how much time before 7.3 is warm? outside temp now 10*C

[KansasIDI]

My Blue Truck started acting up in colder weather. It acts like the thermostat is open. I replaced the thermostat last winter and the old one was closed when I removed it. I still put a new one in since I was already to that point. The new one acts just like the old one did. It seems fine until the temps get down into the 30's. I just do the cardboard trick for the winter time and pull it back out in the spring. Probably almost three years ago now, I left the cardboard in front of the radiator for longer than I had planned. I got a call from a friend and drove to meet him and his wife to eat. It was in the lower 80's and there was a pretty good wind blowing that day (probably 20 MPH). The needle on my mechanical temp gauge stayed right above the 190* mark like normal. The only time that it showed hotter was when I turned easy and had the wind blowing from the side. Then it got to maybe the 200* mark. That was empty. I don't tow very often so I don't have much input in that regard.

If you ask me, these things run cold with a properly working cooling system. Fine by me, it gives some leeway vs running hot…

 

[IDIBRONCO]

If you ask me, these things run cold with a properly working cooling system. Fine by me, it gives some leeway vs running hot…

The funny thing is that it didn't used to do that. I've driven it into a 25-30 MPH north wind holding a steady 65-70 MPH, when it was 5* down to 0* with no cardboard in front of the radiator, and it stayed right below 190*. The only thing that I can see different is that I did the 6.9 cooling mod during the overhaul after that. I don't think that it affects the cooling system that drastically though. I haven't seen anyone who said that it made a difference on their temperature gauges. Maybe it does?

 

[Black dawg]

Have never had trouble getting idi motors up to, or maintaining minimum thermostat temperature.

 

[Cant Write]

Maybe I’m lucky, and I’m really new to IDI’s, but November 2022 headed for the Black Hills I ended up idling for a couple hours in WY at a rest stop.

Must have been 15F with a 30 mph wind. Also; to help the family sleep I putzied along at 55 mph when I was driving.

I had heat the entire time (idling and driving) with my HVAC set on vent and around 3/4 towards hot. Rear heat off as has no temp regulation (full hot when on)

 

[Bart F-350]

Just a little theorie from my side, I might be wrong I might be right?
As far as I know, a cooling system with a thermostat in it should work like this, isn't it?

little circuit includes heater system in the truck, That's the first one to warm up when engine runs.

Big circuit, is after the thermostat, includes the radiator.

engine starts, warms up the little circuit first, including heat in drivers cab. when that circuit is hot enough, bit by bit (by means of the opening and closing of the thermostat) it heats up the big circuit, which will then be cooled down by the outside air passing through the radiator, right?

I'm not sure if by our engines the sensor who provides the signal to the dash gauge is in the little circuit? but I don't see why we should need cardboard or winter screens before our radiators? if this cooling circuit (In total) was working ok, in real cold weather the little circuit would keeping the engine warm enough, while the big circuit would stay cool, wouldn't it?

Or am I looking over something?

 

[Rdnck84_03]

I haven't installed a true temp gauge yet but my dummy gauge always reads low. The heater gets plenty warm even in below 0 temps. During the summer with 100+ temps the highest I have ever seen the gauge is between the O and R, I don't use it to tow so I don't know what it will do loaded.

James

 

[Rdnck84_03]

Just a little theorie from my side, I might be wrong I might be right?
As far as I know, a cooling system with a thermostat in it should work like this, isn't it?

little circuit includes heater system in the truck, That's the first one to warm up when engine runs.

Big circuit, is after the thermostat, includes the radiator.

engine starts, warms up the little circuit first, including heat in drivers cab. when that circuit is hot enough, bit by bit (by means of the opening and closing of the thermostat) it heats up the big circuit, which will then be cooled down by the outside air passing through the radiator, right?

I'm not sure if by our engines the sensor who provides the signal to the dash gauge is in the little circuit? but I don't see why we should need cardboard or winter screens before our radiators? if this cooling circuit (In total) was working ok, in real cold weather the little circuit would keeping the engine warm enough, while the big circuit would stay cool, wouldn't it?

