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Author Topic: MC-5 Fuel Tank Leak  (Read 2105 times)
Fredward
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« on: October 17, 2006, 07:22:55 PM »

My fuel tank leaks when I add more than about 35 gallons of fuel. Gauge does not work, but the stick shows about six or eight inches of fuel when it starts leaking. Is there a seam half way up on the tank that might be leaking? It leaks out of both sides of the coach on level ground just behind the front wheels. (what a mess!) Nothing gets in the bays or AC condenser compartment. Can the tank be replaced? This bus has been totally re-skinned, right over the existing skin so if there was an access panel to remove the tank, I'd have no idea where to find it today. I've got the manuals but don't see any details on fuel tanks.

I seem to remember reading a thread about Detroits and hot fuel and condensation and leaking tanks in MCIs but I can't find it. I've got all winter in Minnesota and a heated shop to figure it out.
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Fred Thomson
Timnvt
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« Reply #1 on: October 17, 2006, 07:51:05 PM »

What year and model is your MC-5? The access panel is (or should be) directly below the filling door.  Yes, the tank is removable.  There is a strap around it holding it in place which could be a bear to unthread the bolts from.  Otherwise it slides straight out.
HTH. Timnvt
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'66 MCI5 6v92 w/HT-740
edvanland
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« Reply #2 on: October 18, 2006, 10:31:28 AM »

As stated the access panel to remove the tank is where you fill it.  On my MCI 7 open the door and at the top are two bolts, one on each side.  Take them out and you should be able to lift the access panel off.  What I did after disconnecting the lines was to loop a rope over the L shaped part of the tank, then hooked up the tractor to that and pulled.  Mine had a plated bolted to the bottom which made it hard to come out.  Then if there is a comerical radiator place near you take it to them and have it pressure tested and they should be able to repair it.  Mine was leaking around the gasket on the plate so I had the plate removed and another one welded in it's place.
Hope this helps
ED
MCI 7
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Ed Van
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Fredward
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« Reply #3 on: October 18, 2006, 05:14:07 PM »

Its a 1964 MC5A. Problem is when the previous owner raised the roof, he reskinned the entire bus; top to bottom. There is no access panel by the fuel tank filler just one huge sheet of solid, riveted steel. I would have to guess where the access panel is, and start cutting the new skin with the torch. Then remove the panel, repair the tank, put it back together and then weld the steel skin back on and repaint. Yuck Undecided I suppose i could get a saddle tank for a truck and install it in the center of the front bay........

You say the tank itself is "L" shaped? Does it go all the way across the bus to the driver's side? Does it go all the way forward to the front bulkhead?
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Fred Thomson
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« Reply #4 on: October 18, 2006, 05:22:33 PM »

Hello Fredward.

The skin in front of the tank is removable on a stock coach.

Look in the filler access and you will want to cut in line with the sides of the cavity that the fuel tank lives in. If you are good with the torch, go for it, I'd use a cutting wheel, since I'm not!!!

The "L" shape is up and down. Where the fuel filler is is the back of the high side of the "L", the tank then ducks under the utility channel running the length of the bus, seen in the bays. The tank pulls out through the skin where the filler access is.

Previous owner needs a kick in the pants for sealing that area up. I wonder what else you can't access due to this foolishness?

happy coaching!
buswarrior
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Stan
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« Reply #5 on: October 18, 2006, 05:45:13 PM »

It is a long time since I worked on a MC5A so I may be guessing some of this. I think on the MC5 only the fiiller neck is visible when you open the filler door. In order to disconnect the lfuel lines you would have to cut out the bottom of the  filler door compartment. In the front of the central heat compartment there should be two caps about 2" diameter near the top. If you remove these caps you can unscrew the bolts that clamp the tank in place. If you get the tank loose I think you could pull it out the drivers side of the bus by removing the panel in the back of the A/C condensor compartment. I would start by removing this panel and see if it will come out that way and then go from there. It would be a shame to buthcher the side of your bus if there is any other way.

This information is all from an old tired brain so do some carefull investigation before you start cutting. I have pulled a 5 fuel tank but took it out the access panel provided. The one I removed had a welded joint around the tank with a couple of inches of seam that had never been welded. It held fuel for more than 20 years with just welding flux in the joint.
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Fredward
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« Reply #6 on: October 18, 2006, 07:49:02 PM »

Stan, that's real useful information. And you are right about the filler access door. There's nothing else in there. Your "old brain" seems to be working just fine - wish mine still did. Do you suppose the tank leaks at the seam? So if I never fill it beyone the seam i'd be ok? I'll snoop around in the AC bay. I've just got batteries and charger in there currently. If its "L" shaped, how would it ever exit through that AC bay. Also, how do i get into the front of the central heat compartment? I can open the access door in the front bay, but that doesn't show me much.......Don't tell me I have to take up the floor next? (The previous owner also covered up the returns, so I don't know exactly where to start digging there either!)

