Have you run it up to 195F, shut it off, let it cool, and then top off thru the bleed screw? If not it could be air in the system, do the hoses get rock hard? Does the coolant smell like exhaust/fuel when you open the reservoir cap?

Clogged Radiator is possible, I’d have flushed the entire system when I replaced the thermostat & watched the water for any deposits and how it flows.

If everything seems fine (hoses aren’t rock hard & it doesn’t blow coolant out of the reservoir cap) it “could” be a faulty temp sensor.

 

Sounds like theres still air in the system.

 

i had this type of issue when i replaced my temperature sensor. the original one was damaged when my coolant froze so i replaced it with one that i thought would work. it was for a different model rover (i forget which) but it looked identical, had the same pins, same thread, etc. when i first started up, everything would be down in the cold zone, then would swing up into the normal, hang there for a while, and then head on up to the red. i tried tracking down air bubbles, thermostat issues, and all kinds of other problems for a couple of weeks before i thought to try the sensor from my parts truck. everything immediately went back to normal, without changing anything else.
i didn't have an ultragauge at that time so i don't know what the readings were. i don't know of any other coolant temperature sensors on the truck though, so my guess is that they would have shown as being high, since that is apparently what the sensor was sending.
right now my ultragauge shows 190-200 under regular driving conditions, sometimes spiking up to 205 or so. i haven't installed my 180 thermostat yet.

 

Did not let it get to 195*, once I shoot the IR temp couple inches from the tstat walk around looked at analog gauge, shoot some more, etc. it had jumped up near the red so I shut if off at that point. No to the bleed screw filling as well. Hoses did not get rock hard (although once I started after it came off the hauler and did some 'touching and feeling' the hoses were dead *** hard', with the new t'stat installed during Saturday's testing, not hard at all). No on the smell, but I will double check that this evening.

Agree on the entire system flush - I had about a 2 hour window to do some 'wrenching' on it Saturday. So I can't rule out the clogged radiator...

 

That's a good point... you and Best 4X4 have noted that... That will be on order today or yanked out of the 04 this afternoon. My symptoms are the exact same as you note above..

 

Proper bleed performed last (expansion tank above the bleeder screw), full stream on coolant coming out. Did i this a couple of times.

Started and let idle for 15 minutes. Gauge stayed in middle of the analog gauge. IR temps at thermostat and hoses around the 140 to 155 across the system. Radiator readings with IR in the 89 to 75 range top to bottom on outside 140 ish on the inside (the best i could shoot with loosing some fingers). Drove around the block and temp gauge spiked up to 3/4. What the heck!?!

clogged radiator, bad temp sensor?

 

Temp sensor is like 16.00 on rock auto (it is different vs 04) big round plug vs a fuel injector looking plug. With IR readings that low I’m gonna go with bad sensor, or the actual gauge (had a crazy acting one on my 02 Westminster D2 I fixed & sold). If it was running that hot the darn reservoir would be gurgling, hoses would be rock hard, and the IR Temp gun would only be off by maybe 5F. Best place I use with an IR temp gun is the temp sensor itself or the black metal coolant pipe going into the aluminum intake (just behind the alternator).

 

Should have the temp sensor by Friday. Hoses were not 'hard' and fully expected the expansion tank to be talking when I got back in the driveway and popped the hot but it was normal, no gurgling, no steam, no overflow, etc. Does the 04 Temp Sensor fit the 99? I have that one parked in the garage and know it's good.

I have yet to be able to get the t-stat reading above 165+/- without the analog reading well above normal so I'm not sure if t'stat is doing it's thing..I did shot the hard pipe at the intake.. Off hand don't remember the reading. Going to check the coolant level this evening to see if anything settled since yesterday evening.

I appreciate your comms and support Best 4X4...I was just over in your neck of the woods (Schulenberg / La Grange) couple of weeks back..

 

I did not read the whole thread but I will chime in with one thing on a errant temp sensor, you cannot plug the tb heater intake line, for some reason you will read hot if you do. You need coolant flow through that nipple. Hopefully the sensor takes care of your issue.

 

Temp sensors are not the same on 99-03 vs 04. In 04 they switched it (connector looks like a fuel injector plug) 99-03 has a round type plug.

Also when she’s totally cool, remove the bleed screw and top it off until you can’t add anymore. After messing with the cooling system it can take up to 3 times to get the air out.

Either you still have air in the system causing the temp sensor to be basically reading hot steam vs coolant, a faultly temp sensor, or you have air down at the thermostat.

The proceedure that works for me is replace whatever needs repaired be it a hose, water pump, coolant hose, or just a drain/flush/fill. Top it off the best you can thru the reservoir, and the bleeder on the T. Then run it up until around 195F, shut it down and let it completely cool. You should be able to top off the reservoir, and thru the bleeder. Let it run again up until 195F then let it sit. Top off if needed and you should be good to go with maybe 1-2 top off’s thru the bleeder.

During all of this how is the heater output? I usually see little to no heat output when there is a lot of air in the system (sometimes you get a gurgle sometimes you don’t).

I’ve only had one D2 not bleed worth a darn and I simply parked it with the nose up on a hill to get the air out. Besides that the only other issue I’ve seen was a supposedly 180F el cheapo thermostat that was actually a 190F....

I’d keep checking the bleeder and make absolutely sure you can’t add anymore thru there. Hopefully that or a new temp sensor will get you fixed up!