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- 1999 - 2003 7.3L Power Stroke Diesel (https://www.ford-trucks.com/forums/forum31/)

- - ECT question (https://www.ford-trucks.com/forums/1515047-ect-question.html)

My truck is a 6 speed so the scan gauge I have will read the ECT unlike the autos. All summer on the scan gauge I only would see about 165 degrees for ECT. Figured bad t-stat, so I bought a ford oem t-stat and finally got around to replacing it. The dummy gauge on the dash reads higher with the new t-stat and my EBPV has now quit running constantly. Both pluses, but I'm still only seeing a high temp of about 160. Is this normal? I think the oil temp is about 10 degrees warmer up around 170 give or take. I was expecting it would get to 190. Was I wrong on that? Just looking for input to see if I have another issue going on.

I guess it depends on how cold Michigan is in November, how long the engine is running and under what conditions, how accurate your ECT sensor is, and how accurate your OBDII gauge is.

Ambient temp this morning is 25 degrees, truck was plugged in all night and it reached 144 on a 10 mile ride in to work. Oil temp was in the 150's. Heat will roast you out. After I changed the stat I checked it with a infrared thermometer and the readings I was seeing at the t stat housing corresponded to the read out on the scangauge 2.

Which thermostat are you running in regards to temperature? They can range from the low 180's to just over 200 degrees before they pop. Perhaps the thermostat is stuck open and constantly cooling with the 25 degree ambient air which is not letting the engine warm up properly?

Something's not right. I have zero issues with getting up to 190 EOT, and I have the stock-rated thermostat. The EBPV can only be engaged if the EOT is 140 or below... so you've been riding cold for a very long time.

Stinky is a fire breathing dragon in the cab - I have to turn the heat down to 1/2 temp and fan to low to remain comfortable in the winter.

I'm with Sous, maybe you got a bad thermostat and it's failed open. You could remove and try boiling it to see it actually works. My truck has no problems getting to 190*

I agree with everyone else, that you should easily see 190* or more.

Here's something no one has mentioned: Have you checked your fan clutch to make sure its not failed in an "always on" manner? A fan clutch can fail either on or off, just like a t-stat. Having the fan engaged all the time will definitely drag down your oil and coolant temps. Unless under heavy loads, these 7.3L's just don't seem to need much help from the fan. Even in 90deg heat in the summer, mine would rarely come on, unless I was sitting in heavy traffic for a while.

It should be fairly easy to hear the turbofan like woosh if your fan is engaged all the time.

While a oem Ford t-stat should work ok, personally I have the DieselSite 203* one installed. 203* is the OEM INTERNATIONAL specified temp. ( Ya know, the people who engineered/designed the motor) Diesels run cleaner and more efficiently with a little more heat. I have had mine in for over 2 years with no problems.

http://www.dieselsite.com/dieselsite203thermostat.aspx
http://www.dieselsite.com/pdffiles/h...nginetemps.pdf

Here's a brief quote from the website:

Quote:

WHY IS 203° BETTER THAN 195°?

Diesels run most efficiently at approximately 200° or above. A factory equipped 192°/195° thermostat will maintain an operating temperature at approximately 165°-170°. The Powerstroke has such an efficient cooling system, that this low flow when the thermostat is slightly open is normally enough to keep the engine cool. The downfall to this is that the engine -- when our trucks are not under load -- never begins to reach its optimal operating temperature. Our 203° thermostat maintains a minimum operating temperature of 190°. This brings the operating temps up from as low as 170° to as high as 203° depending on the operating conditions of the truck. This is closer to the operating temperature range that is preferable in our trucks for optimal efficiency.

When our trucks are under load and are producing higher combustion temperatures the 203° will allow the engine to run even closer to its optimal operating temperature. If the truck is under load and reaches the 203° setting, the thermostat is then fully open. This means you are at the maximum coolant temperature that the truck will reach. Your maximum temperatures are only a few degrees higher than in stock configuration, but these are degrees that you want for better performance. The best benefits come when the same truck is under a light load and would have a hard time reaching this optimal temperature. As stated above, you will never reach this optimum temperature with the stock 195° thermostat. The end result of installing the 203° thermostat should be slightly better fuel economy, less smoke, and maybe a few extra "ponies" to go along with it.

