Coolant Temperature: Fan at Highway Speed

[grpht03ram]

I've been chasing around high coolant temperatures for a while now
220-230*F at highway speeds unloaded
2003 Ram 1500 4.7L

I replaced the entire cooling system: water pump, radiator, fan clutch, hoses, coolant, expansion tank, cap, tstat
I replaced certain things twice: thermostat, cap
Purged air after each repair
All parts OEM new


After a lot of diagnostics and thinking, I decided to try an experiment:

I installed a severe duty fan clutch today, Hayden #2900
I did a controlled highway test drive that would always increase coolant temps up to >225*F
With the severe duty clutch, coolant temps were stable at 215*F +/-5*
60-70 MPH
I expect even better results once ambient temps cool done, it was 103*F during my test drive


I will continue to monitor my coolant system in case this is just masking another problem

The point of this post is to show the effect that a cooling fan has on coolant temperatures despite ram air
Especially an engine driven fan. Electric fans get all the glory

 

[Snake15eyes1998]

you shouldn't have to use a severe duty fan, unless your towing heavy all the time or really hot climate. My truck is the 5.7 hemi. Unloaded, highway speeds. My coolant temperature is around 203-205 all the time. Towing I see around 215-220. I would say, that severe duty fan is masking the problem. Your over looking something.

 

[grpht03ram]

It's possible the oem clutch fan was defective

Whatever the case, I just wanted to make the point that fans do make a difference on coolant temps at highway speed

I only used the severe duty as an extreme variable, for this experiment

I'm not done with my cooling system

And I do live in the desert

 

[tron67j]

Did you use the exact type of coolant called for? It does make a difference. One thing to try is when engine is fully warm, if still running hot turn on heater to full. If your engine temperature goes down you may have a problem somewhere, possibly water pump not working properly even though you replaced, I have had to repeat replacement with rebuilt units. Also, interior gauges are not always best way to know what exactly is going on. Try a separate gauge, I think there also is a way to check separate sensors with Alpha OBD, but not certain if Gen 3 work with that, I never researched with my old one. Good luck.

 

[Snake15eyes1998]

A severe duty would. Like you said, because the clutch is engaged more often. But that also puts a lot of unnecessary drag on the engine. The air rushing through the radiator at highway speeds, is more then enough to keep it cool. Even with a standard fan clutch. Electric fans get all the glory because you can add more cooling without the extra drag put on the engine.

 

[grpht03ram]

I use an OBD gauge for coolant temps

Dash gauge is also accurate

ECT to PCM signal is accurate

Verified coolant temperature with a probe thermometer

coolant temp on the OBD gauge matches ambient temp on a fully cold engine

 

[Snake15eyes1998]

I use an OBD gauge for coolant temps

Dash gauge is also accurate

ECT to PCM signal is accurate

Verified coolant temperature with a probe thermometer

coolant temp on the OBD gauge matches ambient temp on a fully cold engine

Sounds like everything on your truck is good.

 

[grpht03ram]

Final piece of the puzzle:

Installed a new belt tensioner this weekend
It was worn and starting to oscillate more than it should, 150,000 miles on it
I didn't replace it sooner because the bolt was rounded off

Went for the same test drive as before
I had the lowest coolant temps I've seen so far


Also, the OEM fan clutch I removed previously was leaking fluid
The bad fan + bad belt tensioner = high temps

I may go back to a standard, OEM fan clutch soon
The severe duty is quieter than I expected
except when merging on the highway, it's pretty intense!
I'm also starting to worry the severe duty may cause problems later on since its really meant for the 5.7 only

 

[FullForceRam]

215-230F ??? Holy cow.. I'm in ******-fornia and it's been pretty hot over here (Over 100 everyday for a week now) and my truck on freeway unloaded is doing 185-190, towing it goes up slightly to 195-200 - MAYBE a 205 if going up hill.. Stock engine driven fan on a 2008 with 262K miles on her.

 

[grpht03ram]

215-230F ??? Holy cow..

Yup. Not any more

 

[grpht03ram]

215-230F ??? Holy cow.. I'm in ******-fornia and it's been pretty hot over here (Over 100 everyday for a week now) and my truck on freeway unloaded is doing 185-190, towing it goes up slightly to 195-200 - MAYBE a 205 if going up hill.. Stock engine driven fan on a 2008 with 262K miles on her.

how do you check your temperatures?

 

[Sherman Bird]

I wonder if there is crud built up in the bottom of the block passages. I ran into that on a 2002 4.7L Ram 1500 CC some years ago. It kicked my ass. Everything you said was done in addition to head gaskets. Finally, I decided to knock out both rear "freeze" plugs on either side of the block, and fabricated a piece of 3/8 steel brake line that I formed the end into a hook shape. The crud I flushed out that way was astounding.... this was what the "professional" flush machine missed!

 

[grpht03ram]

Its possible. When this reman engine was installed, the tech installed the heater core hoses backwards effectively back flushing the 15 year old heater core into the system.

Who knows what's in there. I may do that one of these days. Since the engine is "new" those plugs should come out easy

 

[FullForceRam]

how do you check your temperatures?

I use the temp gauge on the trucks interior. in fact, all the gauges have been working properly, no reason to believe they aren't.

 

[grpht03ram]

Just so you know, the middle line on the coolant temp gauge is about 210-215*F +/- a few degrees
Anything over 215*F is when it creeps past the center line

This is with an OBD gauge reading temps straight from the computer
I also tested coolant temps with a probe thermometer to verify the OBD reading

You might be running a little warmer than you think. But anything in the 215 range is completely normal for these engines

 

[Sherman Bird]

But anything in the 215 range is completely normal for these engines[/QUOTE]

This is the accepted "norm" in order to comply with EPA emissions mandates.

 

[grpht03ram]

Agreed. When I say normal I mean as it was designed/engineered
The stock 195 tstat isn't even fully open until around 220

The new pentastar V6 is designed to run at 220-230*F !!
The electric cooling fan doesn't even kick on until about 225