6.2L Coolant Temperature

[Ruger]

I have a concern about GEN1 coolant temperature under operating conditions.

I have a 2011 6.2L with about 78K miles. Engine internals are all factory. I have an aFE cool air intake and an aftermarket muffler. No mods to cooling system, no mods have had any effect on the cooling system. I have a temp gauge that reads the coolant temp from the truck's own sensors. Last year I noted that the temp had started to fluctuate a bit, so I took it to the dealer and had the cooling system flushed.

This past Friday I drove 600 miles from northern Nevada to central Colorado, and in the final few miles on a 35mph road with a mild uphill grade I noted that the coolent temp spiked at 215 degrees. Under the circumstances I thought that was a bit high, and in the morning I found a small puddle of coolent on the ground under the truck and the level in the reservoir had gone down.

It seemed to me that a termostat that was not fully opening any more might explain this, so I replaced the original factory thermostat with NAPA's premium stainless steel thermostat. Same temp rating as the factory unit. Now, of course, I'm watching the coolant temp gauge like a hawk. Today while driving around Colorado the coolant temp fluxuated between 195 and 205.

IS THAT NORMAL, AND DOES ANYONE KNOW THE TEMP RATING OF THE FATORY THERMOSTAT?

 

[MTF]

195 is factory.

Here's the thing though, the fans don't jump on until 204 +/- 2 degrees and turn off again at 195 to 200 and won't run full speed until 208 to 210.

I had my Tuner adjust that to 175 I don't see anything above 200 on the hottest day, I'm also running a 175 Hi Flow thermostat too.
I was running a 160 and changed it in the winter to 175 for some heat but it didn't matter, if the fans don't run what's the point. So I leave the 175 in.

 

[Ruger]

Thank you for your response, @MTF.

The new thermostat in my truck is also a 195 degree unit. So tell me, please, are the temp readings I've seen (195 to 205) unusual and indicative of a problem, or typical for a 195 degree thermostat?

 

[MTF]

That is the temp Ford set to get the most MPG with the lowest emissions out of the tail pipe for our trucks. So they claim.

When you run the truck colder you well see a slight mpg. drop because your fooling the PCM to add timing and fuel.
The plus side is you get a few more HP.
It's like when you run in a cool fall morning and notice she's got more pep than all summer long, even though it's more about the cold air.

You can run a colder thermostat I buy mine on amazon there like $8 for a name brand Hi-Flow.
Try a 180 it will help when driving but not sitting in traffic or climbing hills slowly.

here's a pic with part number #2028 and the temp, these are all Hi-Flow

 

[Ruger]

Yeah.

But I am driving home to Nevada tomorrow morning. I need to know about my truck, not yours.

 

[MTF]

Same parts.

And before I did the fan temp update I was running the same temps just like you.
Although I never had fluid loss.
Try "Water Wetter" It may help.

 

[Ruger]

Thanks very much!

 

[COBRA90GT]

What about the coolant leak btw, was that sorted out already ?

 

[Ruger]

Well, I'm afraid that the coolant leak is a partial mystery. There have been no puddles under the truck since I replaced the thermostat. BUT, I drove home 600 miles today at 65 to 80 mph with the vast majority of that trip being spent above 2,000 rpm. Air temps ranged from 40 to 98 degrees. I got home, the truck has cooled off in the garage, and no puddle. But the reservoir level is down about a quarter-inch, and nothing under the hood or under the truck is wet with coolant. Beats the hell out of me!

BTW, a tip that will be useful for anyone who changes the thermostat on a 6.2L. Both NAPA and Auto Zone have listings for two thermostat O-ring seals. One is about $1.99 and is just a little too small in outside diameter and it WILL leak immediately. The other is just a little bigger, the price is $7.99 (for a single O-ring!), and it's the correct part and will not leak. Remember this. Both NAPA and Auto Zone think that either O-ring will work, so why not buy the one that costs 1/4 the price of the other? Leaks are why.

Anybody who has an idea why my reservoir anti-freeze level goes down without evidence of a leak please contribute your wisdom. (No, there isn't anti-freeze in the motor oil. I just changed the oil and after 1,200 miles it looks clear and new.)

 

[bigrig]

Well, I'm afraid that the coolant leak is a partial mystery. There have been no puddles under the truck since I replaced the thermostat. BUT, I drove home 600 miles today at 65 to 80 mph with the vast majority of that trip being spent above 2,000 rpm. Air temps ranged from 40 to 98 degrees. I got home, the truck has cooled off in the garage, and no puddle. But the reservoir level is down about a quarter-inch, and nothing under the hood or under the truck is wet with coolant. Beats the hell out of me!

BTW, a tip that will be useful for anyone who changes the thermostat on a 6.2L. Both NAPA and Auto Zone have listings for two thermostat O-ring seals. One is about $1.99 and is just a little too small in outside diameter and it WILL leak immediately. The other is just a little bigger, the price is $7.99 (for a single O-ring!), and it's the correct part and will not leak. Remember this. Both NAPA and Auto Zone think that either O-ring will work, so why not buy the one that costs 1/4 the price of the other? Leaks are why.

Anybody who has an idea why my reservoir anti-freeze level goes down without evidence of a leak please contribute your wisdom. (No, there isn't anti-freeze in the motor oil. I just changed the oil and after 1,200 miles it looks clear and new.)

I had an issue where coolant leaked out of the reservoir cap. I replaced both the radiator cap and the reservoir cap and the issue no longer exists. You may want to keep an eye on and around your reservoir and tube which connects it to your radiator. That may be the culprit.

Also, you said you had your radiator flushed recently. If you noticed the fluid go down shortly after that, it could be the air getting purged from the system.