How to make a large hole in the bottom of my car?

Question

I want to run a couple of 5/8 inch hoses through a hole under the passenger seat, along the undercarriage of the car, and up into the engine bay. What would be the easiest way to make the appropriate holes? I have never drilled steel before.

Can I do this with a sledgehammer and a metal punch? Do I use a router? Can I do this with a wee little 12V drill and corded Dremel tool? I don't want this to take all day long.

Trueno16V, thanks for the suggestion, but I would rather not have the hoses laying across the passenger footwell. I will have ta take a look under the car tomorrow morning when it's light out, to see if there is anything I can zip tie the hoses to.

My main concern right now is actually HOW to MAKE the HOLES... not why. All I have is a 12V drill and a Dremel, and I want to buy only what I need to do this properly.

NOS? Hell no. My car is a very reliable daily driver that is 11 years old and has never been touched by a mechanic. I'm installing ghetto AC. I am going to remove the hoses that connect to the heater core and "short circuit them." I'll let the radiator fluid drain out of the heater core, then attach hoses that run to an ice chest located in the back right footwell. There will be a 12V marine bilge pump in the bottom, circulating ice cold water through the car's heater core. When it starts getting cold out, I'll drain the heater core back in, plug the regular hoses back in, and top off the radiator fluid.

So how bad an idea is this? :)

Thx guys. I found a 3/4 inch rubber plug dead center of the floor, behind the center console. I just Dremelled a second hole next to it. So now I have a hole for each hose. The only thing is that the manifold is near the hole, but there is an inch or two of space if I keep the hoses taught. So now I have to get a hold of a bilge pump. If it works, I'll post pics on dutchforce.com, somewhere's. :)

Answer 1

i like my rotozip for that kind of thing a dremel with metal bit will work fine after you predrill a small whole. Use a sharpie to mark the hole you want then cut away. Check to make sure you don't hit a fluid line or wires from the bottom before cutting or drilling though. as long as you are only cutting the body of the car its easy. don't try to drill/cut the frame you could weaken it if you do it in the wrong way/place. just make sure you sand the edges so they don't saw at whatever you are putting thru there. what you doing? NOs? if so DONOT go thru floor go thru firewall on passenger side insureing you don't hit anything. thru floor is asking for something passing under car to bust NOS lines and cause big BooM. like if you get in a wreck or hit something in the road.

Answer 2

Remember that you'll need to make the hole larger than the pipe, so you can use a rubber grommet to seal the floor again. Otherwise, you'll have water getting into the car on rainy days - and the sharp edges of the hole will break the hose pretty quickly. Also make sure you're not going to hit and wires or fuel/brake lines once the drill punches through the floor pan. Only the correct size drill bit will make the hole smooth and keep it round. The metal is pretty thin, so a regular drill shouldn't have a problem - just remember to drill a pilot hole first, using a narrow drill bit, then the full-sized hole - this will make it easier on you and on the drill. You can use a Dremel, but it's MUCH harder to make it round and smooth. And unless you absolutely HAVE to have it under the floor, try routing the hose under the console and through the fire wall - it's what the firewall is designed for in the first place. Its also much less likely to be damaged than under the car.

Answer 3

This is a solvible problem. But it depends on how much Money you want to spend. If you want to do it yourself you can save big $$ but you need to do the work. do the following. 1. find the hole. 2. see how much rust is there. That will tell youhow big the repair needs to be. 3. if it is small like 4 inches diameter the get a piece of 3/16 sheet metal from a hardware store that is at least 5 inches in diameter. 4. Cut out all the rusted metal. With snips or a cutoff wheel, or a new Hacksaw blade 5. fit the metal patch 6. Buy some pop rivits and a pop rivit gun 7. Dill holes that fit the rivits around the patch. 8. use a body weld adheasive around the hole the pop rivit the patch. 9. Paint both sides of the patch with a Decent primer and topcoat. if no one will see it no need to be picky. If it is bigger than that you may need to get a patch welder in. Things to note : It is better to do this from the inside if doable,

Answer 4

Buy yourself a stepped drill at Lowe's, Home depot or some other tool store. Use an electric drill and drill from under the car up into the interior. Be careful where you're drilling.
The stepped drills start with a small hole and each step makes the hole bigger and they work great in auto body steel.

Answer 5

You don't need to drill any holes period. If you look on the passenger side, forward against the firewall, you will notice some rubber plugs that lead to the engine compartment. If you route your hoses up the center or side then through those plugs (don't forget to seal them up when lines are routed) you wont need to drill any holes.


Hope this helped

Answer 6

Determine what the OD of the hoses are and add some for clearance and either use the right size drill bit, or get a hole saw and attach it to your drill. No big deal. If you have carpeting under the seat, then you might want to cut it and get it out of way or else the drill bit may grab it and tear it up.

Answer 7

Why would you need to run hoses from passenger compartment to engine bay? Anyways, you could drill through the firewall as long as you can see there isn't anything in the way. This will probably be safer because you wount run risk of damaging hoses while driving?

Answer 8

use a drill and a large bit and it will drill strait through it,the body isn't that thick on it so it shouldn't take long,id use an electric drill though,they tend to drill a lot better than cordless ones do,get the largest bit you can find to do it with,or one at least the size of the hole you need in it,good luck on it.

Answer 9

just make sure you drill em from the bottom so you know you aren't gonna hit any thing...and get some rubber grommets and some convoluted tubing to encase the wires in

Answer 10

use the drill, after applying alittle weight to it should drill right through.