strange that the Heater and condensor fan have no effect on temps, is the cond. fan pushing air or sucking air?. have you considered you got a bad t-stat

 

My first tstat wasn't that old to begin with but I put another 190 on from the dealership at the onset of my problems just incase which had no effect. Then I ordered the genuine LR 180 which once again had no effect.

I'm currently running a pressure test at 20 psi and will get back with results but for now it looks to be holding steady.

 

Sorry Drowssap, the condenser fan is pushing air into the engine bay.

It makes sense to me the temps in the valley by the temp gauge are hot coming off the block and running to the heater core but to make it that hot something is obviously creating too much heat.

My thoughts at this point are possibly early sign of head gasket failure, it has been 60k miles since they were initially done. Or a slipped sleeve, hopefully not.

 

If you ever figure this out let me know.
On my way back from the Washington coast a few weeks ago, I saw a temp spike to 209 while driving at 60mph that dropped back to the usual 186-194 range and stayed there after i backed off the gas slightly to merge onto I5 N. This occurred after several days and 800 miles of freeway running at 60mph + speeds with the temperature consistently within the 185-194 range. I checked the cold coolant levels when i stopped overnight both before and afterwards and the level is good.


I'm wondering whether an inline Tstat would better regulate the temp spikes that are being reported in the 03's and 04's , or is it a better idea to add the oil cooler and see if that has a positive effect?

 

"Heated core lines 227-230 in and out
Coolant temp sensor in the valley 227-230
Coolant resevoir 206-210"

those seem awfully high. plus with the waterfall... maybe some issue with the heater core? maybe do a flush and reverse flush?

how about your oil? got my truck back from the shop and it was running a bit hot, changed the oil back to the Rotella/Mobil1 high mileage blend I use, and they're back to normal.

 

No waterfall sounds at all. I've heard that noise before and it's definitely non existent at this point. I am also running Rotella and have been for about 20k miles with the larger K&N filter.
I'm going to redo pressure test in the morning when it truly cools down tonight. My next thing after that will be to flush/reverse flush heater core and connect the lines to each other to bypass the core and see what I get there.

 

while pressure testing you should be pulling and tugging on every line and hose.

 

Pressured up to 20 psi moved and tugged all coolant related hoses, snugged up a couple of hose clamps, retugged everything and let it sit for an hour. Didn't lose a single psi. pressurized to 25 for another hour with no lose. This is at ambient temp of 37f outside.

 

You sure have covered the bases, couple things to suggest as a possibility are a water pump impeller issue (disinegrated, damaged, rare) or an ac condenser clogged with debris or corrosion ect

 

or a chunk of one of those p.o.s. plastic tees or ys broken and wedged in the cooling system and clogging/slowing the flow