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Can you feel the air being pulled into your front grille?

idrivemopar

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Interesting turn of events this weekend. I was coming back from a cruise in, just a Friday night meetup of about 80 cars at the local Freddys hamburger joint, and I head this strange sound like something rattling under the hood at 3500 rpm, but would go away at 3000 rpm. I started checking things on Saturday, and figured it was the fan clutch, a Flex-a-lite that's been on the car since I rebuilt it. Well I have a heavy duty Hayden fan clutch, so I swapped it out, problem disappeared, and all is quiet, except, when I rev the engine I can hear the air and the fan pulling a lot of air. I went for a cruise after words, and noticed that my temp gauge is now a bit below middle instead of dead center and also that when I run my AC, its colder. So, when I got home, I left the car running and went to pop the hood, and noticed that I could feel air being pulled into the grille. I thought wow this is great, but was wondering since I have never had this before, can you feel the air being pulled into your front grille?
 
That's the whole point of the fan...to pull air through the radiator. Not around it. I've never tried through the grill but I can toss a rag at the front of the radiator and it sticks from the suction.
 
Right, I get that way that air moves through the radiator, and it was adequate before with the old fan clutch, but I have never had this much moving through to where you can feel it in front of the car!
 
A properly working fan clutch should work like a fixed fan when the engine is at temperature and sitting. Running down the road with adequate air flow and engine temperature, should be when it sort of free wheels.
 
The trick is to have a fan that is slightly smaller than the shroud and a shroud that is deep. The suction created by these two will pull the air in. Too small a fan, or no shroud and it will be hotter.
 
How about a pic of the flex a Lite fan and the Hayden clutch probably can't get the front side of it but even the backside would be helpful for my situation thank you
 
How about a pic of the flex a Lite fan and the Hayden clutch probably can't get the front side of it but even the backside would be helpful for my situation thank you
2947 is the low pro HD clutch.
image.jpeg
 
Yes! At idle mine will suck a piece of paper up against the radiator if I just drop it behind the grill. Proper-fitting shroud and 7-blade factory Chrysler fan. If you didn't notice it before the swap, the old clutch was probably on it's way out...OR they were set for different temps. Fan clutches can be adjusted for the temp at which they 'clutch' by tightening/loosening the thermostatic metal coil.
You say your temps went down a little and there's more air movement? You win!!
 
Yes! At idle mine will suck a piece of paper up against the radiator if I just drop it behind the grill. Proper-fitting shroud and 7-blade factory Chrysler fan. If you didn't notice it before the swap, the old clutch was probably on it's way out...OR they were set for different temps. Fan clutches can be adjusted for the temp at which they 'clutch' by tightening/loosening the thermostatic metal coil.
You say your temps went down a little and there's more air movement? You win!!
You are correct, I didn't notice it before the swap, this was a new clutch fan, and the original before my restoration was shot. I am running a factory setup as you are, and so here is a little more information.

I was previously running a flex-a-lite which I now know was just a standard fan clutch, I am now running the Hayden 2747 which is heavy duty, and better suited for the higher revs and the big 28 inch radiator in my car for my 340 as it turns at a higher percentage rate than the standard fan clutch. I also noticed that the Hayden is almost identical to height of my original factory fan clutch, the flex-alite was about 3/8 inch taller, so it was further into the shroud, and I don't think it was moving air efficiently partly because of that and it was a standard clutch so it wasn't turning nearly as much as the HD Hayden. Now, I cant keep a lighter lit in front of the car, have not tried dropping any paper in front to see how it gets sucked in, but I think this is the perfect fan clutch for my setup. This might explain why my AC wasn't cooling very well, but I will have to wait for hotter weather to test that theory.
 
You are correct, I didn't notice it before the swap, this was a new clutch fan, and the original before my restoration was shot. I am running a factory setup as you are, and so here is a little more information.

I was previously running a flex-a-lite which I now know was just a standard fan clutch, I am now running the Hayden 2747 which is heavy duty, and better suited for the higher revs and the big 28 inch radiator in my car for my 340 as it turns at a higher percentage rate than the standard fan clutch. I also noticed that the Hayden is almost identical to height of my original factory fan clutch, the flex-alite was about 3/8 inch taller, so it was further into the shroud, and I don't think it was moving air efficiently partly because of that and it was a standard clutch so it wasn't turning nearly as much as the HD Hayden. Now, I cant keep a lighter lit in front of the car, have not tried dropping any paper in front to see how it gets sucked in, but I think this is the perfect fan clutch for my setup. This might explain why my AC wasn't cooling very well, but I will have to wait for hotter weather to test that theory.
Good deal...and right on time for summer!
 
