Best way to pass wires through the firewall on a ‘10 E350
Thread Starter
Junior Member
Joined: Jun 2025
Posts: 67
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From: San Antonio TX
2010 E350
Best way to pass wires through the firewall on a ‘10 E350
Guys,
I’m installing a front curb sensor on my 2010 E350 and need to pass wires through the firewall to go from the engine compartment to the passenger compartment and trying to figure out the best place to do that. What’s the easiest/safest way to pass wires through the firewall?
Mike
I’m installing a front curb sensor on my 2010 E350 and need to pass wires through the firewall to go from the engine compartment to the passenger compartment and trying to figure out the best place to do that. What’s the easiest/safest way to pass wires through the firewall?
Mike
Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Guys,
I’m installing a front curb sensor on my 2010 E350 and need to pass wires through the firewall to go from the engine compartment to the passenger compartment and trying to figure out the best place to do that. What’s the easiest/safest way to pass wires through the firewall?
Mike
I’m installing a front curb sensor on my 2010 E350 and need to pass wires through the firewall to go from the engine compartment to the passenger compartment and trying to figure out the best place to do that. What’s the easiest/safest way to pass wires through the firewall?
Mike
The firewall is sharp metal that can cut into wire insulation: use rubber gromet or pigy back an existing harness across the firewall on passenger or driver side.
Use sealant to help stop any water penetration.
MBWorld Fanatic!
Joined: May 2018
Posts: 6,600
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
Guys,
I’m installing a front curb sensor on my 2010 E350 and need to pass wires through the firewall to go from the engine compartment to the passenger compartment and trying to figure out the best place to do that. What’s the easiest/safest way to pass wires through the firewall?
Mike
I’m installing a front curb sensor on my 2010 E350 and need to pass wires through the firewall to go from the engine compartment to the passenger compartment and trying to figure out the best place to do that. What’s the easiest/safest way to pass wires through the firewall?
Mike
I use this hole to send wires from interior to engine bay.
I use a hose as protection grommet and keeping it kinda water tight.
The "hole" is under the brake booster.
Here is that service hole
Good luck
Last edited by S-Prihadi; Jan 2, 2026 at 03:20 PM.
