Hood vent design debate

$55.97 shipped to my door from Advance using a 30% off coupon for the full kit -- Thanks

Biggest thing for me, everything was fine and dandy with the tons and 40’s, on trail and on the road. In part to the all new cooling system and electric bypass to run on switch. However once I plopped the winch right in front of the radiator my temps weren’t happy. My fault 100%. I restricted air flow through radiator. It was instantly obvious. So the vents for me were to overcome my negative action. Never had any moisture inside that didn’t come from underneath.

Heat soak is a bit of a pain, and I have thought about doing the vents. my project instead is making a clean cowl hood.
my engine always runs at about 208-210ish, dunno why so warm, but it seems content with that temp range. if I run on the trails or even an extended idle time and shut it off itll run super rough for a bit then it clears back up.
from what I have read, most people missed the original question: heat soak, not an overheated engine.
decent vents would help, or even the blocks that lift the back of the hood up 1"
it would come down to what you wanted to do. if you live somewhere with no rain then those vents you liked would be fine, just keep in mind that if it rains, you may have issues.

I cut my perfectly good 01 hood to install Pontiac GTP vents dead center of the hood. Had heat soak and a perfectly maintained cooling system at the time. The vents cured the problem immediately. That was exactly 8 years ago to the day. I live in Oregon and it rains a lot here. I have had zero issues with rain water or washes and I don't have drip trays. Cant argue with that.

My cooling system is now in poor shape and I ordered all new components including the DEI insulation kit to bring it back to snuff or better. That being said heat soak is terrible right now even with the hood vents.

About two weeks ago, before I could replace my cooling system, the upper rad hose blew on my way to pick up my new pickup. I can tell you, at 55 the steam rolled out the vents and tapered to a point before reaching the windshield. It looked really cool actually. The same steam streams were coming out the sides of the hood (not the wheel wells) and tapering off. Its safe to say that at higher speeds the heat will extract out.

It's also safe to say a poor condition cooling system will exaggerate heat soak even with vents. I do not regret installing my vents but I do regret letting my cooling system go. Thank goodness the head hasn't cracked yet.

freerider15 said:

Actually, the OEM's do a LOT more testing than most people would think. They don't just run calculations then sit on them. I've had more insight into this, as I have a few friends that have or do work for the big 3 (or others).

One thing they do, is ship the vehicles out to Colorado, in the summer, and run them up and down I-70, among other areas. The hot weather (can be 100* or more), plus the steep inclines going up and down I-70 pushes them a bit harder than they can get outside of a lab within reason.

Click to expand...

I worked for Nissan for a summer as an intern (was getting my ME at the time, and the engineering accountant BS I experienced at that internship steered me towards Computer Science) and still have half a dozen friends who work for OEMs or their suppliers. Manufacturers engineer for 95% of their customers, figuring the remaining 5% will just go to the aftermarket. There are some exceptions to this, but on a high volume soccer Mom type vehicle like the XJ, this definitely applies.

Driving up a grade, I’ve never had a cooling issue. Plenty of airflow. 4LO with a large tailwind, boiling over and the dashboard ding of death. My cooling system is 100% new OEM or quality aftermarket. YMMV, but not everyone is people just throwing hood vents at their Jeep to cover up maintenance issues.

freerider15 said:

With discussions from these guys (we're all engineers), more than one of them I came to know through XJ's.

When we've gotten to the subject of cooling, they'll mention that even with larger tires, the vehicles OEM cooling system is plenty adequate as designed. Obviously, things like steering and trans can always benefit from a cooler (and if towing, a trans cooler is always recommended).

Click to expand...

Mine is marginal and 100% stock other than a ZJ clutch.

freerider15 said:

That being said, all electrical under the hood, *should* be rated no less than 1.5 times the operating temperature, in many cases, the electrical should be fine upwards of 400* before issues may start. You'll have issues with the PCM long before wiring and such.

Click to expand...

Was talking about heat cycling causing embrittlement. My coolant plug is cracked.

freerider15 said:

Most of the electrical connections are not fully waterproof, but are water resistant, hence why the TPS and IAC can get really irritated when water gets around them (had it happen myself).

There are some waterproof connections (e.g the Weatherpack fitting on the E-Fan), but most aren't, as they didn't need to be.

Click to expand...

Pulled my TPS connector just now. Has the same seals on the wire and ribbed seal that’s on the O2 sensor. It’s also mounted horizontally, so unless you submarine the whole motor (at which point hood scoops won’t matter), it’s going to get splashed at worst.

freerider15 said:

As to the wheeling in AZ. I've known guys from AZ to Southern FL wheeling full bodied XJ's with anything from 35's to one tons (who still have their AC), and have no cooling issues. I lived in SoCal for a year, driving it to and from CA, and wheeling JV, Calico, etc. without ever a blip on the radar. The only issue I did have, was oil temps wanting to get a little high. I still had AC, full bodied with doors, etc.

Click to expand...

Cool (hehe)! Wish I could say the same.

freerider15 said:

People tend to want to take the shot route, instead of putting in the work to make their stuff work (as had been brought up on this site so many times).

Click to expand...

I don’t think adding things to your vehicle is the short route. I plan to do everything I can to help keep it cool, as I don’t want to be a burden to my buddies.

freerider15 said:

A working T-stat (I would verify operation before install), good water pump, a flushed system (and I mean a full flush without the pump of t-stat housing on), a flushed heater core, and good (not clogged, leaking, etc.) radiator tend to be plenty.

