To electric fan? or not?

[Kalums]

Ok, gentlemen... currently my truck is sitting in the transmission shop getting the TH350 & NP205 completely rebuilt (see picture, that is the input shaft for the T-case). I need advise when I'm in drive sitting for a long period of time say 20 mins or so my truck starts to over heat. I'm going to try moving the manual/non clutch 6 blade (reverse rotation) 18" fan closer to the engine and make it "peek" out of the fan shroud like it is supposed to(swapped in a TBI "K" long block crate motor with serpentine system), but if that does not work...should I just give in and buy electric pulling fans? I do plan on putting in A/C with in the next year hopefully so...I'm pretty sure it will get electric fan(s) then, at the latest. I am finding that the Stock 1971 SBC 350 shroud may not be ideal for this setup as my fan is actually sitting about an inch inside the shroud with a 1 inch aluminum spacer that I'm planning on just eliminating to get that "peek". any insight would be greatly appreciated.
I would like to add to things 1) it only happens in gear, while in park or neutral it does not go above 180-185 with a digital laser thermo and 2) it is a non a/c truck so I'll still need space to add a condenser later.

[72c20customcamper]

180-190 isn’t overheating . It’s normal for the temp to creep up at idle if your sender is in the head that area will be 10-15 degrees warmer than the actual water temp .

[cj847]

I'm no expert on cooling but have a couple of comments that may be helpful.

To check the system: When the truck is overheating, turn the heater on high. If this reduces the temperature significantly, then you need a bigger or better radiator.

When buying an electric fan- Never buy one that doesn't advertise its cfm. Only buy brand names like Derale, Spal, etc.

[Kalums]

Originally Posted by 72c20customcamper

180-190 isnÂ’t overheating . ItÂ’s normal for the temp to creep up at idle if your sender is in the head that area will be 10-15 degrees warmer than the actual water temp .

I think you misunderstood, it creeps up only while idling in gear... not while in park or neutral. While in park sitting in my drive way it stays 180-185. The sender is in the intake manifold next to the thermostat/water neck.

[Kalums]

Originally Posted by cj847

I'm no expert on cooling but have a couple of comments that may be helpful.

To check the system: When the truck is overheating, turn the heater on high. If this reduces the temperature significantly, then you need a bigger or better radiator.

When buying an electric fan- Never buy one that doesn't advertise its cfm. Only buy brand names like Derale, Spal, etc.

This happened while on a run to the dump and sitting in line waiting for the weigh in. The radiator has been rebuilt by a reputable company here in Phoenix and I checked to make sure it had good flow and no leaks when I got it back. Turning on the heater slowed the climb... But didn't stop it completely. If I do go with fans I will definitely not play around with no-name scamazon or flea-bay garbage... Some ppl may have good luck there, but I never have. I was looking at the flex-a-lite brushless fans... I'd just prefer a direct bolt on and not "universal" may/probably won't fit kit.

[Sheepdip]

I prefer and run electric fans mostly because I'm all about function without problems. I purchased a system thru Champion that's made to cool 1000 H.P. which was a direct bolt in aluminum radiator with 2 Spal 30-amp fans. Zero issues with the system and/or overheating. I did wire in a toggle so when I turn on the A/C the fans run continuously rather than cycle off the thermostatic switch/sender. I also installed two 40-amp resettable breakers/fuses to the fans individually.
Your charging system needs to be up to par also as I installed a 175 amp internally regulated alternator.

Some don't like the noise, I can't hear anyway so I don't mind.

[Getter-Done]

I had a 76 Blazer with a 454cid with T350 and 203 transfer case.

On hot and humid days above mid 90's, It would start running towards the Hot side. On a normal day it was fine.

My solution was to put Pusher Fan in front of radiator.

You stated that you plan to add A/C at a later date.
If you choose to use Pusher fans you can just plan ahead for this addition.

After you get your fan positioned in the shroud at the correct depth, That system can stay there.

Another option is putting a Puller fan inside the shroud and keeping the 6 blade fan.

Here is an Old thread below with some good info.

