Anyone install hood vents?

Wildman said:
You might be OK with your underhood temps but some of us aren't. No one is claiming that installing vents will lower your operating temperature one bit. But what is being addressed is the sometimes higher tamps experienced under the hood.
I've got a V-8 in my TJ and my hood would be warm enough that I'd need to wear a glove to open the hood sometimes. I also had some plastic parts melt due to the heat. By installing the hood vents it allowed some of that heat to escape. Just like every other modification we all do to our Jeeps it's a personal choice. If you dislike them then by all means don't install any.
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Early in this discussion there was a mention of running a colder thermostat.

What percentage of TJ's on the road have a V8? Your TJ is not typical or representative of most TJs, or most Jeeps.

I am curious why your underhood temps are so high. How much HP are you running? 304 CJ's did not seem to push out any more heat than 258 CJ's.

When I was a pup in the military, we used to pull JY chevy V8's and put them in CJ's. 283-307 2v was the best. A 327-350 4v would spin like a top when you hit the gas.
 
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With all this back and forth about hood louvers and rain, and with the hundreds or even thousands of these being installed I have not heard from one person that actually has one saying anything about rain

I would think if this were a real problem there would not be dozens of companies producing them.

The only ones saying the rain will cause problems are the ones that don’t actually have one installed. So as a jeep owner that has one I personally have never had an issue with rain causing problems. I am more concerned about the water coming in from underneath

So let’s hear from those of you that have one and where the rain has caused a problem otherwise let’s put this issue or non-issue to rest

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P man said:
You mean like them ricers with the big fart can mufflers? Do you like mazda miatas?
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Nope. I went 40+ years accident free. In the space of two months an old man and a crackhead totaled two of my vehicles. Airbags and size save my life in both cases. No way I want to ride around in a sardine can.
 
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freedom_in_4low said:
On the 05-06 I would think the IAT should be a decent indicator. I regularly see into the 180s in summer if I'm not moving.


At speed I wouldn't expect louvers to make much difference, but I can see it keeping the upper region of the engine compartment quite a bit cooler when idling or crawling. We all know hot air rises so giving it an opening in the direction it wants to go would definitely let the heat out. I don't doubt their effectiveness in underhood temps.

As to whether lower underhood temps provide any benefit is another matter. Someone with better understanding of the PCM programming could probably comment on what happens with lower IATs. I've seen the results of years of heat cycling on my 99 TJ - the harness loom and the vacuum line would crumble if I breathed on them. My 06 has crows feet all over the hood. Would either of those have still happened with hood vents? Don't know.

I'm not partial to the louvered sheet of steel screwed to the hood look. If I was ever to install some, it would have to look believable that it came that way from the factory, both from the top and bottom of the hood.
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If vents are put in the right places they will definitely draw hot air at speed.

Here is an extensive right up that has been around for a while.

http://www.oman4x4.com/hoodvents.htm#theory
 
bmcgc said:
Early in this discussion there was a mention of running a colder thermostat.

What percentage of TJ's on the road have a V8? Your TJ is not typical or representative of most TJs, or most Jeeps.

I am curious why your underhood temps are so high. How much HP are you running? 304 CJ's did not seem to push out any more heat than 258 CJ's.

When I was a pup in the military, we used to pull JY chevy V8's and put them in CJ's. 283-307 2v was the best. A 327-350 4v would spin like a top when you hit the gas.
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I hadn't read back to the beginning so I missed that post.
It's been discussed enough that most people understand that it's not for lowering the operating temperature.
Why mine runs warmer I don't know. But I also knew people would do other things to try to lower the underhood temperatures on YJ's so maybe it's something about the YJ and TJ.
And yes I've had CJ's with swapped in V-8's that weren't as warm under the hood.
On this rebuild I've done everything I could to try and cut the underhood temperatures. Once I've got it running I'll see if it helped.
As far as how many V-8 swapped TJ's are there? Maybe not that many but they are out there.
 
Wildman said:
No... but if it's a concern I'd imagine you could hook up a hose to the drain hole.
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My GC louvers with drain pans exit into the engine bay through a big slot onto the inner fenders. I don't see Motobilt having done anything different that is conducive to easily fabricating a drainage system down past the engine. Also, Jeep didn't care about this for the 1998 5.9L Grand Cherokee. Why are we caring?
 
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jjvw said:
My GC louvers with drain pans exit into the engine bay through a big slot onto the inner fenders. I don't see Motobilt having done anything different that is conducive to easily fabricating a drainage system down past the engine. Also, Jeep didn't care about this for the 1998 5.9L Grand Cherokee. Why are we caring?
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I don't think we are. I was just pointing out an alternative to the regular hood vent.
If it's not a concern then don't worry about it.
 
Wildman said:
I don't think we are. I was just pointing out an alternative to the regular hood vent.
If it's not a concern then don't worry about it.
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Then I will stop pointing out that your suggestion that drain pans do something to keep water out of the engine bay doesn't work.
 
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Brianj5600 said:
If vents are put in the right places they will definitely draw hot air at speed.

Here is an extensive right up that has been around for a while.

[URL]http://www.oman4x4.com/hoodvents.htm#theory[/URL]
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key is at the right place...which is not where ANY of the commonly available TJ hood louver panels are placed.

Not only functional but his actually look better, too (to me, anyway).
 
jjvw said:
Then I will stop pointing out that your suggestion that drain pans do something to keep water out of the engine bay.
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OK whatever makes you happy. I don't think by me mentioning drip pans was I ever suggesting that the water wouldn't be in your engine bay since it obviously has to go somewhere. But it does limit where the water is going and that might matter to some.
 
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jjvw said:
No idea. There hasn't been much study in the off-road world of the long term effects of thermal degradation that I am aware of. All I know is that in both my previous and current careers, heat management was/is a concern in the interest of preservation and longevity. So, this is something I am aware of to consider.

If the plastic bits under the hood of my Jeep survive a few years longer before disintegrating because I did things ten years ago to reduce heat exposure, I will be anecdotally satisfied with my efforts.
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Heat is never good for the plastic components under our hoods. I know first hand from dealing with the harnesses I've been dealing with for the swap that they can be brittle. Loom is replaceable, but my bigger concerns from the start were how the connectors work so I can unlock them and remove them correctly without breaking them. Even when done correctly the brittleness can result in a sad moment.
 
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JMT said:
Heat is never good for the plastic components under our hoods. I know first hand from dealing with the harnesses I've been dealing with for the swap that they can be brittle. Loom is replaceable, but my bigger concerns from the start were how the connectors work so I can unlock them and remove them correctly without breaking them. Even when done correctly the brittleness can result in a sad moment.
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You should add a louver
 
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bmcgc said:
If underhood temps were an issue, sometime in the last 75 years, Jeep would have come up with a solution.
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Like this, and any other long-term problem, they come up with solutions if it could possibly result in lost sales or warranty claims. This won't.
 
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Apparition said:
You should add a louver
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🤣

I think it's too late! But like @PNW_LJ said, I have to stay focused on this swap. I've got side vents on the GR fenders. Does the engine fan not blow the heat back in the engine bay?

My hood is crap. It's got crows feet (been there since I got it in Dec 2016), and I have three dents in it. I hoped I could louver two of them out of existence, but they are right on the line where the large louver's would be, so it wouldn't solve that aesthetic problem.

I do wonder where our TJ's will be 10-15 years from now with all the connectors as brittle as can be imagined.
 
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