Alternative Under Hood Cooling... You Know, Vents And Stuff

[neohic]

I've really been thinking about my under hood temps lately. Seems like anytime I take my '88 out, I always come home and feel the hot air coming up between the hood and the fender. I haven't really put a whole lot of thought into this because my cooling system works great! It's been a little hotter lately and I can't help but think that I should have the same amount of airflow through the radiator that is then exiting somewhere easily. I know that some sort of hood vents or a cowl hood would be ideal, but I really don't like the look of either. Then there's hood spacers, but when it comes to body lines that just don't line up that's what always catches my eye. I've thought about using just a small hood spacer, but obviously the smaller spacer won't be as efficient.

 

Here's what I'm thinking... I think a cowl intake looks great and really cleans up an engine bay. Like this:

 

 

Why wouldn't the same idea work for hot air air to exit? I'm thinking some large holes in the upper firewall that would let air exit through and out the cowl. I hate the idea of cutting up my truck though. Thoughts? Comments? Help me out here...

[skidoo_j]

That would just let the heat  from the engine bay into the cab of the truck.   The Idea behind the intake is it would pull air through the cowl that's already there for your heating system.   

[Pete M]

Meh, I never did care for the slow and boring "passive" methods. :D

 

 

 

 

and unless you like the smell of your engine bay, don't vent it into your cowl. :(  simply having the hole in my hood has made it a necessity to have the cooling fan running on the freeway, otherwise the fumes waft inside.  the fan seems to push the smell out into the air steam and away from the cab.

[neohic]

That would just let the heat  from the engine bay into the cab of the truck.   The Idea behind the intake is it would pull air through the cowl that's already there for your heating system.   

 

:doh: Hadn't thought of that.

[Incommando]

I know of several XJ guys who have done the same mod as Pete. Most folks just opt for louvered hood vents form a Lebaron or similar vehicle. I have pontiac GTP scoops should I ever feel the need.

[HOrnbrod]

http://www.metalcloak.com/JK-Aluminum-Inner-Fender-Wells-p/3290.htm

 

[neohic]

http://www.metalcloak.com/JK-Aluminum-Inner-Fender-Wells-p/3290.htm

 

Interesting.  :hmm:

 

Found this info over on NAXJA:

 

1/2" hood lift- too low, was barely off the weatherstripping, no gap. 

1" hood lift- good gap, aesthetically looks too high, need to lower to 3/4"

Under hood temp sensor location

Fuel Rail temp sensor location

 

With the 1" Spacer, The Results-

 

10 min idle at BK ambient=73.6* underhood=127.9* DIFFERENCE=+54.3* fuel rail=151*

Freeway 55mph ambient=62.6* underhood=86* DIFFERENCE=+23.4* fuel rail=99.5*

 

... from this link: http://www.naxja.org/forum/showthread.php?t=1083426&page=2

[88whitemanche]

Lebaron vents?

 

http://item.mobileweb.ebay.com/viewitem?sbk=1&nav=SEARCH&itemId=261266808061

[neohic]

Lebaron vents?

 

http://item.mobileweb.ebay.com/viewitem?sbk=1&nav=SEARCH&itemId=261266808061

 

 

... I know that some sort of hood vents or a cowl hood would be ideal, but I really don't like the look of either....

 

Nope. Not an option.

[Mark Serva]

Have been overheating at low speeds. Have pretty much done everything else. Now, before I cut holes for vents in my hood I'd like to experiment by lifting or raising the hood about an inch at the hinges to see if that is a fix. From what I read that will really decrease my underhood temps if not radiator temps. 

 

Problem--only 3 bolts holding the hood on. The one that is missing doesn't appear to have a nut on the other side. Could somebody post what the bolts are secured too? Would like to get the right mounting before I remove as I don't want to waste a volunteer assistants time. 

 

Thanks much and  Happy Motoring, Mark

[Incommando]

My MJ had only the engine driven fan as it is a non-A/C truck. The best thing that I ever did for cooling was to add a factory aux. electric fan in the stock position. If you do not have one I would add one first thing. 

 

I am going to raise the rear of the hood as soon as I get around to it. I ended up going with Lebaron vents as someone offered me a stupid high price for my Pontiac ones. This may be the best pic that I have of them

[Marine1Texas]

What we did is raise the back of the hood up 1 inch to allow forward movement of air to push air out behind the hood. So where the hinges attach to hood we added 1 inch washers and push hood up. It push's the air up and out over front of wind shield hood closes like normal and easy way to let extra heat out

[HOrnbrod]

^^  Too much H2O entry doing that.

My first attempt at hood vents is with the ZJ 5.9 factory vents. They basically did nothing with the drip pans installed; w/o the drip pans they were marginally helpful. Hood vents just don't move enough air through the limited XJ/MJ underhood real estate. At least these did not.



Eventually I found a Reflexxion cowl hood and installed it. Now this sucker (literally) really does work. Even sitting in traffic the heat pours out the cowl driven by the dual electric fans up front. Plus there's no noticeable H2O entry to worry about.

 

Here are several more hood vent examples:  http://gojeep.willyshotrod.com/HowtoBonnetVents.htm

[Marine1Texas]

To much air flow going in? You need air flow lol

With a exhaust area the fans that are pulling air have only to push hot air down. With hot air that wants to rise a back vent is always most logical, with less stress on fans. you ever try to push air or pull air in to a enclosed area, the fan loads because of pressure.

My 87 has been like this since 1989, never once run over 205 degrees even sitting in hot Texas sun for hours idling in 27 years. This is the old school way of cooling. Seems to work great for me.

 

Also keep in mind that money money money for mods, this mod only cost about 5 dollars.

[HOrnbrod]

Do you know what H2O is?   :shake:

 

I'm like old school too, but that's just wrong.

[Jeep Driver]

Dual Efans with delay timer after shutdown .......three minutes or so.

[Marine1Texas]

yes I do, however not once ever had water go in the engine bay from that area with any degree.

 

So your saying that a few sprinkles of water is going to hurt something? When your off road thru mud and water that push's heavy mounts of water in.

 

Or are you thinking water going to get in intake? I am not sure why you think lots of water going to get in.

 

 

Dual Efans with delay timer after shutdown .......three minutes or so.

I like that idea. I have only the one electric fan and mechanical fan. I was thinking about a time to go on it after days when it is 110 here in Texas

[Pete M]

 

it may look like a hood scoop, but it is designed to push air out, not draw it in.  got it on a switch/relay.

 

 

 

but if your ride is overheating, then something else is wrong.  MJs didn't need vents from the factory to keep the engine cool so they don't need them now.  :thumbsup:

[Pete M]

for what it's worth, water coming in through the back of the hood (past my failing gasket) was the prime way that water got into my cab (dribbling down and through the various failing firewall gaskets).  :( 

[Marine1Texas]

for what it's worth, water coming in through the back of the hood (past my failing gasket) was the prime way that water got into my cab (dribbling down and through the various failing firewall gaskets).  :(

If I had that problem I would agree. I never had that problem and my back gasket on hood is in very good shape for being 27 years old. I Never had water come in the cab if I did I would not have it done. It work on my truck with out any problems. however can not speak for everyone

[HOrnbrod]

Maybe it doesn't rain in Texas.

 

I can see gaps where the back of the hood is pushed up so high you can stick a 2x4 through. But if it makes you happy Kudo-man - go for it.   :thumbsup:

[Marine1Texas]

I live in North East Texas and it rains about 40 inches of rain a year. some more some less. not as much as Alabama I guess.