Does anyone know if the internals from 240Z Nikki and Kyosandenki pumps, particularly diaphragms, will swap? It might help expand rebuild options is why I ask. Thanks!

Does anyone know if the internals from 240Z Nikki and Kyosandenki pumps, particularly diaphragms, will swap? It might help expand rebuild options is why I ask. Thanks!

You might want to include the Ampco fuel pump which was part number 17010-N3625 as well. As a rule, interchangeability is by the brand, but this is a great question. I have all three kinds on the shelf, but have never replaced the diaphragm. The fiche suggests that the part number for the diaphragm changed after 7/73 and does not fit to the former fuel pump. The later fuel pump, part number 17010-N3625 shows fitting an L26 from 11/73 on. It could be possible that the 260Z fuel pump would be the Ampco brand and not the Nikki brand of earlier Z cars. The Ampco pump I have could also be an aftermarket pump of the era, long before the Kyosan model.

Answering my own question here - in a word, no. The OEM replacement diaphragm I got from Courtesy fits the Nikki but not the Kyosan because of a design difference in the rod that connects to the pump lever. I also was able to compare the new diaphragm with a 510 Nikki and it looks like the innards could be swapped, as some ebay listings for new 510 pumps suggest. The first photo compares Nikki 510 (L), Nikki replacement, and Kyosan. The difference in rod style between the 2 Nikkis doesn't seem to matter. The second pic shows why the thicker Nikki rod design doesn't fit the Kyosan pump.


Reason for all this in the first place is I was hoping to rebuild my non-op Kyosan on the car rather than replacing it. The massive, non-dealer AC compressor bracket blocks getting the pump out without removing all the AC trappings first, including the refrigerant. PITA. Yes, an electric pump is an option being considered.

That was a huge PAIN for me! I just had bought the car and got one from O'reilly's. The stamped together one without screws. I had to take that front bracket loose, take off the fan, the bottom radiator hose and the bottom bracket to the alternator. I may have even pulled the alternator altogether! Can't remember, I got a little tipsy doing that job.

On 25/10/2014 at 10:56 PM, NVZEE said:

Answering my own question here - in a word, no. The OEM replacement diaphragm I got from Courtesy fits the Nikki but not the Kyosan because of a design difference in the rod that connects to the pump lever. I also was able to compare the new diaphragm with a 510 Nikki and it looks like the innards could be swapped, as some ebay listings for new 510 pumps suggest. The first photo compares Nikki 510 (L), Nikki replacement, and Kyosan. The difference in rod style between the 2 Nikkis doesn't seem to matter. The second pic shows why the thicker Nikki rod design doesn't fit the Kyosan pump.


Reason for all this in the first place is I was hoping to rebuild my non-op Kyosan on the car rather than replacing it. The massive, non-dealer AC compressor bracket blocks getting the pump out without removing all the AC trappings first, including the refrigerant. PITA. Yes, an electric pump is an option being considered.

Hi, I know that this is an old subject but having just stripped my pump down I find the diaphram has perished a bit and I am trying to replace it. The diaphram is exactly like the one in the bottom photo on the extreme left. I have obtained the correct material to replace it but can anyone tell me if the diaphram shaft  can be unscrewed to fit a new diaphram.  I would be grateful for any help I receive.   Kind regards. Tonytom B