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Coolant temp getting to hot.

12276 Views 50 Replies 17 Participants Last post by  djb383
It got up to abot 87 outside today which is the hottest it been this year but most definitely not as hot as it'll be in a few months. On my way home from work my ultragauge alarm went off for high coolant temp. It got up to 228 (usually stays right above 200) while I was on the toll road. I was going about 80mph when it happened. I got off the highway and took the back roads home and it cooled down to about 218 and stayed there the rest of the way home. After it cooled off I checked the coolant level and it was full. also checked the fan and it spun with little resistance. Any ideas why it getting so hot?

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Check it out tomorrow and see if it reacts similar.

If it is, stop to idle for it to stabilize (but don't allow it to to stay hot for a long time). Shut it off and immediately spin the cooling fan. If the fan easily spins, the clutch mechanism is likely failing.

Are the fins of the radiator all mashed over? Is the grill/radiator blocked?
Next option would be water pump not circulating coolant properly.

Technically, 87 isn't all that hot. Especially for the highway, no excuse for a cooling system not to cool adequately on the highway. I'd first get the cooling system checked to ensure it's properly flowing coolant. The fan really doesn't do much on the highway.
Radiator and grill have a few bugs but no major blockages. Ill try spinning the fan when its hot tomorrow. I know 230 is hotter than it should be but at what temp should I really start to worry? How big of a deal is it to replace the water pump?

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I'm really not sure what is scary hot, nor have I done a water pump replacement on the engine either.

I think the truck has precautions built in so as not to officially overheat though. If the light hasn't come on or you haven't go to reduced power node I don't believe you're in the danger zone. I'm really not sure though. Not even sure if reduced power will come on with a hot condition either. Many vehicle now have a safe mode.
If you feel it is getting too hot and you can't stop driving, put your heater on and the hvac fan on high.

I've been up to 215 according to Ultragauge, and it is routine when it's hot outside, but not 215 while driving down the highway. Too much airflow passing through to keep it cooler. That is when it's 110 degrees outside too.
The water pump is easy. Just pop the belt and remove the bolts. But where you have the stock fan I'd say remove it first. From what I was told our water pumps as long as not leaking are pretty good. Have u changed your thermostat?
Have u recently had any work done on the cooling system? If so there could be air pockets if not properly bled.
not yet. Im gonna stop and get a new t stat tonight. Stayed around 200 this morning but it was only about 60 outside

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Yep, 200 is too high in 60 degree ambient.


ALL, is there a warning that appears when it's too hot? We get codes for a cold condition, what about a hot condition?
Is there any way to test the thermostat? It got up to 228 and no codes.

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Also make sure your DexCool to water ratio is correct. If your in a hotter climate you may want to add 6 qt of distilled water to 4 qt of DexCool. 60/40 mix
After searching I found that 256*f is when the dic will issue a over heat. I changed my thermostat to the new 195*f and the truck will run warmer so don't be alarmed. According to my edge insight when running and idling around town I will be at about 203*f and when running down the hyw it will stay about the same. If I just sit parked for some time it will creep up and stay at 215*f then drop off again. But hooked up and towing with my 20ft travel trailer and towing in 3rd gear at 60mph it will rest at 204.8*f and the max I hit was 230*f going up big ass hills with the a/c running. At that time out side temps were about 80*f.
Is there any way to test the thermostat? It got up to 228 and no codes.

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Place the stat in a pan of water on top the stove using a cooking thermometer to measure water temp. Bring the water temp up slowly while watching the thermometer. The stat should just barely start to open at it's "rated" temp, it should open smoothly/slowly as water temp climbs and be fully open (+/-1/4") at +/-15 degrees above it's "rated" temp.

Do not place the stat into boiling water, doing so tells u virtually nothing.....it is not exposed to boiling water inside the motor.

Remember, a properly functioning t-stat does one thing only.....determine minimum coolant temp. The rest of the cooling system, it's condition and driving conditions determine maximum coolant temps.
i have a question for all of you running the scan gauges... when you guys are at 220 degrees, where is your temp-gauge reading at???
I'm not sure I've ever seen my scan gauge at 220F to be honest. I've got a 180F thermostat and the trucks gauge reads just a tad over 1/4 when the scan gauge hits 195F or so. If it ever gets to 80F in Conn this year I'll know better.
i have a question for all of you running the scan gauges... when you guys are at 220 degrees, where is your temp-gauge reading at???
We're starting to see 98* days here in Cali and yesterday it was at 210 in traffic, it sat right about the half mark, maybe a tad over.
At 220*f I show just over half way mark. But my understanding is that these gauges are a bit off.
Yes they are, especially if you've redone your cluster with LED's. Then you really never know how off it is, that's why I rely on my scan gauge.
Yes they are, especially if you've redone your cluster with LED's. Then you really never know how off it is, that's why I rely on my scan gauge.
Just curious how would leds in the cluster affect temp gauge?

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You have to take the needles off and put them back on. If not done correctly can throw your gauges off.
That's what she said! :lmao:
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