Different Strokes for Different Folks JK Wrangler Hood Vent

[mmaattppoo]

I have an 01 TJ and have had heat soak issues in the past. The TJ and maybe the JK has a rubber seal that runs across the back of the hood. Pulling off that seal will allow heat to escape. No cutting needed.

I have never had overheating issues with the TJ and didn't notice any drop on the temperature gauge but I do have less issues with heat soak after doing that.

I thought about removing the rubber seal along the back of the hood to improve air flow (nice simple approach...always a good thing), but water ingress onto the engine on a regular basis (and the associated problems that could cause given it rains a lot in Vancouver, BC) guided me to a hood venting option that could be opened and closed as needed....esp. when it's pouring rain. The addition of a pusher fan improves upon the passive venting when driving slow on long climbs and in summer bumper to bumper traffic when there is little airflow through the grill and over the hood.

I've never overheated, but after reading some very disturbing posts about transmissions overheating (burning JKs to the ground) and being concerned about heat soak wear and tear while driving in warm summer conditions I took a few measures to address the issue: 1) added an engine driven fan (moves serious air all the time at the cost of 0.5 - 1 mpg); 2) added a MOPAR factory transmission cooler seriously reduced transmission fluid temps for the 42RLE auto I'm running; and 3) added a pop-up hood vent and fan.

As you've noted, venting alone doesn't really show up as decreases in any measured temperatures from the engine's perspective (esp. since coolant temperature is governed by the JK's 195 deg F thermostat), but wear and tear on plastic and rubber parts should be reduced while running. Heat soak after the engine is turned off will still happen but there's not much one can do about that on a day to day basis save opening your hood ever time you shut the engine off or adding hood louvers that expose the engine to the elements on a regular basis.

 

[Dan Grec]

Hey,

Over here in Africa I'm encountering some seriously hot conditions, and I keep thinking about this thread.

When I'm in stop-n-go traffic the heat under the hood is immense. With my arm resting on the open window I can feel the heat being thrown out the back of the engine bay as soon as the electric fan kicks in, which makes me think I want a fan running all the time.

Are you still happy with the mechanical fan? Do you have the electric option as well?

If I do it, I'll be doing both for certain.

Can you give me an idea of how "deep" the fan shroud is? My next chance for a Jeep dealer is not until Namibia (a LONG way), and I'm tempted to either get the parts sent over to me, or to try and get someone to bring them in a suitcase. I can get the rough measurements on the shroud from my existing one, but I need to know how "deep" it is please.

Also I notice the part number is listed for "automatic" - do you know if there is a different part number for standard transmissions? (I assume if it's any different it will be because there is no trans cooler)

Thanks very much!

-Dan

 

[mmaattppoo]

Hey,

Over here in Africa I'm encountering some seriously hot conditions, and I keep thinking about this thread.

When I'm in stop-n-go traffic the heat under the hood is immense. With my arm resting on the open window I can feel the heat being thrown out the back of the engine bay as soon as the electric fan kicks in, which makes me think I want a fan running all the time.

Are you still happy with the mechanical fan? Do you have the electric option as well?

If I do it, I'll be doing both for certain.

Can you give me an idea of how "deep" the fan shroud is? My next chance for a Jeep dealer is not until Namibia (a LONG way), and I'm tempted to either get the parts sent over to me, or to try and get someone to bring them in a suitcase. I can get the rough measurements on the shroud from my existing one, but I need to know how "deep" it is please.

Also I notice the part number is listed for "automatic" - do you know if there is a different part number for standard transmissions? (I assume if it's any different it will be because there is no trans cooler)

Thanks very much!

-Dan

Hi Dan,

I've been following your adventure on YouTube. Very exciting trip you're on! I was wondering if heat was going to be an issue.

I'm still happy with the mechanical fan and the electric fan. The mechanical fan definitely moves a lot of air all the time and even more when the thermal fan clutch engages at 150°F. The electric fan is necessary (if you have air conditioning) as apparently it kicks on based on pressure withing the AC system. There may be additional temp/pressure inputs that control the electric fan. Here's a link to the forum where I first came across this important engine system modification:

http://www.jkowners.com/forum/showthread.php?t=76475

Sorry. The link takes you to the end of the thread...can't seem to get the link to take you to page one of the thread.

