Normal Coolant temperature

LaMont Owner/Technician Ohio Posted   Latest  
Resolved
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2015 Ram 1500 Outdoorsman 3.6L (G ERB) 8-spd (8HP70) — 1C6RR7LGXFS749486
Engine Temperature Seems To Be A Little High

This truck came in with bad head gaskets. The odometer showed 173,000 miles, so rather than repair this engine, we installed a used one that has 6,000 miles on it. It runs great, but the coolant temperature stays around 220 deg. while driving down the road, and can go as high as 229 deg. while sitting at a stop sign. The fan comes on at 230 deg. We replaced the thermostat prior to installing the engine. I'm wondering if the temperature while driving down the road may be a little high. Any thoughts? Thanks in advance.

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Andrew Diagnostician
Michigan
Andrew
   

Huh, I am wondering if you some type of a flow issue through the radiator. I have used a infrared or a thermal imaging camera to check inlet and outlet temps of the radiator. You should see a temperature change not sure exactly what it should be but I would guess somewhere around 20 deg or so. Another thing to check is to verify you have coolant flow. Do you know what temp the thermostat is…

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LaMont Owner/Technician
Ohio
LaMont
 

Can't seem to find normal temp spec in service info. I forgot to mention that the radiator is new. The old one had a split tank, and was also leaking coolant at the oil cooler.

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Mark Owner
Georgia
Mark
 

Why did the first engine blow a gasket? Radiator flow? Check Mfgrs temp for fan engagement. Cheap temp sensors are everywhere. Use an O.E sensor.

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LaMont Owner/Technician
Ohio
LaMont
 

We installed a new radiator prior to replacing the engine. The temp sensor is the one that came with the engine that has 6,000 miles on it. I can't find a spec. for when the fan should come on, but that seems to be about what I've seen on other vehicles.

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Mike Owner/Technician
New York
Mike
   

Greetings ..... coolant flow restriction in the radiator from the blown head gaskets or frontal airflow restriction .... does sound kinda high though ...... manufacturing defects in the new radiator...? Water pump impeller...?

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LaMont Owner/Technician
Ohio
LaMont
 

I've checked for air restriction and I can see light through the condenser and radiator.

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Eric Owner/Technician
Wisconsin
Eric
 

How are you measuring coolant temperature? Have you checked coolant temperature after the vehicle sits over night to verify the sensor matches ambient temperature? Have you compared actual coolant temperature to the coolant temperature sensor reading? Have you checked with an infra red camera? Have you verified the temperature that the thermostat opens at? Have you installed a new OEM…

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LaMont Owner/Technician
Ohio
LaMont
 

Some good ideas. We have verified actual temperature after a cold soak with ambient temperature. Thermostat is new, but not OE. Measuring coolant temp with a scan tool. Have not used the infrared camera.

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Perry Technical Support Specialist
Texas
Perry
 

The Pentistar 3.6 Cooling system thermostat is fully open at 230 F.

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Perry Technical Support Specialist
Texas
Perry
 

I beleave there is a new part# for the water pump for the Pentastar 3.6 also.

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LaMont Owner/Technician
Ohio
LaMont
 

I found a TSB for a pentastar. It is for a 2013 MY. I'll have to see what year vehicle my engine came out of.

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Perry Technical Support Specialist
Texas
Perry
 

Does the vehicle have Grill Shutters. if so.. un plug the Shutter motor in the open mode and road test again.

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LaMont Owner/Technician
Ohio
LaMont
 

It does not have grill shutters.

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Perry Technical Support Specialist
Texas
Perry
 

I would agree with Eric's post before I would replace any parts.. we would be interested in those findings.

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Stephen Owner
California
Stephen
   

I have a 2012 Wrangler 3.6l I just took it for a drive around the block then let it idle. Temp went to 228 deg then fan came on and turned off at 205 deg. Also it’s 95 here today.

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Paul Mechanic
Illinois
Paul
 

No reference on this particular engine and I know how we can get hyper sensitive on issues we are trying to fix and given what happened to the first engine temperature wise, but I would first find out what t stat is rated at, but more importantly, if fan(s) come on and you can feel a healthy amount of heat come off radiator, you're probably good to go. Good luck. Sorry about the run on sentence.

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Bentley Manager
California
Bentley
 

According to the Stant catalog the OEM thermostat opens at 208 and 15 to 20 degrees later it is fully open. That would put your numbers where the manufacturer designed the system to run. That said I would not want my truck to run that hot and would try to stuff a lower temp thermostat in it.

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Perry Technical Support Specialist
Texas
Perry
   

Good day Lamont, As printed in the Pentastar 3.6 engine interduction training manuel, the engine cooling system thermostat operation is 180F to 230F.

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Stephen Owner
California
Stephen
 

My Pentastar goes to about 230 then the Fan comes on then it comes down to 205 gauge is always at middle. It’s normal.

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James Owner/Technician
Saskatchewan
James
 

Do you have good coolant flow through the heater core? We had one that was a few years older with a 4.7 that needed the waste heat from the heater to open the thermostat. Dumbest design I've ever seen. There is no coolant flow across the back side of the thermostat if the core is blocked. A Hecat flush of the heater core solved it. It would take a while to heat up, but would work up to 240 or so…

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LaMont Owner/Technician
Ohio
LaMont Resolution
 

Thanks to everyone who replied. I guess I'm going to go with the opinion of those who have vehicles with these engines and say that the temperature I'm seeing is normal. A google search also showed quite a few people who said their Pentastar ran in this temperature range also. While this seems a little high to me, I guess I'll consider it normal.

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