Here's my situation my 1999 D1 142,300 seems to be running higher than normal temps. I have replaced the following items Clutch Fan, Thermo 180 , both temp sensors, new reservoir cap also had the radiator rodded out only 10 % blockage also a brand new water pump from AB and a new serp belt. The last couple of days here in Houston temps have been over 100 with heat indexes of 110. My UG is showing temps of up to 212 on the way home today w/o the AC on. Obviously when I replaced the water pump and pulled the radiator I flushed the system and added new 50/50 coolant. I am not hearing any noises coming from under the dash. Thoughts ?

 

My 97 has shown 180-183 at night on way home (so I know things are working); but during day I saw 199 on freeway, and 205 in traffic. All with AC on, and a 180 stat. I just did my HG, took a lot longer than planned, and my radiator may have dried out with what was liquid gunk inside. So I am runing the drive with flush. I shot the radiator with my IR thermometer the other day, and had 30+ degree variation top to bottom. So something is going on with my rad.

So when you crank in in morning, fan clutch should make the fan roar, even spin the electric fan blades slightly. Electric fans should come on as soon as AC is turned on.

Fan belt route? Fan blades on right (cupped side toward block)? Fans (electric and mechanical) both hold paper against grille, air moves toward block? Not uncommon with lots of work to reverse something(s). One bad thing is thermostat install backwards, spring goes inside block, but you knew that.

Pull out rubber strips and inspect space between rad and AC condenser for leaves and crap. Unlikey since rad rodded out. But I wonder if when really hot those strips restrict air flow?

Water wetter? May buy you 3-6 degrees.

The way I look at it, if the truck can drive along at 60 mph at night with 180-183F, then cooling system is working. Repeat during day, and the only thing that has changed is the temperature of the outside air. So engine is not producing more heat, cooling system just can't get rid of it. Last summer my D1 would do 187 on freeway with AC on and 100 outside.

BTW, used to live on FM1960 and work downtown, I know it can be brutal...

 

Some mornings it will run between 177 - 186 and others it will run between 188 - 195, like this week. I'm going to pick up another 180 Thermostat the one I have is a month or two old. As for the strips do you know if anyone has just pulled them out altogether.

 

I don't know, but I may try that and report back. I have a bigger fan than stock on mine (deeper pitch blades, from a 2000 Blazer), so I have more air even when slow.

I guess one other possibility would be drain the coolant, and go back with distilled water and water wetter. Used at the track (antifreeze is slippery), coolant actualy runs a little hotter than straight water, and the water wetter folks claim 20 degree change.

On the stat avoid the fail safe models, and if it has a jiggle device or vent hole, put that at the 12:00 position to pass any steam buildup.

 

That Chevy fan moves an insane amount of air compared to the rover one

 

Yes, but air flow at 60 mph is way more than the fan. 5280 feet per minute. Problem I see with temps are that everything is working fine as long as you are within the start to open temp - wide open temp. (Noobs - a thermostat in truck is not like your AC thermostat in the house, it does not snap on/off). Once you get well beyond say 20 degrees above start to open, you are not in "closed loop" and the water stays in the radiator a shorter time (no stat modulating the flow, and water pump running really fast). This would mean radiator would have to do a great job of heat transfer. Harder to do in hot air.

So at the moment, mine is running hotter than I would like at 199F on the freeway. But I may be stuck with it. 95F outside.

 

Where can I find a good ultra gauge at? odb1

 

UltraGauge OBDII Scan tool & Information Center
Maybe score a used one cheaper on Ebay.

 

I'm in TX too and am having heat issues. I'm running a 170 degree stat and am seeing pretty high temps (on a cool day itll run 79-80C) and when I got back to TX it seems to be all it can do to run under 89. It's a pretty big problem as it seems like above 90C it starts to knock. Not to hijack, but I'm there with you-does anyone have any idea where to start? My 96 with the factory stat seems to run consistently in the 88-90C range and hardly climbs...my 99 SKYROCKETS in traffic. All the fans work as well. About to cut open the hood and put a vent in-it's the one with AC.

 

I have a 95.