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Opeler
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Discussion Starter · #1 ·
ventilation tubes?

Could anyone tell me what the purpose of the 2 clear tubes on each side just above the gas tank?

These tubes are larger than the fuel vent lines which connected to the cannister. The upper end of the tube connects to the body which runs up the panel just over the wheel well and connects to a metal fitting. The bottom end goes to an opening just below the gas tank.

Do these tubes pull out any fumes via changes in pressure when driving or are they part of some other ventilation system (like the vents just above the rear window)?

thanks
 

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Super Moderator
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You said it all. Those clear vent tubes connect to the vent above the rear window. Air passing over the roof of the car draws any fumes out through those vents. If those hoses are cracked or left disconnected, you'll know about it in short order!
 

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Ventilation or Drainage Tubes?

Well, here is one case where Bob and I slightly disagree. The fresh air ventilation system utilizes the low pressure area around the back window and the slots above the glass to draw interior air out of the car. The air exits the interior from the slots at the sides of the glass, with the air flow also helping to keep the rear window clear of condensation. The plastic tubes do not have air flow through them.

The plastic tubes are connected to drainage trays at each side of the rear window, so that any moisture that enters the rear slots are drained out through holes in the underbody. These tubes are capped with rubber ends that are narrowed down to slits, allowing water to pass through but minimizing reverse flow of debris and dirt. Often these caps deteriorate, leaving the plastic tubes wide open. I found that you can pull the plastic tubes out a bit further, then gently heat the plastic tube with a heat gun and "form" the slits in the end of the tube themselves. Make sure that the tubes are sealed against the holes in the underbody, to keep dust from being sucked up into the interior.

Which is where Bob and do agree. If the tubes are disconnected, dust and exhaust fumes will be drawn up into the interior. I just posted a note on this topic at:

http://www.opelgt.com/forums/showthread.php?s=&postid=4651#post4651

HTH
 

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Opeler
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Discussion Starter · #4 ·
ventilation or drainage tubes?

I did some searching last night and came across a picture which showed under sheet metal parts a grommet labeled "water hose deflector grommet." I did more searching in some parts book and came across both the grommet "water hose deflector grommet (rubber)" and the hose "water deflector hose, rear quarter side panel air slots."

So I guess it means that the hose is used for draining water.

thanks for the input.
 

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The tubes are for drainage , not air flow- I had to do an emergency re-route on my gas line and came down through the drainage tube. Work well until I changed it to the proper routing. There was no change in the venting but water sat in the tube because of the blockage caused by the gas line.
 

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Pathologic Opeler
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mystery hose

what is this large hose...I think it is the original.It is a yellowed clear plastic..there is a similiar hose in the interior of the car by the rear window of my gt.it is larger than the gas tank to canister vent lines.

what is the purpose and does it need replaced?
 

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Detritus Maximus
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It is a drain hose from the rear roof vents I believe. If I remember right, it goes up to a fitting by the rear window.

Anybody else confirm this?
 

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Yes, and they connect to the rubber "duck-billed" grommets under the rear floor, below where the gas tank sits.
 

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Detritus Maximus
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Ah, yes, now I remember! The 'duck billed grommets'....I always did like those things. They tickle!:eek:
 

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Pathologic Opeler
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exhaust fumes with window cracked and rolling

if you stick your head in the spare tire area(Trunk?) it smells like exhaust fumes,not raw gas...even when car has been sitting

my tank was welded last year with a new exit tube, new rubber replaces vent lines,charcoal cannister has good lines, top of engine , carb is good with new gaskets and rebuild( no boiling gas in the bowl here),

roll windows up and the smell goes away..as you drive...crack window and it comes back.

tail lights and side markers have new homemade gaskets...I think they are tight.

I am out of ideas..any one?
 

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Old Opeler
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Sucks!

Make sure that none of the rubber bungs in the floor under the fuel tank are not missing or deteriorated. When you open the side windows no doubt there is a strong air movement that "sucks" exhaust fumes into the car.
Make sure the exhaust pipe tips extend far enough back too - back to the edge of the bumpers at least. If they are too short exhaust gases will be pumped back under the car making things worse.
 

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Charcoal Canister Vent?

Where is the charcoal cannister vented to? I see three hoses connected to it. One will be from the tank. One was originally from the Solex bowl vent, which your Weber probably doesn't have (a few do), so where does that connect to? The third connection originally went to the Solex, to a connection that vented into the venturi throat, and sucked accumulated fumes from the cannister into the engine. Your Weber DEFINITELY doesn't have that connection. Did you connect it to the air filter housing? If you just have a hose open from the cannister, it might be the source of some of the fumes. Or, if you have blocked the outlet from the cannister, gasoline fumes will definitely find their way out of even the best sealed vent lines.

Or, you have an exhaust leak under the car, and when you open the window, it creates a vacuum inside which can suck the exhaust in from a multitude of places.

HTH
 

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Pathologic Opeler
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looking for leaks

last night I turned out the lights,then put my shop light in various areas of the trunk..no light leaks anywhere.

then I remembered my partial blocking of the rear vent with glow wire ,wedged in with tape balls..I had definately blocked airflow. the clear water drain tubes are wide open at the bottom.

question 1- should that clear water drain tube exit as a slit?

I pulled it out and went for a test drive...maybe that is it.

qusetion 2-could blockage of the vent be a factor?

I have 2 lines that exit the charcoal cannister...they both dump into the carb.

I am starting to pull for straws.

PS: the exhaust smell wasnt a problem in the past because the raw gas smell
was much stronger( due to gas boiling in the carb)..Piece by piece my car is coming together into something that is a real pleasure to drive.
 

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Opel fan
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drainage and vents

Ok, here are some pics I got from taking part of the roof skin off a scrapper. I was looking for a way to run the power wires for the rear vent LED assemblies we got from JJ. Those vents on the outside top of the rear window do need a drain to shed water that gets into them. They are channeled down do the long vents beside the rear glass inside the car. Along the sides of those inside rear window vents are where the drain tubes ducting begins and they run down the inside of the gas tank area to the outside of the GT in the rear bottom. I think the inside vents help keep the rear window clear and the tubes shed water that gets inside those outside vents, which provide the vacumn. The duck billed caps are there so the drain tubes don't loose too much vacumn but still allow the water to escape and also to not suck exhaust fumes is as well. JM2CW, HTH
 

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Registered
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Someone already asked the question but I will again. You have a new exhaust, does the end of the exhuast extend beyond a vertical line from the edge of the rear bumpers? If not, you could be creating a vacuum under the car and pulling the fumes in through the fuel tank outlet, if that rubber boot is missing, or either of the 3 drain holes under the fuel tank or even the vent line hole that goes through the tank floor. Or even possibly into the vent lines that come down through the rear roof pillers if they have lost the duck-bill feature at the ends of the tubes. All possibilities that could be over looked. It's a shot in the dark, just trying to hit all bases.
 

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Pathologic Opeler
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no duck bill that I can see

where the big clear tubes exit,there is no duck bill,just a big hole..one looks torn.

can these be bought or made?

I drove it to work today..so I went on the lunch break and shot a photo..

weather was SOOO nice today..windows down in the gt
 

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Pathologic Opeler
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looks torn

tooks torn off
 

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Pathologic Opeler
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plug this hole ? what is it?

should this hole be plugged?

I odered 2 new duck bills from ogts...but it seems like smell comes from the spare tire well, not the upper window vent
 

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