flex fan VS clutch fan - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dubie · 09-12-2003, 04:01 PM

I have one of each now. What would be the best to run on my 350?

68 Suburban · 09-12-2003, 04:13 PM

clutch....flex fans are garbage, and they are dangerous.

nate68 · 09-12-2003, 04:31 PM

electric fans

crazy longhorn · 09-12-2003, 04:44 PM

2nd the electric fans! I have 2 -14" flexalites on a hand built shroud......there is power to the rear wheels that you can feel after removing the eng driven fan

I never did like the clutch fans, felt they were too inconsistant. flex fans are down right "spooky" (dangerous), but they work well for keeping a hp eng cool. I have run a flexalite PLASTIC flex fan with good results. It kept my 461 Olds cool in traffic on those 100 degree days....also worked well on my 383. The fan was also cheap, about $10 or 12 through summit racing. That thing did eat a little power to run, but thats better than a smoked engine. if you run a flex, be carefull! Good luck,crazyL

junkyardjohn · 09-12-2003, 04:50 PM

DUBIE .. GO WITH THE CLUTCH FAN. ELECTRIC FANS ARE OK FOR AN AUHSILLARY(SP) FAN , BUT DON'T MOVE ANYWHERES NEAR THE AIR A CLUTCH FAN DOES (CHECK THE CFMs YOURSELF) & FLEX FANS ARE JUST PLAIN DANGEROUS JUNK. JOHN

dubie · 09-12-2003, 04:57 PM

I have the clutch fan already installed on the engine, but my neighbour gave me a 7 blade flex fan last night so I figured I would ask the experts.
Thanks guys

crazy longhorn · 09-12-2003, 05:11 PM

Quote:

Originally posted by junkyardjohn

DUBIE .. GO WITH THE CLUTCH FAN. ELECTRIC FANS ARE OK FOR AN AUHSILLARY(SP) FAN , BUT DON'T MOVE ANYWHERES NEAR THE AIR A CLUTCH FAN DOES (CHECK THE CFMs YOURSELF) & FLEX FANS ARE JUST PLAIN DANGEROUS JUNK. JOHN

The fans I have on the longhorn dont even need to run if the truck is moving(plenty of air flow through the rad). The 383 holds between 185-190 on temp on the hottest days in Illinois, in town or on the hyway! If I start bangin all 6 of those gears.....the fans need to be switched on before I "play"! John, do you have a link to cfm ratings on the eng driven fans? crazyL

tom hand · 09-12-2003, 05:19 PM

Quote:

Originally posted by crazy longhorn
hottest days in Illinois,

I'm sure you rarely need a fan

**COBALT** · 09-12-2003, 05:22 PM

What's involved with installing an electric fan(s)? I'm curious. I've been toying with the idea of dumping the fan, shroud and clutch and simply using an electric fan setup so I can cap that pulley on the water pump.

Do you wire it to ignition? How is it grounded? How does it mount? Are there any required modifications?

crazy longhorn · 09-12-2003, 05:40 PM

Check out the dual fan setup Wes has on his site.. http://www.classicheartbeat.com/cata...assemblies.htm

crazy longhorn · 09-12-2003, 05:44 PM

Quote:

Originally posted by tom hand

I'm sure you rarely need a fan

The temp guage doesnt lie......as long as the truck is MOVING (was the key word), the fans dont need to run much at all. i havent burned up the eng , so it must work

crazyL

junkyardjohn · 09-12-2003, 08:22 PM

SORRY CRAZY LONGHORN ... I DON'T HAVE A LINK.... HERES AN EXCERPT FROM SEPT. 2002 CHEVY DUTY. I'M SURE YOU ALREADY KNOW THIS INFO, BUT MAYBE IT'LL HELP SOMEONE ELSE.
HERE GOES.....
THE BEST ALTERNATIVE TO A MECHANICAL FAN IS A DUAL ELECTRIC FAN THAT CAN PULL ALMOST AS MUCH AIR AS A MECH. FAN, REGARDLESS OF ENGINE SPEED, & THEY CAN SAVE SOME HORSEPOWER TOO. THEY COOL BETTER IN SITUATIONS LIKE STOP & GO STREET TRAFFIC. ALWAYS MOUNT THEM ON THE BACK OF THE RADIATOR TO PULL AIR THRU FOR THE BEST EFFICIENCY.

