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Super Moderator
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OK, you guys are making the moderation thing a bit of a challenge. Somehow a discussion on engine bay insulation went off on the rear window drain direction, which was already underway in another thread, that had expanded to include exhaust leakage into the cockpit. So I split those posts off to a separate thread, which I then merged back into this thread. What the heck is the topic again? :eek:
 

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Pathologic Opeler
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duck bill

Sorry Keith,I did not intend to make more work for you.
I did not know we had to stay on topic in the thread, but it makes perfect sense. A sets of rules or guidlines posted on the opening page might help new users.

Rule 1- might be to do a search first, before a question
Rule2- stay on topic
etc.
topic is drain tubes, here is what the duck billed grommet looks like. lips are thin and maybe they flap as needed.
for me to install, fit is tight: lube up grommet and old tube with wd 40 , put one hand thur taillight hole and postion tube and push, next put little finger in
duck mouth and guide the pipe to position,
 

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Opeler
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recap

Alright, I'd like to nail this before Saturday when I take wife on a date in the GT. So far she likes it but since temp warm up, there's an exhaust smell in the car, just revented tank to cure the gas smell, now notice exhaust (at least I think that's what I'm fighting, could be hot motor smell seeping in from engine bay too I guess).
Let's see if I've got this straight. Opel designed so as car moves down road, vaccum at rear of car pulls air out of the interior though openings in headliner on either side of rear window and out the vent slots along top of rear window. There are moisture collection ducts and big lines that run down through rear tank area and out the bottom of car to allow moisture to exit via rubber ends that close down to slits (often missing).
Any leakage at rear via taillight housings, floor plugs, fuel line/vent line exits or too short tailpipes could cause exhaust fume to enter cabin.
This effect may be worsened if windows are open because now the cabin is a vacuum and sucking air in and if air is coming in through any of the above leaks, then it smells.
So: plug all leaks, check big moisture drainage tube endings under car for missing "duck bill" slits and invent or get replacements.
Or start looking for "normal" sources like exhaust leaks at header/manifold or pipes.
What effect does the front rubber gasket for hood have on engine bay venting? The one across the radiator crossmember, I don't have that one. I'm also seeking out and closing up any firewall openings.
 

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The seal on the radiator support and on each side of it controls air flow through the radiator. The important one is at the front edge of the cowl at the wiper well. That keeps engine air out of the openings under the hood in the cowl. The duckbill vents are available from OGTS, along with seals for all the lights. HTH.
 

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Opeler
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I've got the seal by the cowl vent but, now that I think about it, I tightened up the hood hinge as it was loose. Now the hood at the other end, where it graps the rail is loose and sitting high. I haven't been able to determine what is interferring with it, seems to be hanging up somewhere. It would make sense that if it weren't sealing there then "engine fumes" could enter the cowl but I don't think that's the case because, as I drove home today (highway at 70ish) I had windows up, kick panel vents and side vents open, no smell, cracked my window open: almost instant exhaust smell, closed it; cleared up. Repeated this several times on the ride home. This seems to confirm the "cabin pressure sucking through rear seal failure and pulling in fumes phenomenon" and not a cowl vent taking in nasty air.
So, first chance I get I will start investigating usual suspects.
I do have a cracked brake light lens (lower screw tab gone) so that certainly isn't sealed and is right by exhaust.......
 

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You do have your rubbers on over the tail light assemblies don't you? Same symtoms as yours- until I put my rubbers (gaskets) on. Fumes comining in from the tail pipes with window open. :cool:
 

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Forgot- make sure you have both sets of rubbers on each tail light- the one between the tail light fixture and the body and the one between the tail light fixture and the lens- both are very important :cool:
 

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BTW, there are two gaskets for the rear lites, one O-ring that goes between the reflector and the body, the other a foam rubber flat ring, seals the lens to the reflector. Hth.
 

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Opeler
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hmmmm I don't recall seeing ANY gaskets although I've only removed one lens and one bucket to date (to do tank vent replacement), time to order up a set I'd say (first I'll go pull some off)
BTW tonight i took off the broken lens and ran some rope caulk round the edge as a temp gasket to hold it on and seal it up, no change but that was ONE lens....I'll go investigate
I do have one duckbill yet, the other side I faked it with duct tape just for testing purposes, all other lines and wires have their proper rubber gaskets in place.
I'm off to check those gaskets.....two per light assembly, eh???????
 

