# Is it OK to drill new holes in the firewall?



## reapher (Oct 13, 2009)

I'm also wondering just how important are the rubber grommets? I don't really need to do this now since I made it work with the existing grommet, but this particular one I was working with (2001 monte carlo) was double layered and permanently installed, extremely hard to go through and I was getting ready to just make a new hole when it decided to work. The battery cable wound up running from the lower rear of the engine compartment and all around the engine to get to the battery, in a situation like this or if the existing hole would make the battery cable too short or something is it OK to drill new holes?


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## DaveRulz (Jun 22, 2006)

It's always OK to drill new holes, but you MUST use a grommet.


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## Swedishbrick242 (Feb 2, 2010)

Be careful of where you drill, and you should be fine. Just make sure you don't cut through anything on the other side. Your best bet is near the other existing holes where wires pass through. Like Dave said, always use a grommet, otherwise the firewall will slowly slice through the wire causing, at best, grounding issues, and at worst, a fire...


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## sirsaechao (Jan 25, 2010)

Just double check before drilling. There can be tons of stuff tucked underneath the firewall.


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## Menace Kustoms (Jan 31, 2010)

Yes, new holes are not a problem, but like the others said, USE A GROMMET. My friend caught his car on fire because of a quick installation like that. No inline fuse, and no grommet. No Bueno. Also, you can use some butyl rope to seal the hole up.


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## Bluepelican31 (Jan 7, 2010)

Put a little soapy water on the tip of the wire you are feeding through your factory grommet. Works like a charm. Don't forget a clothes hanger and electrical tape to help guide and pull the wire too.


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## BigAl205 (May 20, 2009)

If you're going to drill, I would suggest using a nail or center punch to dimple and locate where the hole is going to be_ before_ you drill it. You might find out that it's not coming out where you thought it was.


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## nineball (Jan 17, 2008)

you can go to any auto parts store and get pcv valve grommets for under $2 and they come in a huge variety of sizes.


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