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Discussion Starter · #1 ·
Hi, I noticed when removing my gas cap on my newly restored Giulietta, a air hissing sound. Sounds like a vacuum noise. My gas cap has no breather hole. The cap came with the disassembled car so there's no way to know if it is correct. Should I have a vented cap? Is this a standard cap I could purchase from Moss motors?

This is the last time I ever restore any vehicle that wasn't running when I got it! :mad:

Any info on this matter would be appreciated.
 

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Giulia / Giulietta fuel tank venting

George,
The venting is supposed to be taken care of by the overflow line in the metal section that drains under the trunk. The old spiders were not meant to have either a positive or negative pressure in the tank. Thus, no vented cap. With modern fuels with iso propane and other added gasses, modern fuels are more prone to vaporize and stink up your car, with the factory overflow system. Yours may have been blocked, plugged or otherwise altered to decrease fumes. If you need photos of the correct vented system, let me know and I will post them for you. In another thread, "mud dauber" wasps were the cause of a plugged vent:cool:! :DGordon Raymond
 

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Discussion Starter · #3 ·
H Gorgon. Actually the vents are open fine. I had the tank out again yesterday to fix a small leak coming from the vent tube where it comes out of the tank. I had to re-solder around the tube. I checked all the openings with air and filled the tank with water to remove all fumes before soldering. I don't understand how the vent works. It doesnt vent to the outside. It appears to only acts as a loop within the system. If you don't vent to the outside and you remove fluid (volume) then you will create a vacuum.:confused:

George
 

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Vented cap

George,
The pipe between left side of the tank & filler neck is, as you deduced, merely a breather to facilitate filling the tank.
A vented type cap should be used. The breather hole is often hidden under the cap & is virtually invisible.
Hope that this is of some help.
Tony
England
 

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Giulia / Giulietta fuel tank venting

Hi George,
By whatever name, Pn 1365.85.063, a metal tube, not all of it shown in the parts book, leads under the trunk floor, and is supposed to be open at the end to prevent tank overfill. As such, the tank and filler are not sealed by virtue of this "breather pipe" as referred to in the parts book. Not to disagree with Tony, but the main "breather" for this system is this pipe. I will send photo's of the correct tank cap, and this plumbing later today. This is not supposed to be a sealed system:p. Any pressure or vacuum when opening the cap, is a sign that your system has somehow become sealed:eek:. I will send you some close up's of the OEM cap from my totally original spider, with the other photo's later today. :DGordon Raymond
 

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Discussion Starter · #6 ·
George,
The pipe between left side of the tank & filler neck is, as you deduced, merely a breather to facilitate filling the tank.
A vented type cap should be used. The breather hole is often hidden under the cap & is virtually invisible.
Hope that this is of some help.
Tony
England
Is the breather hole in the cap? Would I be able to see the hole?

G
 

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Discussion Starter · #7 ·
I will send you some close up's of the OEM cap from my totally original spider, with the other photo's later today. :DGordon Raymond
Thanks Gordon, Photos will help.

G
 

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I too would love to see a pic of the 'vent pipe' with an opening to the atmosphere!
Gordon, does your '65 have this??
On my '65, tyhe tube just vents air from the front of the tank to the filler neck.
 

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I'm wrong, wrong, wrong!

Hi George, Hi Tony, Hi 101 /105 guy,
Let me start by saying I must be suffering mind melt down:p. TONY IS 100% correct:cool:. 43 years working on these things and I should read more carefully, not trust opinions possibly gathered from other Alfa's, and not trusted the Alfa parts book;). Here are a series of photo's of the #1365.85.063 "breather pipe" in it's entire glory, INCLUDING where it is connected back to the top left of the tank! (I owe Tony a pint!:eek:) When one becomes even slightly "agism challenged", one tends to make assumptions, based on experiences from years, now, gone by. Not good:eek:. Also included are three (3) of the VENTED cap, an original cap, showing a little hole in the middle with a pin valve, plus holes all around the outside lip to VENT IT! No more excuses! Sorry Tony! :DGordon Raymond
 

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Vented Giulia OEM cap.

