Fan clutch or no clutch?

[Thomas Perkins]

Your 1980 Datsun 720 King Cab has so many variants.Here is a Nissan site showing the types of water pumps and fan blades.It also shows for Automatics and stick shifts.If you go to auto part sites,they have many different ones,also.That may be your problem,you may have the wrong one on there.Get away from the thermostat theory.Don't try to change anything,go with the way it was made.Is your engine a Z22,if so so use the parts made for it and it will run like new.Someone before you might have put the wrong parts on it.It's running hot because you have the wrong pump,fan blade,go OEM.https://www.nissanpartsdeal.com/parts-list/1980-nissan-720_pickup/exhaust_cooling/water_pump_cooling_fan_thermostat.html?diagram=210_N01

Edited October 15, 2022 by Thomas Perkins

[Veraciousreasoning]

1 hour ago, Thomas Perkins said:

Your 1980 Datsun 720 King Cab has so many variants.Here is a Nissan site showing the types of water pumps and fan blades.It also shows for Automatics and stick shifts.If you go to auto part sites,they have many different ones,also.That may be your problem,you may have the wrong one on there.Get away from the thermostat theory.Don't try to change anything,go with the way it was made.Is your engine a Z22,if so so use the parts made for it and it will run like new.Someone before you might have put the wrong parts on it.It's running hot because you have the wrong pump,fan blade,go OEM.https://www.nissanpartsdeal.com/parts-list/1980-nissan-720_pickup/exhaust_cooling/water_pump_cooling_fan_thermostat.html?diagram=210_N01

I don't have a thermostat theory mike did and i was just responding. 

 

I look it over and see whats what 

[datzenmike]

The '80 was the last year for the L20B. My info shows clutch fan for air con option. All others the fan bolts to the pump pulley.

[Thomas Perkins]

Mike is right.

Edited October 15, 2022 by Thomas Perkins

[Veraciousreasoning]

Ah so i need one cause i have ac

[datzenmike]

Not just the clutch fan..... some pumps move more coolant than others.

 

 

Stock usual pump...

 

Stock also, but look at the impeller. It's taller and sits deeper into a larger pump cavity.

[Thomas Perkins]

Most all pumps are different,I took out a Auto zone water pump and replaced it with a Oreilly's water pump and the impeller on both were different.The Auto Zone's short bolts were made to not come out of the pump and Orielly's were.So with not being able to get a new Nissan pump,we are getting something that may need modifications.The bottom bolt on my Orielly's pump would not go all the way in,that is the long Nissan bolt,so I just added a fat Washer and it works.Mike is right.Also the pump on Oreilly's page did not look like the one I bought from them.The impeller was different and it didn't have the black pulley,It was silver. Both have a lifetime warranty.Orielly's short bolts came in a package with lock washers and extra one's.Auto Zone's bolts were attached to the pump and won't come out,which Auto Zone's is easier to put in cause the short bolts won't fall out trying to put pump in.As you know,it has one long bolt at the top that stays in the pump.There are 2 long Nissan bolts that go in pump,one at top goes thru a bracket.Both are made in China.So are Rock auto's.Not much been made in America.Whopper's are still good.

Edited October 16, 2022 by Thomas Perkins

[720_Jeff]

The Dayco DP850, has the desirable cast iron impeller.  Damn impeller blades are SHARP!  Be careful when you handle, it can cut you.

 

Only the one long bolt is not removable.  The others come in a bag.

 

Interestingly enough, bought two of them the other day, I needed one, the other as a spare.  The Dayco DP850 was available everywhere, until I purchase the two.  A few minutes later, checking at other places, RockAuto/eBay/Summit/etc, they were all out of stock.

Apparently, all draw from the same warehouses.

 

 

[Veraciousreasoning]

So should i grab a water pump with a taller one to move more coolant? 

[datzenmike]

The cast ones I posted are not sharp, but these stamped steel ones are the worst after market ones to buy...

 

 

I found all the Z22 and Z24 engines have the deeper cavity and taller impellers. These are the ones I put on my L series.

[720_Jeff]

That pump, pretty well represents all the pumps I've seen, that aren't cast iron.  

 

That Dayco pump, actually cut my soft office worker palm.  I held it for a moment in my palm, not realizing how sharp those vanes were, or really more like, even that the pump vane was even sharp.

