Hood Vents and Water in Engine Bay

I have thought about installing hood vents, but have 2 concerns.

1. How does the motor perform in winter conditions with hood vents?
2. Does anyone have problems with water puddling on intakes and electrical components in heavy rains? Is there a correct location for hood vents that would minimize this risk?

My brother has shimmed the hood and in some ways I view this as a better alternative. Thoughts?

some people put hood vents closer to the front of the hood, more near the radiator. no electronics up there

keith_b00ne said:

I have thought about installing hood vents, but have 2 concerns.

1. How does the motor perform in winter conditions with hood vents?
2. Does anyone have problems with water puddling on intakes and electrical components in heavy rains? Is there a correct location for hood vents that would minimize this risk?

My brother has shimmed the hood and in some ways I view this as a better alternative. Thoughts?

Click to expand...

1. I haven't had them in winter yet, so can't answer that

2. I've had no problems with water getting inside while driving, when its pooring out and its parked i just put the section i cut out over the hood vents so no water gets in. although i have forgotten when it was POORING outside and there were no ill effects.

Never had a problem with my hood vents. Mine have decent sized openings and I'm sure plenty of water gets in them, but I've never had an electronics issue. Been through super hard rain and last winter it snowed 2-3 feet here and I drove around in it with out issue. I've also sprayed water in the vents while washing the jeep, no problems.

I think it gets so hot in the engine bay that any water that gets in evaporates pretty quickly.

Another option may be to get some sheet steel / aluminium and make a rain tray. Extend the bolts fastening the vents to the hood, hang the tray off of that, and set it at an angle so that the runoff goes off to wherever you feel it's safest.

Thinking out loud here (because this is the idea I had for when I eventually get around to doing my hood vents), I'd probably point it so that it was down towards the passenger rear of the engine, away from the CPS and exhaust. You've then got the starter to think about, but given how much crud gets splashed up on it anyway it likely wouldn't make a great deal of difference.

No problems with mine. The kid has not complained either. I'd think the rain tray would defeat the purpose of venting off heat, to some extent, so I opted to run with them open. I like to watch the heat waves rise from the vents as I sit in traffic. Makes driving sort of...dreamy.

I have the same concerns,what I will do next spring is this.
I found a pack of 3 baking sheets at Walmart,they have a nice lip on them ,one is just the right size to fit under the vent with a little overlap,will clip out part of the lip ,space the tray down a little lower on one edge to let any water drain away.
On the pass side I found a light piece of steel(Beware of Dog) sign that fits without too much overlap,will space it down like on drivers side.

All I will have to do is take the first step to cut the hood...:shiver:

I went to a local shop that makes magnetic signs and got two pieces of 12"x12" thin magnet in gloss black to match my Jeep. When I know it's gonna rain I throw them on. They stick real well and hold tight at highway speeds.

Minnesota, 8" of rain in 12 hours this summer, 10" of snow in 12 hours last week. Neither has caused a problem with my hood vents or the other 4 vented Cherokees in our local 4x4 club.

I've been running lebaron vents for 2 or 3 years now. the xj is parked over the winter, out in the open and I have never covered them. I have never once worried about it because if you look on the engine, pretty much anything that would get wet through the vents is protected somehow. i have noticed no adverse effects at all.

I went to Home Depot and got some of the magnetic register vent covers. I used them during monsoon season. Inexpensive.

keith_b00ne said:

I have thought about installing hood vents, but have 2 concerns.

1. How does the motor perform in winter conditions with hood vents?
2. Does anyone have problems with water puddling on intakes and electrical components in heavy rains? Is there a correct location for hood vents that would minimize this risk?

My brother has shimmed the hood and in some ways I view this as a better alternative. Thoughts?

Click to expand...

Whats prompted the hood vent thoughts ??

A need ... or a desire for them.

The neeed for vents is generally because of a inefficient cooling system e.g.,

Running temp is too high for the vehicle tasking,
Fans arent moving enough air due to age or quality or incorrect CFM of replacements,
Poor engine bay flow characteristics from having lots of junk under the hood,
Front end changes causing underbody turbulence.
... and probably a heap of other techo stuff .....

Generally you shouldn't have any moisture issues and those people fitting drip trays/covers are just ensuring they dont ... which is a sensible idea.

What do you want/expect from the vents ?

