Loud radiator fan - 76 620

[ErickwithnoK]

If it leaves you stranded somewhere needing a tow home is my point. They don't pay for the tow or the anti freeze lost or the head gasket blown from over heating.

 

 

Early L series on left and later Z series and L series with air con on right.

 

Based on those images, what I need is the early fan clutch. I have the fan blade on the left, and a new fan clutch like the one on the right. Thanks so much for the pics Mike, super informative. I don't know how to distinguish between the early and later style of fan clutch other than it seems the fan bolt pattern is smaller on the early model, something like 4inch diameter, while the later model is a 4.72 diameter. Are replacement fans available? I'm heading to the junkyard right now to check out a couple 620's I've picked through before, I think there may be some fan blades on them. If I can find a later model blade, then my new pump should bolt up. Wish me luck

[datzenmike]

Try the 720 or the S110 second gen 200sx for the larger fan blades.

[ErickwithnoK]

Try the 720 or the S110 second gen 200sx for the larger fan blades.

 

Just got back from the junkyard with a 720 fan, looked and measured like the right fan. Thanks again folks, I'll post again when I see how the sound difference is with the new pump. 

 

Also, I found a 280zx at the yard with a motor/'tranny still in it. Is the 280zx tranny worth bolting into my 620? I know 5 speed swaps are commonly posted about, but I'm wondering what it should be worth in fair condition, and if I should spend more for a 5 speed from a 620. (There's also one of those in the same yard). Currently have a 4 speed and would like to get better highway mileage. Thanks for your opinions.

[ErickwithnoK]

The fan from the 720 still isn't big enough. It's the 4.72 fan, the new clutch measures at almost 5.5. It was stupid of me not to measure the item before going to get a different fan, I believed that it was 4.72 because that's what the product details said it was...not even close. Definitely sending it back now. 

[datzenmike]

If a T-5 turbo 5 speed I wouldn't even bother with it.

 

 

Transmission depends on the year zx. A '79 zx is a mid ratio with a 3.321 ratio first gear and a moderate 16% over drive. Pretty much the same as the '77 and '78 620 and will be fine in any year but the '79.

 

The '79 620 has a 4.11 differential and uses a wide ratio with a lower 3.354 first for easier starts. All other 620 had 4.375.

 

 

The '80zx has a 3.062 first gear and a 0.775 over drive

The '81-'83 has a 3.062 first but a 0.745 over drive. While both will work in a 620 I think the lower first will make it less responsive performance wise and the 25% over drive is going to be difficult to use on the highway climbing hills and into a head wind.

 

See what they want for it. Someone will always want one and you can sell it. 

[ErickwithnoK]

If a T-5 turbo 5 speed I wouldn't even bother with it.

 

 

Transmission depends on the year zx. A '79 zx is a mid ratio with a 3.321 ratio first gear and a moderate 16% over drive. Pretty much the same as the '77 and '78 620 and will be fine in any year but the '79.

 

The '79 620 has a 4.11 differential and uses a wide ratio with a lower 3.354 first for easier starts. All other 620 had 4.375.

 

 

The '80zx has a 3.062 first gear and a 0.775 over drive

The '81-'83 has a 3.062 first but a 0.745 over drive. While both will work in a 620 I think the lower first will make it less responsive performance wise and the 25% over drive is going to be difficult to use on the highway climbing hills and into a head wind.

 

See what they want for it. Someone will always want one and you can sell it. 

 

Awesome, thanks Mike. I'll ask what he wants for it, and what year it is.

 

I figured out the reason for my pump fitment issues. RockAuto sells both "Radiator Fan Clutches" and "Water Pumps" in different sections...I bought a fan clutch, which apparently only comes in one size (for AC models, 5.25 inch fan bolt pattern), but have a lot of water pump options I never saw before because I assumed they would be sold in the same place, since they are the same thing...oh well. I guess I'll order a new one. 

[ErickwithnoK]

Junkyard wants 275 for an '82 280zx transmission. Don't think it's something I want, esp since they quoted me 300 for the 620 5 speed tranny. 

[sebpv]

I paid 300 for a 200sx 5 speed tranny. But thats in Canada. Not many of them around :/

[ErickwithnoK]

I paid 300 for a 200sx 5 speed tranny. But thats in Canada. Not many of them around :/

 

Good to know, thanks!

[datzenmike]

I paid 300 for a 200sx 5 speed tranny. But that's in Canada. Not many of them around :/

 

If that was the '77-'79 S10 200sx then that's a dogleg 5 speed. Totally different 5 speed.

[sebpv]

in a good way or bad?

[ErickwithnoK]

in a good way or bad?

 

My truck requires the longer tranny, not the dogleg. So not better or worse, just different.

[Seeker > 620 KC]

If it leaves you stranded somewhere needing a tow home is my point. They don't pay for the tow or the anti freeze lost or the head gasket blown from over heating.

 

 

Early L series on left and later Z series and L series with air con on right.

Hate do disagree with you DZM... The fan in your pic is the standard 7 blade 620 clutch fan.

