Air leak from my city golf 1.3 carb

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Deniboy
Cadet
Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Air leak from my city golf 1.3 carb

Post by Deniboy »

hI guys i have been battling with this issue/not even sure if its an issue or its suppose to be this way i have a 1.3 city golf and theres a pipe from the brake servo to the manifold with a nipple on it when i start my engine i can hear a hissing sound from that nipple because its left open and as soon as i put my finger over to cover it the engine cuts of but if i hold the throttle and cover it it wouldn't die off i suspect that my car is running lean because theres some misfiring when accelerating at low rpms whilst costing can someone please help or if you have any pictures showing me the correct set up or should there be a hose going to the carb/which i attempted to connect but it was of no good the car only idles when that nipple is left open
VAG Fan
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Location: Pretoria

Re: Air leak from my city golf 1.3 carb

Post by VAG Fan »

That nipple is the connection for manifold vacuum. On some engines, it is connected to the ball-shaped vacuum reservoir. On others, like my 1.6 Fox, it is actually closed off with a cap. So I'm not sure what is the proper set-up for the 1.3.

One thing is for sure, it should definitely not be running open to the atmosphere, because then the engine will be running too lean on idle and low engine loads, especially on cylinder no. 4.

As a first solution, I would suggest closing the nipple (e.g. with a short piece of pipe folded back over itself with a cable tie), then re-adjusting the carb.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
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Deniboy
Cadet
Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Re: Air leak from my city golf 1.3 carb

Post by Deniboy »

But thats the issue the engine will die out, is it true that the only place a mk1 gets air from is through the intake?
VAG Fan
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Location: Pretoria

Re: Air leak from my city golf 1.3 carb

Post by VAG Fan »

The air is drawn through...
... the air filter,
... the carb (where fuel is added),
... the intake manifold
... and into the cylinders.

Any air that enters the engine after the carb, is not provided with the corresponding amount of fuel. It is so-called "unmetered" air.

Your carb is probably adjusted wrongly on both screws, to compensate for the unmetered air:
... additional fuel to compensate the extra air
... reduced idling speed, to compensate the extra air plus fuel.
So you have "two wrongs making a right".

Now when you close the leak, your carb is probably adding too much fuel AND the idle is set too low. This is why the engines stalls when you close the leak. So after closing the leak, you have to re-adjust the carb.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
- - - - - - - - - -
Deniboy
Cadet
Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Re: Air leak from my city golf 1.3 carb

Post by Deniboy »

So you suggest I I adjust my idle speed screw higher by turning clockwise a few turns and close the nipple on the brake servo pipe to see if it idles?
VAG Fan
Lieutenant
Posts: 1440
Registered for: 8 years
Location: Pretoria

Re: Air leak from my city golf 1.3 carb

Post by VAG Fan »

Yes.
Increase the idle somewhat, close the nipple, then adjust the idle and also the CO. Chances are that it may be running to rich after closing the nipple.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
- - - - - - - - - -
Deniboy
Cadet
Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Re: Air leak from my city golf 1.3 carb

Post by Deniboy »

i tried that the past weekend the car drove for about a mile and switched off it refused to start so i opened up the air filter and started manually applying throttle to add fuel into the carburetor throat and it eventually started after a while
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Re: Air leak from my city golf 1.3 carb

Post by panic-mechanic »

so adjust the idle screw some more. emeber there is also idle mixture at the back of the carb.
Stephan van Tonder - Jhb - Putfontein Benoni
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Deniboy
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Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Re: Air leak from my city golf 1.3 carb

Post by Deniboy »

any tips on how to adjust the idle mixture screw
VAG Fan
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Re: Air leak from my city golf 1.3 carb

Post by VAG Fan »

First get the idle speed more or less right. Remember, the engine has to be hot.

Then, for a basic mixture adjustment: Find the mixture screw, normally at the back middle of the carb. The engine doesn't need to be running for this basic adjustment.
1) Make a mark on your screwdriver, e.g. Tippex or masking tape.
2) Turn the mixture screw in (clockwise) completely. COUNT THE TURNS for reference, in case you need to retrace your steps.
3) Turn it out (counterclockwise), again counting the turns. Give it about 2.5 complete turns. The idle should be pretty smooth.

