Seeker > 620 KC

I have the 76 620 emissions diagram and van hose diagrams? They are different from my 79.

Drat, I missed it. would have liked to take my 200SX. I love the museum. The first time I went there were a number of Dats. The guided basement tour is awesome.

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.

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.

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

Riverside CA where the 60 freeway meets the 215 https://www.bing.com/maps?&ty=18&q=Portillo%27s%20Hot%20Dogs&ss=ypid.YN99x162102810&ppois=33.9344711303711_-117.278450012207_Portillo%27s%20Hot%20Dogs_YN99x162102810~&cp=33.934471~-117.27845&v=2&sV=1

Datsunsvin general are really scare down here in So Cal too Bleach.

Correction: York compressor DID mount high on Pass side of L20B

Also, be sure your cooling system is really strong before you add AC. AC on a 4 cyl can quickly kill a tired motor with a 35 year old head gasket! Be sure Rad is clean and pressure tested, no leaks. Orig Nissan AC used an 8 blade (not stock 7 blade) clutch fan with a larger dia water pump shaft, and a fan shroud. Be sure your thermostat is working well, all cooling hose rubber is good. Rebuild your heater control valve to ensure the AC isn't fighting a stuck on heater. Check your freeze plugs are not on the verge of rusting thru. I was able to remove all mine with engine block still in truck and install new affordable brass ones from Rock Auto. Only have the one behind the exhaust left to go. Drove it in once, but gave that one extra whack with a hammer and a 36 inch 3/8 drive extension and it went in too far. Had to pull it out, and I distorted it. Try try again.

It would be an interesting experiment to try. But if the fluid leaked out, wouldn't that mean the seal went bad and needs replaced? How would you seal it back up and have it hold up against heat and dynamic spinning? Silicone?

Yes. The vibration monster York compressor didn't mount high on the pass side. The mech fuel pump had to be removed, and install an electric one back at the tank. Then that hideous cast iron mount bracket had bolts of all dia, with an attachment point down low on the block, another by the head, another bolting to the idler bracket, utilized one of the timing chain inspection cover bolts...absolutely ugly, stupid, and heavy. I haven't weighed my bracket, but I'd guess 20-30 lbs, If you have an early model 620 and aren't required to have a smog pump like Datfish it is much easier to mount a compressor down low on the driver side. Nissan made a bracket for the 720 on that side. Not sure how the belts line up. A guy in Riverside found an aftermarket AC Sanden bracket and was able to adapt it for a new small rotary compressor. He didn't even use an idler pulley, as the compressor swung out to tighten the belt. He had to buy a really short belt as he only had about 3/8" before it would hit either the steering box or frame, can't remember which. If Datfish comes to Eagle Rock swap meet this Sunday in Eagle Rock and look me up, I can show you a couple 620's with working AC and introduce you to the owners to see what they sourced to make it happen and how the ran the belts. One of em is a chop-top done in the 80's. Pics are difficult as it is a tight fit under the hood. Bring a bright flash light. PM me your ph number and We can meet up and look em over.

Shacks510, I believe NevTony has those molds and makes them. He comes to the truck BBQ in Fontana in August. In the past he has offered to bring them for potential buyers so the don't have to pay shipping. I'd PM him now to be sure he has one or can make a run before then.

http://static.carpartsmanual.com/datsun/pickup-1972-1979/large/620-091C-01.jpg The 620 AC idler pulley was the most stupid design idea Nissan ever had. The base was a steel plate bracket that bolted to the front of the head and took the place of the timing chain inspection cover. Then the belt tension adjuster pulley bolted to an adjustment slot. Ii don't recall if aligned with the third groove on the crank pulley or the second one, and the smog pump used the third. It's too late and I'm already crashing, sorry. You might want to research the AC diagrams for the L20b motors for the 510, 200sx or other models for a simpler idler/adjustment pulley. I'm a later KC truck guy. From the link above it looks like the earlier 620 models used the single groove crank pulley, with the bolt on pulley. It doesn't show the belt set up in this diagram.

I post too late at night when I'm really tired and don't always think or type straight... I meant when the fan spins freely by hand and has no resistance, then when the motor is running thevfan doesn't spin enough and causes heating probs. Sorry

There is a guy coming to the ER swap meet that cut down the orig 620 cast iron York comp bracket, then adapted a modern rotary compressor to it. He only had a bolt or two holding the compressor on, but with the roatary compressor there is far less vibration on the mount vs the York compressor. Tried to get pics last time but didn't turn out very good. will try again next Sunday.

The 78-79 620 pickups with Nissan factory AC had a balancer pulley with an additional bolt on 3rf pulley. That way it had its own drive belt. But it also had to use a specific 8 blade clutch fan (5"+ bolt patter) similar to a 720 fan, but it had to be offset further toward the radiator to avoid hitting the crank drive pulley. It's late but I'll get you a pic tomorrow. If the timing indicator and crank pulley marks match maybe that would work if you could find an AC truck.

I've never seen one seize up in So Cal. Typically when they go bad they spin too fast and causing minor overheating issues to give you a heads up when it needs replaced before they die completely vs. an electric that will quit and you may not know it isn't working over the sound of your exhaust then you have a major overheating prob. Either way, Good reaso to always watch temp gauge. If you go stock clutch fan Rock Auto has the same BA pump fur $53+ shipping comes out to the same price. They also have a Gates and a AC Delco pump for less. You can contact RA and they will contact seller to see which pump has a good cast iron impeller vs. a inferior stamped one. FYI the last BA pump And the last AC Delco pumps I bought both had cast iron impellers.

