1996 EX d16y8. 141k. Drive 40 miles each way to work. City driving to get to interstate, then 70mph cruise with added construction stop and go backups. Gauge usually stays just below the point where I can see the top of the "arches" but sometimes, but sometimes when cruising 60-70 it rises over the half way point. Never gets to 3/4 but when it starts happening I always hit the heat and it goes back down and may or may not happen again during the trip and sometimes it never happens at all.

Both hoses get hot so the thermostat is opening.
Fan turns on as it should. Doesn't run very long. I can obviously check this at idle.
Bled the hell out of the system again and it is not air.
Does not lose coolant-or never has. Will keep an eye on after rebleeding.
No oil in coolant or vice/versa.
Water pump is OEM and has 35k on it and is pumping.
Has never overheated since I have owned it at 96k.
Coolant is clean and had the hell flushed out of system hen I did the water pump/timing belt.

Tonight I loaned the block tester from AZ with the blue fluid and kept it on the radiator for the 2 mins sucking in air and the fluid stayed blue. I am down to thinking it is the radiator or the head gasket (even with the test done) or is this normal and I have jusy never noticed it? I keep a pretty good eye on guages and lights. Any ideas?

 

same exact problem

 

first signs of failing thermostat

 

Replacing the thermostat is worth a try because it is cheap and easy.

Was the heater valve wide open when you bled the system?

If the above are fine, replacing the radiator may be the next step.

 

i had the same problem at about 130k i keep having cooling problems i ran a coolant flush and it didnt help the problem i replaced my radiator for a new oreily one and never had the problem again

 

Wow, I forgot how fast this board moves.
RonJ@HT, yes the heater valve was open and as long as the system was open for the exhaust gas block check, I jacked the pass side up and my driveway is already on a bit of an incline and let it go through a few more fan cycles. I had no issue this morning, maybe because it was 50 degrees and had the heat on. However warm on the ride home and no heat on and no issues. Been bled several times, so even though cannot believe it maybe this was it. I do logically now suspect the radiator if always goes away when i hit the heat as the heater core should act like a tiny radiator.

Happens again will just do the radiator and I have a new oem thermo laying around and will do that again as well if I have to do the radiator.

BTW - will probably get it at AAP for the $89. Online coupon through 9/30 code BIG35 is $35 of $85 purchase and you can pick up in local store. Will be $55 total if I have to do it.