Electric or Manual Fan? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chargedstang89 · 07-09-2003, 04:05 PM

I currently have an electric fan on my truck, but since it's gotten hotter, the truck heats up to about 240 degrees or so when idling. The electric fan that is on there was on the truck when I bought it, so I have no clue what kind it is or how many CFM's it can flow. The engine is a brand new crate 350 from GM, and i put a new water pump and thermostat in it as well...including a new radiator. I have no problems with temperature as long as I'm driving, but when I pull a trailer or idle, it heats up a lot. I'm getting ready to put a brand new A/C system in it and I know that is going to add heat as well. Should I put a bigger electric fan or possibly dual electric fans, or should I put a flex fan in it? The truck has a 3.5" body lift on it, so a manual fan doesn't seem to line up without me modifying the shroud. What do ya'all think? Also, I was thinking electirc fans would help with power in my truck since it's lacking. If I should go electric...what kind should I get???? Josh

78SilveradoSWB · 07-09-2003, 04:12 PM

Would stay with an electric fan, but wonder why your temp is getting that high. What temp thermostat you have in there? Seems to be some other problem than just the fan.

chargedstang89 · 07-09-2003, 04:33 PM

well, when it was cooler outside, the truck could idle all day long and stay cool. as it got warmer and warmer as the seasons changed, it started to slowly idle warmer/warmer as i let it sit and run or if i'm stuck in traffic. now it's 90-100 degrees and the truck heats up bigtime idling...especially after i tow a trailer. Like I said, I have no clue how many cfm's the fan that is on it now pulls. It isn't that big of a fan, doesn't seem that high quality either. I believe the thermostat is a 180 degree thermostat. My oil and coolant are full, and again..the water pump was new too.
any clue on which fans to get?

PHOENIX · 07-09-2003, 04:38 PM

How is it wired up, on a thermostat, toggle switch, or other?

I really like the toggle switch I have setup. I can control it anytime, just need to pay attention to whats going on. Living here and having a truck that used to always overheat has trained me to always pay attention to outside temp., engine temp, and sitting still or moving. Its a siccness. Anyway........

Are you using a relay?
Does the fan sound like it is working properly?
Is it a pusher (grille side) or puller (engine side)?
Eitherway can you feel air being blown from the fan?
Do you have a shroud on the radiator now?
Where is the fan mounted in relation to the shroud (inside, outside)?

Your timing and carb are set correctly?
You have changed oil on time?

Fan Details:
Diameter of blades?
Number of Blades?
Curved, straight, etc. ?

If you need to replace the fan, i would go with electric. Make sure to buy one for use on a v-8 engine of your size (5.7L+)

chargedstang89 · 07-09-2003, 05:16 PM

The fan is a puller style fan. There is no shroud around it. The fan is wired into a toggle switch, and i keep that switch turned on as soon as I get in the truck so it is blowing constantly. Yes, I can feel air being blown from the fan and it sounds like it normally does. I do not know the diameter of the fan, but I can tell you that thickness wise, it's only about 3/4" thick. It just doesn't look anywhere near big enough to cool a 4x4 truck with a 5.7L. When I get a new fan, I want to put relays on it so that I do not have to worry about someone else driving my truck and frying it. The oil is changed, so that shouldn't be a problem either. I'm just thinking that this fan is a wuss fan. The timing and carb were adjusted and set by my local shop. I know the guys there and they drag race, so they know what they are doing. I had them do it since I am new to carbs and adjusting them is kind of like Greek to me. The guy I bought the truck from is a complete moron and had everything messed up. I spent days fixing his "jimmy rigging" of many electrical parts in the truck. I think that he just stuck this fan on there because it was something local he could find.

C&C Chevy · 07-09-2003, 05:18 PM

If its only a single fan, it should be atleast 18". Dual 14" fans are the biggest you can go with a stock size radiator.

PHOENIX · 07-09-2003, 05:26 PM

About what percentage of the radiator does the electric fan cover?

Here is a picture of the fan I have in my truck.
It is from a Jeep (5.9L).