BusWarrior; you're right. The manual refers to a circuit breaker panel on in the rear drivers side that is also not currently accessible. Maybe he moved it somewhere else. The guy did a nice job on the caps, skinning and windows, and interior, just got a little overzealous when he was reskinning. He also confided to me that he had to cut a hole in the side after the fact to get at the radiator fill.  Grin
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Fred Thomson
Timnvt
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« Reply #7 on: October 18, 2006, 08:17:34 PM »

Forget about removing the fuel tank via the drivers side A/C compartment.  It will not come through that way as the tank rises from where it nestles under the middle tunnel toward the passengers side and the filler neck.
If the side skin is rivetted sufficiently I'd think it reasonable to cut in an access panel.  There's also supposed to be an access for the battery compartment immediatly adjacent to the fuel compartment. I'm curious whether your starting batteries have been relocated and the space utilized for something else or not?
Timnvt
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'66 MCI5 6v92 w/HT-740
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« Reply #8 on: October 19, 2006, 03:28:09 AM »

I am currently working on installing a fuel guage in the tank of my MC5A, Fred.  The fuel lines and pickups or located on the side of my tank...could take pics with the access door off if that would help you any.  And I could take some measurements as well.

Just let me know...

NCbob
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Stan
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« Reply #9 on: October 19, 2006, 05:49:47 AM »

Peop;e who are currently working on a MC5 should have all the right answers and if the tank won't go out the driver's side then my suggestion isn't worth much.

The tank should be held in with two straps over the top of the tank. The clamp nut for these is accessed through the holes in the central A/C compartment. If you open the door on that compartment in the front of the front bay you should be able to see the plugs near the top of the front wall. They will be painted over and not too obvious but they can be pried out to get at the clamp nuts.

If your tank leaks at 35 gallons, that is the minimum amount you should be running at so it would not be practical to run with the leaking tank.

Since it appears that you are going to have to get to the aoriginal access panel, have a shop with a plasma cutter make the cuts in the new skin. A plasma cutter will leave a clean, narrow cut letting you put the panel back in place with screws, in case you have to remove it again.
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Len Silva
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« Reply #10 on: October 19, 2006, 07:14:33 AM »

I have a 4104 and am not familiar with the MC-5 so this is a shot in the dark.

Just trying to think outside the box here. Might you consider cutting a hole in the floor and bringing the tank up into the bus. Is it possible that that might be easier to repair the floor than cutting a hole in the side of the bus.

Of course, I don't know if the tank will fit through the door and any future tank problems would put you back in the same situation.  Think I just talked mysefl out of it  Huh.  Dumb idea Undecided.

Len
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« Reply #11 on: October 19, 2006, 07:40:38 AM »

Where in MN are you?

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Craig Shepard
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Craig R
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« Reply #12 on: October 19, 2006, 08:55:41 PM »

how do i get into the front of the central heat compartment? I can open the access door in the front bay, but that doesn't show me much.......Don't tell me I have to take up the floor next?  Grin

So, guys, how DOES one get into the front of the central heat compartment, remove the heater core?
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RJ
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« Reply #13 on: October 20, 2006, 08:23:48 AM »

Craig R -

Look at the front wall of the front baggage bin.  You should find a wooden section in the middle, held in with screws.  That's your heater core access.

If you're going to remove the main coach heat, be sure to leave the coolant lines hooked up that supply water to the defroster unit up front. Never know when you will need defrost and/or heat at the driver's feet.

Have fun - it's a dirty job!

 Wink
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RJ Long
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« Reply #14 on: October 21, 2006, 08:20:45 AM »

I've gotten as far as the heater core Wink If you look over the top of that, you see a large space then the A/C "core" -- whatever it's called. How does one get into that large space? How does one approach yanking that A/C heat exchanger Huh
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Fredward
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« Reply #15 on: October 24, 2006, 08:01:43 PM »

Hey Craig,
I figured everybody should see this (now that we've already figured it out) I'm located about 15 miles south of you where the mosquitoes aren't as bad. Looking forward to getting together in the next few weeks.
-Fred
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Fred Thomson
Fredward
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« Reply #16 on: October 24, 2006, 08:15:36 PM »

NCBob: I would very much appreciate a few photogs of what you find in there. I would really like to see how the tank is constructed. Is there a horizontal seam around the middle? Maybe that's where I'm leaking from? Or is the fuel gauge sending unit located somewhere easily accessible? Maybe that's leaking? -Wishful Thinking I'm afraid.
Stan: I do believe I will be contacting my buddy with the plasma cutter. I'm afraid its either that or install a saddle tank from a truck in the front bay.....
-Fred
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Fred Thomson
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« Reply #17 on: October 25, 2006, 04:38:25 AM »

Fred, I'll take the camera to the bus today and take all the pics I can.

Bob
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