Temp runs hotter on Highway

[Troy 82]

At idle or crusing around town, my temp reads just above the 1/4 mark on the gauge. At a constant speed 60 or more it goes between 1/4 & 1/2 on cool nights & just below the half mark if it's hot outside. What is the most possible cause? water pump, Radiator? I ran some radiator cleaner through it, new temp sender. Thanks!

[79gmcc15]

is the coolent level right? stupid question but it happens.. my guage always is at the first mark on the guage. and sometimes when I go on the interstate it might go a little over. but it also hasent been texas type weather here too. I would probly get the car hot, take off the cap and see if the water is moving. useualy if it isent or very slow could point to eather bad stat or pump. but dont pumps make noises when there about to bite dirt? one fairly cheep thing is to flush it. might be good to do befor summer.

[Brad_Olson]

Higher temperatures at speed are often airflow-related...are the radiator (and A/C condenser if you have one) fins clean, unbent, and free of obstructions?

Brad

[edog1]

Could a raditor hose be collapsing and resricting the flow

[Eyegore]

Also check the flow on the radiator, it may to be rotted out. I also had an 82 silverado doing the same thing. Took it to a radiator shop they said there was 30% blockage so that is why it heated up at higher speeds when more coolant is forced through the radiator, it could not handle the extra volume of coolant being forced through. I believe it was $30 to have it rotted out.

[ureckme]

30% block OK 30% of 195 is 58.5 D/F Thats 258.5 deg.s Mine runs at 1/2 mark but this is Arizona. Matt

[PHOENIX]

As stated by others:
Hoses could be collapsing from higher pump speed/weak hoses.
Check hoses, replace if old or cracked.
Pump could be bad.
Check water pump belt tightness, adjust or replace if needed.
Radiator restricted from outside air.
Radiator inside plugged and not flowing properly.
Engine block plugged and not flowing properly.
Check radiator cap, overflow bottle and overflow hose.
Do you have a thermostat if so, what is the rating?
Do you have proper coolant to water ratio and level?
Bad timing or bad fuel/air ratio can cause higher temperatures.
Sometimes the older gauge/sensor do not read correctly.

When was the last time you flushed the system?
I depend on my cooling system a lot out here in Phoenix and replace my coolant/water at least once a year and check for build up.
Have you recently made any changes to your truck?
BTW: I have some autometer gauges, new radiator, hoses, sensor, thermostat, water pump, etc. (my systems is working perfect). I have a 195 thermostat, once the truck is warmed up it runs from 180 to 195. Back and forth all day, you can watch it slowly go back and forth every so often.

[Tom]

Stock water pump and radiator? How many cores? Heres a good one: check your timing for the ignition, it can affect temps. My 3 core/high flow pump runs just under the 1/4 mark at all times.

[1FaastC10]

if its only registering halfway on the guage, why worry about it?

[Troy 82]

I just got back in town, sorry for the late reply. I flushed the radiator & the coolant level is fine. I've checked the timming, it's ok also. Airflow is ok. Bottom hose has the spring in it, keep from colapsing. It has a 160 stat, idling it will stay just above the 1/4 mark. Highway speeds 65mph it goes just under the 1/2 mark. It has a stock pump & radiator (2 core ) I already plan to swap it out for a 3 core. Maybe that's it. If not I will try a new cap, stat, & water pump.

[1FaastC10]

again, if the guage isnt indicating anything out of the ordinary, why are you trying to fix a problem that doesnt exist?

[boxrodz]

I, too, don't think you're having any cooling problems, so long as it registers under the halfway point (~210*). I have a fairly new 3-core radiator, heater core and waterpump. While driving in-town, the temp registers around the 1/4 mark (150*). It'll go up once the weather warms up. On long trips (i.e 3 hrs) and at highway speeds, the temp reaches closer to the halfway mark (~180*). I've been on longer trips and in traffic jams during the summer, and it remains around 180*.