This fan covers all of the radiator top and bottom and allows a little gap at each end 3-6". This little flaps allow air to flow through when driving down the road. Fan works great, but wasnt used on a lot of Jeeps/Dodges. I would recommend that if you do not buy a new fan, you should buy a used stock fan off a v8+ engine.

Anyway you could get a picture of your fan?

PHOENIX · 07-09-2003, 05:29 PM

Inside, shows flaps.

If you can find a fan similar to this in a yard somewhere I would snatch it up. Its a very powerful fan and works great even in this hot Phoenix weather.

just heard on the radio tomorrow should be around 115-117

<---- it feels like this without the smile

C&C Chevy · 07-09-2003, 05:35 PM

Quote:

Originally posted by PHOENIX
just heard on the radio tomorrow should be around 115-117 <---- it feels like this without the smile

Atleast that's "dry" heat.

Eyegore · 07-09-2003, 06:19 PM

I would check on the size of your radiator. How many rows does it have. True it may be new, but the size does matter espically when you change the configuration of the truck. Here in the desert they sold what was called desert tanks (radiators). I had them in my blazers and boy did you need them when four wheeling and it gets over a 105 with the air on. So perhaps you might check your radiator size, see if you can get something larger.

Tom

chargedstang89 · 07-10-2003, 11:06 AM

the radiator is a 3-core radiator instead of the stock 2-core. Also, the fan does not cover anywhere near as much of the radiator as the one in the above picture. I will take a picture of it with my digital camera and post on here tomorrow. I appreciate all of the input. What are some goo vehicles to check in yard for electric fans? i.e. vehicles that have high volume electric fans.

Josh

LOHRTBT · 07-10-2003, 11:45 AM

Dual Electric Hayden's with Hayden Thermo controller... Under $175 New from O Reilly.

Very nice upgrade for the money!

gchemist · 07-13-2003, 09:07 PM

Web page write up.
I would add a four core radiator and upgrade to two fans.

87 STEPPER · 07-13-2003, 09:55 PM

I can't belive no one has asked this ? yet!

What year is this truck????????

If you have a new GM crate eng. why would you have to replace the water pump? Or did it come without one?

And why is the truck down on power with a new GM crate motor in it that's tuned properly by drag racer mechanic's?

Besides needing a new and bigger fan i think you need to find out about that H2O pump!!!

Did you buy this pump? and did you install it?

If so then get the P/N and make shure it's not a reverse flow H2O pump.

Your truck may need a normal rotation H2O pump thats why the year is important to know and this could be the reason your over heating.

Im running a Ele. fan off of a '90's berretta and iv'e had no prob's with it down here in summer with a/c going and a tranny cooler up front.

Also look for a fan off a corsica it's just about the same as a beretta.

I also removed the relay and related wireing for the fan from that same car.

chargedstang89 · 07-13-2003, 11:36 PM

The truck is an '85 gmc sierra. 1/2 ton 4x4. the crate motor is a stock, 190 horsepower 350 from gm goodwrench. the truck is properly tuned. again...it doeesn't run hot at all when driving down the road, it's only when i idle. it just started doing this as the summer has gotten hotter. all fall/winter/spring, the thing ran like a champ. as for being down on power, 190 horses in a 4x4 that has 33" tires and 3.08 gears is why it's down. i need steeper gears. when i romp on the engine, the secondaries kick in like they should, the tranny kicks down, but the truck just doesn't go anywhere. when i take off from a stop pulling my ski boat, the damn thing takes forever to get up to speed, and forget passing someone. no way. I should have known better than to put a stock motor in the truck. i should have at least gotten a 300 horse crate motor, instead of a wimpy 190 horse, but oh well...too late now. i've been thinking about putting a cam and intake in it, but don't want to void the warranty. but anyway...about the fan...i think i'll get duals. i measured the electric fan that's on it now, and it's only 14"....definitely not big enough for the truck.

JP

CustomChevy · 07-14-2003, 01:51 AM

Guess I'll add my 2cents...

If you stay electric, get one that pulls at least 2400-3000cfm.

