Understanding my temperature gauge?

O.K. So I have been listening to some of the old podcasts and reading the forums. I’ve noticed a few people having a temperature problem. So I’ve starting watching my gauge. On my way home tonight and with the ambient air temp at 43 My XJ ran at the first hash mark. In the summer when it’s about 90ish I run a lil over 210 a lil bit more when I stand still.

So my question is... What temperature is the hash marks? Is it running too cold? At what point do I pull over and shut it down?

It has the stock rad. I'm unsure of the water pump and the thermostat. Never touched em in the 4 years we had it. I did put in a new eletric aux fan. (it was making a funky noise) and I replaced the fan clutch.

Good question!

The temperature was about the same here in Utah and my jeep runs similar to yours. However, I have replaced the thermostat with a lower than OEM temperature. I have also replaced the radiator, hoses and water pump. I am curious what everyone else is running at.

I just replaced my radiator (stock replacement 1row) and hoses too, with a fairly new 180° thermostat. Mine has been running about the same as yours, and i consider that mark 155° since that exactly between 100° & 210° as the other two marks indicate.

Yes that is a bit too cold for best mileage, fuel burn, and a better running engine. Its not fatal to the engine, just not best for it. I plan on trying a 195° thermostat as soon as i see what its gonna do when it heats up outside. I'm in Texas, so it won't be long.

Oh, and i like to air on the side of caution and not push it past 230°.

Also, in 43° weather i'm sure you're running the heater. That will usually keep it a little cooler too.

Keep me posted. I will watch mine as Utah heats up, and I will probably swap the thermostat anyway. It's easy and cheap enough.

good point.. I didn't think about the heater..

Saw a pic somewhere where an update XJ gauge had been checked against the scangauge ... and the 1/4 position was about 155 as XJ Wheeler mentioned.

Might want to check those thermostats arent stuck open ... or the temp sender isnt playing up ... coz the minimum, constant, running temp with a 180* fitted ... should be 180* ... unless you are seeing 180ish - 160ish flip flops of the needle.

Today was in the upper 50's and nice enough to drive without heat or A/C. on the highway my temp was about the same (155). In stop and go traffic it crept up to about half way between 155 and 210. (180ish I'm guessing) I'm sure by summer I'll be back to 210.

If I ever get around to it I'm gonna buy one of those Infrared thermometers and make sure the gauge is reading correct.

You should be at exactly 195. Start with water pump, 195 thermostat, temp sensor, fan clutch. New upper and lower hoses. Mine ran at 205 until I finally replaced a leaky radiator and it now runs right a 195 even in crazy heat

I just shot my t-stat housing with a infred thermometer and it read 187 with my gauge showing a lil north of the first hash mark. giving a little for error I think my dash gauge is about spot on.

That's a good spot but just to check hit the temp sensor on the back odd the head (drivers side) with the temp gun.

If its running correctly then it should never go over 195. For years I was about 210. Now im at 195.

On a weekend replace the water pump , thermostat, fan clutch, thermo sensor and the upper and lower hoses. Then test is out.

That should work if not its the radiator. My radiator had small leaks for 12 years. I used that bars radiator sealer for 12 years until one day it just wouldn't work anymore, so I got a new radiator. Now I run 195 even when it's 110 outside.

I never overheat.

Keep me posted.
Send me a private email and we can chat on the phone.

Thanks for the help guys, I couldn't find a temp sensor in the back of the engine. I have a 96 and I'm not sure if it has the original motor.

But like a kid with a new toy I just started shooting random things.
It's about 60 degrees today. I ran it about 20 min mostly highway and a lengthy idle at the tacobell drive tru
T stat housing 200 water pump 187
ittle nipple at heater hose 194 oil filter 143 exaust manifold 433
somewhere close to the injectors 114

By now a small crowd gathered in the parking lot at work. so I spent the next few min shooting other cars at the T stat housing
08 mustang v6 202
88 F250 diesel 188
Some kind of saturn 198

I was mainly worried that my jeep might be running hot and my gauge not showing it corrrectly.. I'm convinced that my gauge is accurate. But i do think that a flush , new water pump an t stat might be in order.. Just as a lil preventive maintance.
Thanks again guys

Sounds good. Funny what people find interesting sometimes.:rolleye0012:

Well if the housing and the thermostat inside has a ton of miles on it, just change it anyway so you know it's working. The parts are cheap.