C3 Plenum

[Jeff W.]

Removed my gas tank today (no, did not find a build sheet) and I am going to replace it(very rusty). My question is why so rusty? Can anyone tell me if there is suppose to be drain hose's for the holes in the bottom of the tray under the rear vent grill? There are two holes, one on each side bottom, and I now understand everytime I wash my car water is dripping on everything underneath. Am I going down a wrong path?
Thanks for the help.

[Joe L.]

Re: C3 Plenum

Jeff-----

There were drains for the rear plenum area (under the deck grilles). The configuration of the drains was different for coupes and convertibles, but both had the drains.

Whether, or not, the drains on your car were once-upon-a-time rendered dis-functional, plugged, or mis-directed, I don't think that this would have had a major affect on the fuel tank. More likely, if the corrosion you describe was external to the tank, the car was driven in salted road areas and some splash got on the tank. Although the tank is pretty well protected from the bottom by the spare tire carrier, there's still plenty of opportunity for splash to affect the tank. Also, the tank is terne-coated steel which offers considereable corrosion protection, but it does not render the tank forever corrosion-proof.

Nevertheless, just a little road salt will get corrosion started and, once started, it will proceed inexorably.

[Alan S.]

Re: C3 Plenum

Hi Jeff,
Yes there is a rubber hose that connects the two drain trays to a discharge valve mounted high and on the inner side of each rear wheelwell. I believe Dr.Rebuid can supply what you need.
Happy New Year
Alan

[Terry M.]

Please tell us the year of your car and

the body style and whether it has air conditioning. All those make a difference as to the configuration of the hoses and whether there are "trays" or not.

[Jeff W.]

Re: Please tell us the year of your car and

It is a convertible and no AC. I know that the coupes have a drain, but I have not seen any hoses to go into the holes at the bottom of the tray.

[Harmon C.]

Re: C3 Plenum

Jeff
You have one of the models where you can see the ground through the vents and they were built that way. If the tank is rusty on the inside it happens with a tank not full during long terms of storage with little driving.

Lyle

[Joe L.]

Re: Please tell us the year of your car and

Jeff------

For convertibles the drains go to the rear of the bulkhead which faces the front of the fuel tank; they are not really visible unless you have the fuel tank out or look from the bottom into the space between the tank and the bulkhead. The drains are designed so that a special shield directs any water drainage DOWNWARD. Drainage should not contact the fuel tank to any significant degree.

I can tell you, for sure, that when I removed the original fuel tank from my original owner 1969 convertible there was virtually no rust, at all, on the tank at any location. Of course, I've lived in California since the car was new. While it's been exposed to plenty of rain during the years I drove it day-to-day (1969-77), it's never been exposed to any road salt. That's the BIG factor.

[Jeff W.]

Re: Please tell us the year of your car and

This is an original jersey car. So I guess the salt is the factor. I was just surprised because there is so little rust anywhere else on the car. Thanks for all the insight.
Jeff