Throw on a new thremostat just to be sure.

Get a radiator flush if it's been a long time, best to keep your system clean. Also, don't use too much anti-freeze. Use 80% water. You only want enough a/f to raise the boiling point.

Check that radiator cap, make sure you got the right poundage.
Best to have a 14 or 16lb cap.

Good luck!!

chargedstang89 · 07-14-2003, 05:16 PM

Would dual 12" electric fans be a good setup for my truck? From what I'm understanding, it seems like that would work well. What does everything think?

C&C Chevy · 07-14-2003, 05:28 PM

nope. get another 14" fan and set it up like Mikes, Gchem's, or Lohrtbt's and it should cool alot better! Your single 14" fan usually puts out 1500-2100 cfm's. Just add another and it should stay very cool.

C&C Chevy · 07-14-2003, 05:37 PM

Here's a link to Mike's write-up. It's the last article. Mike is a Chevy Truck God!

Pic of Mike's setup.

chargedstang89 · 07-15-2003, 01:15 PM

Okay...now I'm in limbo. A guy I work with told me that a Flex fan will pull more air across the radiator, condenser, and tranny cooler than dual 14" fans will. Anyone have any input on this? I was thinking about getting the dual 14" fans from O'Reiley's that were mentioned a few posts above. Any thoughts or statistics?

bigblock73 · 07-15-2003, 01:22 PM

Quote:

Originally posted by chargedstang89
Okay...now I'm in limbo. A guy I work with told me that a Flex fan will pull more air across the radiator, condenser, and tranny cooler than dual 14" fans will. Anyone have any input on this? I was thinking about getting the dual 14" fans from O'Reiley's that were mentioned a few posts above. Any thoughts or statistics?

Flex fans suck..well not literally...just figuratively! They don't cool worth a damn and have had a reputation of "coming apart" and causing damage or injury.

I have never run an electric fan, always had a clutch fan and never had any problems. Some say they take away some HP, but I bet it isn't even enough to notice.

...jeff

LOHRTBT · 07-15-2003, 01:32 PM

Flex fans suck!! haaha Just what Jeff said
Believe it or not..when I took off my clutch fan and went to elec. I noticed quicker throttle response.

LOHRTBT · 07-15-2003, 01:32 PM

and to clarify mine are also dual 14" haydens.

rockman20 · 07-15-2003, 02:41 PM

Clutch fan does rob power.

I ran a flex fan for about 5 years on my Cutlass. Never had a problem except for keeping belts tight. Converted to a dual electric fan setup and noticed quicker throttle response and also better mileage. I want to do this to my truck, but I need to get my radiator tanked and everything first.

chargedstang89 · 07-15-2003, 03:05 PM

So, which pulls more air....a clutch fan, flex fan, or dual 14" electric fans. Keep in mind, I live in St. Louis, so it's very hot and humid during the summer, and there's lots of traffic to sit in. The fan will have to pull air across the tranny cooler, condenser, and then radiator....so, which one out of the three will pull more air????

07-09-2003, 04:05 PM	#1
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	Electric or Manual Fan? I currently have an electric fan on my truck, but since it's gotten hotter, the truck heats up to about 240 degrees or so when idling. The electric fan that is on there was on the truck when I bought it, so I have no clue what kind it is or how many CFM's it can flow. The engine is a brand new crate 350 from GM, and i put a new water pump and thermostat in it as well...including a new radiator. I have no problems with temperature as long as I'm driving, but when I pull a trailer or idle, it heats up a lot. I'm getting ready to put a brand new A/C system in it and I know that is going to add heat as well. Should I put a bigger electric fan or possibly dual electric fans, or should I put a flex fan in it? The truck has a 3.5" body lift on it, so a manual fan doesn't seem to line up without me modifying the shroud. What do ya'all think? Also, I was thinking electirc fans would help with power in my truck since it's lacking. If I should go electric...what kind should I get???? Josh

