Would a new fan and clutch improve my cooling?

[IT Cowboy]

I currently have the 5 fin belt driven fan with no clutch. My truck runs ok and stays cool most of the time but the temp does creep up on the highway during the AZ summer. Would a new 7 fin fan and clutch greatly improve the cooling performance and be worth the cost (about $300)

[Palf70Step]

Clutch fans make a huge improvement IMO. You May need a new fan shroud, but not positive on that. My 70 has that set up with factory 4-core radiator and even in our cruising weather here in mid summer I do not over heat

[Steeveedee]

Cooling at speed doesn't really require the fan, as there is plenty of air flow. Your clutch should be freewheeling.

If it's getting warm at speed, that's usually an indication that the radiator isn't up to snuff. Could be the water pump isn't pumping enough (worn impeller- low probability), or the thermostat is faulty. In my case, I had to put in a high flow thermostat.

[IT Cowboy]

I think the temp creeping up is from heat soak. When I am running on the highway it is usually ok but when I come off the highway and down to cruising and stop and go traffic it them tends to go towards the warm side.

[Sicklajoie]

Originally Posted by IT Cowboy

I think the temp creeping up is from heat soak. When I am running on the highway it is usually ok but when I come off the highway and down to cruising and stop and go traffic it them tends to go towards the warm side.

What's your definition of "warm side"?
Have you ever put an infrared temp gun on the intake and thermostat housing to compare how accurate your actual gauge is showing?

[Stocker]

Originally Posted by IT Cowboy

I think the temp creeping up is from heat soak. When I am running on the highway it is usually ok but when I come off the highway and down to cruising and stop and go traffic it them tends to go towards the warm side.

I agree with Sicklajoie's post above.... but given your description of the issue, I would most definitely consider an 18" 7-blade fan on a Hayden #2747 heavy-duty clutch.
And just for good measure, if you don't already have it, a coolant recovery tank with a sealed-system radiator cap.

[Steeveedee]

In that case, you're not getting the ram air effect. Does your fan continue to spin when you shut the engine off? I think all the clutches fit all the fans, so maybe just replace the clutch first? On that note, how well is your fan coupled to the shroud? Should be ~ 1/2 in and 1/2 out on the blades.

[mike16]

Your radiator is too small or it is clogged with rust or debris.

[PbFut]

Not cooling at highway speed...I'm inclined to agree it's not your fan. Unless I have the ac on, my fans do not turn on while at highway speed
The ram air effect provides plenty cooling for the BPE 400 small block. The fans will come on at the light at end of off pamp. I would look elsewhere than the fan. Caution with the tstats of today. I just went through hell swapping to a 20 degree cooler stat. It took 3 tries to get one that worked correctly. I spent a month thinking it was something I was doing wrong.

[IT Cowboy]

Early last fall I flushed the rad and system and put all new coolant in it and I haven't really tested it on the highway yet. It could have been an air bubble and the old coolant was brownish and hard to tell how long it had been in there. I should have put a high flow thermostat in there at the time but I didn't.

I did forget to mention that when it got warm on me I was on the highway and went from 3300 ft elevation to almost 7000 ft. The elevation screwing with the timing and water boiling point could have really messed with it.

[Hugh in NC]

I went down this rabbit hole a couple of years ago. Here is a very simplified and condensed answer.

There are 5 blade fans and 7 blade fans in several diameters. The more blades the more air movement.

ALWAYS USE A SHROUD.

There are 3 types of fan clutches. Standard duty, heavy duty, and severe duty. The bigger the heaver duty the more air it moves.

Bigger is better.

https://www.haydenauto.com/en/produc...-types/thermal

[Stocker]

Originally Posted by Hugh in NC

I went down this rabbit hole a couple of years ago. Here is a very simplified and condensed answer.

There are 5 blade fans and 7 blade fans in several diameters. The more blades the more air movement.

ALWAYS USE A SHROUD.

There are 3 types of fan clutches. Standard duty, heavy duty, and severe duty. The bigger the heaver duty the more air it moves.

Bigger is better.

https://www.haydenauto.com/en/produc...-types/thermal

Yep -- that explains my post #6 above. With factory A/C, you have an 18", 7-blade fan on a heavy-duty clutch. Hayden #2747 is a direct replacement. I didn't mention a shroud because that is a given.

Of course this all assumes that's where the problem is. Other posts suggest other possibilities. There's plenty to check out.

[my67c20]

Just my 2 cents from a guy not in a van down by the river, but a guy that does live in Tucson. The engine bay is like an oven and does a great job of heat retention. On the highway, there might be some convection action to keep the intake air cooler. In the city, not so much convection and more of a heat dome. If a human keeps sucking in warmer and warmer air, your internal mechanism of cooling (sweating) will not be able to keep up. Somehow humidity play into this as well. Bottom line, find a way to bring in cooler air on hot days and find a way to eliminate excessive engine bay heat.

[IT Cowboy]

It is my understanding that a new fan and clutch wont really help it cool better but instead cool more consistent by moving more air when it normally wouldn't be. Heat soak here in AZ can be an issue. I have considered an electric fan as an assist but I want to keep most of the original look of things if possible. Elevation changes her in AZ are kind of a big deal too that need consideration with older vehicles. AZ is not all flat desert and I live at 3500 ft and often go to 6-7k feet through some mountain passes and travels.

[mike16]

A 19.5 inch diameter fan with 7 blades. And a fan clutch, Hayden pn 2705 might work very well.

