use the torsion bar
frame and work around the exhaust pipe.

Why did I use HF cheap straps instead of some nice small working line I have plenty of around here? Simple, any round line will be too large to fit
some of the places it has to be. Besides, the cheapest line I have handy is about 1$ a foot and junk if it gets greasy.

Sorry I don't have any pictures, but it is really tough to get the job done under the coach and take pictures at the same time. Maybe if I get to help
someone else, I can bring a camera. I hope the word picture is clear enough to help someone do this job without sweat.


Recommending High T GMC net Sun, 29 July 2012 21:06

This is not a treatise on a British mid-afternoon custom.

It is about the GMC Fuel System.

All the coaches were fit with two fuel tanks that have common fill and fill vents Teed together under the coach. The fill vent is the other 3/8 line
that comes out of the sending unit. The T that is the subject of this is near the forward end of the auxiliary (front) fuel tank. This is a design
disaster with the modern foaming fuel. I have been fighting this for six years and gotten quite tired of the whole affair.

When I redid the fuel plumbing, I carried both fill vent lines as far forward and upward as was practical. That turned out to be just under the cab
floor where the fill line doglegs around the wheel well. The end result is that the last three times I have fueled, the fill when so well and so fast
that it was disconcerting. I can fuel at the pump's full rate until shut off.

This can possibly only be appreciated by a few, but I actually took an old software package (purloined from an employer when the package was upgraded)
and ran an less than complete model of the fuel system when filling. This was very fortunate. I learned two things. First was that the fix that I had
in mind would probably not have done any good at all and it would be complex and expensive. The second was that, because the rear (main) tank actually
fills first (with little regard to vehicle trim (ride height front to back), it will always flood the vent line if given the opportunity. If that
flooded vent line is still needed to vent the auxiliary (front) tank, you are SOL (Second On Line) for the only fast fill.

This was no great difficulty in my case because I already had the entire fuel system apart and all over the barn floor. For a normal rational person
or even a GMC owner, it would still not be all that difficult. The good thing is that the hardest part is not all that much of a problem. That is
taking down the entire fill pipe.

I don't suggest that you do this a a primary operation. but next time you are replacing all that leaking rubber house with new, think about adding
this feature.

Matt


jknezek wrote on Mon, 30 July 2012 10:56
I had similar problems to what is being discussed here, but the problem was mostly fixed by replacing the liquid/vapor seperator and completely solved
when I put in new body pads and there was the correct amount of space for the lines to run.


Matt Colie wrote on Mon, 30 July 2012 17:03
Carl,

Fixing that could cure a whole lot of problems..

James Hupy wrote on Mon, 30 July 2012 14:41
What frequently happens on the GMC coaches as they age, the body to frame mounting pads compress and pinch the vent lines to the charcoal cannister.
When those passages can no longer handle the volume of air that is displaced when we fill our tanks with "reformulated gasoline". the displaced air
tries to find it's way out via the fill pipe. What happens then is what many of us experience. Frequent clicking off and gasoline burping back up the
filler neck. Tank venting is important. The cure is to replace the frame cushions, as well as careful routing of the vent lines.
Jim Hupy

Matt Colie wrote on Mon, 30 July 2012 17:03
Jim is close, but he is a little wrong. The fill vent goes along the fill line and to the fill neck. Look in the MM figure 8-3. That T in the vent
line is most of our problem. The vapor valve and carbon canisters are only there to pass the old time evaporative emissions and to be the air vent
when fuel is drawn from the tanks other wise a vented fill cap would do just fine.

Matt

James Hupy wrote on Mon, 30 July 2012 18:10
Matt, for brevity's sake, I intentionally left out the part about the other set of vent lines that terminate at the filler neck. Their main purpose is
to allow a small amount of gasoline to regurgitate up the neck and cancel the pump nozzle, their secondary purpose is to provide additional venting.
That is why I didn't mention them. They most often lay in a depression that also contains the supply line to the carb, as well as the sending unit
conductors. Geez, you guys are a sharp bunch out there.
Jim Hupy
Salem, OR
78 GMC Royale 403

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[Todd Snyder via Gmclist]

I just had mine out and found an inch of rust and sludge on the bottom. I cleaned them out with a garden hose, banging them with a mallet, rocking
them around, until the rate of dust and rust flakes coming out seemed to taper off. Put them back on with all new Barricade fuel/vent/emission lines
and went on a trip with a cabinet full of filters 'just in case'.

Found that cheap inline filters do almost nothing to filter the gas, and the on-carb filter is truly the last line of defense. The 500 mile trip
included 4 changes of the carb filter. It was a hot, smelly, unpleasant job to do on the side of the road.

When I got home, I dropped the tanks again and took them to a radiator shop to have them cleaned with acid and coated them with a fuel tank liner. It
was $250 a tank and took them a month.

Yesterday I put them back on with my 14yo son, he ran the floor jack as I hooked up the lines. It was not a hard job to do. Took us about 2 hours to
put on both tanks.