07-09-2003, 04:12 PM	#2
78SilveradoSWB Senior Member Join Date: Apr 2002 Location: Beaverton, OR Posts: 1,615	Would stay with an electric fan, but wonder why your temp is getting that high. What temp thermostat you have in there? Seems to be some other problem than just the fan. __________________ Mitch 1978 Chevrolet Silverado C 10 454 BB, TH400

07-09-2003, 04:38 PM	#4
PHOENIX Registered User Join Date: Oct 2002 Location: Phoenix, Arizona Posts: 4,703	How is it wired up, on a thermostat, toggle switch, or other? I really like the toggle switch I have setup. I can control it anytime, just need to pay attention to whats going on. Living here and having a truck that used to always overheat has trained me to always pay attention to outside temp., engine temp, and sitting still or moving. Its a siccness. Anyway........ Are you using a relay? Does the fan sound like it is working properly? Is it a pusher (grille side) or puller (engine side)? Eitherway can you feel air being blown from the fan? Do you have a shroud on the radiator now? Where is the fan mounted in relation to the shroud (inside, outside)? Your timing and carb are set correctly? You have changed oil on time? Fan Details: Diameter of blades? Number of Blades? Curved, straight, etc. ? If you need to replace the fan, i would go with electric. Make sure to buy one for use on a v-8 engine of your size (5.7L+) __________________ * AVOID: LOPER'S PERMORANCE / LOPERSPEED.COM OF PHOENIX, AZ & COTTMAN TRANSMISSION *

07-09-2003, 05:18 PM	#6
C&C Chevy Registered User Join Date: Feb 2003 Location: Midwest City, OK Posts: 1,001	If its only a single fan, it should be atleast 18". Dual 14" fans are the biggest you can go with a stock size radiator. __________________ Robert Current: 1986 SWB Silverado 4.3 / TH400 Past: 1985 SWB Silverado 305 / TH350 - sold 1995 1987 1/2 ton Silverado - FI 350 / 700R4 sold 2007 Last edited by C&C Chevy; 07-09-2003 at 05:20 PM.

07-09-2003, 05:26 PM	#7
PHOENIX Registered User Join Date: Oct 2002 Location: Phoenix, Arizona Posts: 4,703	About what percentage of the radiator does the electric fan cover? Here is a picture of the fan I have in my truck. It is from a Jeep (5.9L). This fan covers all of the radiator top and bottom and allows a little gap at each end 3-6". This little flaps allow air to flow through when driving down the road. Fan works great, but wasnt used on a lot of Jeeps/Dodges. I would recommend that if you do not buy a new fan, you should buy a used stock fan off a v8+ engine. Anyway you could get a picture of your fan? Attached Images __________________ * AVOID: LOPER'S PERMORANCE / LOPERSPEED.COM OF PHOENIX, AZ & COTTMAN TRANSMISSION *

07-09-2003, 04:33 PM	#3
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	well, when it was cooler outside, the truck could idle all day long and stay cool. as it got warmer and warmer as the seasons changed, it started to slowly idle warmer/warmer as i let it sit and run or if i'm stuck in traffic. now it's 90-100 degrees and the truck heats up bigtime idling...especially after i tow a trailer. Like I said, I have no clue how many cfm's the fan that is on it now pulls. It isn't that big of a fan, doesn't seem that high quality either. I believe the thermostat is a 180 degree thermostat. My oil and coolant are full, and again..the water pump was new too. any clue on which fans to get?

07-09-2003, 05:16 PM	#5
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	The fan is a puller style fan. There is no shroud around it. The fan is wired into a toggle switch, and i keep that switch turned on as soon as I get in the truck so it is blowing constantly. Yes, I can feel air being blown from the fan and it sounds like it normally does. I do not know the diameter of the fan, but I can tell you that thickness wise, it's only about 3/4" thick. It just doesn't look anywhere near big enough to cool a 4x4 truck with a 5.7L. When I get a new fan, I want to put relays on it so that I do not have to worry about someone else driving my truck and frying it. The oil is changed, so that shouldn't be a problem either. I'm just thinking that this fan is a wuss fan. The timing and carb were adjusted and set by my local shop. I know the guys there and they drag race, so they know what they are doing. I had them do it since I am new to carbs and adjusting them is kind of like Greek to me. The guy I bought the truck from is a complete moron and had everything messed up. I spent days fixing his "jimmy rigging" of many electrical parts in the truck. I think that he just stuck this fan on there because it was something local he could find.

