Mk4 golf firewall access ??

[Shmulzie]

Hey all, I'm in the process of installing my boost gauge and having trouble finding the best place to access the firewall, can someone please guide me. Atm my vacuum line is running through the drivers door wire harness insert it it isn't yet completely installed

thank you in advance

[Umai Naa!!]

Follow the bonnet release cable.

[BL33SU]

otherwise behind/down directly the black box with the fuses there is a gromet

[Sirocco20348]

Yes I did the bonnet release cable as mentioned above. The gromet is found underneath the weather shield. That is my boost line running through and I pulled the gromet up. I plugged the hole up with waterproof silicone.

[JustCruisn]

There is one on the passenger side, behind the glove box. Another is near the AC intake in the rain tray.

[jmcc]

I also ran it though the bonnet release grommet, I punched a hole in it with a screwdriver and then fed the hose through, afterward I put some butyl sealant around it to stop leaks.
To get to it you have to remove the windshield cowling (black plastic in Sirocco's picture)
first you pop the caps off the wipers and unbolt them, Pull the wipers off, they should come off pretty easy, might need a little WD40, you have to pull them back like when you are washing the windscreen to get them off.
Next you have to get the clip out of the fixing, its basically a barbed peice of plastic that runs the whole length of the windshield and pushes into a "socket" just below the windshield. Just start at the drivers side on the top and get your fingers under it and pull and work your way along. MINE WAS CRAZY HARD TO GET OFF the first time, took some working, and needed silicone lube to get back in properly.
Once its off you can see where the release goes in and its up to you from there..

another note, I'd get some 4mm silicone hose and use that, you can get like 10m off ebay for $20, the stuff that comes with the gauges is pretty average and was deforming alot just from heat in the engine bay even after a few drives, it also didn't seal well at on the gauge.

good luck!