Cleaning & coating fuel tanks

[Photoman]

From: photoman  (Original Message)
Sent: 9/16/2003 12:46 PM

Well, I spent the better part of yesterday taking out the rear tank on my 72 D22 Indian M400.    First had to get her up on a couple of 2X10's as it didn't look like there was enuf ground clearance to slide the tank out once I dropped it down.  Glad I checked that before draining the tanks.  I was able to keep her running long enuf to get her up on the boards. 

I had to cut the gas line as I couldn't get to the fitting which is on the top of the tank. Will have to use hose & clamps to re-install.  Also disconnected the ground wire for the sending unit where it attached to the frame, and pulled off the wire that runs to the gauge.   I thought I had about all the gas siphoned out, but I was mistaken.  There must have been about 10 gal left in there.  I was glad I had a couple cement blocks under it or I would have been pinned under the tank when I took out the final bolt holding it up.  Anyway, I got the tank out and the remaining gas drained out.  Had a lot of rust particles in the bottom.  I was able to remove the sending unit from the top of the tank by removing the 5 mounting screws.  The sending unit is very rusty & I'm not sure if it is working.  Would just as soon replace it with a new one, if they're available.  Anyone know? 

The number stamped on the mounting plate is #2225517.    Then I hooked up the garden hose to a hot water faucet in the basement and sprayed hot water all around inside the tank as best I could...more sludge & rust poured out.  Kept doing that until water ran out pretty clear.  I know there is more rust in there that I'd like to knock loose, and I've been told I should dump some gravel in the tank and shake it around, but with the size of the tank (I think it might be 30 gal), it would take Superman & his buddy to shake it around! 

The POR-15 tank repair kit I got comes with a bottle of Marine Clean that is supposed to clean out the sludge, varnish, & rust in the tank, but I want to get as much of that out as I can before using the Marine Clean.  I still have to take out the forward tank, which is mounted differently and is smaller (20 gal?).  It will be a challenge, too, as it's difficult to get at the support bolts...especially the ones right behind the steps.  I'll keep you posted on my progress.  Anyone know how to test the sending unit with it out of the tank in case I can't find a replacement?  Thanks!  Photoman   

[denisondc]

Sent: 9/16/2003 5:39 PM

JCWhitney still lists a unit for mopar vehicles â€"search the index for -fuel level float-. Its in the gauges section, about $17 each. Myself I should get 4 of them, having two winnys each with 2 tanks. I think that rear tank is 32.5 gallon tank. I have put that much in mine that I ran dry. The front tank on my 72 D22 holds 27.5 if I run it dry. My fuel pressure gauge allows me to do this trick.

Also www.jcw.com, if you are one without their catalog. There I found it under the -Fuel and Intake Systems- link, and then to -Fuel Tank Accessories-. Same product.

The way to test your current tank sender unit is to see if the resistance from its terminal to its case goes smoothly from about 9 ohms to about 80 ohms.

While the tank is out I would solder a ground wire to the body of the tank, and to the case of the sender/float unit, and connect both of these to some clean bolt hole on the frame, or even up to the case of the fuel gauges themselves.

Whitney also lists a fuel filler hose, which reminds me: I would advise you replace the dried out rubber section of your filler necks. One of mine is now leaking if I fill up. And they list a fuel tank selector valve, I might also order that! I think it was my main tank that had a drain fitting on its bottom. I got a plug to fit there, of brass, that had a recessed hex to remove it â€" it didn’t stick down as far - one less thing to get scraped from the bottom of the rig.

I put my tank back in using all stainless steel bolts, and in a couple of places I silver soldered-in captive nuts, to make the next removal easier. To raise it back in position I had one end a 16’ 2 by 8 under it, a center support, and my wife being patient as the counterpoise at the other end.

[Photoman]

Sent: 9/17/2003 12:13 AM

Now I'm wondering if the 2 POR-15 tank repair kits I've got are going to do the job. They say in the literature that each kit will coat a 25 gal.
tank. Hope I can strech it enuf to do both of my tanks.
I was able to get the 2nd tank out today. Had to loosen the 2 support straps and then slide the tank to the rear and drop it down where the rear tank had been. It takes long arms and a long wrench and a lot of patience to loosen the bolts holding the straps up. The forward tank had more rust & sludge than the rear tank. The forward tank had a drain plug on the bottom, but it was rusted & didn't want to loosen. I didn't force it as I didn't want to create any more problems than I already have.