I tried the ratchet strap method the first go-around and found it was not for me. The floor jack fits into a center depression in the bottom of the
tank and does a decent job staying there. It's a bit of a wrestle to get it on and keep it from falling off, but once under the coach and lifted a
little it gets easier as it gets trapped between the jack and the underside of the coach. Basic order of putting back in tanks is to position the
tank under where it's going and hook up the lines and wires for gauge. Lift the tank and tilt it to get the rear strap nuts started. Make sure the
rear lip doesn't get tucked in between the frame and the floor, or else you find the front wont lift in the next step and you'll be going back to get
the tank in the right spot. Then check that the lines are where you want them and lift up the front of the tank and start the three bolts. It
should lift with very little force. Then tighten up the straps and the front bolts.
--
Todd Snyder, Buffalo NY
1976 Eleganza II

[James Hupy via Gmclist]

Just a hint on tank dropping/replacing.
I use a floor jack, and I modified the lifting shoe by drilling three
holes in it. I cut a piece of scrap 1/2 " plywood about 18" x 18", drilled
matching holes to the ones in the shoe, and bolted the plywood to the shoe.
The tanks balance quite nicely on the plywood, yet, they can be easily
manipulated on the plywood. EZ-PZ. One person job, no problem.
A caution here. If you are under your coach, be sure, be dead sure,
to have it well supported with high quality lifting and support stands. No
second chances here, one slip and you are done for.
Jim Hupy
Salem, Oregon

[Matt Colie via Gmclist]

James Hupy wrote on Sat, 21 September 2019 14:47

> Just a hint on tank dropping/replacing.
> I use a floor jack, and I modified the lifting shoe by drilling three holes in it. I cut a piece of scrap 1/2 " plywood about 18" x 18", drilled
> matching holes to the ones in the shoe, and bolted the plywood to the shoe. The tanks balance quite nicely on the plywood, yet, they can be easily
> manipulated on the plywood. EZ-PZ. One person job, no problem.
>
> A caution here. If you are under your coach, be sure, be dead sure, to have it well supported with high quality lifting and support stands. No
> second chances here, one slip and you are done for.
> Jim Hupy
> Salem, Oregon

I actually tried that and other things. My best floor jack it a 50+yo Hein Werner and the release knob is all the way at the end of the handle. You
can imagine why this was an issue. Even if I could work the jack, it still needs to be where you want to be.

I didn't use ratchet straps the first successful tank lift, I used some small boat docklines that people like your truly have in abundance. This got
them very dirty, so I later (lifts 3,4 &5) opted out for the 7$ at Hazard Fright straps that I toss when they get nasty.

The 10' ceiling in my working bay is a limit for how high I can get the coach.

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

[Richard Denney via Gmclist]

I use a lightweight aluminum-frame “motorcycle lift” that I bought at
Harbor Fraught. It has a low profile and it’s easy to roll around. It has
about a 15” square lifting platform.

But I’ve also used a plain-old floor jack. I installed Cinnabar tanks in
2003 and that was a difficult conversion. But I’ve dropped them several
times since then and though it’s never pleasant, sometimes it’s what has to
be done.

Rick “who has had more troublesome projects than tanks, by far” Denney

On Sat, Sep 21, 2019 at 2:45 PM James Hupy via Gmclist <
gmc...@list.gmcnet.org> wrote:

> Just a hint on tank dropping/replacing.
> I use a floor jack, and I modified the lifting shoe by drilling three
> holes in it. I cut a piece of scrap 1/2 " plywood about 18" x 18", drilled
> matching holes to the ones in the shoe, and bolted the plywood to the shoe.
> The tanks balance quite nicely on the plywood, yet, they can be easily
> manipulated on the plywood. EZ-PZ. One person job, no problem.
> A caution here. If you are under your coach, be sure, be dead sure,
> to have it well supported with high quality lifting and support stands. No
> second chances here, one slip and you are done for.
> Jim Hupy
>

> --
'73 X-Glacier 230 "Jaws"
Northern Virginia
Offlist email: rick at rickdenney dot com

[Bruce Hart via Gmclist]

How to clean out the gas tank

https://www.bing.com/videos/search?q=removing+rust+from+metal+gas+tank&&view=detail&mid=8E6908DAC4E2B5438ED18E6908DAC4E2B5438ED1&&FORM=VDRVRV

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class

[Dave Stragand via Gmclist]

A “transmission jack adapter” can also be handy for this kind of thing. It snaps on most floor jacks in place of the lifting cup and has arms that adjust to securely lift items like transmissions. I have used mine on a couple of old MoPar fuel tanks and it worked great.

-Dave
1978 Transmode near Pittsburgh

[Billy Massey via Gmclist]

Hahaha! Awesome!

:-)
bdub

On Sun, Sep 22, 2019, 7:04 AM Bruce Hart via Gmclist <
gmc...@list.gmcnet.org> wrote:

How to clean out the gas tank
>
>
> https://www.bing.com/videos/search?q=removing+rust+from+metal+gas+tank&&view=detail&mid=8E6908DAC4E2B5438ED18E6908DAC4E2B5438ED1&&FORM=VDRVRV
>
>

[Bruce Hart via Gmclist]

Just a little ingenuity.

I pulled my tanks this week-end and the PO before me put rocks in the main
tank and I can't get them out, they caught between the baffles and won't
fall out. Bummer.

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class

[Bruce Hart via Gmclist]

I couldn't tell where the rust was at in my tanks until I took a mirror and
inspected the inside of the top portion of the tank it is very rusted.

[James Hupy via Gmclist]

Yup, that is what happens when you store vehicles long term with the tanks
not full. Moisture collects on overhead surfaces due to condensation.
Jim Hupy
Salem, Or

On Sun, Sep 22, 2019, 6:16 PM Bruce Hart via Gmclist <