AND FEB. 2002 CUSTOM & CLASSIC TRUCKS
IT'S NO SECRET THAT ELECTRIC FANS ARE PRETTY MUCH THE NORM OF THE DAY. BUT THERES A CATCH WHEN IT COMES TO FANS:YOU HAVE TO GET SOMETHING WITH SUFFICIANT POWER TO COOL THE CAR, BUT AT THE SAME TIME GET ONE THAT DOESN'T HAVE A RIDICULOUSLY HIGH AMPERAGE DRAW. BUT REMEMBER, IN A TRUCK WITH A SMALL-OUTPUT (STOCK) CHARGING SYSTEM, THE PERFORMANCE DIMINSHES AS THE ENGINE SPEED DECREASES. SLOW SPEEDS = LOW AIRFLOW THRU THE RADIATOR & CAN RESULT IN OVER HEATING. SO DON'T SKIMP WHEN IT COMES TO ALTERNATOR AMPERAGE.

ALSO.. NOT ALL FANS ARE CREATED EQUAL.... YOU NEED A FAN THAT MOVES AT LEAST 2400 CFMs OF AIR. WHEN SEARCHING FOR ELECTRIC FANS, I THINK YOU'LL FIND THAT MOST OF THEM DON'T. HOPE THIS HELPS JOHN

crazy longhorn · 09-12-2003, 08:37 PM

Thanks john, I do agree that most of the elect fans dont pull the cfm that the crank driven fan did

from what I see on "sales pitch", a 400 hp sb should be running 4000-4500 cfm on elect fans. Mine runs 2700-2800 cfm, & does great cruising.....runs a little more idling in traffic, & flat runs on wide open throttle! The way it was explained to me was that most of the driving that you do wont be pulling max power (or making most heat).....the 1st 4 gears in that longhorn will run that temp from 180 to 200 degrees d@mn fast if the fans arent running! Its not the same , I do agree! I think that climate has a lot to do with the mix, as we say HOT in Illinois, & we are talking 100 degrees.......nothing like you see out your way ,Ill bet

crazyL

Longhorn Man · 09-12-2003, 09:54 PM

Dubie, i would personally toss that flex fan in the trash. I have seen them explode and rip right through the hood. Sliced through i like it was paper.
It is not n isolated incident, there are stories of it happening in every aumotive group you see, and I have seen the remains of 3 other flex fan explosions. (however, I did not see them blow up with my own eyes)

Injected68LS1 · 09-13-2003, 12:34 AM

My flex fan exploded! That ruined my perfect exterior. It wasn't the fans fault though because my water pump shaft broke off at full throttle. It cause 2K of damage.

GET an electric fan. But get a good one. I have a 16", curved blade fan by SPAL. It flows plenty and I don't even have a fan shroud. It is just on the back of my radiator and tranny cooler. Another plus is that you never have to lean over a fan blade to adjust your engine.

I live in Southern California and I have never overheated with this fan.

enjoy

**FRENCHBLUE72** · 09-13-2003, 10:08 AM

Clutch fan or the plastic flex a lite fan work's great too..

slam33 · 09-13-2003, 02:46 PM

My 2 cents worth, I've been running flex fans for a lot of yrs and have never had one go on me. I have a flex in my driver and it's been there for 5 yrs now. Clutch fans put a lot of weight on the water pump bearing, for me I don't like that. Electric fans worry me as to there reliability. Is it going to quit on me while I'm stuck on the 405 in the middle of the day ? For me the less moving parts something has, the better.

junkyardjohn · 09-13-2003, 03:42 PM

THE OLD RULE "THE LESS MOVING PARTS THE BETTER" DOESN'T ALWAYS APPLY TO FANS. LOL

bobs409 · 09-13-2003, 05:08 PM

The last flex fan I had, had to be hammered out of my hood! Right through the hood and the reinforcement under it like a hot knife through butter. NEVER AGAIN!

Mine was the stainless steel type and from the flexing, one blade broke off. (not the rivets)

My truck now wears a good old steel 4 blade, no frills fan. It doesn't overheat, so that's good enough for me.

*racedvl* · 09-13-2003, 07:35 PM

Quote:

Originally posted by 68 Suburban
clutch....flex fans are garbage, and they are dangerous.