I was wondering if the fan is the culprit also.

Here's what I'm seeing exactly on the scan gauge 2. ECT warms to 254 and then instantly drops to 127(I assume this is when the t-stat opens) since the gauge in the dash isn't even reading yet and the oil temp is around the 120ish range I find it hard to believe the coolant is actually 254 other than maybe right where ever the pcm is pulling its reading from.
After this truck continues to warm and EBPV runs until truck hits 144 on the scangauge 2 then it no longer engages unless ECT drops below 144. Typical temp I'm seeing is 155-165 which is the same as the old t-stat would do. Reason I don't think the new t-stat is bad.

Another note. about as high as it got is about 165 temp wise this summer even with ambient temps up in the 70's and 80's. Only time I would see the 190's was pulling our fifth wheel or horse trailer.

Fuel mileage isn't suffering I'm seeing 16 consistent and sometimes 17 hand calculated

Quote:

Originally Posted by Sous (Post 17577040)

I don't know the actual temp other than it's them oem motor craft t-stat. But I'm sure they don't make a 165 t-stat lol.

Quote:

Originally Posted by fordboy2 (Post 17577686)

Have you tried changing the ECT sensor.? I would also check the wiring to/from the sensor.
Also, are you sure your monitoring the correct PID on the scan gauge? There are some wacky ones that just don't work right. I can't help you with that though. Maybe Tugly,or someone else familiar with Scan gauge configuration, can help there.

There is no way your coolant is 254*. It would be at a rolling boil and puking out of the overflow/degas bottle. There is also no way, coolant temp would instantly drop 127* ( in half) from the t-stat opening.

Quote:

Originally Posted by carguy3j (Post 17577719)

Have you tried changing the ECT sensor.? I would also check the wiring to/from the sensor.
There is no way your coolant is 254*. It would be at a rolling boil and puking out of the overflow/degas bottle. There is also no way, coolant temp would instantly drop 127* ( in half) from the t-stat opening.

This might be your problem and a good catch by Carguy3j. :-drink

I don't know about you, but I would certainly be able to tell if the fan clutch on my truck was stock on. It is like a Harrier jet trying to land vertically under the hood when the fan is on. Even at 55 MPH or so it is very clear the fan has kicked on.

Quote:

Originally Posted by Sous (Post 17577725)

That's what I thought on the fan, I don't think it hardly ever has turned on, on any of my 7.3's. But I do know what my 6.0s all sounded like. And I have definitely not heard it on here.

I also wondered about the pid which is why I checked it with the thermometer to find the temp was about the same. Plus it corresponds with the EOT once the temp drops to the 127. I find it hard to believe it hits 254 also. The first time I seen it do it I about crapped.

Well I don't think the fans the issue as I don't hear it run. Drove it on a 20 mile 55/60 mph stretch tonight and the etc reached 160 and eot was 176. Assuming that's accurate I guess I don't know where to go from here.

I am not familiar with the ScanGauge tool, but I would start looking at it for faults at this point. Maybe try TorquePro and see if you get the same readings from the ECT and EOT.

1. It is not the fan stuck on.
2. It is not the thermostat stuck open.
3. It is not the sensor.

Not much more involved really...

Yo fordboy...ill second your temps, bro...first off, I believe your seeing the 254*, why.. Because I've seen them temps feeding my wvo system..picture of the gauge, showing my wvo contact, made him a believer. Coolant was tapped into line coming off front of motor...
. Second off, I too see the same temps running if not loaded. I just switched tstat from a duralast to OEM 195*..now, highest is 180* no load, 195*ish towing, do see 210*ish up hills.... with high 17mpg. Even hit a 18.19mpg last month..Duralast stat, gauge never above 160ish, unless towing...i always chaulked up my low temps to the coolant filter....run your truck, because mines been this way fur 7yrs 👍