Dealing with the heat

[ARigutto]

I recently moved from Alaska to Arizona and drove my 2003 Dodge Ram 2500 down. I recently rebuilt the engine and transmission, but the truck is still at stock power level(250hp). I am new to the triple digit weather and just want to make sure that the coolant temps I have been seeing aren't going to lead to an issues. I commonly have been seeing the gauge go above 200 degrees and I would say it normally peaks at about 210. Is it normal to see temperatures like this even when their is no load on the truck? Is there a way to keep the temps down just to provide more leeway if I ever do tow anything? What temp does the fan normally kick on?

 

[Darkbloodmon]

AK to AZ is a sharp change alright. Stock thermostat is a 190*, I'd say those temps are normal dependent on your ambient temp unloaded. As for towing in the triple digits I would verify your clutch fan is functioning as it should as well as the cooling system. I would recommend the fleece coolant bypass with a 180* T-stat in that climate if you're looking to tow, your stock T-stat is going to be working hard opening and closing. It's a nice failsafe if the stock one has failed closed. I've personally seen milder and more consistent temps on my own truck with it, but I'm in the south. I don't recall the temp the fan kicks on at I'll check my 03 FSM and report back if someone doesn't already beat me to it on this thread.

I'm sure others will chime in about OEM parts only but I'm using a Stant superstat in my 03 over a standard T-stat. It opens and closes faster. No issues with it.

I recently installed an OEM clutch fan and I'm having issues with it even with my upgraded cooling and intake system(Rad, intercooler), I was going up a 6% grade in 5th gear with roughly 400lbs of payload in the bed and I was still cresting over 200*. This is in NC ambient was maybe 80- high 70s from memory.

 

[ARigutto]

AK to AZ is a sharp change alright. Stock thermostat is a 190*, I'd say those temps are normal dependent on your ambient temp unloaded. As for towing in the triple digits I would verify your clutch fan is functioning as it should as well as the cooling system. I would recommend the fleece coolant bypass with a 180* T-stat in that climate if you're looking to tow, your stock T-stat is going to be working hard opening and closing. It's a nice failsafe if the stock one has failed closed. I've personally seen milder and more consistent temps on my own truck with it, but I'm in the south. I don't recall the temp the fan kicks on at I'll check my 03 FSM and report back if someone doesn't already beat me to it on this thread.

I'm sure others will chime in about OEM parts only but I'm using a Stant superstat in my 03 over a standard T-stat. It opens and closes faster. No issues with it.

I recently installed an OEM clutch fan and I'm having issues with it even with my upgraded cooling and intake system(Rad, intercooler), I was going up a 6% grade in 5th gear with roughly 400lbs of payload in the bed and I was still cresting over 200*. This is in NC ambient was maybe 80- high 70s from memory.

While I had the engine out I installed the fleece coolant bypass because I was already there. The truck got new radiator hoses, a new radiator, a new water pump and a new 190* thermostat. If changing the thermostat helps that is an easy fix in my book. How would you recommend checking the fan clutch?

 

[Darkbloodmon]

How would you recommend checking the fan clutch?

I'm still reading up on it myself, the fan clutch is a bane of these engines with it cutting the wiring harness, causing no start conditions, and affecting A/C (Critical) and cooling performance.

There should be plenty of diagnostic threads on it, just have to sort through the symptoms in my case. As far as checking the fan clutch, just review the conditions it's supposed to turn on and verify yours performs as specified. I'll check my 03 FSM since I have some spare time now.

 

[Darkbloodmon]

Just went through my 03 FSM on the cooling and AC system. I didn't find any specified number for diagnostics on the clutch fan engagement temperature. It's ECU controlled based off the coolant temp sensor and A/C system sensors.

Essentially it said, you'll get a DTC code if something is wrong. Maybe someone with diagnostic access on systems and components can dig deeper as to the testing.

 

[User113]

If you have any way of monitoring the truck's PIDs, you could compare the Fan-PWM (which represents the percentage of clutch lock time) to Fan Speed (which reports the actual RPM). You would then have to factor in ES (the actual engine speed). Probably too complicated to do on the fly, but you might be able to detect large deviations from what is being commanded.

BTW, 200° is OK, but 210° seems too high. 50/50 antifreeze boils at 223°.

Also, on these trucks, fan doesn't really just "kick on." ECM can modulate (within limits) via a PWM signal the actual fan speed regardless of engine speed, or let it free-wheel. Except, of course, when it is too busy doing other things...

 

[ARigutto]

Just went through my 03 FSM on the cooling and AC system. I didn't find any specified number for diagnostics on the clutch fan engagement temperature. It's ECU controlled based off the coolant temp sensor and A/C system sensors.

Essentially it said, you'll get a DTC code if something is wrong. Maybe someone with diagnostic access on systems and components can dig deeper as to the testing.

What would you think about covering a portion of the radiator with piece of cardboard and running it until it heat up enough for the fan to engage? I have heard it is very noticeable when it comes on but I have never heard it myself.

 

[ARigutto]

If you have any way of monitoring the truck's PIDs, you could compare the Fan-PWM (which represents the percentage of clutch lock time) to Fan Speed (which reports the actual RPM). You would then have to factor in ES (the actual engine speed). Probably too complicated to do on the fly, but you might be able to detect large deviations from what is being commanded.

BTW, 200° is OK, but 210° seems too high. 50/50 antifreeze boils at 223°.

Also, on these trucks, fan doesn't really just "kick on." ECM can modulate (within limits) via a PWM signal the actual fan speed regardless of engine speed, or let it free-wheel. Except, of course, when it is too busy doing other things...