Ditto!!!

casey · 09-13-2003, 09:59 PM

all i have to do is imagine that fan coming apart when your playing under the hood, I find those clutch fans don't last, my truck kept over heating with the clutch fan so I put a stock 5 blade on problem solved, as far as power loss goes you might only care if your always racing

nate68 · 09-13-2003, 10:38 PM

a higher output at idle alternator is a definate must when dealing with electric fans. i killed a powermaster one in about a year's time and i dont drive that many miles in a year. i bought another powermaster but one that puts out 70 amps at idle, peaks at 2000 rpm. $125 for polished aluminum one from summit. well worth the money and no more jumpy tach.

*rickspickuppart* · 09-13-2003, 11:00 PM

flex and electric are always a problem in hot areas, if the oem thought they were a better idea they would have used it, ours is a 542 cid motor w/ a mech fan and a severe duty clutch on a reverse rotation serpintine w/ a full and it never gets 1/4 of the way up the gauge (with a/c on in arizona)

GMC Jim · 09-16-2003, 01:06 AM

Have had several vehicles with clutch fans ( over the past 25 years!).....Never any problem; but possibly the weight of the clutch fan might shorten the life of the water pump bearing...( I have replaced water pumps.....
Using a clutch fan with my 402 engine with a marginal 3 core radiator and air conditioning.. On rare occasions; 100 degrees and slow traffic... pegged the temp indicator needle....to remedy just shut off the air conditioning, blower to high speed and heater on.. Rev up the engine some; temp comes to normal in less than a minute!.........Jim

Mechanic · 09-16-2003, 01:34 AM

Ok,
I'll check in on the fan issue. My experience with Flex-a-Lite electric fans has been with class D, 84 passenger school buses. We repowered 8 buses with Cat 3208 turbocharged 250hp engines back in 1992. When we took the cummins 555's out, the cummins hydraulic fan drives went with them. We left the same radiators in place and installed 4 Flex-a-Lite fans (2 outside, 2 inside) and the controllers with each power unit.

The only problem we have experienced has been some of the relays in the contollers failing. They were Bosch-type 40 amp relays and about 30% of them failed. After the first 2 or 3 failed we replaced them with HD Cole Herse continuous duty relays. As far as the fans themselves, they really move some air!

My suggestion for anyone trying to cool using these fans would be to use a dual-circuit Kysor brand switch to control on and off, and a Cole Herse relay to handle the amp load.

09-12-2003, 04:01 PM	#1
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	flex fan VS clutch fan I have one of each now. What would be the best to run on my 350? __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

09-12-2003, 04:13 PM	#2
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	clutch....flex fans are garbage, and they are dangerous. __________________ Just sitting here contemplating contemplation.

09-12-2003, 04:31 PM	#3
nate68 Registered User Join Date: Jan 2000 Location: ca Posts: 1,110	electric fans __________________ 68 short step, 406/700r4, 9" w/discs.

09-12-2003, 04:44 PM	#4
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	2nd the electric fans! I have 2 -14" flexalites on a hand built shroud......there is power to the rear wheels that you can feel after removing the eng driven fan I never did like the clutch fans, felt they were too inconsistant. flex fans are down right "spooky" (dangerous), but they work well for keeping a hp eng cool. I have run a flexalite PLASTIC flex fan with good results. It kept my 461 Olds cool in traffic on those 100 degree days....also worked well on my 383. The fan was also cheap, about $10 or 12 through summit racing. That thing did eat a little power to run, but thats better than a smoked engine. if you run a flex, be carefull! Good luck,crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

09-12-2003, 04:50 PM	#5
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,427	DUBIE .. GO WITH THE CLUTCH FAN. ELECTRIC FANS ARE OK FOR AN AUHSILLARY(SP) FAN , BUT DON'T MOVE ANYWHERES NEAR THE AIR A CLUTCH FAN DOES (CHECK THE CFMs YOURSELF) & FLEX FANS ARE JUST PLAIN DANGEROUS JUNK. JOHN __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST

09-12-2003, 04:57 PM	#6
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	I have the clutch fan already installed on the engine, but my neighbour gave me a 7 blade flex fan last night so I figured I would ask the experts. Thanks guys __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

09-12-2003, 05:22 PM	#9
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	What's involved with installing an electric fan(s)? I'm curious. I've been toying with the idea of dumping the fan, shroud and clutch and simply using an electric fan setup so I can cap that pulley on the water pump. Do you wire it to ignition? How is it grounded? How does it mount? Are there any required modifications? __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

