Sitting in traffic for 40 min 30 degrees Celsius this thing is keeping my block and it’s components nice and cool

 

I just completed my inline mod yesterday, with a new radiator and water pump. My temps didnt come down as much as yours though. I still see it reading 200.

 

What's your ambient BD? 200 idling or highway driving?

 

Ambient yesterday was 103, Disco temp was 203 driving around town. I wasn’t so concerned about that but was hoping for a greater decrease with the three changed components. Was a little more concerned this morning showing low through high 190’s and the occasional 203 with ambient in the mid 70’s at 60-65 mph on the highway.

 

Your truck will run ambient plus 100 give or take 5-10 degrees, so 203 when it’s 103 is pretty good.

I wouldn’t worry too much until I was at 210 or a hair more. If you’re at 220 that’s too much. Damage starts to happen above 230. I turn the heater on at 210 usually to help bring it down. I like to be under 200 but there’s not much you can do if the outside temp is over 100

 

At highway speed on level ground the factory D2 cooling system can only maintain an engine temperature of 100 degrees over ambient (80 degree ambient = 180 degree engine, 90 degree ambient = 190 engine, etc) regardless of what thermostat is installed. Pulling a steep grade or a trailer the temperature will be even higher. The water pump does not pump enough water too keep the engine cool at idle in hot weather with the AC on. If the engine is revved to approximately 1000-1200 rpm the temperature will come down to normal temperatures (remember, 100 degrees over ambient) or once normal driving resumes. Overall your temps sound normal.

 

Around town at 100 degrees Fahrenheit I run 180-190 ac on or off don’t matter

highway it’s 190-195 ac on 70 mpg

the temperature will start to rise of your really pushing it 70-80 mph as that engine is working

as soon as you drop to 55-60 mph the temp drops

our cooling system is very capable it just gets a bad rap from the leaking weak spots

 

TX is not a fun place during the summer especially Houston/SETX area. I took the XD into Houston last weekend for a friends birthday party. I was running 193F with the AC on at 60MPH. Then traffic on good old I-45 came to a stop as something happened what looked like 2 miles up ahead. I sat there, and it went to 195, 198, 200, 204, 206, 210, and it settled at 220F. I was like OH HECK NO, so I got off the darn freeway, and pulled over. I turned it off and let it sit for about 15min. It gave me time to navigate a route using side streets. I got back out onto the roads, and the Severe Duty Fan Clutch was hard at work. I left the AC off and I got it down to 204F cruising at 35-40MPH. Once I got out onto the open road I got it back down to 193F and turned the AC back on.

I ABSOLUTELY HATE HOUSTON traffic with a passion........ I continue to try n give that place a break, but no matter what I always get stuck in some silly traffic for hours and then find out it was all due to a ladder in the road or something people could have got together and moved vs sit in their vehicles and stare at it for 1-3hr's....

My D2's (1 with the inline mod) and the rest without are 204-215F no matter what. When the sun hides behind some clouds or you get out of concrete city temps always drop. As long as you get up to 215-220 at the absolute most and once you get to moving the temps drop from the fan clutch doing it's job, and air flowing thru the radiator = all good. It's when the temps climb and climb without stopping = you have issues. The Air Intake temp that day in Houston was 151F on my ScanGauge II..... It's usually down in the 110-115F range.

 

I had to wait for my daughter at the airport a couple summers ago - mid afternoon flight arrival. I was in the cell phone lot, AC on - 95-100 degree ambient. Disco would sit there and start around 190 and keep going up, I would rev the engine to 1500 rpm and it would come back down to 90, back to idle climbing again. Must have done that routine 10 cycles waiting for her plane to arrive. AC was keeping me cool though.

 

Nice to hear the posts on this. I too run into traffic and see my temps get up to 206-210. I’ve renewed everything in my cooling system and scratch my head at times reading another Members updates after they ran without coolant for several hours….Had steam coming out of the coolant reservoir and hear strange engine sounds. Next post they just topped off with coolant and are running fine at 170 with original components. Etc. I’m exaggerating somewhat but….
I did learn recently ‘thanks Extinct’ that bumper lights can affect cooling. Who would have thought !