07-09-2003, 05:29 PM	#8
PHOENIX Registered User Join Date: Oct 2002 Location: Phoenix, Arizona Posts: 4,703	Inside, shows flaps. If you can find a fan similar to this in a yard somewhere I would snatch it up. Its a very powerful fan and works great even in this hot Phoenix weather. just heard on the radio tomorrow should be around 115-117 <---- it feels like this without the smile Attached Images __________________ * AVOID: LOPER'S PERMORANCE / LOPERSPEED.COM OF PHOENIX, AZ & COTTMAN TRANSMISSION *

07-09-2003, 06:19 PM	#10
Eyegore What Hump? Join Date: Apr 2003 Location: New River AZ Posts: 2,009	I would check on the size of your radiator. How many rows does it have. True it may be new, but the size does matter espically when you change the configuration of the truck. Here in the desert they sold what was called desert tanks (radiators). I had them in my blazers and boy did you need them when four wheeling and it gets over a 105 with the air on. So perhaps you might check your radiator size, see if you can get something larger. Tom __________________ Lil red 86 c-10 99 Sub 78 Camper Special w/ 454

07-10-2003, 11:06 AM	#11
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	the radiator is a 3-core radiator instead of the stock 2-core. Also, the fan does not cover anywhere near as much of the radiator as the one in the above picture. I will take a picture of it with my digital camera and post on here tomorrow. I appreciate all of the input. What are some goo vehicles to check in yard for electric fans? i.e. vehicles that have high volume electric fans. Josh

07-10-2003, 11:45 AM	#12
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	Dual Electric Hayden's with Hayden Thermo controller... Under $175 New from O Reilly. Very nice upgrade for the money! __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

07-13-2003, 09:07 PM	#13
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Web page write up. I would add a four core radiator and upgrade to two fans. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

07-13-2003, 09:55 PM	#14
87 STEPPER STILL PLAYS WITH TRUX Join Date: Nov 2002 Location: Melbourne, Fla. Posts: 2,764	I can't belive no one has asked this ? yet! What year is this truck???????? If you have a new GM crate eng. why would you have to replace the water pump? Or did it come without one? And why is the truck down on power with a new GM crate motor in it that's tuned properly by drag racer mechanic's? Besides needing a new and bigger fan i think you need to find out about that H2O pump!!! Did you buy this pump? and did you install it? If so then get the P/N and make shure it's not a reverse flow H2O pump. Your truck may need a normal rotation H2O pump thats why the year is important to know and this could be the reason your over heating. Im running a Ele. fan off of a '90's berretta and iv'e had no prob's with it down here in summer with a/c going and a tranny cooler up front. Also look for a fan off a corsica it's just about the same as a beretta. I also removed the relay and related wireing for the fan from that same car. __________________ ~~Bruce~~ MY 87 STEPPER MY 99 2D/WD TAHOE

07-13-2003, 11:36 PM	#15
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	The truck is an '85 gmc sierra. 1/2 ton 4x4. the crate motor is a stock, 190 horsepower 350 from gm goodwrench. the truck is properly tuned. again...it doeesn't run hot at all when driving down the road, it's only when i idle. it just started doing this as the summer has gotten hotter. all fall/winter/spring, the thing ran like a champ. as for being down on power, 190 horses in a 4x4 that has 33" tires and 3.08 gears is why it's down. i need steeper gears. when i romp on the engine, the secondaries kick in like they should, the tranny kicks down, but the truck just doesn't go anywhere. when i take off from a stop pulling my ski boat, the damn thing takes forever to get up to speed, and forget passing someone. no way. I should have known better than to put a stock motor in the truck. i should have at least gotten a 300 horse crate motor, instead of a wimpy 190 horse, but oh well...too late now. i've been thinking about putting a cam and intake in it, but don't want to void the warranty. but anyway...about the fan...i think i'll get duals. i measured the electric fan that's on it now, and it's only 14"....definitely not big enough for the truck. JP

