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How long to warm up?

20K views 28 replies 11 participants last post by  Airstreamer67 
#1 ·
Ever since I first got my truck I have thought it takes way too long to get up to temperature. I finally changed out the thermostat thinking it might have been stuck open, but I can not tell a difference. I could let it set and idle for at least 20 minutes (85 degrees outside today) and the temp gauge will barely move. Is this normal, or is there something else I need to be checking?
 
#2 ·
Idle does not make much heat. What temp thermostat did you install? Is your fan clutch seized?
 
#5 ·
Diesels just don't warm up like gas engines do. If the Motorcraft thermostat is for a 94-95 it is most likely 205*. If it is for 96-97 it most likely is 195*. To get the hotter (203*) thermostat for the 96-97 it needs to be ordered from Dieselsite. If the fan is turning hard all the time the fan clutch may have failed. Most of the time when fan clutch's fail they lock on. But I've also seen it do the opposite. My older son's IdI fan clutch is locked on and my younger son's powerstroke fan clutch never engages.
 
#6 ·
Cylinders in a diesel engine take in a full "gulp" of air on every intake stroke, but only inject a very small amount of fuel at idle. They are very fuel efficient at idle, but very thermally inefficient because all that air sucked in robs the engine of heat and blows it out the exhaust pipe. I can drop my 7.3's temp 40* just by downshifting off the highway to a stop - lots of air, barely any fuel.
Contrast that to a gas engine which has a throttle plate to greatly reduce the amount of intake air at idle in order to keep the fuel mixture correct. Diesel doesn't care about it's A/F ratio.

Also remember, the 7.3 is 960lbs of cast iron, adding more for fluids. It takes a lot of energy to warm that up!
That's why the 7.3 has an EBPV - its to slow down the air leaving the motor.

The dieselsite t-stat probably won't help warm up times, but it will keep the engine warmer, which is supposed to help other issues.
 
#8 ·
The factory temperature gauge can be misleading. In my truck, when the needle hits the "N" my engine temps are about 200F. That's where it generally stays. Lots of folks think the truck is running cool since the needle stays on the "cool" end of the gauge. In my truck, when it's on the N it is at full operating temperature.

I would say that the OP's truck is acting normally, at least according to my truck. Taking only 3.5 miles from a cold state to reach "N" is quick, I'd say.

And as noted, it never really gets warm when just idling.
 
#10 ·
I don't really pay attention to temperatures except when I'm driving. I don't have a coolant gauge so I just go off oil temp readings to know where my truck is at which during the winter is a don't worry about it situation. As long as it isn't leaking coolant and the catch tank is where it should be I do not care about the temperatures. Been doing it that way for the past 372k miles between my father and I when I bought it off of him.
 
#11 ·
Thanks fro the input guys. I guess I was overly worried. When I first got my truck I read on hear or another forum where a couple of guys said they did not drive their trucks until the thermo needle was on at least the N. I was like my truck will never move then. I have been keeping RPM's really low until I saw the needle really start to move. Again thanks for the information.
 
#12 ·
There's no PID for coolant temp on the OBS. If you want a more accurate idea of temps, get a monitor so you can watch oil temp. The coolant temp sensor just sends a signal to the dash and not the computer. But your temp gauge sounds like it's acting just fine.
 
#13 ·
I have a 96 7.3 and use Torque Pro to monitor my truck. The temp guage on the dash has been operating just as you explain going up to the "N". So this does read coolant?

With and OBD reader, I can see EOT, but not ECT. How can I get ECT on an OBD reader? Mine just flashes -40

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#14 ·
Obs doesn't have a coolant temp sensor going to the pcm. It staying at N could be the thermostat stuck open. These trucks will run cold just idling with a working system.

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#15 ·
I guess what I was asking is where can I put a coolant sensor?

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#18 ·
Depending on driving habits of the day, my gauge tops out at the N. I've never seen it any higher than that. If its cold out or I'm babying it, it'll sit down towards the line. Driving to work, it takes a few miles of light throttle and cruise control to warm up. So far, its been treating me well!
 
#19 ·
These cooling system are very efficient. Running too cool is not a good thing. The oil needs to get warm enough to push out moisture.

Mine was barely getting to the "N". Put on some gauges and that was barely 160.

Put in a 205 thermostat and it idles much smoother, better throttle response, better mpg, and it overall drives much happier.
 
#21 ·
Water pump was done before I purchased the truck 3 years ago. Not sure what thermostat I've got in it. Anyway to tell? It's been below freezing in Montana and I can do 75 down the freeway with 190°-195° on the EOT. Idle drops to 160-165. I don't know own how to take a coolant temp reading. I did however replace the radiator cap with a new 15 psi cap.. if that helps.

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#27 ·
What about warm down? Does anyone run turbo timers on their powerstroke? I feel like if you've been driving down the freeway towing 10 tones that you might want to circulate some antifreeze and maybe let the bearings in the turbo cool down a few minutes but dont want to sit in the truck waiting.
 
#28 ·
I let the EGTs get to 400 or below before I shut it off. It gets there very fast usually. Only place oil will coke is in the turbo, so my thinking is, cool EGTs, cool turbo, good to shut off. You'll be waiting a while for oil temps to come down. It's not the hot circulating oil that cokes up, if so it would be coking everywhere. It's the non flowing oil left in the hot turbo that does.

Turbo timer in my opinion is a waste of $$. Take an extra minute and you'll be fine.
 
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