[72c20customcamper]

Originally Posted by IT Cowboy

I think the temp creeping up is from heat soak. When I am running on the highway it is usually ok but when I come off the highway and down to cruising and stop and go traffic it them tends to go towards the warm side.

Anytime you go from highway to stop and go the temp is going to rise . I can run all day at highway speed at 180-190 degrees but when I exit the temp will climb a bit . I have a 7 blade fan with Hayden heavy duty clutch fan . Truck never overheats . When you say warm what are we talking about? Is your sender in the head or the water jacket in the manifold ? Has your truck ever actually overheated . Fluctuations in temp will always happen no way to avoid it
Head temp will always be warmer than the actual water temps by 10-15 degrees . My BB Chevelle will read close to 210 when the fans kick in. The water temp is at 195 when the sender in the radiator kicks on the fans .

[mike16]

Look at Hayden fan clutch specifications on their website. Several to choose from.
Choose one that begins to work at a desired temperature. Be carefully also to choose one that compliments your thermostat

[IT Cowboy]

Originally Posted by 72c20customcamper

When you say warm what are we talking about?

Last summer I was running 65 on a 4 lane hwy for about 2 hours. I went from 3000 ft to 6700 ft elevation. The temp needle crept up to above 3/4 and I pulled off at an exit and the temp continued to rise. I was facing a direction with no breeze blowing to the front of the truck and when I shut it off it was boiling over. It only took a few minutes for it to calm down and it still had coolant in the overflow tank. After it cooled down I continued on my trip and it was fine for the rest of the trip and on the way home. I dont think it was hot enough for long enough to do any damage. When I got home from the trip I changed the oil and flushed the cooling system and added new fluid and it has been fine since. I am really thinking the elevation change had something to do with it and running on the hwy for an ext period in high altitudes.

[Sicklajoie]

Originally Posted by IT Cowboy

Last summer I was running 65 on a 4 lane hwy for about 2 hours. I went from 3000 ft to 6700 ft elevation. The temp needle crept up to above 3/4 and I pulled off at an exit and the temp continued to rise. I was facing a direction with no breeze blowing to the front of the truck and when I shut it off it was boiling over. It only took a few minutes for it to calm down and it still had coolant in the overflow tank. After it cooled down I continued on my trip and it was fine for the rest of the trip and on the way home. I dont think it was hot enough for long enough to do any damage. When I got home from the trip I changed the oil and flushed the cooling system and added new fluid and it has been fine since. I am really thinking the elevation change had something to do with it and running on the hwy for an ext period in high altitudes.

Like I said earlier, do yourself a favor and get yourself an infared thermometer gun. They're cheap enough and more trustworthy than a vague factory gauge.
https://www.harborfreight.com/121-in...ter-63985.html

[Steeveedee]

Based on those symptoms, I would have the radiator rodded out before going any further into it.

[dagnabbitt]

Originally Posted by Hugh in NC

ALWAYS USE A SHROUD.

https://www.haydenauto.com/en/produc...-types/thermal

It's amazing the effect that a shroud has. First thing I would try, since it is the least invasive option. Over 50-60 years shrouds tend to be broken or removed and thrown away. Most of the trucks of our era that I see have little more than the finger guard intact.

[72c20customcamper]

Originally Posted by IT Cowboy

Last summer I was running 65 on a 4 lane hwy for about 2 hours. I went from 3000 ft to 6700 ft elevation. The temp needle crept up to above 3/4 and I pulled off at an exit and the temp continued to rise. I was facing a direction with no breeze blowing to the front of the truck and when I shut it off it was boiling over. It only took a few minutes for it to calm down and it still had coolant in the overflow tank. After it cooled down I continued on my trip and it was fine for the rest of the trip and on the way home. I dont think it was hot enough for long enough to do any damage. When I got home from the trip I changed the oil and flushed the cooling system and added new fluid and it has been fine since. I am really thinking the elevation change had something to do with it and running on the hwy for an ext period in high altitudes.

I would look at the radiator first ,since you have a direct drive fan right now . Not sure if a 7 blade clutch fan will increase the air flow since it’s never a one to one like a direct drive .

[IT Cowboy]

I ordered a clutch and 7 blade fan to install. It looks like a pretty straight forward job - unbolt and bolt in. Will the old fan and the new one slip in without removing the shroud?

[72c20customcamper]

Originally Posted by IT Cowboy

I ordered a clutch and 7 blade fan to install. It looks like a pretty straight forward job - unbolt and bolt in. Will the old fan and the new one slip in without removing the shroud?

Can’t fully remove the shroud because after you put on the fan there is no way to install the shroud . I just remove the upper two bolts on the shroud and move it towards the engine and R&R the fan assembly. The fan can be done with the shroud mounted but there’s not a lot of room to work

[IT Cowboy]

Originally Posted by 72c20customcamper

Can’t fully remove the shroud because after you put on the fan there is no way to install the shroud . I just remove the upper two bolts on the shroud and move it towards the engine and R&R the fan assembly. The fan can be done with the shroud mounted but there’s not a lot of room to work

I think my shroud is in decent shape but I do not want to crack it. I have the Bog block so I am hoping there is a bit of wiggle there. I might even put the fan on the clutch while holding it in the shroud and then hand the clutch on a stud until I can get it all bolted in. I am sure there will be some level of swearing and a couple of beers involved.