On Board Fluid (OBF) System - Complete

[Daless2]

On Board Fluid System

Several days ago I asked for your ideas, suggestion and assistance in developing an On Board Fluid (OBF) System for a Jeep.

The primary function of the OBF system is to store extra fluids, which are commonly taken off road, outside the Jeep in the space inside either the bumpers or rocker guards. The system was to be air tight and pressurized to aid in the installation of these fluids when needed.

Thank you for your input. As a result of our discussions this is what I have elected to do.


Using Rocker Guards:

My rocker guards are airtight, made of 2x4-inch boxed steel and 48 inches long. The steel walls are 3/16-inch thick.

I have elected to kill the idea of storing fluids inside some type of bladder. The bladder idea, while sound was too complex to solve at this time. I will revisit it at a later date.

Because there will be no bladder, fluids will be stored directly inside the rocker guards. This design will limit the storage of only one type of fluid in each rocker guard (or bumper) instead of the original thought of storing multiple types.

My plan is to store gear oil in one rocker guard, and either ATF fluid or engine oil in the other.

Here is an early picture of what my OBF System looks like using the rocker guards.




I gave considerable thought to where I would mount the two values. I chose these positions because they appear to be out of the way, yet easily accessed when needed.

The Fluid Flow Valve is nicely centered (almost) in this position, allowing me to reach all drivetrain components with a short 6-feet length of light duty hose.

The air valve / fluid fill plug location allows easy access to pressurize the system or to fill it with fluids.


Calculating Fluid Storage Volume:

Given these dimensions of my rocker guards (2x4x48 inches) I am able to calculate how many cubic inches of unused space are available inside to store fluids.

Please note that 3/8-inch (.375) has been subtracted from each outside dimension to compensate for the 3/16-inch steel wall thickness.

1.625 x 3.625 x47.625 = 280.5 Cubic Inches


One cubic inch of space will store 0.63 fluid ounces. To determine how many fluid ounces can be stored in each rocker guard I have used this formula.

280.5 Cubic Inches x 0.63 = 176.75 fluid ounces


There are 32 fluid ounces in a quart. To calculate how many quarts this is simply divide fluid ounces by 32.

176.75 fluid ounces / 32 = 5.52 quarts


Required Parts and Usage

You will need a few fitting and valves to complete this project as I have done it. While I had most of these parts in my shop, each is readily available at Ace Hardware, Home Depot, or any number of other stores of these type. I am estimating the total cost if you had to purchase all these parts to be under $15.

All fitting are made of Brass and are NPT (National Pipe Thread) standard.

Here is a photo and a description of the parts part.




Schrader Valve and Cap – A – This is nothing more then a tire inflation valve. The threads are ¼ NPT male. This valve will be threaded into coupler B1 and used to pressurize the rocker guard with air.

Couplers – B(1) & B(2) – These are female to male brass couplers. The female side has ¼ NPT threads, the male side has ½ NPT threads.

The Schrader Valve (air valve) is threaded into the female end of the B(1) coupler. The male side of this coupler is treaded into a drilled and tapped hole you will make in the rocker guard.

The B(2) coupler is threaded into a second drilled and tapped hole you will make in the rocker guard and will hold the “fluid valve assembly” in place.

Hose Barbs – C(1) & C(2) – These brass hose barbs will fit a 3/8-inch hose on one end and have ¼ NPT threads (male) on the other.

C(1) will be used to connect the fluid valve assembly to a hose to assist in installing fluids as they flow from the rocker guards.

C(2) is threaded to the bottom of coupler B(2) and will resides inside the rocker guard. This part will perform as a pick-up tube. Fluid will be pushed through this fitting from the bottom of the rocker guard and then out the remainder of the “fluid valve assembly”.


Ball Valve – D – This is a standard ¼ NPT (female/female) brass ball valve available in most plumbing departments. I know Home Depot sells this for $4.00.

This ball valve will control the flow of fluid through the “fluid valve assembly”. Hose barb C(1) or Plug E will be threaded into one end. The other end is treaded into coupler F.


Plug – E – This is a ¼ NPT (male) brass plug. It can be used to close off either the Ball Valve D or the Elbow G if you want this ability.


Coupler – F – ¼ NPT (male/male) brass coupler. Used to connect Ball Valve D and Elbow G.


Elbow – G – ¼ NPT (female/male) brass elbow coupler. Used to connect Coupler F and Coupler B(2).


Machining and Assembly

You will have to perform some light machining prior to assembling the Fluid Flow Valve and fitting both valves into the rocker guards. This is what I did.

Step 1: Thread Brass Coupler B(2)

The B(2) Coupler is a female to male brass coupler. The inner female threads do not go all the way to the end of the fitting. You will have to run ¼ NPT tap through this fitting to extend the threads all the way through. The brass is relatively soft. The tap should cut right through without any difficulty.

These threads will be used by the Hose Barb C(2).


