Correct fan for an l20b??

[gino_the_terrible]

I recently did a water pump on my 76 620, and the new pump I got from Oreily’s has a clutch on it that is way bigger than the old one so my fan doesn’t fit it. After a decent amount of forum sleuthing, I can’t figure out what fan that I need. Any help is greatly appreciated! 

[DanielC]

There are several different fans, fan diameters, fans with and without clutches, and at least two different thickness water pumps that I know of.

I put a L-20-B engine and transmission from a 1980 720 truck that had air conditioning in a 1970 521.  The 1980 engine had the thicker water pump, with clutch, and seven blade fan.   This fan had a larger diameter bolt circle to mount on the fan clutch.  At the same time I got the 1980 720 L-20-B engine from the junkyard, there was also a second L-20-B engine, also in a 720 with out air conditioning.  If my memory serves me correctly, I believe that engine had a normal thickness water pump, and a fan without a clutch, I could easily be wrong on that.  

 

This is waterpump, clutch and fan from the L-20-B with AC

 

This is a smaller 7 blade fan, without a clutch.  It will bolt on to a L-16, L-18, or L-20-B waterpump, without a clutch.   It will also make a lot of noise.   I am not sure if there is a waterpump with the bolt pattern on a clutch to match this fan.

 

This is a L-16 fan, sitting on top of the other two fans.  It is used without a clutch.

 

I also have a larger four blade fan, it is on the L-20-B engine in the 521 truck.  It fits the stock L-16 fan shroud just fine.  

By the way, the 1970 521 with the L-20-B engine is using the stock 521 radiator.  I have  not had any cooling problems.  If the temperature starts to creep more than half way on the temp gauge, I need to add coolant to the radiator.

 

So, the fan you need is the one that fits (bolts on).  If you have the 7 blade fan, you probably want a fan clutch to keep the noise more tolerable.   The four blade fans are less noisy, and do not need a clutch.

 

Edited June 6, 2020 by DanielC

[datzenmike]

 

You probably need the one on the left. The right one is from a 720 Z20/22/24 or an '80-'83 S110 200sx Z20E or Z22E

 

Why not take it back and get the right one???

[ducky]

On 6/5/2020 at 8:49 PM, datzenmike said:

 

You probably need the one on the left. The right one is from a 720 Z20/22/24 or an '80-'83 S110 200sx Z20E or Z22E

 

Why not take it back and get the right one???

 

Is that fan on the right the 21060-N8650? I tried a different one to replace my cracked one, but it's too big, even though I can mount it with the adapter for A/C. As a couple other threads talk about, the L20B seems to be 380mm diameter.

[datzenmike]

Don't know. The Z24 truck engine and the '80-83 S110 200sx Z20 and Z22 used a 21060-8560. It's my picture and I had both so it's probably one of them.

 

 

[ducky]

OK so once again, in the interest of helping future generations, I'll provide some good info for people looking to get a new fan.

 

This one has been a journey for me. There are no used L20B fans for a 620 that I could find on eBay. Well, there was one, but it was in Thailand or something, and why buy something used that might not show up, or just crack in a few years again anyways?

 

I was looking around, and originally purchased a fan for a 1990 D21. They're cheap and available from Rock Auto. The diameter is right around 410mm, but it's only about 15mm from the radiator core support and about 10mm from the inside of the shroud. That's a no go.

 

I then found the 21060-N8560, which was used on the 200SX. This one is really available on eBay, but not much else, though is brand new. Diameter is about 390mm,which is only a hair bigger than stock. The big issue is the mounting flange is on the opposite end of the hub. So to make this work, I got 3/4" spacers to add between the flange and adapter for the a/c fan.

It's not very light, and it's physically a deeper fan, but thinking it's going to work just dandy.

It also appears to be really close to the alternator nut, but that's basically how close the original was, so I'm not super worried.

 

If anyone else has a idea on a similar size mechanical fan, but with the flange on the correct end, please let me know so I can get an extra just in case.

 

 

Edited May 15, 2022 by ducky