Hood vents
Member
Joined: May 2016
Posts: 122
Likes: 7
From: Enid America
Year: 1989
Model: Comanche (MJ)
Engine: 5.7L LS1
what DsXj98 said. The "5.9L Limited" Grand Cherokee was a limited production ZJ only available in '98. The vents are somewhat rare but show up on ebay or in the junkyard from time to time.
Seasoned Member
Joined: Apr 2012
Posts: 261
Likes: 15
From: Puyallup, WA
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0L
It's to get the attention of the average driver. There were 2.4 million XJs produced. The overwhelming majority of the people who drive/drove those have never seen this board. We're really the "elite" among XJ drivers who have actually tried to learn more about what we're driving. The rest of them may not have any idea what the temp gauge actually means, and I suspect that weird jumping (which I've seen myself when dealing with my head crack) is for them.
I do have an OBDII adapter and DashCommand for my iPhone, I forgot all about the sensor functions on that. Pretty much just used it to check and clear CEL codes for myself and friends.
Senior Member
Joined: Feb 2015
Posts: 514
Likes: 15
From: South Georgia
Year: 1996
Model: Cherokee(XJ)
Engine: 4.0l
For a factory look I went with 5.9L ZJ vents. These vents were also available on the euro market Orvis Edition XJ but were mounted on the hood with adhesive and non-functional. I found some junk yard 5.9L vents with drip trays and mounted them a little more forward than the Orvis Edition. This allowed me to avoid the underhood supports and install the drip trays correctly (trimmed slightly to fit). Why Jeep didn't actually do this on Euro XJ's is beyond me. I liked the results so much that I've put them on both of my recent builds. Pics:
CF Veteran
Joined: Jan 2015
Posts: 1,381
Likes: 3
From: Southern Maryland
Year: 1991
Model: Cherokee
Engine: 1999 4.0L
Rugged Ridge makes some functional hood vents for TJs and JKs. They don't form correctly to the XJ hood but pull down nicely if you add more screws. 1/8" holes and #6 screws did the trick for me.
So far I have only cut one half-sized hole in the driver side to test with, and although I can see and measure plenty of heat coming out the engine still gets hot on the trails. I am going to cut the driver hole to full size next, and if that doesn't work will try a couple of other things before I make a hole on the passenger side.
So far I have only cut one half-sized hole in the driver side to test with, and although I can see and measure plenty of heat coming out the engine still gets hot on the trails. I am going to cut the driver hole to full size next, and if that doesn't work will try a couple of other things before I make a hole on the passenger side.
Member
Joined: May 2016
Posts: 122
Likes: 7
From: Enid America
Year: 1989
Model: Comanche (MJ)
Engine: 5.7L LS1
BMW's Yas Marina Blue. I'm pretty excited to get this XJ on the road!
Nope! I do have a professional HVLP paint system and some experience though.
Nope! I do have a professional HVLP paint system and some experience though.
Member
Joined: Feb 2015
Posts: 109
Likes: 0
From: Oregon
Year: 1987
Model: Cherokee
Engine: 4.0
I'm using basic, painted aluminum louvers. They vent a significant amount of heat. I think less than $20 on ebay. I sanded them and used some leftover black from the fenders. Angle grinder to cut the holes and bolted on. Ran them through a winter of nasty weather with no problems.
No, I don't lick fish.
Joined: Mar 2011
Posts: 11,169
Likes: 26
From: Northern Kentucky
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0
The idea of the vents is to allow a means of egress for the air that is pulled (or pushed depending on your traveling speed) through the radiator. A hood scoop is just going to create more drag than is already there and make bad gas mileage even worse with little (if any) benefit.
Newbie
Joined: Apr 2016
Posts: 3
Likes: 0
Model: Cherokee
That makes perfect sense, I'd hate to go backwards on my mileage after upgrading the injectors and cold air intake system. I have just noticed that in the summer heat I get a really bad knock. But in the cooler spring/fall weather, the engine sounds fine. I figured that if I could force air directly onto the head I can keep the engine compartment temp down. In reality, I'll probably try the hood scoop(med size) and if it has too much negative results I'll replace it with a vent.
