Hood Vent Install
01-28-2014, 09:09 AM
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Year: 2000
Model: Cherokee
Engine: 4.0
Hood Vent Install
I saw these vents on a forum member’s Jeep and really liked the look and functionality. I had to think long and hard about cutting holes in my hood. When I decided to take the plunge, I thought I would document the effort. List of tools and material required below. These are marine vents, made of ABS plastic and available in black and white. You can get them from http://www.go2marine.com or http://www.westmarine.com or probably many other marine supply places.
01-28-2014, 09:11 AM
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Year: 2000
Model: Cherokee
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Hood Vent Install
I have a lot of maple trees in my yard and the stupid little helicopter seeds get into everything. To keep them out, I got some screen (called hardware cloth for some reason) at Lowes. I cut a piece an inch longer and wider than the opening. This allowed me to fold the edge over for a half inch flange all around. I sprayed the screen with silver paint then used black RTV to glue them in to the vent. Don’t put the RTV on too thick or it won’t fit in the opening you are going to cut. You may want to add the screen after the vents are test fitted in the hood.
01-28-2014, 09:14 AM
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Year: 2000
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Hood Vent Install
To prep the vehicle, I laid several old sheets over the engine compartment to catch metal residue from the cutting and drilling. I put a wooden block under each front corner of the hood to hold it up so I wouldn’t accidently cut through the valve cover or anything else important. Watch out for the hood release cable. It goes right under where the left vent goes. Make sure engine is cold. I also put a sheet over the windshield because the glare was blinding.
01-28-2014, 09:16 AM
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Year: 2000
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Hood Vent Install
I used masking tape to cover the area to be cut so I could accurately lay out the holes. If I ever do this again, I would probably move the vents back a little more, but not so much as to interfere with the hood brace. The engine is angled down from the front. The farther back the vents are, the more clearance you have between the vents and the top of the engine. I have a bad habit of mis-measuring when I work with wood, so I rechecked every dimension several times before picking up any cutting tools. Also, there may be vents that look like these, but are dimensionally different. Measure EVERYTHING several times before cutting. It’s cheaper than buying a new hood.
01-28-2014, 09:18 AM
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Year: 2000
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Hood Vent Install
Before you start cutting:
If you cut the hole to the above dimensions, then drop the vent in the hole, it won’t fit. The vent has little stiffeners, two on each side, one on each end. The location of the stiffeners is shown in the above photo by the tick marks on the cut line. You have to use a round file or Dremel tool to cut a little notch in the hood for the stiffeners to fit in. DON’T cut the hole bigger to allow for the stiffeners. When you drill the holes to bolt the vent in, there may not be any metal to drill into. There is a little less than 3/16” from the edge of the hole for the vent to the edge of the hole for the bolts. Better to cut the hole slightly undersize and fine tune it than have one that’s too big.
Lesson learned: Found out that you need to make short cuts and let the metal cool. If you don’t, the paint around the opening will melt and peel off. When I removed the masking tape, it pulled off the paint around the hole. Had to prime and paint it before bolting in the vent. Also, excessive heat build-up could possibly cause the metal to warp. You may want to start on one hole, cut an inch or so, then switch to the other hole to let the metal cool.
If you cut the hole to the above dimensions, then drop the vent in the hole, it won’t fit. The vent has little stiffeners, two on each side, one on each end. The location of the stiffeners is shown in the above photo by the tick marks on the cut line. You have to use a round file or Dremel tool to cut a little notch in the hood for the stiffeners to fit in. DON’T cut the hole bigger to allow for the stiffeners. When you drill the holes to bolt the vent in, there may not be any metal to drill into. There is a little less than 3/16” from the edge of the hole for the vent to the edge of the hole for the bolts. Better to cut the hole slightly undersize and fine tune it than have one that’s too big.