Looking at an old Atsugi water pump from my old truck, yeah those vanes sharp as can be, even after being well used.  Atsugi, could that be the Original pump, think the truck had 220k on it.

 

 

Edited October 17, 2022 by 720_Jeff

[Veraciousreasoning]

Ill see if the one i have currently has that depth.

[datzenmike]

Sharp edges are more noisy, less efficient and prone to cavitation. Generally they are just .... cheaply made. Makes you wonder what quality the bearing is too.

[Veraciousreasoning]

So tomorrow im headed to the junkyard to find a radiator fan. The one i thought would work is not gonna work. 

 

If i cant find one can i just use solely an electric fan? I just wanna ask again so be 100% certain and i dont blow a head gasket or ruin my truck 

[datzenmike]

That's what temperature gauges are for, so you know if you are over heating.

 

Factory fan is the best bet as it simply replaces the old one. Electric fans have to be made to fit.

 

These are the two used on the 720. Likely the L20B uses the one on the left. If you have your old one take with you and get the right one. They do not interchange unless you change the water pump also.

 

[Veraciousreasoning]

27 minutes ago, datzenmike said:

That's what temperature gauges are for, so you know if you are over heating.

 

Factory fan is the best bet as it simply replaces the old one. Electric fans have to be made to fit.

 

These are the two used on the 720. Likely the L20B uses the one on the left. If you have your old one take with you and get the right one. They do not interchange unless you change the water pump also.

 

I have the one on the left 

 

The problem is ive tried O'Reilly, napa, autozone, and advanced autoparts and none of their water pumps w/ clutch fit the fan even though this is the factory fan. Ive been trying for weeks to find one that fits and im losing my freaking mind lol

 

[datzenmike]

Try the one for the '78-'79 620 truck.

[Veraciousreasoning]

14 hours ago, datzenmike said:

Try the one for the '78-'79 620 truck.

Ill give it a go.

[Thomas Perkins]

I just found this one on ebay.https://www.ebay.com/itm/115408391197?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1DDSW85VbSWiQRgs5XHN2xA89&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=115408391197&targetid=1644837435723&device=c&mktype=&googleloc=9011420&poi=&campaignid=16743749222&mkgroupid=138744546207&rlsatarget=pla-1644837435723&abcId=9300842&merchantid=423909020&gclid=CjwKCAjwzNOaBhAcEiwAD7Tb6HP6yPDEVQ5qeLCl3XVSACxQUSXkzY7keLLPgmR0SYOODd8hklRX4xoC3KYQAvD_BwE

[Veraciousreasoning]

8 hours ago, Thomas Perkins said:

I just found this one on ebay.https://www.ebay.com/itm/115408391197?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1DDSW85VbSWiQRgs5XHN2xA89&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=115408391197&targetid=1644837435723&device=c&mktype=&googleloc=9011420&poi=&campaignid=16743749222&mkgroupid=138744546207&rlsatarget=pla-1644837435723&abcId=9300842&merchantid=423909020&gclid=CjwKCAjwzNOaBhAcEiwAD7Tb6HP6yPDEVQ5qeLCl3XVSACxQUSXkzY7keLLPgmR0SYOODd8hklRX4xoC3KYQAvD_BwE

 

Nice. Ill buy it in the morning 

[Thomas Perkins]

Trace out the new gasket in case you ever need a new one cause you know you will never find another one,Auto part stores has gasket material.I have a boat load of it.

[Veraciousreasoning]

56 minutes ago, Thomas Perkins said:

Trace out the new gasket in case you ever need a new one cause you know you will never find another one,Auto part stores has gasket material.I have a boat load of it.

Funny thing is the gasket they sell fits perfectly. I have 5 of them as backups 

[WestPac720]

My truck is running fine with no issues and I have AC. Recently I decided to change my water pump and stock fan from the 7 fins to the 8 fins, just to get more airflow and for piece of mind. I also changed out my plastic radiator to an OEM one with the shroud that was still usable. The shroud directs more air flow to the rad for better cooling.We’ll see how it goes in the next few weeks. Good luck on yours. I found out later that the water pump in my truck was a cheap China made one. I changed it to the cast iron impeller and it was manufactured in Japan.

[WestPac720]

[WestPac720]