Those are the exact vents I want

 

Nice Jeep! Should be operating at about 210-220 though.


Those look pretty good, man. Simple and effective. I might do these with mine.

 

Ok I'm officially in love with those fender flares! They would look amazing on my 99 2 door!

 

Who makes that bumper? I think i might want one. Sorry for jacking the thread! I just have to know.

 

Logan's Metal made the bumper as I recall.

 

Are there hood vents that can be closed to let the engine warm up and once it does I can close them? Just curious because I don't want the engine to never warm up

 

Hood vents will not prevent the engine from warming up. The cylinders are generating several hundred degrees of heat inside the motor. It doesn't need heat welling up around the outside of the motor to get the motor to operating temperature.

An engine running cold is usually the result of someone putting the wrong thermostat in the motor.

 

For a factory look I went with 5.9L ZJ vents. These vents were also available on the euro market Orvis Edition XJ but were mounted on the hood with adhesive and non-functional. I found some junk yard 5.9L vents with drip trays and mounted them a little more forward than the Orvis Edition. This allowed me to avoid the underhood supports and install the drip trays correctly (trimmed slightly to fit). Why Jeep didn't actually do this on Euro XJ's is beyond me. I liked the results so much that I've put them on both of my recent builds. Pics:

 

Ah thanks. Would the hood vents help keep the engine temp down when driving fast enough on a steep grade for about 30 minutes? There is a grade along a highway route I will be taking my jeep a lot because it's how I get to my favorite destination.

 

So the question of the day is this, WHAT is the optimum temp that the engine is suppose to run at and at what temp do we need to worried about to prevent damage to the motor.

 

210 degrees. That's why it's smack dab in the middle of the temp gauge.

 

210° is normal.

230° is alarming because it signals that you have a problem that can quickly run away.

Under the correct pressure and with the correct coolant/water mix, the coolant should resist boiling until it reaches 260° to 265°. Once it boils is when the coolant is no longer doing anything to cool the engine, and serious damage starts happening.

The problem with these numbers is that you can't run, say, 240° overall without risking that some parts of your motor are running much hotter and boiling away coolant in local pockets. When coolant boils, that red mud precipitates out of it, clogging up the system and eating the water pump so that cooling efficiency is even further reduced. Up to 220°, however, you're usually safe.

 

What is the temp at the first tick mark past 210? When 1 of my 3 generic e-fans died during the hot weather while my AC was on (fan lead wasn't crimped properly) the needle hit that mark and then immediately jumped past the next one all the way to the one just before 260 and gave me the CHECK GAUGES heart attack. There's no way the temp spiked that quickly, because I was watching it creep slowly the whole way to the first tick past 210, and it did it a few other times as the fans would eventually seppuku one by one (replaced them all with SPAL pullers and they've been solid).

I have zero cooling problems now, but I always wondered what the hell was the point of a gauge that goes into warning mode even though it's barely above nominal temp?

 

It's to get the attention of the average driver. There were 2.4 million XJs produced. The overwhelming majority of the people who drive/drove those have never seen this board. We're really the "elite" among XJ drivers who have actually tried to learn more about what we're driving. The rest of them may not have any idea what the temp gauge actually means, and I suspect that weird jumping (which I've seen myself when dealing with my head crack) is for them.

Most of the coolant temperature "gauges" in cars on the market now don't actually give you anything close to an accurate representation of the temperature. My Subaru was designed for track use, yet the needle on the coolant "gauge" hits the center mark at 170° F, then stops and stays there at least until 210° (the highest I've had it). A 40° swing is "normal"? That swing may be even larger, because I don't know how hot you have to get it before it budges off that center position.

I only know it does that because I run Torque and monitor the actual temperature on a dedicated engine tablet. What's ridiculous is that the car actually has that data but doesn't display it because the "gauge" on the dash is really little more than an advanced idiot light. At least the XJ gauge shows you some of the subtle changes around the 210° mark instead of just sticking there regardless of whether the temp is really 180° or 230°.

By the way, the computers in the '97+ XJs will read out the actual temperature in °F on Torque through a Bluetooth OBDII adapter. I had a bad fan clutch and was watching the temp click up and click down as I was in stop and go traffic. Torque is the next best thing to an aftermarket gauge.

 

Can you elaborate more on these vents?
What year ZJs, trim, etc, to look for?
I'm very interested in these.