IMHO - A shimmed hood is about the best bang for buck setup, in terms of results ..... for slow speed work. Fitting some insulation between the hinges improves the venting result for higher speed use as well.

1/2" shims has proven adequate for me ... on a variety of vehicles.

Just gotta get used to the traffic accident look ....

A vent at the front is normally the "best" vent .... as long as the loss of flow to the rear of engine bay isnt of a concern ... and it concerns me with the XJ .... but maybe not with a WRX subaru.

A vent at the central, rear section of the hood - in the high pressure zone - works fine/very well at very slow to slow speeds.

A vent at the rear sides of the hood works fine/very well at low and high speeds.

The temps generated by a 4.0l XJ engine/manifold can really be no different to that of a 4.0l TJ ..... The XJ hood gets stinking hot by comparison - because its almost resting on the tappet/valve cover ...

A cowl hood alleviates the XJ heat dissipation situation somewhat ... but doesnt provide a general purpose, all speed, venting action as good as some other alternatives .... and imho, blocking the rear inlets and fitting vents something similiar to the ones in the link below ...... would probably work well and is what I would do - except I'm satisfied with the shimmed hinges.

Vent position suggestion --> http://www.jeepforum.com/forum/f177/xj-trail-vents-cowl-hood-776348/#post7223483
Underhood hot spots info --> http://www.oman4x4.com/hoodvents.htm

:cheers:

The underhood temps of the XJ and 4.0 are pretty high.

This may be a combination of the engine compartment size vs. the engine and its components, plus ANY engine running a header seems to see higher temps.

Now, what does all that heat do to the plastic pieces and the wiring harness? Noticed how things seem to get real brittle under that hood? Is that due to the prolonged high temps or just crappy materials?

Reducing under hood temps might prolong the life of your XJ's parts and pieces.

Ways to reduce the under hood temps: you could spacer up the rear of the hood with washers--cheap, quick, effective are the upside, might act as a guillotine in a collision is a possible downside. Hood with built in scoop is another choice, but the only one I know of has clearance issues with the wipers when the hood is opened. Hood vents can be cheap or expensive depending on your skills/wants. Another option is an old-fashioned hood louver press if you can find someone in your area that still does that work.

My only concern with water/snow under the hood is the TPS on my Renix's throttle body. Still haven't cut one open (destructive) to figure out where I can drill a small hole and inject dielectric grease into one of them.

I dont get the whole concern with drip pans. When I go offroad my whole engine is covered in mud. I go to the carwash and spray the engine bay off. Nothing is gonna happen.

I was in the middle of making my own vents from household air vent covers, but then my rad went. With my new CSF 3 core, and the rear hood spacer mod, Im running really cool.

Temps had been running high until I retrofitted an electric fan, but heat is the #1 killer of engines. Since I see so many running vents on here I felt it to be a good idea to improve air flow in the engine bay, though my temps have been kept in check. Are the factory bolts rated to any particular sheer strength to prevent the guillotine effect?

carves said:

Whats prompted the hood vent thoughts ??

A need ... or a desire for them.

Click to expand...

Oh damn, we brought out the Australian vent hater again.

WE WANTS THEM CUZ THERE COOL OK?!?!

I've never been a big fan of the look of hood vents on the XJ, but their benefits outweigh the aesthetic issues I have with them...

I've been needing to address my heat soak issue in my 2001 and have been debating between the fan timer route, or going with hood vents.

If I was to take the latter route, I would like to replace the depression in the sheetmetal that runs down the center of the hood with some honeycomb aluminum - either all the way from the front to the rear, or the rear half or so of the hood. Do you guys think that would provide adequate ventilation?

My Jeep gets heat soak really bad. I can't get gas without it spitting and sputtering for the first 30 seconds afterwards. Hopefully hood vents will stop this.

This is how I did the 97, Huge difference in engine bay temp. Louvers from a 280ZX...

keith_b00ne said:

My Jeep gets heat soak really bad. I can't get gas without it spitting and sputtering for the first 30 seconds afterwards. Hopefully hood vents will stop this.

Click to expand...

Just a heads up: Muddeprived went through an EPIC quest to rid his XJ of heat soak, including hood vents. He ended up with an electronic timer that runs the aux fan for 5 minutes after engine shutdown.

Search for Muddeprived's heat soak thread.