GolfGTIforum.co.uk
Model specific boards => Golf mk4 => Topic started by: J5H VW on 07 January 2008, 12:50
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Guys, can hear a noise that sounds like leaking air coming from my engine bay - kind of like the very very early stage of an exhaust going, or a split in a air hose.
When I opened the bonnet, there is a black unit to the left of the power steering reservior. I think it has two hoses connected to it.
Does any one know what this is? There is a hose coming off the top of this unit that is about the diameter of a pencil (about 5 - 10mm) that goes a short distance towards the rear of the engine bay and connects to something near (but not related to) the for the coolant tank. This hose has a split in it. But does not seem to have anything flowing through it etc.
I know its a bit hard to describe, will see if I can get a photo up.
But in the mean time....any clues as to what this is/ what the unit does?
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Found a pic of an engine bay (i know its a Seat - but its close enough unless someone has one of a mk4 golf i can use!)
See here ->
http://i161.photobucket.com/albums/t212/mkm250680/DSC00086.jpg (http://i161.photobucket.com/albums/t212/mkm250680/DSC00086.jpg)
The unit I am on about is on just about visible on the left of the photo, between the screen wash and the coolant tank.
What does this do?
Also, the hose that is split on my car is the one that runs from this unit, to just over the power steering tank, its the one that is visible against the coolant tank in the picture.
Once again, anyone got any clues as to what this does?
I knows its not a great description, but any help is much appreciated.
Cheers.
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im sure someone will correct me if im wrong but that unit looks like the fuel pump and that lead your showing maybe the power for the pump. does the unit create a ticking sound when the engine is running?
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Yes it does make a ticking sound. But that hose does not have any wires in it! As I say, the hose is split for the end, and when I pulled it back, there is nothing inside.
I can run the car without this bit connected - but its a bit suspect since you said it could be fuel related. Reason I say this is that I thought I could smell petrol for the last few weeks, but was never sure.
Any more help guys n girls?
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Im convinced that is the fuel pump. Ill have a look on mine when i get in from work tonight and see if i have any wires. That thing you say is split has what appears to be an electrical plug on the end attaching to the pump, and also ribbed plastic casing which wires generally run through. vaccume and fuel etc generally are smoothe rubber hoses so i would presume that this should have wires in it to power the pump.
:smiley: :smiley:
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Cheers mate, much obliged. I will see if I can work out what this one does too - its the ribbed plastic cased one.
Mysteriously seems hollow though :shocked:
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the black unit you are talking about is to do with fuel its an evap canister, its to do with emmisions the fuel tank will give off fumes and it cant be vented into the atmosphe so a pipe from the top of the fuel tank runs up to the black canister and then it will let the fume into the inlet mainifol to go into the engine an be burt, the clickin noise is wen its lettin the fumes into the engine. and you say your pipe has split if its the one goin to the manifold it will be suchin in to much air making the noise you discribed. i would get a new pipe for it but i dont fink theres any hurry.
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Guess that makes sense for why I can smell fuel also - since the pipe has a split in it.
Is it safe to have this vapour just discharging into my engine bay? :undecided:
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actualy thats a good point surspose it mite not be safe lol. you best get a new pipe or put some tap round it untill u can get the pipe
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the black unit you are talking about is to do with fuel its an evap canister, its to do with emmisions the fuel tank will give off fumes and it cant be vented into the atmosphe so a pipe from the top of the fuel tank runs up to the black canister and then it will let the fume into the inlet mainifol to go into the engine an be burt, the clickin noise is wen its lettin the fumes into the engine. and you say your pipe has split if its the one goin to the manifold it will be suchin in to much air making the noise you discribed. i would get a new pipe for it but i dont fink theres any hurry.
You learn something new every day.
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Cheers for the help guys - might have to get some tape out for now till I can get a replacement hose.
Anyone know where I can find more info about this evap canister? Anyone know the part number by chance?
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I think you guys are right about all this. Just found this (c/o VWvortex):
Diagram of fuel system:
http://monty.syr.edu/vw/20vforum/AWDVacDiag.gif (http://monty.syr.edu/vw/20vforum/AWDVacDiag.gif)
The Key to the diagram is system is found on this link (but also pasted it for convenience):
http://forums.vwvortex.com/zerothread?id=2666114 (http://forums.vwvortex.com/zerothread?id=2666114)
Key:
1 - Vent line
From gravity valve at fuel tank See "Fuel Tank, Removing and Installing" item no 8. See: Fuel Tank\Service and Repair
2 - EVAP canister
With Evaporative Emission (EVAP) canister purge regulator valve -N80-
3 - Turbocharger
4 - Check-valve
For EVAP canister system
5 - Pressure unit
For Boost Pressure Regulation Valve
6 - Deceleration shut-off valve
7 - Wastegate bypass regulator valve - N75
Valve is activated (pulsed) by the Engine Control Module (ECM)
Checking activation: See Output Diagnostic Test Mode (DTM), activating. Refer to "On Board Diagnostic". See: Computers and Control Systems\Testing and Inspection
8 - Brake booster
9 - Check-valve
For brake booster
10 - Air filter with Mass Air Flow (MAF) sensor - G70 -
11 - Pressure control valve for crankshaft housing ventilation
12 - Combination valve
For Secondary Air Injection (AIR) system
Checking. See: Emission Control Systems\Air Injection\Testing and Inspection
13 - Fuel pressure regulator
14 - Check-valve
15 - Recirculating valve for turbocharger -N249-
16 - Secondary Air Injection (AIR) solenoid valve -N112-
Checking. See: Emission Control Systems\Air Injection\Testing and Inspection
17 - Crankcase ventilation
18 - Check-valve
For EVAP canister system
19 - Charge air pressure sensor -G31- / charge air cooler
20 - Secondary Air Injection (AIR) pump motor - V101 - *
Checking function. See: Emission Control Systems\Air Injection Pump\Testing and Inspection
21 - Vacuum reservoir
The suspects are number 1 and number 2!