07-14-2003, 01:51 AM	#16
CustomChevy Registered User Join Date: Nov 2002 Posts: 461	Guess I'll add my 2cents... If you stay electric, get one that pulls at least 2400-3000cfm. Throw on a new thremostat just to be sure. Get a radiator flush if it's been a long time, best to keep your system clean. Also, don't use too much anti-freeze. Use 80% water. You only want enough a/f to raise the boiling point. Check that radiator cap, make sure you got the right poundage. Best to have a 14 or 16lb cap. Good luck!! Last edited by CustomChevy; 07-14-2003 at 01:53 AM.



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07-14-2003, 05:16 PM	#17
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	Would dual 12" electric fans be a good setup for my truck? From what I'm understanding, it seems like that would work well. What does everything think?

07-14-2003, 05:28 PM	#18
C&C Chevy Registered User Join Date: Feb 2003 Location: Midwest City, OK Posts: 1,001	nope. get another 14" fan and set it up like Mikes, Gchem's, or Lohrtbt's and it should cool alot better! Your single 14" fan usually puts out 1500-2100 cfm's. Just add another and it should stay very cool. __________________ Robert Current: 1986 SWB Silverado 4.3 / TH400 Past: 1985 SWB Silverado 305 / TH350 - sold 1995 1987 1/2 ton Silverado - FI 350 / 700R4 sold 2007

07-14-2003, 05:37 PM	#19
C&C Chevy Registered User Join Date: Feb 2003 Location: Midwest City, OK Posts: 1,001	Here's a link to Mike's write-up. It's the last article. Mike is a Chevy Truck God! Pic of Mike's setup. __________________ Robert Current: 1986 SWB Silverado 4.3 / TH400 Past: 1985 SWB Silverado 305 / TH350 - sold 1995 1987 1/2 ton Silverado - FI 350 / 700R4 sold 2007

07-15-2003, 01:15 PM	#20
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	Okay...now I'm in limbo. A guy I work with told me that a Flex fan will pull more air across the radiator, condenser, and tranny cooler than dual 14" fans will. Anyone have any input on this? I was thinking about getting the dual 14" fans from O'Reiley's that were mentioned a few posts above. Any thoughts or statistics?

07-15-2003, 01:32 PM	#22
LOHRTBT BeWarE tHe eViL CrAnkTOe! Join Date: Oct 2002 Location: Yukon, OK Posts: 3,605	Flex fans suck!! haaha Just what Jeff said Believe it or not..when I took off my clutch fan and went to elec. I noticed quicker throttle response. __________________ ~Dave~ You can call me Mike, Mike Oxlong - 1986 Chevy SWB - Stock for now - *1986 Chevy Custom SWB* *Stolen 6/26/05* - 1985 Chevy SWB SOLD - 1999 T/A Some mods www.cardomain.com/id/ramairdave AIM Screenname - Jester84

07-15-2003, 02:41 PM	#24
rockman20 "The dude abides" Join Date: Apr 2003 Location: North Dakota Posts: 472	Clutch fan does rob power. I ran a flex fan for about 5 years on my Cutlass. Never had a problem except for keeping belts tight. Converted to a dual electric fan setup and noticed quicker throttle response and also better mileage. I want to do this to my truck, but I need to get my radiator tanked and everything first. __________________ RockMan 1993 Chevy Silverado C3500 1 ton dually 1994 Honda Civic 1969 Oldsmobile Cutlass S 1953 IH Farmall Super M New to the fleet: 1992 Subaru Loyal

07-15-2003, 03:05 PM	#25
chargedstang89 Registered User Join Date: Oct 2002 Posts: 90	So, which pulls more air....a clutch fan, flex fan, or dual 14" electric fans. Keep in mind, I live in St. Louis, so it's very hot and humid during the summer, and there's lots of traffic to sit in. The fan will have to pull air across the tranny cooler, condenser, and then radiator....so, which one out of the three will pull more air????

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