CAV Safety Alert

[Veek]

As some of you know, I recently replaced a leaking fuel cell in my CAV. After some vigorous driving, I noticed a new fuel smell. I've already addressed the filler caps so I pulled the inspection plate over the fuel gauge and discovered it was wet with gasoline.
I pulled the new cell and discoved the attached.

[Veek]

I will leave it to the keen eyed observers to determine if you can spot the problem as I pulled the foam inspection/replacement plates.
Notice anything unusual??

[Alain Vanhollebeke]

uhhh,,, where's the gasket for the plate closest to the top of the pic?

[Pat Buckley]

That you used an electric drill to remove the fasteners?

Sorry! I couldn't resist!

[Bill Bayard]

Since the tank was built by Buck Rogers Aviation, maybe the lack of a gasket was part of a secret sabotage plot by
Ming The Merciless to blow up Buck and Dale Arden in their new CAV spaceship! That drill is actually a ray gun! [img]/ubbthreads/images/graemlins/grin.gif[/img]

For the young and uninformed, Buck Rogers was an early, VERY cheesy, weekly radio serial, starring Buster Crabbe, about a space travelling hero(Buck)vs. his arch enemy(Ming), later turned into short film serials.
It was a classic in the US during the 40s(radio), 50s&60s(TV), and was almost as bad as the Thunderbirds! [img]/ubbthreads/images/graemlins/tongue.gif[/img]

[Pete.]

Hey Bill, the Thunderbirds are GREAT [img]/ubbthreads/images/graemlins/laugh.gif[/img]. Or is that go? [img]/ubbthreads/images/graemlins/confused.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[Craig White]

Bill I'm glad I was not the only one that thought of that of old TV show when I read the brand name of the tank. Yep, we got Buck as well in Aussie land. And of course Thunderbirds.

Looks like a little more attention was needed when assembling that tank. Maybe it was a Friday tank. [img]/ubbthreads/images/graemlins/smile.gif[/img] Seriously for safety's sake, you just don't want to have problems like that.

[Frank Catt]

Veek, its a bit of a bugger getting the tanks out of a CAV, but having got them out ( I have two out at the moment ) I am glad for the warning to check the gaskets, Thanks, Frank

[Veek]

Thanks to all. I knew the responses would be memorable. This forum certainly is populated with a witty bunch with a keen eye.
As you noticed, check the gaskets before you place a new cell in your car. The rear was delivered with, the front without. Shame on me for not checking before I installed the darn thing. I was fooled by the fact that gasket sealant was evident in the fastening screws. None was between the plate and the cell. Buck and his cadets need a little lesson on quality control. I sent the old cell to Floats and Cells in Memphis to give me a quote of fabricating another. http://www.ffcfuelcells.com. I figure in 5 or so years I’ll need to replace them and I don’t want Buck to have another opportunity to turn me and my car into a smoking greasy spot on the road.

The benefit from all this is my cell replacement regimen is down to an afternoon (and four beers). The secret is to use a wooden broom handle to finesse the nipples on the back of the cell under the cross supports on the cell cavity.

[Gary Gibbs]

Thanks for the update Veek. Did you add a new gasket or use a type of sealant in place?

What suspension parts must be removed to remove the tank? I am changing the roll bar setup in my demonstrator and I need to weld above the tank. Thought it was a good idea to remove the tank [img]/ubbthreads/images/graemlins/smile.gif[/img]

Thanks
Gary

[Bob Childress]

Hi Pat,

We have talked about a safety upgrade for the CAV fuel cells consisting of a wagon wheel "flap" check valve for the base of the filler neck in the front, and air vent check valves with roll over sealing for the nipples at the back. I am still working to get the back of my car reassembled. I have not yet started the fuel cell upgrade but I plan to make those improvements next. So, your post is very timely and I am sure will also be appreciated by other CAV owners.

Can you or other forum members give me a few pointers about testing and/or working on fuel cells?

1. Do you think the cells can be air pressure tested for leaks or bad seals while still in the car (i.e.; seal the back and front nipples, add an air intake valve and pressure value, inflate to 10psi ( ? ) and watch for a pressure drop, hissing sounds, etc.)?

2. If the cells do have to come out, when and how do the fuel sender wires get detached? Besides a broom handle, any other little tricks?

3. An finally, can you give me the exact inside, outside, and height dimensions of the front fuel cell filler neck nipple? I would like to order the a set of check valves before I start taking the front of the car apart.

Thanks,

Bob

[Veek]

Hi Gary,
It is such a pain and it puts so much stress on the nipples, I'd put a welders blanket over the cell after you disconnect it from the filler neck rather than pull it out. I worry about the wear and tear on the nipples.
However, if you do pull it, I found that by removing the caliper, rotor, and both ball joint blocks, I have enough room to wiggle it out. (Only the A arms remain in place.) As I mentioned, the hassle to me is delicately passing it through the cell cavity.
Hope that helps.

