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Old May 5, 2007 | 10:29 PM
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Default rear deck grille question

the grilles on the rear dect right behing the rear window on my 74 goes into nothing, my dads 72 is cut out and lets water drain through, was mine supposed to be cut out, and if so how would i do it? would i need to do "duct work"? i hate the water pooling in there and leaving horrible water marks, seeing as thought i wash it everyother time i drive it, it would be kinda nice to hav a drainage system

Miles
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Old May 5, 2007 | 10:47 PM
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The vents exhaust passenger compartment air in non-air-conditioned cars. In 74 and 75 coupes with air conditioning the vents are present, but get blocked with flat black painted plates.
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Old May 5, 2007 | 10:51 PM
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Originally Posted by Al Czervik
The vents exhaust passenger compartment air in non-air-conditioned cars. In 74 and 75 coupes with air conditioning the vents are present, but get blocked with flat black painted plates.
dads got AC but non blocked vents, so that was JUST for 74-5?

so im wrong in thinking it was for water?

Miles
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Old May 5, 2007 | 11:07 PM
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Originally Posted by randommj
dads got AC but non blocked vents, so that was JUST for 74-5?

so im wrong in thinking it was for water?

Miles
Yes it was a 74-75 thing. I think the vents were part of the 'Astro Ventilation' system
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Old May 5, 2007 | 11:52 PM
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The purpose of those vents was to exhaust normal cockpit airflow. However, the "active" vents (non-A/C units) also had to allow rain, wash water, etc. to be drained...hence the drain lines to the fender wells.
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Old May 6, 2007 | 12:29 AM
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Originally Posted by 7T1vette
The purpose of those vents was to exhaust normal cockpit airflow. However, the "active" vents (non-A/C units) also had to allow rain, wash water, etc. to be drained...hence the drain lines to the fender wells.
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Old May 6, 2007 | 01:41 AM
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Default How do you clear the plenum drains?

I've got a 70' Vert w/no AC. Is it possible to clear the rear plenum drains without removing the gas tank?

I've tried running a clothes hanger down to clear with no success. I think the problem may be that the exit grill is blocked but I can't get to it from underneath because of the gas tank.

This is a demon I've been dealing with since purchasing the car in 1987.

Thanks

James1970
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Old May 6, 2007 | 09:13 AM
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The non-A/C vent ports were operated by a vacuum servo; the servo opened AND CLOSED OFF those vents, as required. With the engine off, I believe the vents were closed [can't poke anything in there then]. Start the engine, put control in VENT position and check them to see if they're open.
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Old May 6, 2007 | 09:27 AM
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Originally Posted by James1970
I've got a 70' Vert w/no AC. Is it possible to clear the rear plenum drains without removing the gas tank?

I've tried running a clothes hanger down to clear with no success. I think the problem may be that the exit grill is blocked but I can't get to it from underneath because of the gas tank.

This is a demon I've been dealing with since purchasing the car in 1987.

Thanks

James1970
I just learned something from you James. I thought for sure the vents drained to the fender well. We just replaced the drain tubes and the drain itself on my buddies 1970 Coupe and they drain in the fender well. I just came back in and our convertibles only have a block off plate there. I guess the tank has to come out for ours.
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Old May 6, 2007 | 09:50 AM
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No such problem with my 71 vert w/air. The area under the deck vents is completely open. Water would fall in an area ahead of the gas tank onto the rear of the tire carrier.
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Old May 6, 2007 | 11:30 AM
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Originally Posted by Eddie 70
I just learned something from you James. I thought for sure the vents drained to the fender well.
This is how it is on my '72. I thought it was there to keep water from pooling. Never realized it was so complicated.
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Old May 6, 2007 | 01:05 PM
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My 71 AC Vert has the flaps to the pass. compartment riveted, but there are wells with drain tubes under the deck vents. the drains run off to the side of the gas tank, not into the fender wells.
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Old May 6, 2007 | 01:15 PM
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Originally Posted by 7T1vette
The non-A/C vent ports were operated by a vacuum servo; the servo opened AND CLOSED OFF those vents, as required. With the engine off, I believe the vents were closed [can't poke anything in there then]. Start the engine, put control in VENT position and check them to see if they're open.


True in my 74 convertible. Damn thing still works...amazing...
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Old May 6, 2007 | 01:44 PM
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The deck vents should be behind the rear bulkhead for '71 and later convertibles. The vents stayed put but the bulkhead moved forward. They should be in front of the rear bulkhead on a '70 convertible. Coupes had deck vents mounted further forward than convertibles, and all the coupes vents were over the interior storage compartment.

Below is a pic comparing the rear bulkhead (from below) for a '70, on the left,, with a '73, on the right. Both are convertibles with a/c.



As you can see the bulkhead moved forward 4 full inches after 1970. This resulted in '71 and later cars having the deck vents behind the bulkhead while the 68-70 had them in front of the bulkhead. (Also a loss of 4" in storage space for the 71 and later cars.)
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Old May 8, 2007 | 03:14 PM
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Default Plenum Drains

Eddie 70: Happy I could "spread the joy" with you. Truth be told, anything I know about C3's was learned from those on the forum.

Tom 73: Great photos! Thanks for posting them. If I could only get to those darn drains my problem would be solved. As it is, I can't wash the car with a hose or be caught out in the rain. All because of those blasted drains!!

Thanks again for your input!

Best,

James1970
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