I checked a couple auto parts stores in town today and neither one had the sender units. Most of the ones they have now have electric pumps built onto them. I sure wouldn't want a pump mounted inside my gas tank! Who was the idiot that came up with that idea? I was already planning on replacing the rubber connector hoses that connect the tanks to the filler tubes. Didn't find them either. The place I checked, Car Quest, had 2 sizes..2 big, and 2 small.   He figured they were 2 1/4" diameter. I'm going to check a couple more places tomorrow. May have to order from JC Whitney as well as the sender units.

going to test the senders tomorrow like you said. The one in the forward tank was REALLY rusty, tho, and I don't have much hope for it. I'd much rather replace both since I have the tanks all apart.

[Photoman]

Sent: 9/17/2003 9:30 AM

When I was rinsing the tank out with hot water, I was tipping it from one end to the other, and it seemed like there were some baffles inside the water was traveling thru. Any idea what the baffles are for?

I'll coat the smaller tank first, and then if there is any extra that drains out after I'm finished, I'll add it to what I pour into the bigger tank. 

[Photoman]

Sent: 9/17/2003 12:37 PM

I checked every auto parts store in town today looking for a fuel level sender unit for my gas tanks. Struck out everywhere, except MoPar had a universal unit that included the gauge for $32.75. Looked like it might work (had the same mounting holes). I was hoping to just get the sender
without the gauge...should be a lot cheaper. The universal sender that JC Whitney has is only $17 + ship., but I'm wondering if it will work with my present gauge. Anyone out there ever installed one of these universal jobs and did it work with the original gauge?

[denisondc]

Sent: 9/17/2003 3:30 PM

The baffles make the tank stronger, less likely to change shape or open at a seam, when you go over bumps with over 200lbs of fuel in there. Also they prevent more sloshing - which always speeds up the evaporation of the fuel as you drive. I bought my fuel sender at a local auto parts store, but that was over 10 years ago. Someone on the site had gotten the whitney item and used it - that was a year or two ago.
And if mopar had a universal unit that included the gauge, I have to wonder if it would work with the gauges that are now in your rig?

On my 72 D22 M400 the main tank is held up by 2 L brackets that bolt to the frame and reach under the tank, and they have to be undone to let the tank drop down, but the aux tank is held up by U straps that pass under it, and bolt to the chassis above the tank, in difficult to reach places. I cut those U brackets at the inner part of the horizontal section, and welded on brackets to bolt the now two pieces of each U bracket back together. Those bracket bolts are easy to reach now. My solution to the misery of reaching to work the rusted nuts/bolts for those U straps. 

[Photoman]

Sent: 9/18/2003 1:01 AM

I'm sure my tanks are the same size as Denison's...32.5 gal rear tank & 27.5 gal front tank. I'm working on both tanks at the same time as far as
cleaning them out with the Marine Clean. Takes 24 hours of soaking, rotating the tanks from time to time to make sure the solution reaches all surfaces inside the tank. Thanks for explaining the need for the baffles. I was hoping they weren't in there just so the rust would have more surfaces to form on. 

[Photoman]

Sent: 9/18/2003 1:17 AM

The sender in the rear tank checked out just like you said..9 ohms to 80 ohms, so it evidently is still okay. But the other sender wasn't
anywhere close to those readings. I can't remember exactly what it read, but I know it's bad. Was really, really rusty.

My tanks are mounted just like you described yours. That's a great idea cutting the u brackets for the front tank in half and welding brackets on them so the two halves can be bolted back together. I'm definitely going to get that done before I put the tanks back up. Thanks for the tip!

[denisondc]

Sent: 9/18/2003 5:20 AM

If the range of resistance values is the same, or nearly so, I presume it would work. You might be our test-case though. When I need to drop my aux tank again, I will only have to undo the two unrusty -stainless- bolts and nylock nuts, pivot the outer half of the two U straps 90 degrees, and the tank wil drop out. I also left enough extra fuel line length and sender wires length for that drop .