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I guess I'm not the only one having this problem. I removed my fuel tank last month, welded up damage around the fuel tank outlet the PO had created, replaced the fuel outlet boot, installed the missing rubber bung, replaced both torn duck bills and reattached the drain hose that had come undone. Even checked the gaskets on the tail lights. And yes, my stock tail pipes extend past the rear bumper. After all of this I still have exhaust getting into the car with the windows open. What am I misssing? I'm going to check the engine compartment tonight with a flashlight after dark.
 

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Pathologic Opeler
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check for light leaks

crawl in behind the gas tank in a dark garage, now have your understanding wife walk around the car with a shoplight..where you see light leaking in are areas that need plugged.

also you may see leaks around the wires that feed the license plate, and bumperettes ..i did. I bought rubber grommets at a hardware store for these.

also check the engine bay..there are manny areas there, such as the heater core entrance in the engine bay, on the firewall.


my car has been real fumey, and I am still fighting it. A snorkel for the carbs is supposed to help( i am not using one).

i drive with the window down..oil leaks are so bad in my car right now..that I have a lots of fumes to overcome.
 

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Opeler
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After all of this I still have exhaust getting into the car with the windows open. What am I misssing? I'm going to check the engine compartment tonight with a flashlight after dark.
I'm in the middle of this yet too. Wonder if this was a problem with GTs from day one? Or just now that they're old and "leaky"? It's a cool design; the whole "cabin vacuum venting thing" until it backfires, then it's not so cool! I must admit that well testing yesterday, it was effective to leave the windows up and vents open, at speed a decent flow of air, wonder if it could be improved? some air "deflectors" inside the panels maybe? a little "scoop" right by the kick panel vent to shovel more air at me? I did redo the dash vents when I had the dash out, flex hose instead of the disintegrating "cardboard" OEM suff, they didn't really "attach" to the firewall/cowl as I recall, just sort of point in the general direction, alright I'm digressing. It was pretty darn warm in that car yesterday afternoon, about 82, my back was drenched in sweat, not that I mind much, I expected it.
 

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engine bay fumes

had exhaust problem with my 73 gt that eluded me for some time. the exhaust header pipe - the dual pipe that connects w/flange to the exhaust manifold) is prone to breakage where the head pipe is welded to the flange. get under the car and look for evidence of exhaust leakage by aiming a strong light at the bottom of header at the flange. as with most manifold connections, reassembly will require a new (inexpensive) gasket AND they 're LOTS of fun to separate!
also - i replaced solex with weber DGAV 32/36 on my recirculation-equipped engine and never had a fuel fume problem - just required new mounting studs. check to ensure the heat shield (horizontal) is in place between manifold and carb and that the metal line leading from the manifold port to the egr valve isn't leaking.

hope this helps.
 

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Rear Window vents

Starting on the teardown and rebuild of my 1971 GT. Not real happy with the above rear window vents. Found out the flow through ventilation never really worked well therefore the rear pop-out windows from 1971 on. After looking at the system air had to be pulled up through the body cavity and out the top. I am looking at closing off the top vents and installing small bar led brake and turn signals. As for the flow through ventilation I am looking at 2 -3” louvers in the area below the rear window and behind the side window. This will access the cavity and air flow over the louvers will pull the air down and out. These louvers will provide more of an opening that currently exists at the higher vents and should improve air flow. I plan to put SS screen behind the louvers to keep insects out when parked. I have talked to the gentlemen in CA who fabricates the louvers and if installed at an angle the louvers will shed rain and will not allow water into the cavity. ( At least no more moisture than what gets in from the existing opening). I am not sure of the exact routing of the drain tube and will work that out when the body is cut to install the louver panels. I believe the drain is for the interior vents so there should be on issue with the current configuration. Any ideas out there in OPEL Land?
 

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Just Some Dude in Jersey
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The LED thing in the vents is a cool idea, but I wouldn't cut any extra vents into the body. It would be simpler to just get some pop out side windows and put them in. You could take the booties off of the drain hoses where they exit at the bottom of the car. That might increase your airflow. I have my side panel floor vents closed off and all my flow through air comes out my side dash vents. Frankly, I'm looking for a way to shut off the air flow through those, too.

In the Spring/Summer/Fall, and 50*+ in the Winter, my windows are always down and the pop out windows are always open. We get almost as hot and steamy here in Jersey as you do down there. If you have the windows up you're going to roast, that's just the way it is. GT's give off a lot of heat into the passenger compartment.

I just don't think you'll get any bang for your buck by cutting extra vents in your body. You could take the rear window out entirely and still roast in the Summer.

Do your LED thing and leave the body intact is my vote.
 
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