Banned
Joined: Feb 2014
Posts: 2,379
Likes: 18
From: Florida
Year: 2000
Model: Cherokee(XJ)
Engine: Golen 4.6L
Think about it like this: You have an "in" door and an "out" door, and you want to get a lot of people through as fast as possible. If you tell people to go in through the "out" door, they'll jam up the people coming from the opposite direction, and fewer people will be able to flow through the "in" door. You'll move fewer people through. Likewise, if you push air through your hood, it will jam up air coming through the "in" door of your grille, potentially causing less air to flow over your radiator.
Remember, heat rises. The heat problem under the hood of an XJ comes from heat welling up against the hood and not being washed out by the flow of air coming in through the grille, often because you're not moving fast enough to wash it out. If you install hood vents with the louvers pointed away from the air flow so that it's not scooping it into the engine bay, heat will be able to escape upward when you're sitting still, and when moving the air flowing over the louvers will create a negative pressure or suction that will pull air up through them and out of the engine bay, so that cool air can come through the grille with the most efficiency.
As Basslicks said above, a scoop is for putting air into the motor, not into the engine bay around the motor. When you have a functional hood scoop, it will either seal right on top of the air cleaner or have a duct running to the air cleaner that forces cold air directly into the engine's intake. When you see hood scoops that are not connected directly to the engine, those are just for looks and either do nothing at all for performance or actually hurt performance by creating back pressure inside the engine bay.
Newbie
Joined: Apr 2016
Posts: 3
Likes: 0
Model: Cherokee
You're thinking about it backwards. If you force air through the hood down into the engine bay with a scoop, you will create backpressure inside the engine bay that will make the radiator less effective. Air should come in through the front grille and be dispersed out through the bottom (or hood, if you install vents).
Think about it like this: You have an "in" door and an "out" door, and you want to get a lot of people through as fast as possible. If you tell people to go in through the "out" door, they'll jam up the people coming from the opposite direction, and fewer people will be able to flow through the "in" door. You'll move fewer people through. Likewise, if you push air through your hood, it will jam up air coming through the "in" door of your grille, potentially causing less air to flow over your radiator.
Remember, heat rises. The heat problem under the hood of an XJ comes from heat welling up against the hood and not being washed out by the flow of air coming in through the grille, often because you're not moving fast enough to wash it out. If you install hood vents with the louvers pointed away from the air flow so that it's not scooping it into the engine bay, heat will be able to escape upward when you're sitting still, and when moving the air flowing over the louvers will create a negative pressure or suction that will pull air up through them and out of the engine bay, so that cool air can come through the grille with the most efficiency.
As Basslicks said above, a scoop is for putting air into the motor, not into the engine bay around the motor. When you have a functional hood scoop, it will either seal right on top of the air cleaner or have a duct running to the air cleaner that forces cold air directly into the engine's intake. When you see hood scoops that are not connected directly to the engine, those are just for looks and either do nothing at all for performance or actually hurt performance by creating back pressure inside the engine bay.
Think about it like this: You have an "in" door and an "out" door, and you want to get a lot of people through as fast as possible. If you tell people to go in through the "out" door, they'll jam up the people coming from the opposite direction, and fewer people will be able to flow through the "in" door. You'll move fewer people through. Likewise, if you push air through your hood, it will jam up air coming through the "in" door of your grille, potentially causing less air to flow over your radiator.
Remember, heat rises. The heat problem under the hood of an XJ comes from heat welling up against the hood and not being washed out by the flow of air coming in through the grille, often because you're not moving fast enough to wash it out. If you install hood vents with the louvers pointed away from the air flow so that it's not scooping it into the engine bay, heat will be able to escape upward when you're sitting still, and when moving the air flowing over the louvers will create a negative pressure or suction that will pull air up through them and out of the engine bay, so that cool air can come through the grille with the most efficiency.
As Basslicks said above, a scoop is for putting air into the motor, not into the engine bay around the motor. When you have a functional hood scoop, it will either seal right on top of the air cleaner or have a duct running to the air cleaner that forces cold air directly into the engine's intake. When you see hood scoops that are not connected directly to the engine, those are just for looks and either do nothing at all for performance or actually hurt performance by creating back pressure inside the engine bay.