Step 2: Grove Hose Barb C(2)

You cannot see this in the photos but I cut an “X” shaped grove in the bottom of the Hose Barb C(2). The grove is about 3/16-inch deep. I did this to assist in the flow of fluids into the hose barb (Pick-up tube). I cut this grove with a small angle grinder. (Obviously it doesn’t have to be fancy.)

Please note, I am installing my OBF System in rocker guards, which are only 1.625 inches deep inside. As it works out, Hose Barb C(2) will fit this application perfectly. When fully screwed in the nipple end of the hose barb sits off the bottom of my rocker guard, by about 1/8-inch. If your rocker guards are deeper you have about ¼-inch of adjustment built into the threads. (Just don’t screw it in all the way.)

If you are modifying this system for use in a bumper you will need to make this pick up tube longer. While I have not done this I would think a short length of gas line hose attached to the end of the hose barb would do the trick. Just make sure it clears the bottom of the bumper inside. I would imagine you could also use a short piece of ¼ NPT brass pipe cut to the length you need as a pick-up tube.


Step3: Drill and Tap

You will need to drill two 5/8-inch holes for the two valves. Give some thought to where you want the valves to be.

TIP: Keep the rocker guards level when you drill and later tap these holes as small metal fillings will be dropped into the rocker guards. If you keep it level and move it as little as possible. This will enable you to remove most of the metal fillings with a retrieval magnet tool.
After you have drilled the two 5/8-inch holes you will have to thread them with a ½ NPT tap.


Step 4: Flush Inside

Clean the inside of the rocker guard.

Once the holes are drilled and you have run the tap through them remove as much of the metal filling with a magnet.

To get the rest you will have to flush the rocker guard out. Find two plugs, cork, rubber, whatever you have.

Plug one of the holes and then stand the rocker guard on end and pure rubbing alcohol or brake cleaning fluid inside. Plug the second hole and with a friend rotate the rocker guard all around. Pull the plugs and rain the rocker guard. Do this procedure again and then follow it up with a good does of compressed air to dry things out and blow any dust out.

What does the rest of the inside look like? It should be clean if the unit has been sealed since new. If there is surface rust you are going to have to deal with it somehow. One way would be to pour in Hammerite Rust Cap paint to coat the entire interior of the rocker guard. When cured this epoxy based paint will not be affected by oil fluids.

Another idea would be to use Epoxy Appliance Paint. I have seen this at Wal-mart for bout $4 a can.

Perhaps a third way would be to use that liquid plastic that you dip tool handle in. I have no experience with this liquid plastic so you will have to check this out for yourself. I offer this only as a possibility.

My rocker guards looked as good as new inside.


Step 5: Assemble Valves

Assemble the Fluid Flow Valve fittings.

Assemble the Air Valve / Filer Plug.

Use Teflon tape on all threads to ensure a tight seal.

When all the fittings are assembled the valves should look like this.



(Please note, in this picture the fitting are only hand tight. Make sure you make yours wrench tight.)


Step 6: Install Valves

Prior to installing these valves I dropped four strong round magnets into each rocker guard. The idea is to have any metal fillings, that I may have missed, stick to the magnets like the plug on the AX-15 transmission. Don’t know if it will work, but I don’t think it will hurt.

Install both valves in the tow ½ NPT holes you made in the rocker guard. Once again use Teflon tape to ensure an airtight fit.

Here is what the valves should look like when installed.



Please note these valves in this picture are not installed on my rocker guard but rather a full-scale cardboard box covered in black tape. (Thanks Luc, I found a use for the tape!)


So where am I at?

I have completed this little project and tested it out. I put 4 quarts of Gear Oil in one rocker guard and then pressurized the rocker guard to 30 PSI.

After connecting a 3/8-inch hose to the value I was able to remove 3.8 quarts of oil in under 2 minutes through the hose. Obviously the location of the nipple sticking down into the rocker guard does not allow all the oil to be pushed out. I will address this by putting in more oil then I will need to use.

My rocker guards are currently in my heated basement curing from the fresh coat of Hammerite. I will give them a few days and then remount them to my Jeep. Hopefully by them my daughter will be back home with my digital camera and I will post a few more pictures.

Please note I do not have any trail experience yet with my new On Board Fluid System.

If anyone has any questions or would like a copy of this write-up in MS Word format please send me an email at email.id@worldnet.att.net I would be happy to send it to you.

Frank

Daless2

[Art Welch]

I'd have to think for a while before storing fluids without a removable bladder since every part of my jeep seems to be touched by a plasma torch or welder a couple of times a month. That said however you do an awesome job on these writeups! Wow. I should have responded with the same comment to your writeup on calculating CG. Great work.

[TJRON]

I'm wondering:
If you can't compress a liquid and your rails are completly full of liquid, it seems the only way you could crush them would be for some thing to bust. A good blow would spread the hydraulic load out over the entire inside surface of the rail and it seems to me it would be very hard to crush.
Yes, that is a good write up.
Maybe I would cap off the access and attach the fittings if I need the contents?