 

The 620 AC fan had 8 blades and a little flatter pitch. The mount plate was offset as to move the fan forward as much as possible toward the radiator (1"or so) so it would not strike the bolt-on pulley attached to the harmonic balancer/drive pulley. I had to swap out a lot of them in 1976 at Joe Vittone's (Empi) import auto mall: Datsun, VW, Honda, Suburu, Lotus, Fiat, Jensen Healy, Jaguar. It was one of the first import (or the first) multi import dealer/mall in the country. I'll see if I can find my pic of the two side by side.

 

http://static.carpartsmanual.com/datsun/pickup-1972-1979/large/620-091C-01.jpg

[Seeker > 620 KC]

 

It's late and I can't get the pic to post using my iPad. Will have to try to post pics from computer tomorrow. Also have pics of bolt on drive pulley and balance.

 

The standard 620 clutch fan has 7 blades that are 4 3/4" long, with 3 7/8" wide mounting holes.

 

The 620 AC fan has 8 blades that are 4" long, with 5" mounting holes.

 

My prev post was backwards. The longer blade standard blades have the flatter pitch, the AC fan has more more curl or pitch.

[ErickwithnoK]

It's late and I can't get the pic to post using my iPad. Will have to try to post pics from computer tomorrow. Also have pics of bolt on drive pulley and balance.

 

The standard 620 clutch fan has 7 blades that are 4 3/4" long, with 3 7/8" wide mounting holes.

 

The 620 AC fan has 8 blades that are 4" long, with 5" mounting holes.

 

My prev post was backwards. The longer blade standard blades have the flatter pitch, the AC fan has more more curl or pitch.

 

Thanks for more info

[Seeker > 620 KC]

The 620 water pump has to be changed to accommodate the larger 5" bolt pattern fan. It looks to be the same water pump, but I'm guessing (never measured one) that clutch has a larger diameter shaft and bearing to handle more fan blades and torque. There is one more blade, but the mounting circle is broader and the fan blades shorter, so I also assume the 8 blade fan must draw more air through the radiator. I haven't installed on since 1977 and am sure it must be a noisy thing when engaged. But, when it gets to be 105 degrees out, could be well worth it. Will let you know when I get it all up and running. 

 

 

This is the Nissan 620 bolt-on AC drive pulley along side the original harmonic balancer / drive pulley.

 

 

 

 

[datzenmike]

in a good way or bad?

There are advantages to both. The FS5W63A has a 3.382 first and your '73 would have had a 3.675 to make starting off with a load easier. For use as a commuter it would be fine. The 71B has a choice of 3.062, 3.321 and 3.592 firsts. The 63A will handle an L20B, the 71B will handle a 280zx six cylinder, draw your own conclusions.

 

 

There are two.

Keep in mind that a vehicle driven primarily in town doesn't use 5th that much. A fifth gear does not make it go faster. Over drive is simply to lower highway revs and may increase mileage very slightly.

 

 

The FS4W63A from a '77-'79 S10 200sx. Rare to find one, rarer to find one not worn out or rebuilt. Same length as your 4 speed so the drive shaft does not need shortening. It's an adequate transmission with a unique shift pattern of reverse above first, speedometer in the same location, and was never used in the 620. You will need to modify the transmission mount.

R,,2..4

1..3..5

 

The FS5W71B from a later 620, 280z or zx non turbo, 810 and Maxima. As you can see this is a much stronger six cylinder transmission used in many more vehicles and more plentiful to find. There are wide, mid and close ratio gear choices and mild to wild over drives. The 71B is longer than your 4 speed so shorten your front driveshaft or get one from a '74 or newer 620 that is already the correct length for this transmission. Has regular H pattern shift.

[ErickwithnoK]

I was too stupid to take a picture of the fan before I took it off, so now that I have the right fan clutch installed i can't figure out if the fan is supposed to be proud towards the radiator or closer to the motor. The mounting face is offset on the fan, which way does it go? Looking up pictures online to try to figure it out. I think it does matter, the fan blades are curved slightly so they will work differently depending on which way it's mounted. 

[datzenmike]

No it won't, the fan will work the same no matter which way it faces. Direction of spin changes it.

[Ranman72]

No it won't, the fan will work the same no matter which way it faces. Direction of spin changes it.

i think this is correct but not sure 

when i reversed the motor on an electric fan i had to reverse the blade too 

so will the stock blade pull air no matter which way it is turned ?

[ErickwithnoK]

It changes how much air the fan blows, the blades have a curve to them,they are not flat.

[ErickwithnoK]

Rest of the install was easy and the car is a whole lot quieter now. Thanks again for all the help.

[submmbob]

Wow, I just went thru all of this at about the same time. The parts store sold me a clutch/pump for a truck w/ ac, prob thinking in AZ that everyone has ac:)

 

I tried finding a fan that would fit. O'Reillys had one in stock that looked close. It was the right bolt pattern but it ended up being too deep. I went back to the store that sold me the pump/clutch and found out about the difference between ac and non-ac then. They exchanged the pump even though I had already installed it which was cool. I haven't had time to put it all back together and have been driving the Corvan.

 

Does anyone sell a replacement fan? Mine is ok but starting to show a few cracks.