Link: https://67-72chevytrucks.com/vboard/...d.php?t=710462

[Steeveedee]

After various efforts made to get my truck to run cooler, I installed a high flow thermostat. Not saying that that is your answer, but it is certainly a simple, cheap thing to try, which worked in my case.

[PbFut]

When you swapped engines, did you up the stall speed on the torque converter? The additional heat created by higher stall converters will bump up the calories the radiator must dispose of. This is by the way of increase in coolant temps as the the radiator works to pull the heat out of the tranny fluid. Adding a tranny cooler may solve your issue. With a 2200 stall, I get some heat issue with long in town stop light runs on very hot days. I see the converter climb and then coolant will creep up. I have gauges on the tranny line, and pan.
As for adding electric fans. Avoid if you can. The old electric system in these truck will be over taxed without a fair amount of rewiring and upgrade to alternator.

[Stocker]

You mentioned having a 6-blade fixed fan. Have you considered a factory-type 7-blade on a good HD fan clutch like a Hayden 2747? That's the setup for a factory A/C truck, mine has it and does not run hot.
I also have a sealed system with a recovery tank so the radiator is always full of coolant -- no air.

[72c20customcamper]

Originally Posted by Kalums

I think you misunderstood, it creeps up only while idling in gear... not while in park or neutral. While in park sitting in my drive way it stays 180-185. The sender is in the intake manifold next to the thermostat/water neck.

Idle may be to low . What does it get to in gear after 20 minutes . And if your stopped in traffic you can always pop it into neutral I do this at times . That being said electric fans have a downside with power drain if you don’t upgrade your system . I had to put a 110 amp alternator on my Chevelle and at night the headlights still dim when the fans kick on at idle .

[Kalums]

Originally Posted by PbFut

When you swapped engines, did you up the stall speed on the torque converter? The additional heat created by higher stall converters will bump up the calories the radiator must dispose of. This is by the way of increase in coolant temps as the the radiator works to pull the heat out of the tranny fluid. Adding a tranny cooler may solve your issue. With a 2200 stall, I get some heat issue with long in town stop light runs on very hot days. I see the converter climb and then coolant will creep up. I have gauges on the tranny line, and pan.
As for adding electric fans. Avoid if you can. The old electric system in these truck will be over taxed without a fair amount of rewiring and upgrade to alternator.

When I swapped engines and put in the serpentine system I upgraded 90% of the wiring, only part left to do was heater and A/C wiring which will be done when I put in the A/C system. The transmission was untouched until the shop currently working on it got it... So whatever factory was, is what it had. The new converter is a fully brazed converter for an Allison @ 2500 stall (according to the shop, not sure what that all entails but it comes with a 2 year unlimited milage warranty and they have been around for over 35 years... So I'm going to run with it).

[Kalums]

Originally Posted by 72c20customcamper

Idle may be to low . What does it get to in gear after 20 minutes . And if your stopped in traffic you can always pop it into neutral I do this at times . That being said electric fans have a downside with power drain if you don’t upgrade your system . I had to put a 110 amp alternator on my Chevelle and at night the headlights still dim when the fans kick on at idle .

I've currently got a 140 amp CS144... And don't have any heavy electrical draws other than lights. The plan is to go with brushless motor fans that don't draw as much but... I can see where A/C + 2 fans + stock lights would be taxing. Also I did increase the idle from about 620 to 750 and added advance to 12 degrees base timing.

[Kalums]

Originally Posted by Stocker

You mentioned having a 6-blade fixed fan. Have you considered a factory-type 7-blade on a good HD fan clutch like a Hayden 2747? That's the setup for a factory A/C truck, mine has it and does not run hot.
I also have a sealed system with a recovery tank so the radiator is always full of coolant -- no air.

That is actually what I wanted but I couldn't find a 7 blade reverse rotation 18" fan in metal, I found a few in plastic... But worry about longevity. Arizona does a serious number on plastics under the hood.

[HO455]

You didn't mention what kind of cooling you have set up for the transmission. My preference for heavy duty cooling is the factory plate style inside the radiator and a plate style aftermarket installed before the factory cooler. That will remove heat before it gets to the engine coolant.

