CAV Safety Alert

Bob:

Here is a picture of the CAV fuel cell cavity. The problem associated with getting it in and out that Veek discussed has to do with the square tube bracing seen at the top of the cavity. The cell fits fine into the cavity, but the two 1.5" raised bungs at the rear are to tall. Seen from above, looking down on your door sill area, the square bracing would look like a 'W' pattern. The bungs have to be massaged under each of the three cross braces as the cell comes out and goes back in. Naturally, reaching all but the first one seen in the picture is the challange.

ON A MORE SERIOUS NOTE ABOUT PRESSURIZATION of the tanks....ATL, one of this countries formost manufacturers of fuel cells says, "INFLATION - ATL tanks and bladders are NOT to be inflated or pressurized. However, leak testing of the containers with less than 50 gallons capicity may be performed at 1/4 psi (6"water) maximum pressure. An accurate gauge amd a redundant pressure regulator system are essential. Overpressurizing may elongate the tank or bladder and damage its seams without visual evidence."

Regards,

Buzz

 

Photo

 

[Pat]

One thought would be to go "low tech" and put a rubber plug to seal your fuel filler opening and let your car sit overnight or in the sun for a few hours. Then pull the plug and if your hear a gentle hiss, you know it's holding pressure.

 

[Bob Childress]

Thank you Buzz, Pat, and Dan. I will now get my fuel cell inspection and upgrade done with lots of pictures which should be avialable in a couple of weeks.

Bob

 

[Ian Clark]

Hi Guys,

Great posting. Any type of fuel tank construction, steel, aluminum, plastic etc. is suseptible to damage from pressurization.

Fuel systems are designed to be pressurized after the fuel pump(s) and on injected cars up to the injectors and fuel pressure regulator.

Where you can get into trouble is with fuel injection systems is with return lines to the tanks.

Simply putting a fitting into the bung supplied on the top of the tank will not do.

You must ensure the return line discharges at the bottom of the tank so the fuel coming back is submerged instead of spraying like a nozzle into the tank above the fuel inside.

Been there, done that, bought the t-shirt. However before determining the source of the pressure, vented filler caps could not be fitted.

Cabureted cars with no return lines do not have this issue.

The factory will be supplying long fuel return tank fittings on cars ordered with fuel injection specified.

The fix is easy to do on existing cars. Keeps you on your toes though

All CAV owners with Tech questions are invited to call or email directly, thanks. [email protected]

 

[Pat]

Ian,
This brings up another warning. Avoid the temptation to pull the alloy fuel pick up out of the cell to provide clearance to assist in the placement or removal. It is attached to a pick up hose that rests on the bottom of the cell and you will pull those apart if you yank the pick up out of the cell. This would not be a good thing as the pick up would no longer be able to intake the fuel at the bottom of the cell.

 

[Pat]

Re: CAV Safety Alert Postscript

I had a discussion with the repair facility that fixed my old (now replaced) fuel cell. I was curious as to why it failed and they indicated that the front "chin" under the filler tube had a lamination separation. They told me that it looked like the lower front was pulled apart by an external force (versus the glue undoing). My guess is that when the cell was originally installed the bottom of the cell underneath the filler was compressed and torn as it was stuffed under the front cross member. The bottom of the cell lamination would have been scraped on the lower edge of the cell cavity steel sheet. So I'd suggest some protection for the chin of the cell as you install it to minimize the chance you'll tear it when forcing the neck into the cell cavity. Another safety note, if you have ever hand wiped the inside of the cell cavity; you’ll notice the steel shielding over the water pipe has a razor sharp edge. So helicopter tape the length of the edge for good measure. I also asked the repair facility if the cell needed to lay flat on the bottom of the cell cavity. (Mine was about 10mm off the floor of the cell cavity) they indicated that it really didn't matter as long as the majority of the cell had support. I shimmed mine to the floor anyway.
I’ve also been curious as to the interest in this thread. How many of you have had to change cells or is most of the interest preventative? If you are changing them, was there a leak? It may be wise to let the factory know so they can beef up any systemic weakness.