Gentlemen,
I use the Mopar 2806070 torque drive fan clutch. This unit reacts to RPM not temperature as do the ones with air temp sensing element. Which one is better? Depends on the intended application or the owners expectations.
My objection to the Hayden unit is the universal bolt circle (slotted mounting holes) not its performance. I'm sure that it costs considerably less that the $300 I paid for the Mopar repop unit from Tony's parts (a great source for stuff). This of course is just my opinion.
Bob Renton
 
Good deal...and right on time for summer!
LOL, well, the car has been done since 2014, its just things like these that take a while to discover that keeps me tinkering, but yes, will be a good test this summer to see how things go!
 
Here is a receipt stuck to my grille, I dropped it about 6 inches out and it got sucked in. You can see the hood isnt fully closed either. Now i guess this is the difference with heavy duty clutch that rotates at 70 to 90 percent of engine rpm versus 50 to 70 percent with standard duty.
20190529_141505.jpg
 
Interesting this thread came up. I am running a factory fixed fan with no clutch and wanted to swap to a clutch fan setup so I got the heavy duty Hayden 2947 with the short neck and also got a 5 blade mopar viscous fan recently. So I mount it all up and the paper suction test that worked before was now a no go. The fan was PUSHING air out the grill now instead of pulling. I thought I mounted the fan to the clutch backwards but as I flipped it around the blade pitch looked the same. I know my big block spins clockwise over the top towards the driver as you are facing the car and a small block spins counterclockwise. Are there designated opposite direction fan blade pitches for small block and big block? I thought the mopar viscous 5 blade was one fits all? Here’s a photo of my 5 blade fan that was pushing air.

EBB790A0-6704-4F17-9C44-DEAD0FE6FDD3.jpeg 51E8C7B9-CFD8-4994-B2AC-663A08CE5F5A.jpeg
 
Gentlemen,
I use the Mopar 2806070 torque drive fan clutch. This unit reacts to RPM not temperature as do the ones with air temp sensing element. Which one is better? Depends on the intended application or the owners expectations.
My objection to the Hayden unit is the universal bolt circle (slotted mounting holes) not its performance. I'm sure that it costs considerably less that the $300 I paid for the Mopar repop unit from Tony's parts (a great source for stuff). This of course is just my opinion.
Bob Renton

Well the unit I use is the Hayden 2797 severe duty clutch, it doesn't have slots.. It does have two drilled patterns so if you really look closely you'll see the dual pattern but looking at the edge of the clutch you don't see the obvious slots... Since I drive my cars allot it hot conditions I want the engine to stay cool & I want the A/C to work well so a severe duty clutch earns it's place in front of my engine....
Screen Shot 2019-07-22 at 22.36.19.png
 
Interesting this thread came up. I am running a factory fixed fan with no clutch and wanted to swap to a clutch fan setup so I got the heavy duty Hayden 2947 with the short neck and also got a 5 blade mopar viscous fan recently. So I mount it all up and the paper suction test that worked before was now a no go. The fan was PUSHING air out the grill now instead of pulling. I thought I mounted the fan to the clutch backwards but as I flipped it around the blade pitch looked the same. I know my big block spins clockwise over the top towards the driver as you are facing the car and a small block spins counterclockwise. Are there designated opposite direction fan blade pitches for small block and big block? I thought the mopar viscous 5 blade was one fits all? Here’s a photo of my 5 blade fan that was pushing air.

View attachment 805524 View attachment 805525

Big Block & small block rotate the same direction, You have a reverse rotation fan from a late model vehicle with a serpentine belt.. And your spinning it in the standard rotation....
 
Interesting this thread came up. I am running a factory fixed fan with no clutch and wanted to swap to a clutch fan setup so I got the heavy duty Hayden 2947 with the short neck and also got a 5 blade mopar viscous fan recently. So I mount it all up and the paper suction test that worked before was now a no go. The fan was PUSHING air out the grill now instead of pulling. I thought I mounted the fan to the clutch backwards but as I flipped it around the blade pitch looked the same. I know my big block spins clockwise over the top towards the driver as you are facing the car and a small block spins counterclockwise. Are there designated opposite direction fan blade pitches for small block and big block? I thought the mopar viscous 5 blade was one fits all? Here’s a photo of my 5 blade fan that was pushing air.

View attachment 805524 View attachment 805525
Yep that's for spinning the other direction. I have a Derale 6-blade, used it for about two weeks (until I came across an OE 7-blade that I'm still using).
The Derale is 18" diameter, a little heavier than the viscous units but it's yours if you want it..I also have a 20" (19-3/4" actual) 5-blade viscous fan that was off an RV if I remember...it's used but other than being a little dirty it's fine. It was a tad too big for my shroud. You can have either one, free, just p.m. me a shipping address if you're interested..
20190723_063831.jpg

20190723_063853.jpg
 
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