The above forum post has quite a bit of discussion about the mod.

I had a quick look online and really couldn't find any specifics regarding any differences between radiators for 3.8L V6 engines with auto or manual transmissions. What I do know is that the factory automatic transmission cooler is not part of the radiator instead it is integrated at the base of the air conditioner condenser...the primary reason that the factory transmission cooler is so very ineffective.

Here are a few photos I took earlier today of the mechanical fan shroud with a tape measure for scale and the fan/thermal clutch assembly:

The fan shroud extends approximately 12" towards the engine from the front of the warning label on top of the plastic radiator cover.

Note: when I ordered the shroud, electric fan mount, mechanical fan, and thermal clutch my local dealer had to "force" the order through Chrysler's parts system. Apparently these items (esp. the fan shroud) are not intended for the North American domestic market. You may have an easier time ordering the necessary parts in Africa (Namibia) since it's a hot climate region that's similar to the middle east where the mechanical fan is factory installed equipment.

EDIT: one additional detail. Not sure what you're running for an oil filter but one thing to bear in mind is that the larger capacity oil filter does not clear the blades of mechanical fan. I found this out the hard way but caught it before the blades broke off. I now run the standard capacity oil filter.

Hope this helps. Let me know if I can help with any other details.

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[Dan Grec]

...
Hope this helps. Let me know if I can help with any other details.

Wow, thanks again so much for the details and photos.

I have to imagine the electric fan would kick in if the engine (somehow) got hot enough, so it's a nice backup to have.
I'm just running a stock (little) oil filter so should have no worries there.

And holy-cow clean engine bay! That thing is spotless. Mine doesn't exactly look like that right now

Hmmm, the shroud is pretty deep at 12 inches, that's going to be hard for someone to bring in a suitcase I think.

Maybe you're right, I'll wait till I'm down in Southern African and see if a dealer down there can get what I need - if I'm lucky the 3.8 JKs down there came with them and it will be easy!

Thanks,
-Dan

 

[mmaattppoo]

Glad I could help out. I hope you find what you need once you safely reach Namibia.

Yah. The engine bay is quite clean. It gets a wash down with Simple Green after every trip...not that my trips are near as epic as your current adventure.

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[Dan Grec]

Glad I could help out. I hope you find what you need once you safely reach Namibia.

Yah. The engine bay is quite clean. It gets a wash down with Simple Green after every trip...not that my trips are near as epic as your current adventure.

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Thanks again so much. I'm looking to accelerate this plan and get it ASAP.

One more favor please - can you measure the mechanical fan and tell me the radius? i.e. length from the center of the clutch out to the end of the blades?

If I can't get the parts sent to me for a reasonable price, I'm going to use a generic fan and clutch, and I'm wondering what size to keep an eye out for.

I'm also going to cut a vent in the hood, I'll be using yours for inspiration!

Thanks again,

-Dan

 

[mmaattppoo]

Thanks again so much. I'm looking to accelerate this plan and get it ASAP.

One more favor please - can you measure the mechanical fan and tell me the radius? i.e. length from the center of the clutch out to the end of the blades?

If I can't get the parts sent to me for a reasonable price, I'm going to use a generic fan and clutch, and I'm wondering what size to keep an eye out for.

I'm also going to cut a vent in the hood, I'll be using yours for inspiration!

Thanks again,

-Dan

Hi Dan, I get a measured fan diameter of approximately 19.5" (radius = 9.75") measured from the center of the thermal clutch.

The clearance is pretty tight between the fan and shroud. If you can't find a 19.5" diameter fan I'd recommend going slightly smaller rather than slightly larger.

Yah. I can imagine the under hood temperatures you're experiencing with high ambient temperatures. JK's really need some means of venting hot air from the engine bay. Cutting a vent of any type will definitely help out.

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