[Veek]

Hi Bob,
I've provided some thoughts after each question.

1. Do you think the cells can be air pressure tested for leaks or bad seals while still in the car (i.e.; seal the back and front nipples, add an air intake valve and pressure value, inflate to 10psi ( ? ) and watch for a pressure drop, hissing sounds, etc.)?

Sure, you can buy a rubber plug at the hardware store and put a Schrader valve in it and plug both nipples and with a bicycle pump do a 10psi leak-down test with a tire gauge.

2. If the cells do have to come out, when and how do the fuel sender wires get detached? Besides a broom handle, any other little tricks?

Under the carpet on your doorsill you will see a round inspection plate. It is access to the fuel level-sending unit. You will see the wires and can disconnect them from there. After they are disconnected, pull them and tape them to the sill. You don’t want the cell to snag them on the way in our out.

3. An finally, can you give me the exact inside, outside, and height dimensions of the front fuel cell filler neck nipple? I would like to order the a set of check valves before I start taking the front of the car apart.

Unfortunately, mine’s back in the car. You can see yours by pulling the access panes behind the front wheels. The rubber neck at the base of the steel filler tube is actually the neck of the cell.
In answer to an earlier question, I made replacement gaskets for my cell with NAPA gasket stock coated liberally with Permatex HYLOMAR. It won’t leak but you can pull it apart later if you need to.

Bob, I think you still may have my phone number. I’m off tomorrow if you want to talk about it.

[Frank Catt]

Gary, I have just installed a sill mounted shifter in a CAV, which involves cutting and welding adjacent to the tank, so I say do not risk it - take the tank out first because of the need to both cut and weld ( TIG ) Its difficult but not impossible, and it means you can check a lot of other stuff while its out, including debris under the bag, self tap screws inserted dangerously near the rubber bag etc etc. It will also give you the opportunity to assess any (necessary ?) strengthening needed in this area. Frank

[Veek]

Frank, good point. If there is cutting and welding on the cell cavity definitely remove the cell. I was thinking you were mounting the roll bar on the floor and not the fuel cell sill. In light of my recent experience, also have a look (and sniff) from the battery box forward as well.

[Dan Weilacher]

I would be very careful preasurizing those tanks. 10 PSI is a pretty good charge if you think about it. Being in the aviation field I believe most bladder tanks have 3 to 5 psi MAX put on them and then check for leaks with a soap/water solution.

[Gary Gibbs]

Thanks all for input. I also think the 10 psi is too high, but would guess 3 - 5 might be ok.

[Frank Catt]

Veek, another safety issue raised in this discussion, I will not have any Electrical apparatus in the side panels adjacent to the bladder tanks, the battery goes forward into the front compartment against the bulkhead behing the radiator, all other wiring goes into the boxed panels behind the seats, the only wires near the tanks are the sender earths. If there were to be a crushing side impact that ruptures the tanks, the last thing you want is an ignition source in the same area.Frank

[Bob Childress]

Hi Guys,

I am very jazzed that all the fuel cell issues are being discussed here with specific suggestions. Like Frank and Pat, I happen to be doing this work right now, so the advise and experiences of others is perfectly timed. I actually did the battery stuff last week. Getting the battery and all the electrical wiring out of the same body cavity as the fuel cell is a relatively easy job on the CAV.

Battery
I ordered all my parts for this job from Summit Racing. A new red 1-gauge wire was run from the standard CAV master disconnect switch, along the right side of the interior under the gray plastic cover plate with the heater hoses and into the front of the car. A new ground connection was made to the chassis in the front end.
Putting the battery in the front is a close fit and required some trial and error fitting. I ended up using a vented marine battery box and cut 2" off the top so that the battery box cover would sit low enough to clear the front clip nostrils. A 0.80" SS tray with flanges on all four sides was fitted 1/8" above the sway bar to hold the battery. Two 1 1/4" diameter aluminum spacer were made to hold up the front of the battery tray. The tray was bolted in place to the passenger side foot well and through the spacers to the belly pan. The battery is actually held in place by two hold down bolts that go through the tray, and up through the bottom of the plastic battery box, through to a steel strap across the battery. Silicone was used to re-seal the bottom of the battery box where the bolts went through. The marine battery box included a nylon strap which is just used to hold the plastic top on the battery box. Everything was done with 5/16" grade 8 hardware and nylon insert lock nuts or safety wired.

Remote Terminals
Mostly because this was the first time I had done this job, I mounted a set of remote 12 Volt and Ground terminals in the engine compartment and used the same holes and wires that the original CAV battery had used. In retrospect, the remote terminals did not have to be mounted flush and could have been installed on a raised bracket bolted to the chassis. The wires that used to go the battery could then have just been connect to the terminals on the new bracket. This would have made the job much easier and is probably what I would do now if I had the job to do over again.

Here are a few pictures in a sequence of posts.....

[Bob Childress]

picture #2