George and all others watching my embarrassment, here's the last three photos of the VENTED OEM cap! :eek:Gordon Raymond
 

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Discussion Starter · #11 ·
Hi George, Hi Tony, Hi 101 /105 guy,
Let me start by saying I must be suffering mind melt down:p. TONY IS 100% correct:cool:. 43 years working on these things and I should read more carefully, not trust opinions possibly gathered from other Alfa's, and not trusted the Alfa parts book;). Here are a series of photo's of the #1365.85.063 "breather pipe" in it's entire glory, INCLUDING where it is connected back to the top left of the tank! (I owe Tony a pint!:eek:) When one becomes even slightly "agism challenged", one tends to make assumptions, based on experiences from years, now, gone by. Not good:eek:. Also included are three (3) of the VENTED cap, an original cap, showing a little hole in the middle with a pin valve, plus holes all around the outside lip to VENT IT! No more excuses! Sorry Tony! :DGordon Raymond
Actually that was part of my original question: ;) "I don't understand how the vent works. It doesn't vent to the outside. It appears to only acts as a loop within the system. If you don't vent to the outside and you remove fluid (volume) then you will create a vacuum."

Thanks for the great photos and the time you spent to solve this problem. I had an idea this is how it is supposed to work and it's nice to know I still have a few brain cells left.

As your cap photos clearly shows there is a vented cap in the system. My cap is not vented so there is my problem. I may try to modify my existing re-chromed cap. I wonder how the pin valve in the cap works.

Thanks again.

Cheers,

George
 

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George,
You might try Christian Ondrak, OK parts in Germany for the correct OEM cap. The pin valve is a stubby nail like thing that hangs through the hole. Any liquid sloshed up closes the valve so it can't escape through the vents around the rim. I tested it by blowing on it. It seals about 90%. The OEM caps were painted black. Probably the only way to modify yours would be to disassemble it. They look like the outside is pressed over the inner riveted assembly. I'm not sure how it would come apart without damage. Try Christian first for an original. If that fails I may be able to scrounge up a restorable one.
Let me know. Best, Gordon Raymond
 

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I just use the cheapie, universal, "bayonette"-style caps that they sell at NAPA auto stores. They don't seal all that tightly, so I suppose you could say that they self vent. I haven't noticed fuel sloshing out from the filler when the tank is full, though obviously that would be a safety hazard.
 

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I would try drilling your cap to match Gordon's. It will vent and you will save the new chromed part.
Just keep under 1 G cornering and no gas will spill out! ;^)
Randy
 

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Now I'll have to check

Seems to me that as long as there was no venting going on, simply drilling through the cap outside of the gasket would solve the problem. The people who made the replacement gas cap the original poster has forgot the holes.

Now, with gas fumes inside the ****pit when the tank is over half full I'll have to go out and check my own holes!

Jeffrey
 

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Discussion Starter · #16 ·
This is what I ended up doing for the moment. I am making a screw-in one way valve to indct into the cap center hole.

George
 

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Nice modified cap!

Looks good George:cool:! If you blow in the middle hole, does the air come out the outside ones? If so you should be fine. I wouldn't worry about the pin valve, unless you like to overfill. As I mentioned, it really does not seal 100% anyway:p. However, as was mentioned, since I OFTEN corner at 1 G +, :)rolleyes: :eek::eek:) I'm glad to have the leaky valve on my "Jewel"! :D Gordon Raymond
 

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Gordon,
Slightly off topic, but at least related ... Does your '65 Veloce use the mechanical fuel pump (bolted to the lower corner of the timing cover, beneath the distributor) or does it have the Facet electrical pump back near the fuel tank? I know the Giulietta Veloces used electrical pumps, but my two '65 Veloces have the mechanical pump. And the Giulia parts book seems to indicate that the mechanical pump is correct. Just curious, because I'd like to use the most correct pump now that the restoration has started to creep into gear on Veloce #2.
Thanks, Jim
 

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Fuel pumps.

Hi Jim.
Correct for your installation is the mechanical pump driven off a lobe on the distributor shaft. My car is a one-off, in that it is an Ausca spider with GTA running gear. As such, when raced, it used the pair of Bendex electric pumps, in back. These were always overkill, as the only need for the pair was when it was REALLY HOT, and vapor lock might be a problem. This never happened:rolleyes:, so when one Bendex finally died, I went to the single Facet. That also works perfectly. The parts book shows the later cars all with the Fispa mechanical pump. As once a race car, the electrical pump has the advantage of STOPPING fuel flow at the flick of a switch, whereas the mechanical continues to pump as long as the engine runs. Also interesting is that in my particular car, the mounts for the electric pump were in place when I purchased the car. You might check under some other '65's and see if they came with the bracket back by the tank as well. Does this help? :DGordon Raymond
 

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Discussion Starter · #20 ·
Looks good George:cool:! If you blow in the middle hole, does the air come out the outside ones? Gordon Raymond
Yes it blows fine. The photo is a little deceiving, there is plenty of opening. Nice car Gordon. I like the air horns (stacks)

Cheers,

George
 
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