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Old 01-05-2012, 01:28 PM   #11 (permalink)
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It does, and that might work! I think a single one would be sufficient.

I was also considering TIG welding up the crack, but I'd prefer not to since that's going to compromise the cad plating and introduce the possibility of corrosion, especially with all the alcohol in the fuel nowadays...

I believe they make metal versions of Nylon zip ties, where the metal strip is passed through a sort of a buckle and folded over. Something like that might work, as well.

I was also seriously considering the possibility of making a new cap from scratch. I have access to a lathe and mill at work - the only question would be what material to make it from.
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Old 01-05-2012, 01:57 PM   #12 (permalink)
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Quote:
Originally Posted by Oo-v-oO View Post
It does, and that might work! I think a single one would be sufficient.

I was also considering TIG welding up the crack, but I'd prefer not to since that's going to compromise the cad plating and introduce the possibility of corrosion, especially with all the alcohol in the fuel nowadays...

I believe they make metal versions of Nylon zip ties, where the metal strip is passed through a sort of a buckle and folded over. Something like that might work, as well.

I was also seriously considering the possibility of making a new cap from scratch. I have access to a lathe and mill at work - the only question would be what material to make it from.
oh yeah, like the bands on CV boots. But I guess you can use needlenose pliers to cinch them up?

yeah, I'd comfortable with stainless for the 'hose clamp/garter belt idea', but really, I'd be guessing even on that. there are several stainless alloys and they aren't necessarily corrosion free in all circumstances. But, we KNOW the factory solution seems to have a problem. (but, maybe some type of misplacement of the o-ring causes xtra stress? may be a small fraction of all the cars)

and, as for machining a replacement, I have no idea if Delrin or anything else would work in a gas environment either. Does that cap just snap on or does it 'bayonet' on?
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Old 01-05-2012, 02:21 PM   #13 (permalink)
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Yeah, not sure on material compatibility. If I was the primary driver I would be a lot more open to experimentation but you know that when momma is unhappy, everybody is unhappy and not having her car makes her less than happy.

The junkyard finally got back to me, the entire assembly is what they are listing so I am going to go pick one up tomorrow. Then, I will have a spare I can experiment with.

The cap does push on and turn, like a bayonet. The tabs are not symmetrical, either - of the three, one is about twice as wide as the other two so you can only put it on one way for whatever reason. I don't see why that would matter because as I recall the rest of the cap is symmetrical.

One thing I have been wondering is what the purpose of this cap is in the first place. I didn't spend too long checking it out since it was really cold out when I was working on it, but my guess was that it was the bottom of an accumulator. Anybody know?
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Old 01-08-2012, 02:59 PM   #14 (permalink)
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I swapped the cap off the junkyard pump today. While I had the original pump out and laying on a board before taking the broken cap off, I noticed that gas was dripping out from between the junction of the cap and plastic body it connects to.

When I got both of them apart, I put my calipers on the junkyard O-ring then on the Viton -138 O-ring I put in ours. The -138 measured .105" thick, while the junkyard O-ring measured a full .125" thick. I still had our original O-ring and while it was somewhat distorted from where it had popped out, I got an average of about .118" thick.
That's a huge difference!

I coated the OD of the junkyard O-ring plus the ID of the junkyard cap with a little clean motor oil to prevent the O-ring from rolling over and assembled them onto our original pump assembly since it was a whole lot cleaner than the junkyard one. Assembling the cap took a little more force than it did with the -138 O-ring, which is good as it shows that there is a bit more interference now. I put it all back together and we'll see how it works, but I feel confident that this will take are of the problems with restarting after it had been shut off.

Based on my findings, I would have to say that the -138 O-ring someone else specified is NOT the correct one for this application. From charts, the -138 has a cross-section of .103", ID of 2.112", and OD of 2.318".

The plastic section of the pump assembly that the O-ring slides over is ~54mm (2.126") and the ID of the metal cap where the O-ring rests is ~59mm (2.323").

I think it is actually supposed to be a #-928 metric O-ring with a cross-section of 3mm (.118"), ID of 53.09mm (2.090") and OD of (2.326"). This would seem to provide the necessary "squish" to seal it up.

Amazon currently has a 12-pack of 75 durometer Viton -928 O-rings listed for $12 or a 5-pack of 70 durometer nitrile (Buna) listed for a buck. They also list EPDM O-rings in that size, don't use them as EPDM is NOT compatible with gas!

Hope this thread helps someone who comes along later...
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Old 01-08-2012, 05:14 PM   #15 (permalink)
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Quote:
Originally Posted by Oo-v-oO View Post
I swapped the cap off the junkyard pump today. While I had the original pump out and laying on a board before taking the broken cap off, I noticed that gas was dripping out from between the junction of the cap and plastic body it connects to.

When I got both of them apart, I put my calipers on the junkyard O-ring then on the Viton -138 O-ring I put in ours. The -138 measured .105" thick, while the junkyard O-ring measured a full .125" thick. I still had our original O-ring and while it was somewhat distorted from where it had popped out, I got an average of about .118" thick.
That's a huge difference!

I coated the OD of the junkyard O-ring plus the ID of the junkyard cap with a little clean motor oil to prevent the O-ring from rolling over and assembled them onto our original pump assembly since it was a whole lot cleaner than the junkyard one. Assembling the cap took a little more force than it did with the -138 O-ring, which is good as it shows that there is a bit more interference now. I put it all back together and we'll see how it works, but I feel confident that this will take are of the problems with restarting after it had been shut off.

Based on my findings, I would have to say that the -138 O-ring someone else specified is NOT the correct one for this application. From charts, the -138 has a cross-section of .103", ID of 2.112", and OD of 2.318".

The plastic section of the pump assembly that the O-ring slides over is ~54mm (2.126") and the ID of the metal cap where the O-ring rests is ~59mm (2.323").

I think it is actually supposed to be a #-928 metric O-ring with a cross-section of 3mm (.118"), ID of 53.09mm (2.090") and OD of (2.326"). This would seem to provide the necessary "squish" to seal it up.

Amazon currently has a 12-pack of 75 durometer Viton -928 O-rings listed for $12 or a 5-pack of 70 durometer nitrile (Buna) listed for a buck. They also list EPDM O-rings in that size, don't use them as EPDM is NOT compatible with gas!

Hope this thread helps someone who comes along later...
brilliant investigation!
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Old 01-09-2012, 08:12 PM   #16 (permalink)
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Thanks!

Car is back to normal now, starts up immediately after sitting overnight, even.
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Old 04-02-2012, 03:04 PM   #17 (permalink)
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what years/models are likely to have caps compatible with -say- an 03 H6 Outback?
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Old 04-02-2012, 03:09 PM   #18 (permalink)
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00-04 is where I'd start
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Old 04-02-2012, 03:30 PM   #19 (permalink)
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I also wonder if individual PARTS for the aftermarket Airtex or Bosch (other?) units might be available and if they'd fit/work on OEM?
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Old 04-02-2012, 11:04 PM   #20 (permalink)
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well, I got a reply from tech services at Airtex and individual parts from their assembly are not available for sale separately.


dunno if they would even be the right size/configuration - but if it was cheap enough, may have been worth try.

I might try to email Bosch. wonder if Denso makes the part for Subaru or ????

seems a shame someone might have to spend $200 - $400 when they just need a $19.95 part.
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