That won't help his heater get hotter.

 

Sorry I should have been more clear. I was referring to the quoted info in the previous post about the temp sensor at the back of the head. Sorry for any confusion

 

Measuring with an IR temp gun on the housing what are typical readings? Should it measure close to the 210* expected to be seen on the gauge? My housing doesn't seem to ever read above 180*. At the back of the head the readings are closer to 210 and sometimes 220. I have a 195* motorad t-stat, a hesco high flow waterpump, a hesco housing, and a three core all metal (non-aluminum) radiator, new hoses, new head gasket, newly surfaced and pressure tested cylinder head, new temp sender, new fan clutch, an aux fan out of a 2000, and a manual tranny (no trans cooler or extra heat added to radiator). I expect this thing to run cool but on my stock gauge (sender at back of head) it reads about 215 at an idle and 230+ running down the highway. At this point I figure it's one of three things: 1) my new rad is plugged 2) my block is cracked or 3) my stock gauge is inaccurate

 

Seems like coolant temps would be cooler at the back of the head and hotter at the front. Coolant enters the back of the head (from the block) and picks up more heat as it travels thru the head to the front, where it exits the motor. Surface color/texture can affect infrared readings, so I've read.

When coolant is flowing properly thru the heater core, both heater hoses will be hot as heck.

Presuming the entire cooling system is in top notch condition, coolant temp should be right at the t-stat rating this time of year. Actually running 210* with a 195* stat in freezing cold weather using the heater doesn't make much sense.

 

I thought Duma Jones used an infra-red camera and dispelled any myth that there was much difference in coolant temp as it traveled through the block.

 

I can't remember the context that was in or where that thread went.

I have heard many times though that the rear runs hotter due to being so far away from the fan. Theory is supported by a theme of problems with #6 cylinder

 

Guess I missed the IR camera thread, duh......help the dummy (me) find it.

It's my understanding the #1 cylinder bore is subject to slightly more wear due to it receiving the coldest coolant, thus not expanding as much as the following cylinders. Probably not much of a difference in coolant temp from back to front but the head is long and the longer the coolant remains in the head, the more heat it absorbs.

 

The lower hose is the supply hose and the upper one is the return line. I'm not certain if you flushed the core out using the lower line until water ran out of the upper on that you'd have an air block? Do you get good air flow? Really good air flow? Are your blend doors working correctly? Not directional but heat/ac doors?

 

FWIW, that was changed by the Factory on '97 up XJs.....'97 up the top hose/nipple is the supply line.