I have replaced thermostat, radiator, clutch fan and added water wetter. Temps around town are great, mid 190's. But on the highwy I am back hitting 206-208.

Could having an aftermarket bumper block too much of the air flow?

 

Well duh.

The winch and lights restrict air flow.

 

Lmao spike, did you make sure you bled your coolant system properly after your changes? My grill is covered way more than yours with factory T-stat and i run around 194 on interstate.

 

Snake oil's will not help engine temps.
Over sized tires and a huge lift will make the engine work harder at highway speeds.
The tires because they weigh more, the lift because now you have more aerodynamic drag.

 

206-208 seems fine to me. As long as temps are stable and the fan's not kicking in (I believe at 212 on these trucks?) I have always been fine with higher temps which make the engine slightly more efficient.

Also, not much point in water wetter unless you're running straight distilled water and really need the extra detergency. Been there, done that. Makes barely any difference when using with antifreeze.

 

Yeah it is bled ok. Actually had the shop do it last time. It must be the addition of lift/ tire resistance/roof rack that is killing my highwy temps. I have replaced all of the cooling components.



Crazy thing is several folks including other bumper manufactures said no. The bumper designs don't affect cooling.

Do you think it woud make a noticible difference by moving the control box under the hood out of the way, I have the wireless remote so access isn't an issue? Or is this just the way it will be?

 

You will make little effect. The cubic feet per minute at 60 mph is 5280 X square footage of radiator (in a perfect world, a little more with the viscous fan). If the radiator is not sludged or calcium coated inside, the radiator is capable of maintaining normal temps for guys in the desert.

While obstructions block the theoretical maximum flow, you are way below that.

IMHO - radiator sludge can be detected by infra red thermometer - "shoot" the fins low and high after running and switching off. If close (like 10 degrees) top to bottom, all the tubes are open. If cooler at the bottom, no coolant flow or restricted in those rows. 2/3 of a radiator won't do in the summer. But you replaced the rad already - new or used?

And the 82 C "grey" thermostat will drop temps 6-10F. But it won't fix a sludged radiator.

Now at idle, the physical air blockages are more likely to cause a problem, as the air flow drops to 800 - 1000 feet per minute (viscous clutch fan and electric fans).

I've got a Mercedes with about half the radiator blocked by bumper and front shroud. No issue.

BTW, if overheating when trailering, here's another way to drop those underhood temps....

 

There is more then enough air flow with that and most other after market bumpers, that is not causing your higher high way temps. You are running great in town temps, probably better then most, your high way temps should be in the 194 to 197 range and should be looked at.
As for Spike's statement that fish oil won't help cool the engine off, he is right, but most of the Coolant additives like Super Cool, Water Wetter, Purple Ice and Lucas's Coolant additives will help in a few ways, they lower the temp some, they prevent scale build up, lube the water pump and prevent electrolicis, probably spelled wrong.
As for running these products with distilled water, most will tell you not to, that it should only be used with a 50/50 coolant mix.
As for your higher temps on the road, based on what you have done so far, I am not sure where to point you. Were those temp. readings done with the a/c on and was the electric fan running?

 

Mike - yes the ac was on and when I checked the electric fan was running.

Savnah - yes I only get hot on the highwy. Around town/ in traffic is just fine. I am just confused since I hve never had a truck run hot on the highway, I lways had trouble in town due to air flow. As mentioned earlier, new radiator, thermostat, fan and antifreeze. I guess I just want cooler tmps on the highway.

 

[QUOTE=ebg18t;335983]Yeah it is bled ok. Actually had the shop do it last time. It must be the addition of lift/ tire resistance/roof rack that is killing my highwy temps. I have replaced all of the cooling components.

Just because a shop did it does not mean if was done right
And mine has alot of mods done to it and my lights are totally blocking my grill from much air flow and i still run around 194 on interstate with factory thermostat. Maybe if you want cooler temps you could look into a 180 stat and see if that helps get you what you want.