Lesson learned: Found out that you need to make short cuts and let the metal cool. If you don’t, the paint around the opening will melt and peel off. When I removed the masking tape, it pulled off the paint around the hole. Had to prime and paint it before bolting in the vent. Also, excessive heat build-up could possibly cause the metal to warp. You may want to start on one hole, cut an inch or so, then switch to the other hole to let the metal cool.
01-28-2014, 09:22 AM
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Hood Vent Install
I started with a pneumatic high speed cut-off tool to cut through the hood so I could get the saw blade in. Then switched to a saber saw/jig saw with a fine tooth metal cutting blade to finish cutting the hole. I could get a straighter cut with the saw. You can use a drill to drill a hole in each corner before you start cutting to make the installation a little neater. Sharp corners and right angles in sheet metal are stress points and can cause cracking or splitting of the metal.
01-28-2014, 09:25 AM
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Hood Vent Install
After you cut the holes and file the notches for the stiffeners, drop the vent in the hole and mark the bolt holes for drilling. Remove the vents and drill the holes. I found some stainless steel, socket head bolts at Home Depot that fit perfectly and look good. I used lock nuts so they wouldn’t back off and drop onto the engine. Remove the masking tape, but don’t bolt the vents in yet.
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01-28-2014, 09:27 AM
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Hood Vent Install
Second Lesson learned: ABS plastic and sheet metal expand and contract at different rates. I bolted the vents in nice and tight and by the end of the Summer, the plastic was cracked on all four corners. I ordered new vents. Before installing them, I elongated the holes in the hood to allow for movement due to the expansion and contraction. I put a silicone sealer around the hole and set the vent in place. I reinstalled the bolts using new lock nuts and tightened them down to where the nut was barely, barely touching the underside of the hood to allow the for expansion and movement without cracking. Don’t bolt the vents in yet.
01-28-2014, 09:29 AM
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Hood Vent Install
To make a rain shield/drip pan to keep water off of the engine, I used an aluminum cookie sheet. This cookie sheet was made from two pieces of aluminum with the top piece crimped around the edge to the bottom piece. I removed the crimp and used the bottom piece. To drain the water out of the drip pan, I took a thermostat housing off of a Toyota engine and tapped it to accept a ¾”NPT brass hose fitting. I drilled holes in the corner of the cookie sheet, bolted on the thermo housing. Attached a rubber hose to the fitting and routed it to drain the water away from the engine block. A simpler method would be to just use a piece of the radiator hose that was attached to the thermostat housing. Cut a piece with a 90 degree bend in it and orient it to route the water away from the block, wiring, coil packs, etc.
01-28-2014, 09:36 AM
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Hood Vent Install
An aluminum angle and pieces of aluminum flat bar are used to hold the cookie sheet drip pan to the underside of the hood. Sheet metal screws hold the braces to the hood. Machine screws and lock nuts hold the cookie sheet to the braces. Pop rivets could also be used for a more permanent installation, but can easily be drilled out if necessary.
Checking the clearance between the drip pan and the top of the engine is a pain. I finally ended up removing the vents from the hood so I could work through the vent holes. Determining how much to bend the braces to clear the engine was trial and error. I thought about cutting a rectangular hole in the center of the drip pan to allow more heat to reach the vents. A flange around the hole would keep the water in the pan. Maybe next time.
I’m sure there are other ways to suspend the drip pan under the hood that would work just as well. I thought about using longer bolts to hold the vents in and running them through the drip pan. A spacer would hold the drip pan off the hood and another nut would hold the pan on. Would have made a neater installation, but could aggravate the expansion/contraction problem. A better solution may be separate flathead screws through the hood with the screw head concealed by the vent flange.
The drip pan works well. After I drive through any car wash or wash the Jeep at home, I can pop the hood and there won’t be a drop of water on the engine.
Checking the clearance between the drip pan and the top of the engine is a pain. I finally ended up removing the vents from the hood so I could work through the vent holes. Determining how much to bend the braces to clear the engine was trial and error. I thought about cutting a rectangular hole in the center of the drip pan to allow more heat to reach the vents. A flange around the hole would keep the water in the pan. Maybe next time.
