The NPW Fan Clutch Scam   

Don't buy any NPW ("Nissan Pump Mfg. Co. Ltd.") products!  They are fakes!

I own a 1992 Nissan Terrano (Pathfinder) SUV, that has a Z24 engine. After 23 years of service, and nearly 200,000 kilometers, its water pump started leaking, and had to be replaced. I went to the Nissan parts dealer in my area, to buy an original spare part, but he told me that Nissan no longer provides them, and that instead they were selling a GMB pump as a replacement. So I bought that one.

This vehicle uses a water pump that has the viscous fan clutch permanently fixed to it. While the original pump/clutch unit, made by Atsugi, has a thermally controlled clutch, the GMB replacement sold by Nissan CIDEF in Chile only has a non-thermal one. In fact the box of the GMB pump identifies it as a replacement part for several smaller Nissan engines, not the Z24. But the salesperson assured me, with Nissan representative authority, that this unit would do, so I bought and installed it. At first the fan ran very fast all the time, made a lot of noise, but very soon the clutch became lame, and after barely 5000 kilometers, less than one year, it would no longer provide enough cooling on a hot day!

So I had to replace it again. After much searching, I found a pump/clutch combo sold under the brand name NPW, which allegedly stands for "Nissan Pump Works". The actual company name is "NISSAN PUMP MFG. CO. LTD." This name looked very fishy to me. Nissan doesn't make its own water pumps, as far as I know, let alone spares for an almost antique car! So it was clear from the beginning that "Nissan Pump Mfg." most likely has nothing at all to do with "Nissan Motor Company Ltd", and I wonder what the people of the real Nissan company think about a small company using their name... But the pump/clutch unit, shown at right installed in my car, looked decent enough at first sight. The pump housing looks as robust as the original (not as thin as the GMB), the fan clutch has the full diameter (not smaller and with an adapter ring, as the GMB was), and there is a bimetal spiral on its front, hinting that this is a thermally controlled clutch. The impeller is just stamped sheet metal instead of the cast iron of the original Atsugi, but that should be OK. The box says that this unit "meets or exceeds original equipment manufacturer's specifications". So, what could go wrong? I bought this NPW unit and installed it on my car.

When I started the car, surprise! Instead of the usual behavior of thermally controlled fan clutches, which after a cold start spin up fast for several seconds and then calm down, this one sped up fast - and stayed fast. Very fast in fact. Much too fast! I went for a short drive, and the fan ran like crazy. The noise was huge, so loud that people in the streets turned their heads to see where this noise was coming from. And the engine didn't really want to revv up beyond 2500 RPM or so! The fan was causing a very obvious drag. Definitely the thermal control was not working at all, and this NPW fan clutch was driving my car's fan very fast all the time, even while going downhill in freezing weather!

Bringing it back to the store would probably be just a waste of time, because they won't take it back after I installed, tried and removed it - at least not based on my verbal assurance that the fan clutch isn't regulating its speed properly. There is no way how I could show that in the store. Driving there and having the salesperson look and listen to the car is impossible, because there is no parking space near that store, and the salesperson will hardly accept hiking to where I can park the car... So I decided to take off the front of the fan clutch, to see if the oil flow valve is stuck, or bent, or something.

BIG suprise!   

As soon as I had the front side off, I very nearly fell on my rear end: This fan clutch does not have any thermal regulation system!  There is no oil flow valve, no separation wall between the working area and the fluid reservoir, nothing! It's empty!!!! The spiral on the front, which may or may not be an actual bimetal (i didn't try heating it), doesn't connect to anything inside the clutch, and exists purely to mislead the customer into believing this is a thermally controlled fan clutch, while in fact it is a non-thermal one!!!

I had never expected scammers to go this far!


For comparison, this is the inside of the original Atsugi fan clutch's front. You can see the sheet metal plate separating the reservoir from the working chamber, the rectangular oil port, the valve sheet that gradually opens and closes this port when rotated by the bimetal spiral on the outside, and two blocks next to which are the oil return holes, through which oil is pumped back into the reservoir. You can also see the two rivets, installed in slots, that allow aligning the valve plate to the bimetal spiral during manufacture, so that the fan speed regulation acts at the correct temperature. All this is simply missing in the NPW clutch!

But the spiral on the front of the NPW sure looks nice, huh? Too bad that it's there just as a useless decoration, or rather to mislead ME and YOU, the customers, into thinking this is a thermally controlled clutch!

Frankly, the blob of glue holding the spiral in place should have been a giveaway that this is a scam, but I was too stupid to think that far, and too desperate to finally get a usable spare part for my car.

Just in case you think that there could be something in the back side of the NPW clutch, that interacts with the spiral to regulate the oil flow, rest assured that this is not the case. Here is the photo.
I wonder if the pump itself is any good. For the moment it seems to work fine, but how long will it last? I mean, a company that makes a non-thermal clutch in the shape of a thermal one (with the bulge of the reservoir!), and adds a purely decorative spiral to make customers think it's a thermally controlled clutch, loses all of my respect! I no longer think that any product of these people can be any good.

Is NPW the only company faking thermal control on their fan clutches? I doubt it. Reading up in user groups and fora on the web, there seems to be a widespread general opinion that aftermarket fan clutches just don't work correctly. I'm not a car mechanic, I maintain only my own car, so I haven't inspected any other aftermarket clutches, to confirm or deny this. I only can tell that this NPW clutch is a scam.

So, my urgent advice to anyone buying an aftermarket fan clutch is: Be VERY careful!  Scam artists are reaching into your pocket! Some (perhaps many!) fan clutches that look absolutely like thermally controlled ones, and are sold as such, really are non-thermal clutches, and do not work correctly on most cars!

And my big problem now is: Where do I get a good, real, usable water pump/fan clutch for my car?  Or how do I get the impeller off the original one, to replace its worn seal?

Back to the homo ludens mechanicus.