I picked up a small lot of FD parts off Ebay recently, and it included a full set of OEM O-rings in the packaging. I also got a set of nearly-new Nippon Denso primaries, and they included o-rings as well.

The OEM O-rings are much harder than the Denso pieces - enough that when I first saw the OEM O-rings I wondered if they would even seal properly. Given that they may have seen a shelf life of 10 years, are they any good?

Dave

 

Flex them and pinch them . Did they crack or deform . If not put o ring grease on them when you install them .I use Corning corporation MOLYKOTE 55M silicone o-ring grease .

 

Thanks for the tips. I doubt they will crack, but I will try it. I will bet they don't spring back immediately though.

Have you noticed the Mazda O-rings are harder than most? I worry they'll leak since they don't seem to have any compliance.

Dave

 

There was a report a while back of the o-rings being supplied from some of the injector cleaning companies not sealing as well as OEM o-rings. The OEM o-rings do seem stiffer than the few alternative o-rings I've seen.

 

It's possible that the OEM o-rings were compounded with fuel contact in mind and will swell and soften slightly when in contact with gasoline.

 

Sweet, thanks everyone. I'll report the results when I re-set my injectors and run the FP pressure test.

Dave

 

Following up, I talked to Ray Crowe today, and he shared this:
- New Mazda injector O-rings are soft, by his description. The ones I have are hard enough that I can't really squish them in my fingers, only bend them. The price for new Mazda O-rings is $9.00/ea for the secondaries, adn $7.19/ea for the primaries.

- The Injector insulator (grommet, $3.75) is in his opinion more important to getting a leak-free seal, and should be replaced 'when you're in there'. He says he's never replaced his o-rings, he re-uses those.

Interesting. Just more reason to perform the FP grounding pressure test when working with injectors.

Dave

 

We have had our first issue with a top-feed o-ring a week or so back and have since changed suppliers with what we feel is a better o-ring.
If any of our customers are having any problems with this, please drop me an email and I will supply you with new ones.

Be careful with using Silicone, it can kill catalytic converters.

Gordon
WitchHunter Performance

 

The amount af silicone I use will not ever get to the cat in your life time . It is not poured in , just lightly rubbed on .

 

What material do you use in your o-rings, and how does it compare to the stock material?

Also, can you comment on the function/replacement of the injector grommets?