09-12-2003, 05:40 PM	#10
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Check out the dual fan setup Wes has on his site.. http://www.classicheartbeat.com/cata...assemblies.htm __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

09-12-2003, 08:22 PM	#12
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,427	SORRY CRAZY LONGHORN ... I DON'T HAVE A LINK.... HERES AN EXCERPT FROM SEPT. 2002 CHEVY DUTY. I'M SURE YOU ALREADY KNOW THIS INFO, BUT MAYBE IT'LL HELP SOMEONE ELSE. HERE GOES..... THE BEST ALTERNATIVE TO A MECHANICAL FAN IS A DUAL ELECTRIC FAN THAT CAN PULL ALMOST AS MUCH AIR AS A MECH. FAN, REGARDLESS OF ENGINE SPEED, & THEY CAN SAVE SOME HORSEPOWER TOO. THEY COOL BETTER IN SITUATIONS LIKE STOP & GO STREET TRAFFIC. ALWAYS MOUNT THEM ON THE BACK OF THE RADIATOR TO PULL AIR THRU FOR THE BEST EFFICIENCY. AND FEB. 2002 CUSTOM & CLASSIC TRUCKS IT'S NO SECRET THAT ELECTRIC FANS ARE PRETTY MUCH THE NORM OF THE DAY. BUT THERES A CATCH WHEN IT COMES TO FANS:YOU HAVE TO GET SOMETHING WITH SUFFICIANT POWER TO COOL THE CAR, BUT AT THE SAME TIME GET ONE THAT DOESN'T HAVE A RIDICULOUSLY HIGH AMPERAGE DRAW. BUT REMEMBER, IN A TRUCK WITH A SMALL-OUTPUT (STOCK) CHARGING SYSTEM, THE PERFORMANCE DIMINSHES AS THE ENGINE SPEED DECREASES. SLOW SPEEDS = LOW AIRFLOW THRU THE RADIATOR & CAN RESULT IN OVER HEATING. SO DON'T SKIMP WHEN IT COMES TO ALTERNATOR AMPERAGE. ALSO.. NOT ALL FANS ARE CREATED EQUAL.... YOU NEED A FAN THAT MOVES AT LEAST 2400 CFMs OF AIR. WHEN SEARCHING FOR ELECTRIC FANS, I THINK YOU'LL FIND THAT MOST OF THEM DON'T. HOPE THIS HELPS JOHN __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST Last edited by junkyardjohn; 09-12-2003 at 08:30 PM.

09-12-2003, 08:37 PM	#13
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Thanks john, I do agree that most of the elect fans dont pull the cfm that the crank driven fan did from what I see on "sales pitch", a 400 hp sb should be running 4000-4500 cfm on elect fans. Mine runs 2700-2800 cfm, & does great cruising.....runs a little more idling in traffic, & flat runs on wide open throttle! The way it was explained to me was that most of the driving that you do wont be pulling max power (or making most heat).....the 1st 4 gears in that longhorn will run that temp from 180 to 200 degrees d@mn fast if the fans arent running! Its not the same , I do agree! I think that climate has a lot to do with the mix, as we say HOT in Illinois, & we are talking 100 degrees.......nothing like you see out your way ,Ill bet crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

09-12-2003, 09:54 PM	#14
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Dubie, i would personally toss that flex fan in the trash. I have seen them explode and rip right through the hood. Sliced through i like it was paper. It is not n isolated incident, there are stories of it happening in every aumotive group you see, and I have seen the remains of 3 other flex fan explosions. (however, I did not see them blow up with my own eyes)

09-13-2003, 12:34 AM	#15
Injected68LS1 Registered User Join Date: Jul 2003 Location: So. Cal. Posts: 389	My flex fan exploded! That ruined my perfect exterior. It wasn't the fans fault though because my water pump shaft broke off at full throttle. It cause 2K of damage. GET an electric fan. But get a good one. I have a 16", curved blade fan by SPAL. It flows plenty and I don't even have a fan shroud. It is just on the back of my radiator and tranny cooler. Another plus is that you never have to lean over a fan blade to adjust your engine. I live in Southern California and I have never overheated with this fan. enjoy __________________ 1968 Chev SWB with 1998 Corvette LS1 305hp and 320 ftlb to the wheels (stock engine!) AEM EMS and wideband O2 sensors Bowtie Overdrive's 700R4, stage 3 Baer 4 wheel discs and 20s http://iciclelanding.com/aperture?album=2049&view=album