The next steps:
- Transmission cooler (this can help engine temps since the trans runs through the radiator)
- ZJ fan clutch - I've seen a few systems where the fan clutch needed replacing, and that helped a bit. People tend to assume because the fan is there, and somewhat rotates it's working as it should
- E- Fan bypass switch - this can really help with just sitting around. Stopping on the trail for lunch? Let the e-fan run. Hell, I think most people just assume their E-Fan runs properly :laugh:
- Exhaust wrap - While it "may" cause a shorter exhaust header life span, it will significantly help direct the heat down and out the exhaust, instead of lingering in the engine bay.
- For the late models, injector heat soak can be an issue. There was a TSB about this, and there should be heat reflector shielding around the injectors and intake. I've got a 2001, and will be replacing it on mine. I could go all out with DEI wrap, but I'll take the easy route for now.

Click to expand...

I’ve got a 97. I’ve done everything other than the exhaust wrap and bypass. When my XJ was overheating, the AC was set to stun and the fan was on 100% of the time. The exhaust wrap will definitely crack an already crack-prone manifold.

I get it, you don’t like hood vents. No need to laugh at those who do. It’s entirely debatable if you need them, it’s not debatable that they work. They’re not something akin to Pep Boys “performance” parts.

I wheeled my '94 on 4.5" lift and 31's in Moab with stock gears and stock 125k mileage cooling. All I had to do was remove my grille to improve air flow to the radiator and I never overheated. When I built my '99 it had proper 4.88 gears on 6" and 33"s, I upgraded to a Hesco water pump and an all aluminum 2 row radiator. Wheeled in Moab again, never got close to overheating. As has been mentioned, hood vents are a bandaid to some other problem.

Heavyopp said:

If I recall correctly none of your XJ's have the cali emission pre-cats under the hood

Click to expand...

You are correct, but if you've been following my real heat disaster thread, shielding goes along ways. I wished I had realized that much earlier on! Cheap and easy shielding could have been done to avoid it! I just got back from a major towing event which includes long steep/rugged (4wd) towing.
http://naxja.org/forum/showthread.php?t=1145993

Would not a raised hood hinge suffice to let lot of heat out, yet maintain rain protection? Maybe lift the rear of hood at hinge with spacers and longer bolts say an inch or two?

The 2001 runs a set of Napier vents; the 1987 is fine the way it came. Different opinion? Pound sand.

:wave:

Black1990jeep said:

Would not a raised hood hinge suffice to let lot of heat out, yet maintain rain protection? Maybe lift the rear of hood at hinge with spacers and longer bolts say an inch or two?

Click to expand...

The lower windshield is a high pressure area at speed. This will cause higher pressure in the engine bay and reduce radiator efficiency.

Kittrell said:

I wheeled my '94 on 4.5" lift and 31's in Moab with stock gears and stock 125k mileage cooling. All I had to do was remove my grille to improve air flow to the radiator and I never overheated. When I built my '99 it had proper 4.88 gears on 6" and 33"s, I upgraded to a Hesco water pump and an all aluminum 2 row radiator. Wheeled in Moab again, never got close to overheating. As has been mentioned, hood vents are a bandaid to some other problem.

Click to expand...

You chose aftermarket radiator and water pump, others choose hood vents. Neither are bandaids if they help, they’re just mods.

freerider15 said:

Here's the OEM MOPAR heat shield:

https://www.amazon.com/dp/B01EIBMUS...a432-fe6d90b388b5&ie=UTF8&qid=1524240237&sr=1

Here's the full kit from DEI:

https://www.amazon.com/Design-Engineering-010378-Engine-Injecter/dp/B015NOKWQY

You can shop around on both of them and probably find them a little cheaper, or through Advance Auto and use coupon codes.

I haven't ordered mine yet, and I haven't decided if I just want to do the single shield, or the full kit.

EDIT: With a 30% off Advance Auto Coupon code, it comes to $56.03 shipped. So, I'll probably just do the full kit, as it comes with injector covers, manifold heat shield, and a fuel rail cover.

Click to expand...

Mine was done by the dealership per the service bulletin. It is much better but will still heat soak when it is really hot out. If I had done it myself I would have bought the complete kit.

DaJudge said:

Mine was done by the dealership per the service bulletin. It is much better but will still heat soak when it is really hot out. If I had done it myself I would have bought the complete kit.

Click to expand...

My 2001 had the heatshield, but like anything else needs to be changes out after use over time. It's not sealed fiberglass, so any moisture, dirt, etc. all soaks in.

In reality, most any XJ could benefit from the kit.

DaJudge said:

Mine was done by the dealership per the service bulletin.

Click to expand...

Does anyone recall seeing the FSB number/name for setting the electric fan to come on 10* sooner. I know it was a fix for late models but not sure what years beyond 2001. Someone posted it on the boards here but for the search of me I cant find it again.

I don't know for sure but it sounds like a bandaid straight from Chrysler.

Rockwood said:

You chose aftermarket radiator and water pump, others choose hood vents. Neither are bandaids if they help, they’re just mods.

Click to expand...

If you say so......:thumbup:

Some years actually came with blankets installed to the underside of the hood.

Bent said:

Some years actually came with blankets installed to the underside of the hood.

Click to expand...

I believe that's more for noise insulation

four_shot said:

I believe that's more for noise insulation

Click to expand...

Without a doubt, that's definitely what it is. None the less it still has an R value. My 87 never had it, nor my 01. My son's 95 does have it though.

My 86 had it. My 97 does not. I dont recall a difference in underhood temps. But rhe 86 was a 2.8L, so there's a bit of apples and oranges happening.

A little closer to topic, i thought that the cowl induction scoop from the early 90's cavalier Z24 would have looked nice on the 86.

think that blanket could have been a safety thing too, like a fire suppressant type deal

Every thing but my YJ that had a carb had the insulation on the hood. See it much less with EFI. Prob had to due with warm up?