Injector Cap O-ring Durometer

[banderso]

From the looking around I've done, it seems like the o-rings most people use are McMaster-Carr 9464K24. They're Viton, dash number 111 with a durometer of 75A, listed as medium harness. I'm guessing these are what ship with the good return line kits from Conestoga and others.

But McMaster also lists a soft version of the same o-ring with a durometer of 60A. The description says the soft rings offer a better seal in low pressure applications. The McMaster number is 1284N14. Does this seem like it might be a better option?

A little background on why I'm asking: I recently replaced my return lines, caps, o-rings, fuel filter, and olives. I was still getting air in the system. I noticed the cap on injector 1 wasn't fully seated. Seems like I would have noticed this during install, so I wonder if it popped back up somehow. Anyway, I pushed the cap back down but I'm still getting a lot of air in the system. I figure my next step is to pull the caps back off, look for damaged o-rings, and try to seat the caps again. I'd like to have o-rings on hand, so I figured I'd order some.

Thanks.

 

[icanfixall]

Where did you purchase this return line kit? Did you "clean off" the plastic flash from the bottom of the caps with an exacto knife? Many kits need to clean off the sharp edges so they don't cut or nic the o rings. Did you lube these o rings before forcing the caps on the injectors? To install an o ring its recommended the top o ring is installed in the top groove and then the bottom o ring is installed down over the top one.Never try to install the bottom o ring first. There is a big chance you will damaged it by taking it out of the top groove and install in the bottom groove.

 

[banderso]

Purchased from Conestoga - very friendly people.

No, I didn't clean any flash. I've heard of this, but didn't notice any.

I used what I thought was a liberal amount of vaseline as lube. But this time I'm gonna go crazy with the lube.

I installed the top o ring first, and rolled the bottom one over it.

Thanks.

 

[OLDBULL8]

Lube the injector grooves also, twist the caps a little when all the way On, that relieves any O'ring stress from installing them. Make sure the hoses don't push on the caps.

 

[franklin2]

Check the top of the fuel filter housing carefully, see if you have any fuel seepage around the fuel heater connector. This is the elbow wiring fitting on top of the filter housing. Mine was damp with fuel in that area and it turned out to be the latest leak/place for it to get air.

 

[Thewespaul]

As for the durometer difference, I would say that would be a better choice going with the low pressure viton, those return lines see little pressure

 

[banderso]

I ordered some of each type of o ring, so I'll mess with it when they come in. I'm inclined to try the soft ones like Thewespaul says. Any other thoughts on this?

When I take it apart again I'll do as oldbull suggested - lube the grooves in the injector and give the caps a twist. I think my hose lengths are pretty good and shouldn't be applying any pressure to the caps.

I'll take a look at the top of the fuel filter housing as well. Thanks for all the suggestions.

 

[icanfixall]

Well you purchased a very good kit from a very good reputable source. When you remove the caps just scrape the underside edge so the o ring has a bevel to start the o ring on. Just be sure nothing gets inside the cap that gets cut off.

 

[banderso]

Yea, thanks for the tips. To be clear, I don't think there was anything wrong with o rings that came with the kit. I'm just planning for the possibility that I damaged one during install. The soft ones caught my eye as maybe an even better option.

 

[franklin2]

Not all the time, but most of the time if you have a air leak, there will be some dampness around where it is leaking. If all your cap and injector areas are completely dry, I have my doubts that is what your problem is.

 

[Macrobb]

Make sure to grease your O-rings and inside the caps, with high temp wheel bearing grease.
It /works/. Vasoline does /not/.

Since doing that, I've had excellent luck with return caps not being a problem - the grease helps them seal, and being high-temp, it tends to stay in place and continue to help.

 

[Thewespaul]

Why do you say vasoline doesn’t work? I’ve never had an issue using it

 

[Macrobb]

Because I've done many sets across many IDIs. Originally, I used vasoline, because that's what the guys at Ford suggested(about 11 years ago). I'd have trouble - most would seal, one would leak, I'd remove and fix that... and the next would leak due to being 'disturbed'. This is with brand new O-rings. Just... a real pain.
One day a few years later, I couldn't find the vasoline, so I used wheel bearing grease. No problems at all.
They hold up a lot better to movement, to getting 'disturbed'... I can remove the capa, pull the injectors and reinstall them with the same O-rings and chances are it'll still seal.
I've been using it the last 5 years easily, and it's really nice.
Oh, and to prove a point? I always use the cheapest return line kits on Ebay. Work just fine with a little lube!
Try it and tell me what you think.

 

[towcat]

once again, axle grease will attack the o-rings. use cautiously.
spray silicone lube is compatible with the o-rings.
see pics for installation suggestion, new o-ring leak issues have literally stopped.

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[Thewespaul]

Can you post a pic of what you use? I’d be worried of using grease with those o rings as towcat said. Haven’t had a issue with vasoline but like you said if they get disturbed they have to be reseated