Or am I looking over something?

Yes this is the theory of how it is supposed to work.

I am not sure if these engines run a small thermostat bypass hose like most other ford engines do (I have not had to do anything with the water pump on mine yet and haven't really paid attention while working on other things).

If they do have the bypass I would guess that just it is allowing enough cold coolant into the engine and with the efficiency of these huge radiators that it keeps the temps below thermostat temp.

If that is the case it would be an option to put some sort of a restriction in the bypass to slow the circulation and thus allowing the thermostat to control it.

Someone that is more familiar with the setup used on these engines can either confirm or shoot down my theory.

James

 

[Black dawg]

Just a little theorie from my side, I might be wrong I might be right?
As far as I know, a cooling system with a thermostat in it should work like this, isn't it?

little circuit includes heater system in the truck, That's the first one to warm up when engine runs.

Big circuit, is after the thermostat, includes the radiator.

engine starts, warms up the little circuit first, including heat in drivers cab. when that circuit is hot enough, bit by bit (by means of the opening and closing of the thermostat) it heats up the big circuit, which will then be cooled down by the outside air passing through the radiator, right?

I'm not sure if by our engines the sensor who provides the signal to the dash gauge is in the little circuit? but I don't see why we should need cardboard or winter screens before our radiators? if this cooling circuit (In total) was working ok, in real cold weather the little circuit would keeping the engine warm enough, while the big circuit would stay cool, wouldn't it?

Or am I looking over something?

Yes, if the thermostat is working correctly, engine should have no trouble reaching thermostat temp. If the thermostat isnt leaking and is functioning correctly engine will run close to thermostat temp regardless of ambient temp. The reason the winter front helps is that the thermostat is fairly slow moving, and in cold temps it will open slightly to regulate engine temp, and if engine isnt being worked it takes very little cold coolant to get back to t stat temp, except now the thermostat is slowly closing and engine temp goes slightly lower than expected (too efficient of radiator for low load cold temp). Cold front reduces efficiency of radiator, making engine temp slightly more consistent.

Also, if that little check ball is missing in the thermostat housing, a slight amount of coolant will flow all the time causing slow warm up and some trouble maintaning temperature depending on load and ambient temp

 

[KansasIDI]

I have an enormous aftermarket radiator, and I too have done the 6.9 cooling mod to my 7.3

 

[FrozenMerc]

It would be interesting to put thermocouples in the inlet and outlet of your radiator to see exactly what is going on. My guess is your thermostat is just cracking open enough to maintain 145 degs in cold weather, especially with a large, efficient rad that results in low coolant flow and a large temp drop across the rad.

 

[Black dawg]

It would be interesting to put thermocouples in the inlet and outlet of your radiator to see exactly what is going on. My guess is your thermostat is just cracking open enough to maintain 145 degs in cold weather, especially with a large, efficient rad that results in low coolant flow and a large temp drop across the rad.

I think in conditions where the amount of heat the engine is putting in the coolant is constant, that the t stat does open far enough to maintain that temp, but in varying conditions I think that there is probably some movement of the t stat?

 

[Bart F-350]

I had a 100Km round trip to the inspection two weeks ago, and it was fairly good weather, 20*C, and the gauge did only move to the beginning of the scale.
The radiator you couldn't touch, so warm.
Now with the cooled down engine I did get the electric cable off from the temp sender, and had the cable touching ground, and my gauge did go to the end of the scale. so that is ok.
I do think that my coolant temp sender id U/S now.
It's the sender at front of the engine in the head at drivers side. Is this the only one for the 7.3IDI?

Anyone a suggestion which to use and where to get one?
Oh please note, I'm not in the US.

 

[Rdnck84_03]

I'm not sure what kind of brand availability you have over there but I have always had fairly good luck with STANDARD brand.

James

 

[mf7lakes]

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