Be aware that the new stall converter you are getting will make more heat than a factory converter.

Do you have a voltmeter installed? If or when you go to electric fans you will need one to monitor the voltage at idle. Many alternators are rated for high output but not at idle speeds. Being able to monitor your battery voltage will save you headaches.

[Kalums]

Originally Posted by HO455

You didn't mention what kind of cooling you have set up for the transmission. My preference for heavy duty cooling is the factory plate style inside the radiator and a plate style aftermarket installed before the factory cooler. That will remove heat before it gets to the engine coolant.

Be aware that the new stall converter you are getting will make more heat than a factory converter.

Do you have a voltmeter installed? If or when you go to electric fans you will need one to monitor the voltage at idle. Many alternators are rated for high output but not at idle speeds. Being able to monitor your battery voltage will save you headaches.

Yes, I do have an aftermarket 9x13 Hayden external cooler, supposedly rated for 40k... But we all know how manufacturer's "ratings" work and I bypassed the radiator internal cooler. When I did my conversion I did install a square-body voltage meter and my alternator is outputting about 14.5-14.7v and roughly 80A at idle.

[HO455]

Sounds like you have the bases covered.

Do you drive the truck in cold weather much? If so you might want to consider plumbing the factory cooler back into the transmission cooling. Without the heat from the radiator in cold weather the transmission can run cold. Meaning the oil never reaches a high enough temperature to cause moisture/condensation to evaporate from inside the transmission.

[Kalums]

Originally Posted by HO455

Sounds like you have the bases covered.

Do you drive the truck in cold weather much? If so you might want to consider plumbing the factory cooler back into the transmission cooling. Without the heat from the radiator in cold weather the transmission can run cold. Meaning the oil never reaches a high enough temperature to cause moisture/condensation to evaporate from inside the transmission.

If you mean anything under 60 degrees... I state an emphatic "NOPE" *laughs* it barely gets to the 60s here in Phoenix during the "winter". 120...seems like 20+ days a year, usual temps in the upper 80s to upper 90s(or higher) , 200+ days a year... Cooling is hard to maintain here.

[LS short box]

On all my projects (mostly LS swaps) I run the biggest alum rad I can fit. Single Spal 16" puller fan. Covers the whole center of the rad. Ran that fan on LS1's, LS6's, LS3's and a LS2 stroked to 427 cubes. Never over heated. I've used both the ECM and Painless kit for temp control. On at 205 and off at 195 degrees. Yes in warm weather they cycle a bit my 98 Wrangler has 16 years on the LS swap with a Spal fan and Painless temp control. Zero issues.
On my 68 C10 with a LS6 swap I used a Afco generic rad. Never has come close to over heating even in 90 plus degree heat.
Pic.

[Kalums]

Originally Posted by LS short box

On all my projects (mostly LS swaps) I run the biggest alum rad I can fit. Single Spal 16" puller fan. Covers the whole center of the rad. Ran that fan on LS1's, LS6's, LS3's and a LS2 stroked to 427 cubes. Never over heated. I've used both the ECM and Painless kit for temp control. On at 205 and off at 195 degrees. Yes in warm weather they cycle a bit my 98 Wrangler has 16 years on the LS swap with a Spal fan and Painless temp control. Zero issues.
On my 68 C10 with a LS6 swap I used a Afco generic rad. Never has come close to over heating even in 90 plus degree heat.
Pic.

Nice, I just got the 3 core stock rad rebuilt... So I'm not enthusiastic about replacing it but I will be looking into the larger puller fan(s) for the rad and possibly a pusher for the trans cooler and condenser

[Extended Power]

Originally Posted by PbFut

When you swapped engines, did you up the stall speed on the torque converter? The additional heat created by higher stall converters will bump up the calories the radiator must dispose of. This is by the way of increase in coolant temps as the the radiator works to pull the heat out of the tranny fluid. Adding a tranny cooler may solve your issue. With a 2200 stall, I get some heat issue with long in town stop light runs on very hot days. I see the converter climb and then coolant will creep up. I have gauges on the tranny line, and pan.
As for adding electric fans. Avoid if you can. The old electric system in these truck will be over taxed without a fair amount of rewiring and upgrade to alternator.

