MajorCollateralDamage

So here's what I've done so far:

New radiator
New water pump (Correct direction of flow, checked impeller direction)
New T stat (Had two, tested this one in boiling water)
New radiator
New upper hose
New lower hose
Bled system
New temp sending unit on back of engine
New fan sensor (don't know official name, it's on the tstat housing)
Flushed system
Compression test, that passed
New radiator cap

Ok. Why the HELL IS MY TEMP GAUGE ON MY DASH PEGGED TO THE RIGHT AFTER 5MIN OF IDLE! FFFFFFFFFFFFFFFFF.

I didn't mind throwing parts at it since it's got 200k miles and needed them anyways.

The auxiliary electric fan hasn't kicked on yet, and I don't blame it since when I use my laser temp gun the Tstat housing never reads above 190*, the back of the engine after me driving on the highway for 10min and then idle for another 10min doesn't read above 215-220. The aftermarket temp gauge I put on the Tstat housing says it's not getting above 180* after 25min of driving and idling.

My next step is to test the radiator pressure to see if my head gasket job was a success. It runs fine.

Am I paranoid? What am I doing wrong? Is there something I'm missing?

I want this issue fixed so I can go ahead and put a lift on this bad boy.....


Help?

XJlimitedx99

You're not overheating, it's the gauge. I can't tell you how to fix it but if you're reading 190 at the t-stat and your gauge says differently than it is the gauge.

HEAP of JEEP

Sounds liek you have either a bad sending unit or a bad gauge. I mean if your gun and an aftermarket gauge are both telling you that the temp is fine, then why wouldn't you believe those two? Hell, I'd put more trust in those two than the stock temp gauge anyways. I mean, I know I I'd rather have the dash gauge reading right too, but start narrowing your focus to that. Sure sounds like your cooling system, itself, is working just fine. Now focus on why the gauge isn't giving you a correct reading... and that's probably the sending unit, the wiring between the sending unit and the guage, or the gauge itself.

MajorCollateralDamage

I'm just wanting to be 110% sure. I'll start looking up wiring diagrams and looking for other threads having to do with that issue. How long on average does it take a 4.0 to warm up?
I'm just still shaken up by blowing the head gasket once and then not looking forward to doing the same job twice. Thanks for the advice so far....

XJlimitedx99

My XJ takes about 10 minutes or so to get to operating temp at idle.

Have you ever done a gauge test?

ehall

Replace with Standard brand (rockauto.com) or MOPAR (dealer) gauge sending unit

Parts store house brands suck

MajorCollateralDamage

Well, to follow up, I did a radiator pressure test and it passed...Then I did some more fiddling around and it turns out you guys are right, it's the gauge. I bypassed the dash gauge and got accurate readings. I also hooked it up via obd2 and it read accurate. It went up to 205° and the electric fan kicked on and got it back down to around 185°. So yes, it's time to move on to other repairs. Thanks for the advice and help. I'll worry about fixing the dash gauge later, I've already got a decent one installed.