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L Motor Electric Fan Water Pump Mod


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First you take a Beck Arnley Part # 1310796 Water Pump or similar.




Here is a comparison of standard L series pump for: standard transmision without AC, automatic without AC, and automatic with AC.


Standard transmision without AC




Automatic without AC




Automatic with AC




First remove the 4 phillips head screws then take of clusch cover (becareful there is oil in these). Let it sit upside down to drain the oil for a few minutes to drain oil. I then spray it out sith brakekleen. Next I take my air cutoff tool and cut as far as I can into the clutch without cutting the pulley,




then I take a board and set the water pump on it and take hammer and a chisel to split the clutch in half. Remove all pieces of aluminum.




Do the same procedure to the back part of the clutch. (Aluminum)




Do the same procedure to the bearing outer race. (Steel)




Do the same procedure to the roller cage. (Alloy)




Do the same procedure to the bearing inner race. (Steel)




You will be left with about a 3/4" shaft sticking out in front of the pressed on pulley just cut this off flush with the lip on the pulley. You are done.






This mod will gain about an 1 1/2" to 2" clearance when adding electric fans.


This mod was originally done by datzenmike I believe. You could also press the clutch of in one piece if you have the arbor press and a bearing splitter, but this is the Ratsun Way.


Thank you datzenmike for the information to do this mod.





Edited by Charlie69
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No, thank you for the great tech. write-up and pictures! Many of us run electric fans with or without stock rads and sometimes the difference between making it work or not is just an inch or so. This shows how easy it is to convert your stock pump over to electric fan. Good job!

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This mod will gain about an 1 1/2" to 2" clearance when adding electric fans over using a Stock clutchless water pump.






By the time you add the stock fan to the clutchless water pump it ends up being about 1.5" to 2" difference.


Yes motivated the pulleys are the same spacing for belt purposes, however the pulley is deeper on the clutchless water pump which means the shaft is longer.


When I set the modded pump and the clutchless pump with pulley no fan side by side there was a 3/4" difference in height with the modded pump being shorter.


I hope this helps to clear up any confusion. I will pull the modded pump off my motor tomorrow and take a picture of the 2 pumps side by side. I did this today but forgot to take the picture. My bad. sorry


Also I get my water pumps from the j/y no more than $8.00. When ever I go to the j/y I watch for water pumps and any other bolt on excessory that looks new or near new after all this is Ratsun.

Edited by Charlie69
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Skib, its to make more clearance for using an electric fan


I just can not stump Skib. Thank you again Skib.


Thank you Fisch for the koodos.


As for the wiring as I build the harness for my truck I will do a write on certain parts of the wiring and the electric cooling fan will be covered even though it has been covered already.

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When Icehouse and I compared notes we found that we both used the inline temp sender from the mid '80s 200sx. It's a short length of pipe with the sender on the side. All you have to do is cut the lower rad hose and remove an inch or so and slip it in line with a couple of gear clamps. I have one on my truck but haven't bothered with the relay yet. As long as I'm moving, enough air passes the rad that it won't overheat. With my '82 Z22 720 3 core rad, I can easily wait through any traffic light. I will use this in line sender to trip a relay connected to the battery and the electric fan. It doesn't really matter how hot the rad water gets as long as the water returning to the motor does not exceed 190? or whatever the sensor is set at.

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this is a good thread but what is a good water pump for a l20 that's just a

stock rebuilt block and a fully built and ported w53 head 44's/long tube header?



Just about any L series pump will do. L20Bs tend to have a clutch fan on them. Z20/22/24 motors have water pumps with a deeper internal cavity and larger pump vanes. Avoid rebuilt ones that have stamped out cookie cutter vanes. The stockers are cast iron and smoother to prevent cavitation.

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I did this mod on my toyota truck. I used a temp sensor from a Fiat Uno, plumbed into the rad return pipe to trip the electric fan relay. The Uno sensor trips at 54 degrees C. But I went back to the stock clutch fan after a while, cos I didn't like the idea of no air blowing over the hot motor, especially off - road.

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When I daily drove my wgn a few years ago, my fan clutch went bad and I nearly cooked my motor. I thought I was improving things by converting to a non-clutch water pump. I lost about 4mpg :( I later found out that you can get the silicone gel from napa to put back in the clutch.


For clearance issues....I love the idea of this mod! I just hope the pump doesn't go bad any time soon!

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If it does I will get another $8.00 pump out of my garage and mod it and change the bad pump out. I have had better luck with pumps from the j/y than I have with pumps from Checker Auto & AutoZone. Although someday they might be hard to find.


I am tempted to order the one with the cat iron impeller from Rock Auto and mod it.

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Wonderful How to guide charlie.

I was directed over here from someone on InfamousNissan.

I've installed an electric fan on my 720 and am looking to do the same thing, I was planning to use a L series pump, with a KA pump pulley, not sure if it will work, but from what I can find it looks like it just might.

Is there another way to do this, in my case, besides chopping up one with a clutch fan?

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Awesome writeup!!! And to think that I was trying to throw away a brand new clutch type water pumps away!!!!!!!!!!!!



Yep Mike the S12 is an awesome temp sensor! remember red bad white good. The red switches at 205ish the white at 185ish.




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I know this might be a stupid question........ but can I use ANY L20B waterpump?


For example: Can I walk into my parts store and ask for a 1979 Datsun 510 waterpump?


I know the '79 used a clutch fan,,,.. so will ANY clutch fan from a L20B work?

I have had better luck with pumps from the j/y than I have with pumps from Checker Auto & AutoZone.

Why?,,,, is there a better brand to look for???... My nearest Junkyard is 2 hours away... and the parts store is 40 mins,,, my time (on my days off) is valuable to me

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Can I walk into my parts store and ask for a 1979 Datsun 510 waterpump?


I know the '79 used a clutch fan,,,.. so will ANY clutch fan from a L20B work?


I do not see why not, the only thing that I watch for on the clutched water pumps is that the belt groove in the pulley lines up with your crank pulley belt groove. On my 1976 620, 1978 620, and 1980 720 L20B's all had the same clutch fanned water pumps. The 620's were automatic trans and the 720 was 5 speed.


The reason I feel I have better luck with good used ones out of the JY I can buy 6 to 8 of the JY water pumps to every 1 store bought. I have had 2 Checker Auto & 3 Autozone water pumps bad out of the box. So whenever I am j/ying I watch for good relatively new parts for cheap prices. There are 8 u-pull it type j/y within 30 miles of where I live. All of these have 50% off days, so there is a lot of competion.


Also If I destroy one doing the mod it does not cost me as much. I honestly feel that the quality of aftermarket parts is lower today and quality control has suffered to from all the U.S. companies out sourcing the rebuilds and remanuctures to overseas company.


This mod is probably not for everyone but, for some people it will get them a little mre clearance for installing an electric fan.

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