OE Steel fan vs. 11 blade plastic fan

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

Several people have swapped their OE 5 blade steel fan for an 11 blade plastic fan. Is this really an improvement? I would think that the OE fan would be engineered to move more air since the diesel has an intercooler to draw through in the radiator stack. Some have said the plastic fan is quieter, but I'm don't really car about the noise. I'm not convinced that swapping the fans is an improvement. It's got to be cheaper to make the plastic fan, and if so, why didn't the CRD come with that originally if it is more efficient?

Lancer · **Posted:** Sun Jun 05, 2016 4:30 am

As I understand it (something I read on it a couple of years ago) the steel fan comes into its own towing a heavy load (I think it was up to the max of 5000 lbs) up an incline in high temperatures. On the other hand, its not so efficient at lower loads. If you are not going to that extreme, the nylon fan shifts more air at lower loads and because its mass is a lot less it has an effect a bit quicker being easier to "get started".

It is quieter, but I'd suspect not by much, and some claim a bit more fuel economy, but I'd be hard pressed to say I noticed any. It should be teamed with the Hayden clutch for greater efficiency, but thats probably the case with the steel fan - the original fan clutch is not the best. I will say that I had better cooling after it was fitted than before.

Dent · **Joined:** Sat Aug 04, 2012 11:05 pm **Posts:** 275

Thanks for the thoughts. I'm replacing the clutch this week, but I'm trying to decide whether changing the fan is worth the time and/or money, or if even prudent.

thermorex · **Posted:** Sun Jun 05, 2016 9:05 am

The steel fan plus good clutch has I believe about 5400-5600 cfm at 4000rpm, this is from gde. So if you tow light loads and not a long way, you may be better with the plastic fan. Or an electric fan.

95Z28A4 · **Joined:** Sun Mar 30, 2014 9:53 am **Posts:** 297

I swapped to the 3.7L nylon fan when I replaced the OEM fan clutch. There isn't any extra effort involved, just more $$ for the fan. I swapped to the nylon fan for reduced noise and fuel efficiency. The difference in sound is noticeable. I don't know for sure if the nylon fan affects MPG as I have done a lot of small modifications that are directionally correct to increase MPG. The sum total of the mods is about +2 to +3 MPG. I have not towed more than 3000 lbs.

FYI......slip two thicknesses of corrugated cardboard between the fan and the radiator to protect the radiator from the fan blades when it slips from your hands. This has happened to a few lost members and the result was purchase of a new radiator. The metal fan is heavy and the edges of the blades are sharp. I read a similar warning and decided to heed the advice. I am glad that I did. Trying to snake the fan, fan clutch and fan shroud out at the same time caused me to lose grip of the fan and it slipped from my hand falling against the radiator. The cardboard protected the radiator and no damage was inflicted. Another benefit of the nylon fan is it is "radiator friendly".

WWDiesel · **Posted:** Sun Jun 05, 2016 1:39 pm

I installed a 11 blade GM plastic fan and Hayden/NAPA heavy duty fan clutch last year. Both are available at your local NAPA dealer and cost a lot less than the Mopar fan. NAPA had both items in stock when I picked mine up. The GM 11 blade fan uses a slightly different clutch than the CRD Mopar or Hayden units; the GM fan bolt pattern is a little bit larger in diameter but the NAPA/Hayden fan clutch made to fit it uses the same exact screw on hub fitting...
The GM unit was used on a multitude of GM trucks and is rated for heavy duty towing. The fan actually sets a little bit closer to the back of the radiator and I think it is slightly larger in diameter but not enough to even come close to hitting the fan shroud. I do believe it helps a little on fuel mileage, but the increase is very small. I also firmly believe it helps on better cooling in around town stop and go traffic if nothing else helping the AC to perform better in our hot southern climate... As to noise, never hear the thing.. I do not tow often and when I do, it is small loads... :wink:

GM fan tophic and part no.s:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=82941&hilit

Infinite_Karma · **Posted:** Mon Aug 15, 2016 10:01 pm

Same WWDiesel, I upgraded to the 11 bladed fan & HD Fan Clutch, and modded the Fan Shroud.

My full post with photos is here: http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=83766

PALiftedKK · **Posted:** Mon Aug 15, 2016 10:40 pm

adding my

, a steel blade being heavier will put a much larger load on the water pump bearing. the steel blade do a better job with towing and when the clutch is near its full engagement point.

i added a non oem mechanical fan assembly a little while ago. saved a hundred bucks and got better parts. buy pats that would match your style of driving (on road, off road, towing).

peteyz24 · **Posted:** Tue Aug 16, 2016 5:14 am

Water pump is driven by the timing belt, therefore is behind the timing cover. The bearing the fans rotates on is solely for the fan.

mass-hole · **Posted:** Tue Aug 16, 2016 2:31 pm

Lancer wrote:

As I understand it (something I read on it a couple of years ago) the steel fan comes into its own towing a heavy load (I think it was up to the max of 5000 lbs) up an incline in high temperatures. On the other hand, its not so efficient at lower loads. If you are not going to that extreme, the nylon fan shifts more air at lower loads and because its mass is a lot less it has an effect a bit quicker being easier to "get started".

It is quieter, but I'd suspect not by much, and some claim a bit more fuel economy, but I'd be hard pressed to say I noticed any. It should be teamed with the Hayden clutch for greater efficiency, but thats probably the case with the steel fan - the original fan clutch is not the best. I will say that I had better cooling after it was fitted than before.

I would tend to agree with this. This is pure speculation, but at lower rpm I would imagine the closer blade spacing of the plastic fan probably helps but as rpms increase they may actually get in their own way. Meaning, since the time between each blade passing through a certain area is less it may not be getting as much bite. The steel fan may do better in this regard.

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MM53 · **Posted:** Tue Aug 16, 2016 6:25 pm

The OEM fan is just a piece of metal with no sensors. The rotational speed is controlled by the engine rpm and fan clutch I dont see how towing would make a difference or how the fan would know I was towing but I would like to go to the GM set up.

geordi · **Posted:** Tue Aug 16, 2016 9:33 pm

Max rotational speed might be controlled by the engine, but engagement or not is controlled by the hot air passing through the radiator. As the air gets hotter, the thermoclutch engages more and spins the fan closer to the speed of the shaft.

Towing puts more load on the engine and heats the air hotter, so there you go.

WWDiesel · **Posted:** Tue Aug 16, 2016 9:52 pm

MM53 wrote:

The OEM fan is just a piece of metal with no sensors. The rotational speed is controlled by the engine rpm and fan clutch I dont see how towing would make a difference or how the fan would know I was towing but I would like to go to the GM set up.

You will not be sorry for going to the 11 blade GM setup...it rocks!!! If it can keep a big GM V8 at normal temperatures while towing a much heaver load, it should be able to handle our little old 4 cylinder diesel... It really made a big difference in my AC performance in stop and go traffic in the central GA 100+ summer time heat and high humidity...

OE Steel fan vs. 11 blade plastic fan

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