This sounds like the best answer as he is considering the fact of the transmission cooler inside the radiator, and in drive, you are definitely making heat if the stall speed is not correct.

Yes, pull your fan out of the shroud about 3/4”-1”.
Yes, add an external transmission cooler if you don’t already have one.

By adding AC you are gonna be blocking even more airflow and adding even more heat to the radiator, so the more heat you can take away from the radiator, the better. (Use only the biggest external transmission cooler you can find...eg: 2003-2007 Ford F-series with the 5R110.

I could not run a mechanical fan with my setup, I had to go electric fans. I also run a Ford F-series transmission cooler which is not in front of the radiator and has its own custom made shroud and electric fan.
Another thing I added that helped....cowl filler panels.
The air has to pass through the radiator and can’t go above/around it.
Also have a 4-core aluminum rad, and EMP Stewart high flow thermostat.

[weq92f]

Originally Posted by Extended Power

...<snip>...

Another thing I added that helped....cowl filler panels.
The air has to pass through the radiator and can’t go above/around it.
...<snip>...

.

This will prevent your fans sucking hot engine bay air rather than cool outside air while stopped at idle. The hot air can just get recirculated without those panels. Hot air is sucked toward the grill, goes over top of core support then down and through the radiator.

I sealed the radiator to the core support with plain ol' stick on weather stripping. Otherwise there's a gap that still allows air to come from under the hood. There's still a gap at the bottom but that's more difficult so seal up.

I too use a pusher fan on the condenser. It made a noticeable difference in the A/C performance. It's wired through a trinary pressure switch and so doesn't run 100% of the time.

Hth,

-Kevin

[Kalums]

Originally Posted by weq92f

.

This will prevent your fans sucking hot engine bay air rather than cool outside air while stopped at idle. The hot air can just get recirculated without those panels. Hot air is sucked toward the grill, goes over top of core support then down and through the radiator.

I sealed the radiator to the core support with plain ol' stick on weather stripping. Otherwise there's a gap that still allows air to come from under the hood. There's still a gap at the bottom but that's more difficult so seal up.

I too use a pusher fan on the condenser. It made a noticeable difference in the A/C performance. It's wired through a trinary pressure switch and so doesn't run 100% of the time.

Hth,

-Kevin

Good to know, I will definitely keep this in mind when I can afford the A/C system. Here is Phoenix I'll need all the help my a/c system can get...

[MARKDTN]

I like electric fans. Takes load off the water pump snout and properly controlled doesn't run when not needed. 1990-96 Corvette setups are nice and can be installed with minimal brackets and fabrication. TPI IROC Camaro dual fans are also decent. Without fuel injection for the ECM to control the fans you will need a controller. You can read up on "BMW switch, Volvo relay, Taurus fan" swaps for a junkyard cheap route to control fans. This swap is usually for 2-speed fans but could be used for dual single speed fans to turn 1 on and then both. If you don't care about brands a 2000 Contour/Cougar dual 2-speed fan is probably about the right size.

[Kalums]

Originally Posted by MARKDTN

I like electric fans. Takes load off the water pump snout and properly controlled doesn't run when not needed. 1990-96 Corvette setups are nice and can be installed with minimal brackets and fabrication. TPI IROC Camaro dual fans are also decent. Without fuel injection for the ECM to control the fans you will need a controller. You can read up on "BMW switch, Volvo relay, Taurus fan" swaps for a junkyard cheap route to control fans. This swap is usually for 2-speed fans but could be used for dual single speed fans to turn 1 on and then both. If you don't care about brands a 2000 Contour/Cougar dual 2-speed fan is probably about the right size.

So far, most of my reading has been about single speed fans and I'm really not getting much about if I'm going to need a large single fan or 2 smaller fans for the rad and a pusher for the condenser + the trans-cooler... That is possibly 4 fans I need to figure out how to mount and supply electricity for... (yipes)