datzenmike Posted June 30, 2008 Report Share Posted June 30, 2008 Many of you have them some have swapped them onto their L16 or 18s. Most stock L20Bs had them. It's purpose is to save energy by allowing the fan to 'slip' at higher speeds where it isn't needed anyway. Forward momentum of the vehicle forces more than enough air past the rad. The clutch is really an aluminum disc attached to the pump shaft. A bearing supports an outer aluminum housing, (and fan) surrounding the disc and is free to turn relative to the pump shaft. Between the outer housing and the inner driving disc is a viscous silicone oil that provides drag against the fan housing. At low speeds there is least resistance to moving the air with the fan so is spins close to pump speed, but as RPMs rise so does the air resistance on the fan blades and there is slippage. Here are two examples of Datsun/Nissan thermostatic clutch fans: http://i138.photobucket.com/albums/q251/datzenmike/motorclutchfansLarge.jpg[/img]"] The smaller left one is from an L20B the other is from a Z20E 200sx. I believe most Z engines are the larger size. Any 280z cars I have seen used the larger. Both will interchange between L and Z motors. The KAs are probably the same but won't have a VEE belt pulley. If you swap sizes you must swap the plastic fan as well. Note the larger one has a thermostatic coil in front. When heated by over hot rad air it unwinds and locks the clutch internally to provide more air flow for cooling. Here's another difference between L and Z pumps: http://i138.photobucket.com/albums/q251/datzenmike/Lenginewaterpump.jpg[/img]"] http://i138.photobucket.com/albums/q251/datzenmike/motorLwaterpump.jpg[/img]"] The top is from an L20B and has a much shallower housing and thinner propeller than the lower Z pump. All Z series pumps I have are larger like the bottom one and completely compatible with the L20B engine. Gotta assume the bottom one flows more water. I have decided to run an electric fan on my Z24 implant into the 620. With the 200sx rad the clutch fan, even without blades is much too close for my liking, so I cut it off. I disassembled the clutch before cutting: http://i138.photobucket.com/albums/q251/datzenmike/720stuff002Large.jpg[/img]"] The object above with six holes in it on the left is the driving disc. It is sandwiched between thew two case halves with a rubber seal. The oil is silicon but looks and feels like 90W gear oil. If it leaks out, the clutch becomes free wheeling and slips so much it will over heat at low speeds. To check, the fan should turn with firm finger pressure and should not spin freely. It is also possible for them to seize and have no slip. It won't over heat but will sound like a WWII bomber engine. The right half (in the center) has some mechanism connected to the thermostatic spring in front, for locking against the driving disc but I could not figure it out. http://i138.photobucket.com/albums/q251/datzenmike/720stuff003Large.jpg[/img]"] To the right is the water pump and pulley. For added insurance I mig welded it on as well later. Quote Link to comment
Z-train Posted June 30, 2008 Report Share Posted June 30, 2008 Is there a water pump pulley that will align with L-20 crank pullies so you can use a L-24/6/8 water pump & clutch? Quote Link to comment
datzenmike Posted July 1, 2008 Author Report Share Posted July 1, 2008 They are pressed on and I don't think it would work. I realize the inline six had some pulley alignment issues if used on a four cylinder. A better bet would be one from a 720, bigger propeller. Haven't seen a 280 inside. Quote Link to comment
]2eDeYe Posted July 1, 2008 Report Share Posted July 1, 2008 Is there a water pump pulley that will align with L-20 crank pullies so you can use a L-24/6/8 water pump & clutch? There are 2 (clean) methods that I know of. One: Buy a spacer pack from your local parts house. They usually contain various thickness spacers. Put them in between your pulley and pump to push the pullley out to match. Requires longer studs. Two: Slot your alternator mount holes and run the L-24/6/8 crank pulley. Easy to say, but machining is required. Whichever pulley I can locate first will dictate my decision...a single groove L16 pulley or a single groove L24 pulley. If I can't find one before I get to that point... spacers will fit it to my stock L20 pulley The third way is to put washers between the pulley and pump, but this can lead to bad juju ;) I'm also choosing to run an electric fan. The Z waterpump I bought has no fan clutch. Fan clutch is one of the few ideas I hate with a passion :P Anyone have a single groove L series pulley I can buy? :D Quote Link to comment
datzenmike Posted July 1, 2008 Author Report Share Posted July 1, 2008 Redeye, what Z series didn't have the clutch? I ass-umed they all did. Quote Link to comment
]2eDeYe Posted July 1, 2008 Report Share Posted July 1, 2008 Can't remember what the year cutoff is. I would imagine it parallels the truck clutch years. Quote Link to comment
datzenmike Posted July 1, 2008 Author Report Share Posted July 1, 2008 Understand,... it was a Z car Quote Link to comment
]2eDeYe Posted July 1, 2008 Report Share Posted July 1, 2008 Yep, not the later Z22/24 stuff. The Z car pump has a more efficient impeller, like the Z series one in your pic. I'll try to remember to get a pic of the Z car one this evening. Quote Link to comment
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