I’m sure there are other ways to suspend the drip pan under the hood that would work just as well. I thought about using longer bolts to hold the vents in and running them through the drip pan. A spacer would hold the drip pan off the hood and another nut would hold the pan on. Would have made a neater installation, but could aggravate the expansion/contraction problem. A better solution may be separate flathead screws through the hood with the screw head concealed by the vent flange.
The drip pan works well. After I drive through any car wash or wash the Jeep at home, I can pop the hood and there won’t be a drop of water on the engine.
01-28-2014, 09:40 AM
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Hood Vent Install
After you get the drip pan situated with proper clearance from the engine, remove it, install the vents, bolt them in, then, reinstall the drip pan. Before I did my final install on the drip pan, I spray painted it black. I think the install turned out pretty good and the screen in the vents adds something to the good looks of the vents.
01-28-2014, 09:52 AM
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Hood Vent Install
In retrospect, I can see that this procedure would work for most any hood vent install, the only difference being the dimensions locating the vent and the location of the drip pan. The cost of the install was minimal. I had everything laying around the garage except the vents ($4.99 each at Go 2 Marine), 1/4" opening hardware cloth ($9.97 for 2' x 5' piece at Lowes), Stainless Socket Head Screws and Nuts ($2.98 pack of 8 at Home Depot) and Toyota thermostat housing ($2.86 at Pull-A-Part).
Supplies:
2 - vents
16 - Flat head stainless screws and stainless lock nuts (vents to hood)
10 – Machine screws and nuts or pop rivets (drip pan to braces)
8 - Hex head sheet metal screws or pop rivets (drip pan braces to hood)
2 – Hex head bolts and nuts (thermostat housing to drip pan)
2 - 4” x 12 ¾” pieces of hardware cloth
1 - 12” x 18” aluminum cookie sheet
1 - 1” x 1” x 1/8” thick aluminum angle x 36” long
2 - 1” x 1/8” thick x 36” long aluminum flat
1 - Toyota or similar thermostat housing
1 - Brass hose barb, ¾” NPT
1 - piece of heater hose (or radiator hose)
1 - hose clamp
1 - Tube of Silicone sealer
1 - Tube of Black RTV
1 - Black spray paint
Tools:
High speed cut-off tool
Saber saw/jig saw
Electric drill and bits
Dremel tool
Hacksaw
Screwdriver
Round file
Nutdriver or socket & ratchet
Vise and hammer (for bending aluminum flat bar)
Masking tape and black marker
Tape measure
Wire cutters or tin snips
¾” NPT tap
Supplies:
2 - vents
16 - Flat head stainless screws and stainless lock nuts (vents to hood)
10 – Machine screws and nuts or pop rivets (drip pan to braces)
8 - Hex head sheet metal screws or pop rivets (drip pan braces to hood)
2 – Hex head bolts and nuts (thermostat housing to drip pan)
2 - 4” x 12 ¾” pieces of hardware cloth
1 - 12” x 18” aluminum cookie sheet
1 - 1” x 1” x 1/8” thick aluminum angle x 36” long
2 - 1” x 1/8” thick x 36” long aluminum flat
1 - Toyota or similar thermostat housing
1 - Brass hose barb, ¾” NPT
1 - piece of heater hose (or radiator hose)
1 - hose clamp
1 - Tube of Silicone sealer
1 - Tube of Black RTV
1 - Black spray paint
Tools:
High speed cut-off tool
Saber saw/jig saw
Electric drill and bits
Dremel tool
Hacksaw
Screwdriver
Round file
Nutdriver or socket & ratchet
Vise and hammer (for bending aluminum flat bar)
Masking tape and black marker
Tape measure
Wire cutters or tin snips
¾” NPT tap
Last edited by Bldg365; 01-28-2014 at 10:05 AM. Reason: Left out key word
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