09-13-2003, 10:08 AM	#16
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,594	Clutch fan or the plastic flex a lite fan work's great too.. __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

09-13-2003, 02:46 PM	#17
slam33 Registered User Join Date: Aug 2001 Location: Long Beach, Ca Posts: 1,432	My 2 cents worth, I've been running flex fans for a lot of yrs and have never had one go on me. I have a flex in my driver and it's been there for 5 yrs now. Clutch fans put a lot of weight on the water pump bearing, for me I don't like that. Electric fans worry me as to there reliability. Is it going to quit on me while I'm stuck on the 405 in the middle of the day ? For me the less moving parts something has, the better. __________________ 71 LWB 350/350still working on it but it's going tp be sweet. www.geocities.com/stevemau/slam33page.html " TARGET=_blank>http://www.geocities.com/stevemau/slam33page.html?1004806705410 </A>

09-13-2003, 03:42 PM	#18
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,427	THE OLD RULE "THE LESS MOVING PARTS THE BETTER" DOESN'T ALWAYS APPLY TO FANS. LOL __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST



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09-13-2003, 05:08 PM	#19
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	The last flex fan I had, had to be hammered out of my hood! Right through the hood and the reinforcement under it like a hot knife through butter. NEVER AGAIN! Mine was the stainless steel type and from the flexing, one blade broke off. (not the rivets) My truck now wears a good old steel 4 blade, no frills fan. It doesn't overheat, so that's good enough for me. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-13-2003, 09:59 PM	#21
casey Registered User Join Date: Jan 2003 Location: Kelowna B.C. Canada Posts: 2,048	all i have to do is imagine that fan coming apart when your playing under the hood, I find those clutch fans don't last, my truck kept over heating with the clutch fan so I put a stock 5 blade on problem solved, as far as power loss goes you might only care if your always racing

09-13-2003, 10:38 PM	#22
nate68 Registered User Join Date: Jan 2000 Location: ca Posts: 1,110	a higher output at idle alternator is a definate must when dealing with electric fans. i killed a powermaster one in about a year's time and i dont drive that many miles in a year. i bought another powermaster but one that puts out 70 amps at idle, peaks at 2000 rpm. $125 for polished aluminum one from summit. well worth the money and no more jumpy tach. __________________ 68 short step, 406/700r4, 9" w/discs.

09-13-2003, 11:00 PM	#23
rickspickuppart Account Suspended Join Date: Jul 2003 Posts: 1,284	flex and electric are always a problem in hot areas, if the oem thought they were a better idea they would have used it, ours is a 542 cid motor w/ a mech fan and a severe duty clutch on a reverse rotation serpintine w/ a full and it never gets 1/4 of the way up the gauge (with a/c on in arizona)

09-16-2003, 01:06 AM	#24
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	Have had several vehicles with clutch fans ( over the past 25 years!).....Never any problem; but possibly the weight of the clutch fan might shorten the life of the water pump bearing...( I have replaced water pumps..... Using a clutch fan with my 402 engine with a marginal 3 core radiator and air conditioning.. On rare occasions; 100 degrees and slow traffic... pegged the temp indicator needle....to remedy just shut off the air conditioning, blower to high speed and heater on.. Rev up the engine some; temp comes to normal in less than a minute!.........Jim __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).

09-16-2003, 01:34 AM	#25
Mechanic Registered User Join Date: Jun 2003 Location: Seattle Posts: 77	Ok, I'll check in on the fan issue. My experience with Flex-a-Lite electric fans has been with class D, 84 passenger school buses. We repowered 8 buses with Cat 3208 turbocharged 250hp engines back in 1992. When we took the cummins 555's out, the cummins hydraulic fan drives went with them. We left the same radiators in place and installed 4 Flex-a-Lite fans (2 outside, 2 inside) and the controllers with each power unit. The only problem we have experienced has been some of the relays in the contollers failing. They were Bosch-type 40 amp relays and about 30% of them failed. After the first 2 or 3 failed we replaced them with HD Cole Herse continuous duty relays. As far as the fans themselves, they really move some air! My suggestion for anyone trying to cool using these fans would be to use a dual-circuit Kysor brand switch to control on and off, and a Cole Herse relay to handle the amp load. __________________ Shop Labor $75, if you watch $100, if you help $125, Wisecracks-$25, Boxjobs-don't even think about it. Yes,Cash.

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