Well I finally got rid of the idiot light guage cluster and put in the one with real gauges. I've only had the XJ for a few weeks now so I'm trying to establish a baseline of 'normal' readings and have been doing lots of things to make sure everything is good under the hood.

My first question is about cooling. I've noticed since I've had a real gauge that the needle sits one line below the 210 reading, when I'm driving. However if I sit at an idle for more than say 5 minutes temp goes up to 210+ and the electric fan comes on. The attached picture was taken tonight after I'd been waiting in the drive thru line at the In-N-Out burger... It was 43 degrees out. Electric fan running as I was waiting inline. That being said I don't have a factory fan shroud around the mechanical fan..it was gone when I bought it. After all of the above being said is this normal??

My second question is about Voltage/Amperage. Since I've owned the XJ I noticed that the headlights dimm at idle. The voltage gauge reads at 14 when driving normal but drops down at idle with the headlights dimming as well as dash panel and accessory lights dimming ect. Is this my alternator that's bad??

Attached is a picture taken at idle tonight while I was waiting inline at the drive thru..

No light, no worry.

a little fluctuation in the temp gauge is fine as long as its not going up large amounts, keep in mind when your sitting at idle theres no air being pushed through the rad just a bit being pulled so it will be a bit hotter, the lack of fan shroud will affect the fans performance as its just pulling air from all around instead of a focused area through the rad. all in all it sounds fine.

the lights dimming issue may be a weak alternator or a bad voltage regulator, you could try getting a load test done on your alternator or do it yourself to see if its getting tired.

good luck

Cool thanks Mud-Dog!

Since u've only had the XJ a few weeks, I'd suggest looking into what has/hasn't been done regarding cooling system maintenance and maintenance in general. +210F in 43F ambient just seems a little toasty and the efan running seems to verify that. The efan "on temp" is 218F.

The shroud around the belt driven fan absolutely/positively needs to be in place. The XJ cooling system is mediocre at best......all components must be in place and functioning perfectly. My concern is, it's your present cool/cold ambient temps is what's delaying/masking a possible overheat situation down the road. Next spring/early summer (higher ambient temps) you may be caught off guard. Verify coolant temp and the factory gauge reading with a infrared temp gun.

Since cooling seems to have been covered, I'll toss in my $0.02 for the voltage.

Simple as this....

IIRC, your volts should never drop below I think it's 13.8v when the truck is running. Irregardless of idle or cruising. My XJ never drops below said amount; it did once, and sure enough my alternator was bad. That's why I love my OBDI; bad alternator = low volts = CEL.

Go load test your alt at autozone or advance... I bet you'll find out you need a new one.

FROM PERSONAL EXPERIENCE!!!! If you end up needing a new alternator, please avoid Autozone, and ESPECIALLY avoid Advance. Advance alts have some of the worst ratings ever, and I personally have had autozone alts go out in a matter of months (my Focus for example... which is a pain in the **** to replace). Go NAPA, O'Reilly (that's in my XJ now), or even venture to see if there's any alt shops in your area that can rebuild your current one!

And make sure the mechanical fan is working correctly. Also from that picture, oil pressure is borderline low. I would verify the reading to the gauge is accurate.

Is the voltage supposed to go up to around 15 when you are driving. Is it possible to overcharge a optima. Cause I think tat is what happened to me. I have since replaced the battery but I don't want it to happen to the new battery

My 2 cents. You need a shroud on the mechanical fan. Clutch fan could also need replacing.

The voltage readings on these gauges leave something to be desired. I would verify the charging voltage at the battery with a meter.

As for the oil pressure reading, I'm gonna ask what brand of oil filter is currently installed on your Jeep, and how high does the gauge read at speed?

When I hook it up to a voltage meter it says that it is pushing 14 and the diagnostic thing says that my alternator and everything reads good to go but then when I get in my truck, the volt meter looks like it trying to use between 15 and 16. I'm wonder if the jeep have some sort of voltage regulator and if it might be bad. I'm still new to the jeep scene. Thanks