For fine adjustment of the mixture:
3) Turn the screw clockwise SLOWLY, until the idle starts to fall or becomes rough.
4) Then turn it back out (counterclockwise) SLOWLY, until the idle returns to its smooth, higher level.
5) Then turn the screw out (counterclockwise) by another quarter to half turn.

All of this mixture adjustment will somewhat affect the idle speed. So you may need to correct the idle speed at some stage, and then return to the mixture adjustment.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
- - - - - - - - - -
Deniboy
Cadet
Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Re: Air leak from my city golf 1.3 carb

Post by Deniboy »

After few years I finally decided to put on a original carb on and all is well blocked the air leaks etc car is going well but now my issue is Everytime I'm on a slight incline "ass up face down" my idle starts dropping to stalling point but one I'm on a straight road or even parked "face up ass down"she idled beautiful what could be the cause of this?
VAG Fan
Lieutenant
Posts: 1440
Registered for: 8 years
Location: Pretoria

Re: Air leak from my city golf 1.3 carb

Post by VAG Fan »

This is probably due to a wrongly adjusted fuel level inside the float chamber. It also happens sometimes when going through a left or right turn, causing jerking. (Called "corner surge")

You'll have to make sure that
a) the float level is adjusted correctly, and
b) the needle and seat valve is sealing properly, so that it doesn't overfill the float chamber.

Same principle as a float valve in a toilet cistern. You adjust the float lever to adjust the water level. But if the valve is not sealing properly, it will still overflow, regardless of adjustment.

With Keihin carbs, the float level is normally adjusted purely mechanically. You have to take off the top housing from the carb, then gently tilt it sideways that the float level gently closes the needle valve without actually depressing the spring. In this position, the bottom edge of the float bulb is supposed to be parallel to the top housing. If it's not, you can turn the needle cage, which is mounted in the carb top with a fine thread. The adjustment screw is normally hidden underneath a plastic cap, right next to the fuel inlet.

If you still get flooding on a downhill, after this adjustment, you need to service (replace) the needle and seat. One can buy a carb service kit, which contains a new needle and seat. Goldwagen used to have them.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
- - - - - - - - - -
Deniboy
Cadet
Posts: 60
Registered for: 4 years 7 months
Car Make: vw
Car Model: 1997 city golf 1.3

Re: Air leak from my city golf 1.3 carb

Post by Deniboy »

thank you so much for the reply, i noticed my plastic cap from the float adjustment screw is missing so it was definitely tampered with does turning that screw out restricts the amount of fuel going into float bowl?
VAG Fan
Lieutenant
Posts: 1440
Registered for: 8 years
Location: Pretoria

Re: Air leak from my city golf 1.3 carb

Post by VAG Fan »

The screw doesn't restrict flow as such. It's the level of fuel that's adjusted.

The needle and seat valve cuts off the flow, once the fuel reaches a certain level in the bowl. The screw simply adjusts the height of the needle valve mechanism relative to the carb housing. Turning the screw in (clockwise) lowers the needle mechanism, i.e. the valve closes the seat sooner, which means the fuel level in the bowl will be kept lower. Turning the screw out (counterclockwise) raises the needle mechanism, i.e. the valve closes later, meaning the fuel level in the bowl will be allowed to rise higher before the needle closes the seat.

In your case, I would turn the screw a half-turn to one complete turn in (clockwise). Make notes. Then see whether this solves the downhill flooding. Also do a long full-throttle pull, e.g. accelerate up an incline (3rd gear 50 - 80 or 4th gear 70 - 110). If there is any hesitation or jerking, you have lowered the float level too far, and need to back the screw out.

The best way is actually to take the top off the carb and adjust the needle mechanism visually, like I described above. If, after adjustment, you still get flooding, then the seal on the needle is worn, which allows unwanted fuel into the bowl, and the whole mechanism needs to be replaced.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
- - - - - - - - - -
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