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Author Topic: Drop fuel tank  (Read 1481 times)

Adam Hicklin

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Drop fuel tank
« on: March 07, 2018, 07:04:42 AM »
Since I’ve had my coach there has been a small but persistent fuel leak coming from the top side of the fuel tank.  I can see fuel dripping from the top down the side of the tank.  Also, there is the pervasive smell of diesel fuel, all the time.  My question is, would it be worth dropping the tank to investigate?  Is it even possible?  What type of connections would I find, and would they even be serviceable?  As I said, this isn’t a big leak, but it is annoying.  Your input would be appreciated, especially if you have tackled this issue.  Thanks in advance. 

Jerry Carr

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Re: Drop fuel tank
« Reply #1 on: March 07, 2018, 01:19:00 PM »
Adam I don't know for sure about your fittings but would just pass on a piece of information. If you have the plastic snap style fitting they can leak and will also allow air into you engine fuel that could result in engine damage and performance issues. You may want to contact Dave our Cat Master Mech. for more information. Yes, the tank can be dropped I did see Dave and Jim do this repair at Hemmit.   
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Jerry Carr
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Dave Atherton

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Re: Drop fuel tank
« Reply #2 on: March 07, 2018, 02:05:58 PM »
Adam, your fuel leak is more than likely at the connection at fuel pickup tube on top of fuel tank.
Not knowing builder type of fitting used at build but the plastic push on connector with plastic clip
may be the one. You also have a tank vent and gen set pick up tube also on top that are lot easier
reach than engine pick up tube.  Would suggest first check your engine fuel line at primary fuel
filter for air. This can be done by removing the fuel line connection and putting a short piece of
clear plastic hose from hardware store into system than start up engine to look for air bubbles
coming from front tank to engine. If you find no air bubbles that will than make repair of fuel leak lot easier because location of gen set and tank vent location toward tank front.
Dave Atherton Retired Cat Mechanic
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Adam Hicklin

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Re: Drop fuel tank
« Reply #3 on: March 07, 2018, 03:01:10 PM »
Dave, can the gen set and vent fittings be accessed without dropping the tank, or will the tank need to be dropped regardless?

Gerald Farris

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Re: Drop fuel tank
« Reply #4 on: March 07, 2018, 03:57:29 PM »
Adam,
First, when do you notice the leak? If it is only after a fill-up or when the tank is full, it is probably the check valve in the end of the vent hose. This is usually accessible without dropping the tank as it will be in the end of the vent hose on top of the tank at the front edge of the tank and usually on the drivers side. On your coach it is normal to get a slight amount of fuel out of the vent hose if you try to squeeze all of the fuel that you can in the tank at a fill-up. However, if the leak is only when full and not from the vent hose, you may have a leak at the connection on top of the tank and this requires dropping the tank.

Next, if you notice the leak mostly when the engine is running, you may have a fuel return line leaking. However, if the leak is when the generator or heating unit are running, it is probably the return line for that unit, and both of these require dropping the tank.

The procedure for dropping the tank will vary depending on what chassis you have. The early production 98 Marquis (I think the first 26 coaches) has a Gillig chassis and the access to tank connections is usually a little easier than the latter production coaches that were on a Magnum chassis. If you have a Magnum chassis, you will be able to lower the tank enough to gain access to the top of the tank without removing it if the front of the coach is raised for clearance and blocked for safety with a minimum amount of fuel in the tank. However, you will not be able to remove the tank without removing the front axle, so if removal is needed, best see a good chassis shop.

Last, there are three other leak locations that will leak at all times that you have over a quarter of a tank of fuel, and they are the filler hoses that go into the side of the tank and the fuel gauge sending unit in the side of the tank. The repair method for these leaks is fairly obvious.

Gerald   
2002 Solitaire (2017 -  )
2000 Marquis, C12 (2004 - 2017)
1993 Patriot  (2000-2004)

Adam Hicklin

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Re: Drop fuel tank
« Reply #5 on: March 08, 2018, 05:36:33 AM »
Thanks Gerald.  It’s the Magnum chassis.  Maybe leak isn’t the correct term.  Maybe more of a seepage.  I see the telltale oily dirty muck down the side of the tank.  It never appears wet, like a constant leak and seldom is there any evidence on the ground, unless it has been sitting in the same place for a long time.  But the heavy deisel smell has been constant.  I’ll do some more investigation and see if I can tell when exactly it’s happening.  Check the easiest things first.  In anticipation of possibly having to drop the tank, I’ve run it down pretty low on fuel.  Can someone explain the proper way to block the suspension to make it safe to work under?

Joel Ashley

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Re: Drop fuel tank
« Reply #6 on: March 08, 2018, 10:35:36 AM »
This may not be relevant since you smell diesel.  I once noted something similar that I thought was a fuel tank vent leak of some sort, but turned out to be a tech had failed to fully tighten/seal the filter after changing the genset oil.  Road draft sent a minuscule but persistent spray back onto the fuel tank, mixed with road grime.

As to chassis and body support, I carry high rated jack stands myself, as per my axle loads, but many here prefer to rely on stout wood blocking.  One could also drive up on planks that give more than safe clearance even if air was dumped.

Joel
« Last Edit: March 08, 2018, 02:13:26 PM by Joel Ashley »
Joel and Lee Rae Ashley
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Dave Atherton

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Re: Drop fuel tank
« Reply #7 on: March 08, 2018, 02:30:46 PM »
Adam, on Jim Nichols fuel tank the tank vent and gen set fuel line could be reached on top
of tank for inspection. Tight fit between gen set brackets with gen set pushed out and fuel
tank. We just lowered the fuel tank down and let it set on front axle gave is enough room to
Work  to change fitting on engine pickup tube in tank middle Dave Atherton Retired Cat Mechanic
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