Hi all. I just wanted to get some info from other members regarding coolant temperature on your scanner. What seems to be normal and what is too high. I have my observations below.

I have a 2000 XJ with the California/NY emissions. Mileage is at 100413 (100k). I have a new radiator, thermostat and temperature sending unit. The water pump is 2 years old, and I only drive about 5k miles a year.


so I hooked up my "scanner", which is dashcommand app on ipad. Temps were high 80's and sunny. I was reading 195-198 while driving around, at speeds over 35mph. if I dropped below 35, the temps would go up to around 200- 210 depending on speed and how many times I stopped for lights/stop signs.

The big difference was at idle. It only took 2 minutes to go from 200 to 218, and then quickly from 218 to 226. It stayed at 226 while sitting at idle. Obviously the e-fan was on. I opened the hood to see if that would lower the temps but it did not help. It stayed at 226

I did this test twice. The second idle time the temps were 223

just wanted to see if anyone else has checked their coolant temps at idle with a scanner. Thanks

 

Those readings jive with mine. I have a scangauge that's always on and reading engine temp. The gauge on the cluster isn't accurate. At 240 the instrument gauge will read slightly over 210, and at I believe 245 it will shoot over to almost 260. That is by design so people won't freak out until it's time to freak out.

 

Another observation from this morning -At idle I was at 221 on the dashcommand app, the gauge was slightly over 210, and the e-fan was not on. Yesterday it was on when the app read 223. So the app is either reading 4 or 5 degrees higher, or the app is spot on and the e-fan is engaging at 222 or 223 , not 218 when it is supposed to. I will get another scanner or another app to check against dashcommand. My bet is the app is reading a little higher.

 

Time to verify the temp with an IR temp gun.

 

Those numbers are not bad, but you may have a fan clutch that is starting to go. The typical symptom of a bad fan clutch is normal temps on the highway that rise at idle.

Actually, that's behaving exactly as it's supposed to. In '99 and earlier, the efan came on at 218. However, in 2000, Chrysler changed it so that it doesn't come on until 223, then it stays on until the temperature drops to 217. Here's a direct copy and paste from the 2000 FSM:
As you can see, the 2000 also doesn't come on automatically when you turn on the AC like it did in the prior years. These changes frequently confuse owners of '00 and '01 XJs because they get incorrect advice from people who owned earlier XJs and don't know there's a difference. We've had people here spend hours of useless troubleshooting of a system that is behaving exactly as it should. Don't do that.

 

Thanks. I knew the fan didn't come on automatically with the a/c like years past, but I did not know it came on at 223, not 218. So the app scanner is dead on.
I will read up on the fan clutch. I bought the Jeep in 2003 with 35k on it, and as far as I know it is the original fan clutch.

 

Thanks for the advice. I changed the clutch fan and the idle temps are not rising so fast and not going up as high. I wish I had changed it out years ago.

 

At least yours was still in the early stages. Last one I had go out would shoot up to 235 so fast at red lights that a gremlin appeared in the seat next to me playing a slide whistle and giggling.

 

mikesignal,

I have a 96 xj sport, low miles, in great condition. I run full-time obd2 data on a small digital dash. My numbers are about the same as yours. Your 2nd idle test that reached 223 is about what mine will reach on a hot summer day sitting at idle (depending on wind speed and direction, etc.).

My e-fan comes on at 221f (exactly) according to the obd2 temperature reading. So my max temperature doesn't usually go higher than about 223f while sitting at idle. I can also bring it down by increasing my idle RPM with the pedal (if you go from 750rpm to about 900-1000 rpm, it will typically cool down a bit provided the fan clutch is working properly).