I agree with 210* being to high especially for not being loaded. Also I am no expert but I believe boiling temperatures go up as pressure goes up.

 

[Darkbloodmon]

What would you think about covering a portion of the radiator with piece of cardboard and running it until it heat up enough for the fan to engage? I have heard it is very noticeable when it comes on but I have never heard it myself.

You can try that, just keep in mind the engine takes a while to get up to temp just idling. Typically on cold start the fan will "roar" and then settle down as the ECU adjusts to temp readings.

Easiest way to test it since you're living in the climate currently would be to just drive it. Stop and go traffic at op temp with the A/C on full blast. A quick pull on the highway at op temp; enough to see the needle climb, then pull over and observe the temp as the ECU tries to regulate it without air flow.

 

[ARigutto]

You can try that, just keep in mind the engine takes a while to get up to temp just idling. Typically on cold start the fan will "roar" and then settle down as the ECU adjusts to temp readings.

Easiest way to test it since you're living in the climate currently would be to just drive it. Stop and go traffic at op temp with the A/C on full blast. A quick pull on the highway at op temp; enough to see the needle climb, then pull over and observe the temp as the ECU tries to regulate it without air flow.

I'll try it out tomorrow.

 

[Ozymandias]

Stock fan clutch loses performance over the years, yours after 20 years is sure down 50% or so.

But your temps do not scare me in triple digit heat, if they stay steady then at 200 or even 210 it's all good.

 

[Tuesdak]

Is it normal to see temperatures like this even when their is no load on the truck?

Wait till it really gets hot out. X2 on how old if the fan clutch? If it's over 5 years old I suggest a new MOPAR fan clutch because the A/C will be the first to blow up from a weak fan clutch. You need to use a lower fan speed on the A/C till you hear the engine fan come up to speed when starting out.

"The way to keep the engine temps down" shouldn't be a problem. I had to work hard on grades with my 2003 to get it over the cooling system capacity towing. You will be more concerned about A/C performance here. Just be aware it takes 2 min for the A/C to quit dumping heat into the stack (from high pressure gas still condensing) after being shut off. This is why the "Turn off A/C" signs are sometimes 2 miles before the grade.

 

[Mikey-KE7LBB]

My '09 should be 100% locked at 225° according to FSM, so yours should be around the same.

My stock fan clutch failed several years ago and I replaced it with a mechanical one, so I haven't had any issues with engine temp, but AC performance suffers a bit.

 

[SSage]

My 2003 has the original fan clutch. I have to really be pulling hard or going very slow with a big load to see 212 on the Edge Insight. The cooling system has been a good performer, never felt like it was going to overheat. Have gone through a couple water pumps though, radiator and thermostat are still original. I've changed the coolant a few times, Zerex premium stuff in there now.

 

[bcbender]

X2 on the fan clutch... have you tried the A/C with engine idling that is how I noticed the fan clutch was shot.. every time I idled the truck with the A/C on it would blow HOT air.. otherwise it was fine.. Also don't skimp, Genos has the MOPAR clutch for ~400$... only way I know of to check performance it go to a dealer.. but then you're half way to a new fan clutch money wise.

 

[bcbender]

I agree with 210* being to high especially for not being loaded. Also I am no expert but I believe boiling temperatures go up as pressure goes up.

Yep.... @14PSI, water boils at about 250F... then the coolant mix adds about another 10 or so to that.

 

[ARigutto]

Wait till it really gets hot out. X2 on how old if the fan clutch? If it's over 5 years old I suggest a new MOPAR fan clutch because the A/C will be the first to blow up from a weak fan clutch. You need to use a lower fan speed on the A/C till you hear the engine fan come up to speed when starting out.

"The way to keep the engine temps down" shouldn't be a problem. I had to work hard on grades with my 2003 to get it over the cooling system capacity towing. You will be more concerned about A/C performance here. Just be aware it takes 2 min for the A/C to quit dumping heat into the stack (from high pressure gas still condensing) after being shut off. This is why the "Turn off A/C" signs are sometimes 2 miles before the grade.

I am assuming the clutch is probably the same one from the factory or it is at least 10 years old. So when the A/C is on does the ECM command the fan to come on a little bit? Thank you for the knowledge about the A/C dumping heat in to the system and I'll keep that in mind when I get to some big hills. At the end of each drive I try to let the engine idle for 2-5 minutes with everything off just to try and get a "proper" cool down.

 

[ARigutto]

X2 on the fan clutch... have you tried the A/C with engine idling that is how I noticed the fan clutch was shot.. every time I idled the truck with the A/C on it would blow HOT air.. otherwise it was fine.. Also don't skimp, Genos has the MOPAR clutch for ~400$... only way I know of to check performance it go to a dealer.. but then you're half way to a new fan clutch money wise.

I still have some A/C when I am stopped but it isn't as good as when I am driving. I also noticed last week that my A/C was really struggling so I took a good 5-10 minutes and tried to wash all the bugs and debris out of condenser, radiator, intercooler, and power steering cooler. It helped a decent amount and i noticed everything staying a little cooler or cooling off faster. Any idea what the temp difference should be from outside to the air coming out of the vents with the A/C on?

 

[Darkbloodmon]

Any idea what the temp difference should be from outside to the air coming out of the vents with the A/C on?

Yes!, that I did see in my 03 FSM in the A/C Section I'll go find it now.

 

[Darkbloodmon]

Performance Temperature and pressure table on 24-3

Ambient 70* : Center panel outlet 45*
80*: 45*
90*: 55*
100*: 55*
110*: 64*

Table also has the Condenser out pressure at service port (High side) if you need those as well.