Flushed the entire cooling system twice to rid the engine of the orange Dex-Cool. Pure distilled water ran through the system both times and came out 100% clear the second time. Used a shop vac in reverse to blow air through the rad. Very good flow, no weird gunk coming out.

Refilled with Peak Global Lifetime and a bottle of Water Wetter. Truck has a 92*C (197*F) thermostat in it. Took a look at the thermostat while I had the system apart. 4 moderately large holes in the upper plate. Did not bench test.

Put everything back together, bled the cooling system. Let the truck cool off, topped of the expansion tank and lifted it above the bleeder until it started to come out. Put the screw in immediately.

Let the truck idle for 20-30 minutes. Heat worked, but temps only climbed to about 176-8 and seemed to stay there. Hopped in and headed home, relatively flat back roads, temps around 180-190. Reached my 1.5 mile hill, 35-40mph at 2.5k rpm. Temps came up to 200-210. Reached the top temps came back to 190-197.

Parked in my driveway, nose up more than the rear. Cracked the bleeder one last time. No air. No waterfall inside the truck. Expansion tank full.

Started it back up again and took another ride. Mostly downhill, temps between 175-180. Small hill incline, temps came up to 190-200 again.

Got home and checked the radiator temp spread. Nice and warm in the top and super cool near the middle/ bottom.

What do you think could be the issue? The upper hoses are brand new also and did not seem unbearably hot. Could hold onto them for a couple seconds with bare hands. No excessive pressure. Must be the thermostat right? Just weird it's staying in a good temp range, especially for a 197*F thermostat. Ambient Temp - 60*F

New-
Pressure cap
Upper hoses with T
Lower hose from T-stat to rad
Idler puller
Serp belt

Thanks
Charlie

 

How old is the thermostat?

Honestly, my vote is on an air bubble somewhere in your system. I'd bleed again. You shouldn't be staying in the 175-180 range any time if you've got the 190 stat because the stat wouldn't be open below 190. You're seeing the lower temps because the temp probe is in the radiator and the coolant that's still in the rad is getting cooled when you're not under load. This is caused by the bubble because you're not getting coolant flow when you aren't under load. Been there myself, I bled the system and I was good.

I'd replace the stat either way. Do the in-line thermo mod, that's one of the very next things on my own list.

 

I was under the immpression the temp sensor for the ECT through the OBD port was located on the engine near the intake manifold towards the front. Didn't know it was in the rad. Now I'm a bit worried. 2004 D2

How would you suggest bleeding the system better from here?

 

Your temps do not really sound that far off normal to be honest but if you want to try bleeding again I can tell you how I do it.

While the engine is stone cold lift the expansion tank away from it's clips and prop it up with a bungee cord or something to hold it up so you have your hands free. Fill expansion tank all the way up and take your hand and squeeze the bottom and top radiator hoses a view times to try and get any major bubbles out. Refill the expansion tank all the way up again and get ready for the messy part. I completely remove the bleeder screw so a good amount of fluid comes out and I continue to fill the expansion tank as coolant flows out the bleeder. After a good amount of coolant has come out the bleeder (I do about a 1/4gal) I quickly put the screw back in and tighten it back up. At no time during the bleed process should the fluid in the expansion tank get low. Put the expansion tank back down where it goes and top the fluid up to the "Full when cold mark". Start the truck and turn the heat to max to make sure you have heat and then go for a drive. Top up the expansion tank if necessary after it cools back down.

 

Bled the system again this morning while it was stone cold. Pulled the expansion tank and lifted it with the bleeder out. Almost immediately started gushing coolant from the bleeder, put the screw back in without introducing any air.

Got in and drove and temps only reached about 180 all the way to work. Got to work and felt around. Still cold on the bottom of the rad. Top hoses warmish, not overly hot. Felt the top of the cylinder heads and they seemed to be a good temp. No leaks, no steam, expansion tank still full.

Im at a loss here. Any more suggestions? I parked the front end up on a curb while i'm at work, I'll crack the bleeder one more time later on.

I also have a motorad 180 that I put in last night, but it too didn't seem like it was opening and the temps climbed to about 200 when idling. Shut it off right away. Going to bench test that today too.

 

those Motorad t-sat are junk they all run hot, if they even open. the LR TD5 180 stat is what you want.
have you given any consideration that your radiator is simply filled with crap and the coolant isn't getting into that bottom part of the radiator

 

I took the Motorad stat out and put the one that was in the truck back in. Branded with 92* on the plastic.

The radiator looks very new and when I flushed it out, everything seemed to be flowing fine.

 

I just ordered a new rad. I'll put it in tonight and see what happens. For clarification, the ECT sensor is near the intake manifold behind the AC compressor correct?

 

You ordered a new rad, but are sticking with that thermostat?

 

I'm going to bench test both thermostats to ensure they are working, but I did order a spare also.