Ron

I like the way my Jeep is now..... I'd just like it, well, a little higher off the ground with more ground clearance!

[Wumpy]

Frank,

That is a superb write up. It's also pretty ingenious (sp). My rear bumper would likely hold a generous amount of some fluid or another.. I'm just trying to decide what! Your write up seems to make it pretty simple to do as well.

R/
William

Could we be looking at something on the magnitude of Exon Valdez with added pneumatic gusto?

Frank:
A great way of cleaning the carbon and crud from inside of steel weldments is fill with Muriatic acid, (Available at any pool store) let it set for two to four hours, drain and refill with a mild baking soda mixture then rinse with water and dry.
Garry

[Daless2]

Good Morning folks, and thank you all for your comments.

This design, at best is a "workable compromise".

I have no doubt that by putting this idea out in the public domain someone else will figure out solutions to some of these issues and make for a better solution for everyone.

Criticism, suggestions and ideas for improvement are welcomed. They generate new thoughts and better solutions.

ghall - Gary,

Your point of the potential of another Exxon Valdez is well taken.

There certainly is a risk with just a single wall between the oil and the environment.

That wall for me is 3/16 inch thick. For the type of Jeep'n I do I think that is pretty good, but I wouldn't advise it for those who are more hard core in their Jeep'n.

Maybe a OBF System in a bumper would be better.

I haven't given up on the original idea or using an air tight bladder inside the rockers or bumpers. I just haven't come up with a low cost viable solutions for that yet. Any ideas?

I never gave murriatic acid a thought! Great idea! I need to find out how to safely handle and dispose of this stuff and I will add your idea to the write-up. Thanks!

William,

If your bumper size is typical, 2x4x54 inches you can put a little more then 2 gallons of fluid in it.

Once again, thanks for your comments. Any others???

Frank

[Hellbender]

Very good writeup and execution! Neat idea.

Brad

2000 TJ 4.0L, A/T, all factory options.
Jeep Rater Score 360
http://www.hellbender.rockcrawler.com/
NRA Lifetime Member

[MJR]

Yes very interesting. I would be concerned (doing rocks mostly) that the fitting themselves are the most likely thing to break when a rock kisses it on a off camber situation. I like the idea of using unused spaces to store things. It would be I think unlikely that the rail itself would ever fail even with considerable abuse.

It was noted that it would be curious what effect this might add strength wise to the rail itself. It should also help a little with have more weight lower on the vehicle.

Got Groceries ?

[Daless2]

Thanks for your comments folks,

TJRON,

Ron, I didn't mean to ignore you and your thoughts on possible rocker guard strength increase if it was completely filled with fluid. I am by no means a hydraulics expert. Was kinda hoping someone else would chime in with some more info.

As you said, fluids do not compress. I would think that any energy applied to this setup would indeed result in pressure within the rocker being equal on all surfaces. But I don't know if this would be goodness or not.

On the down side, equal pressure everywhere might cause the pressure to find the weakest point to rupture. Perhaps a point that would not necessarily be involved if the rocker guard wasn't completely filled.

I just don't know.


Hi MJR,

Thanks for your comments. I suppose it is possible that the valves could get knocked off in an off camber situation. I have them placed as best I can to protect them.

I do have the option to remove the fluid flow valve and replace it with the brass plug while Jeep'n. This would greatly decrease that valves profile. Then if I need the fluid, take the plug out and put the valve in, pressurize and use.

The air pressure / fill pug has a very small profile so I don't think I have too much to worry about there.

One of the primary reason for doing this was to reclaim some space from inside my overly crowded Jeep.

An other was to put the extra fluid weight as low as possible in the Jeep, thus effecting the Center of Gravity of my Jeep by lowering it.

Thanks Brad.

Between you and Stu I have more then a few examples of how to do a good write-up. I'm just trying to put something back for all the value I have received from many other folks sharing their info.

Once again thanks to you all for your comments.

I wish you all a Happy New Year,
God Bless,

Frank

[Hellbender]

Frank,
If there is air space inside, the worry/thought about hydraulic pressure rupture/strength increase would be a moot point, (unless a high speed impact was involved) as the air WOULD compress.

Ever thought about a remote release (aka, ...007) applied to the the road behind you, in case of pursuit?


Brad

2000 TJ 4.0L, A/T, all factory options.
Jeep Rater Score 360
http://www.hellbender.rockcrawler.com/
NRA Lifetime Member

[Daless2]

Hello again Brad,

Yes your right about the air space providing for a compression cushion.

I plan to keep at least 1 quart of volume for air so I can artificially compress the air (via OBA system) when I want to extract the fluid under pressure.

I think I would get in a lot of trouble if I did a 007 remote release on this thing.

Then again, maybe I could fill them up with some type of Day-Glo slime green glow-in-the-dark environmentally friendly stuff!

Can you imagine the affects of that stuff hitting my rear tires and being fantailed into the air?

I think if I were behind me I would shoot me!

Frank