Colorurbox, DO NOT use contact cement on your original 36 year old vinyl material. It has a very high probability of distorting and ruining the old vinyl. This week I was in a hurry to repair an original door panel board and orig vinyl. I negligently followed this recommendation without first testing a scrap piece. Why? Because I've used contact cement for all kinds of other jobs and didn't take the time to think about what I was doing. I cut the board off a clip board and glued it on the back of the existing door panel board to back plate it. I had to put down layers of contact cement. There was a hole in the orig board and the contact cement bled thru the foam an distorted my nice orig black vinyl material. As pissed off as I was at ruining my door panel I let it go and hought it was just old material breaking down. Picked up the Dap Weldwood contact cement can and read it ( like I should have done before using it on a new material.) "The solvents in this product may damage painted surfaces, vinyls, & other plastics." Duncan had the best intentions and was lucky not to have that occur. I surmise his didn't distort more than likely because he was using new material with a strong fresh bond, and the vinyl is web-backed.

Right on.

Knoriega PM Tdaaj. He might. Also PM me and tell me how your chop-top is doing with a new water pump and 620 AC fan. No more cooing issues?

That is an aftermarket AC unit that hangs under the dash, even if it might have Datsun printed on the switch plate. And the AC drier is an aftermarket utilizing slide-on hose fittings with hose clamps. The compressor bracket looks to have been removed and the stock fuel pump reinstalled. Looking at the damage in the pics it is probably due to a loose York compressor bracket, or an over zealous PO using the wrong bolts or over-tightening. I can't tell you how many broken front covers and burned up L motors I saw back in the day due to individuals and "specialists" adding after market AC's. They were accustomed to bolting on those big vibration piston York compressors onto American made steel V-8 motors that could handle it. When they started slamming those units onto the L motors they broke stuff all the time. It is sad the latest AC technology combined with their ignorance with import cars, made them specialists at killing the reliable little Datsun motors. I agree with Banzai. 1) First find another front cover and replace the broken one. Put a WTB ad, I would think someone will help you source a reasonably price one. Protect the motor from bleeding oil and further damage from vibration and unsecured bolts. 2) Remove the AC condenser if it is still there blocking the flow of air thru the radiator. Free! (couldn't see if it is still there in the pics or not.) Flush and back flush the motor. DZM has numerous posts about how easy it is, and free, or just a thermostat gasket. 3) Put in a reliable stock NEW clutch fan from Rock Auto, they're cheap. Rock Auto has a Gates or AC Delco for $35-45 + shipping. This is a no brainer for reliable cooling. Get the thing running well before "tricking it out." I can't tell you how many guys with heating problems I see at meets, only spin their fan to see they have a worn out clutch fan. I mention it to them... they want a quite 4 blade fan instead while they get stuck in So Cal traffic, only to have more heating problems. I laugh my ass off. 4) Find a stock 7 blade 620 fans, they're still pretty common and easy to find and reasonably . Another WTB ad should solve that. 5) Find yourself a fan shroud. If it had AC back in the day it looks like someone took it off and didn't put it back on. Add coolant and you have a no problem, no-worry cooling system as long as your hoses, freeze plugs, and head gasket are still ok. Back in the 70's I drove all over the desert communities in Riverside, San Bedoo, and Palm Desert with this setup and never had cooling issues. Or you could try an aftermarket electric fan setup. I like the concept for being quieter. I just have yet to see a setup that looks like it will pull as much air as a stock fan, or installs as neatly as the stock set up. I gave my AC advice to Noriega something on ratsun. He cut down a stock cast iron compressor bracket, bolted on a rotary compressor to it. He too was using a stock worn out clutch fan and had heating probs.. I sold him an 8 620 blade AC fan, and he bought a new clutch fan, can't wait to see it again on his chopped 620 at the ER swap meet in a couple weeks and see how its doing now.

I've thought of doing this myself, and have a water logged 620 black door panel now I'd like to salvage. 25% of the panel is warped and water logged. Drying it out now. I'm debating on reworking it, or just spaying it down and flattening it out.. Kudos for going for it. My concern is how thick your material is. It looks to be 1/2" thick??? Won't that protrude out from the door a lot and catch shoes, fingers, etc? I'll be very impressed if the vinyl skin can be glued back down without stretching out the pattern it or getting lumps. There is a UFO fabric supply store in Vista and one in San Diego that does custom home upholstery. They sell spray on adhesive glue ($7-8 a can) for gluing foam together, gluing material to backing boards, and for custom molded foam for upholstery seats and the likes. But I think the working time is limited. You might want to try it on a couple smaller practice pieces first to learn how tacky it is and avoid any bubbles, ripples, and the likes. Can send you a pic when I get home. I'm sure most fabric stores carry it, or something like it.

thanks Ted, I think you nailed it. Now I just have to find one cheap. Saw one on eBay for $25. Datsun dog dishes are cheaper! Lol

These wheels came on a 76 620 I bought, I know they aren't 520/620. Missing one center cap. Been googling but can't find them on another vehicle. Anybody have one or know what vehicle they came off

Yeah, that initially screwed me up too. carpartsmanual.com for the 620 shows two different part numbers 40160-T3060 for the Right, and 40161-T3060 for the Left. But I ordered two of the same ball joints for both sides from Rock Auto and they worked out fine. I'm pretty sure the aftermarkets manufacturers were smart and remanufactured it so one part would work for both sides. No need to machine two different parts and numbers. The beauty of remanufacturing!