Home » Public Forums » GMCnet » Combination valve leaking fluid - suspect defective part
| Combination valve leaking fluid - suspect defective part [message #226929] |
Thu, 24 October 2013 20:18  |
MichaelP
Messages: 65
Registered: October 2012
Location: Ohio
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[EDITED OVER THE PAST TWO DAYS AS I'VE NARROWED DOWN THE PROBLEM WITH OUR COMBINATION VALVE ]
...Just had our combo valve replaced (two months ago=431 miles) and now there is substantial fluid dripping out of the brake line connection at the bottom of the valve. Pedal went to nothing overnight.
After two days diagnosing, pumping, bleeding, dripping, I've determined the main source of the leak is out of the METERING VALVE. Looking at the cross section provided by "The Pedantic Mechanic" it appears the seal between the metering spring and the valve bolt has failed. I'd assume this thing was originally designed so you could change the pressure, i.e. "meter", the front brake lines, although, for all I know, this could be a working function of the valve -- though I highly doubt it given it's apparently causing air go get into our system.
We're gonna chance it and make the 150 mile drive to Buford tonight after traffic, hoping this is indeed the source of the leak and not the brake line itself, which I originally suspected. (I held my finger directly under the metering valve nut while someone pumped the pedal, and my finger was wet with brake fluid -- the only place it could come at that angle was from the metering valve. I tried tightening it down, and it did tighten a little bit, but fluid still poured out.
I have a few questions:
1. What's the point of this metering valve, anyway, if psi on our coaches is usually desired as high as possible, rather than have the ability to back it off.
Anyhow, I may try to get a better grip on the valve nut and give it one last wrench before leaving, but I'm afraid I'll shear something on this crappy part, so probably just leave it and put our trust in metal tolerances, and hope it doesn't get worse during the 2.5 hour drive.
Wish us luck!
[Updated on: Sun, 27 October 2013 16:31] Report message to a moderator |
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #226932 is a reply to message #226929] |
Thu, 24 October 2013 20:34  |
werewilfs
Messages: 329
Registered: July 2012
Location: Rappahannock County, VA
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Do you need any Black list numbers? Looks like there are a couple of people within 40ish miles of you.
Jared & Stefanie Kohl
Amissville, VA
73 PD
On Thursday, October 24, 2013 9:19 PM, Michael Pisano <mapisano@gmail.com> wrote:
This may be the last straw in our GMC journey. Just had our combo valve replaced and now there is substantial fluid dripping out of the brake line connection at the bottom of the valve. Pedal went to nothing overnight. In the middle of nowhere here in LaGrange, GA, where we'll hopefully find a mechanic daring enough to try to repair us. Otherwise we're looking at a 150 mile tow back up to Buford and Zeb Frady's shop.
GRRRRRRR.
Can't friggin believe this. New combo valve, new brake lines, and we're dead in the water WITH NO FRIGGIN BRAKES.
Stay tuned. Last time we took this to a non GMC place we got a master cylinder that didn't fit under the hood!
Wish us luck. :x
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Jared & Stefanie Kohl
Rappahannock County, VA
1973 Painted Desert "Onslow"
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #226939 is a reply to message #226929] |
Thu, 24 October 2013 21:15 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Michael,
As my sign off notes I'm pedantic!
To me there are fittings on the front, top, and back of the combination valve so when you say "at the bottom of the valve" I assume
the one that is leaking is the back (rearmost) fitting which feeds the rear brakes.
See the cross section here:
http://www.gmcmhphotos.com/photos/member-galleries/p37696-combination-valve-cros.html
I am starting to suspect a manufacturing problem with these valves as that is the fitting that leaked on mine and someone else
reported a leaking fitting on a combination valve.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Michael Pisano
Sent: Thursday, October 24, 2013 8:19 PM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA
This may be the last straw in our GMC journey. Just had our combo valve replaced and now there is substantial fluid dripping out of
the brake line connection at the bottom of the valve. Pedal went to nothing overnight. In the middle of nowhere here in LaGrange,
GA, where we'll hopefully find a mechanic daring enough to try to repair us. Otherwise we're looking at a 150 mile tow back up to
Buford and Zeb Frady's shop.
GRRRRRRR.
Can't friggin believe this. New combo valve, new brake lines, and we're dead in the water WITH NO FRIGGIN BRAKES.
Stay tuned. Last time we took this to a non GMC place we got a master cylinder that didn't fit under the hood!
Wish us luck. :x
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Combination valve leaking fluid, no brakes in LaGrange, GA [message #226942 is a reply to message #226929] |
Thu, 24 October 2013 21:20 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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also check that the "metering valve" is tight. on my new valve it was slightly loose after about a year in service. I thought so too that my line was bad.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #226949 is a reply to message #226929] |
Thu, 24 October 2013 22:22 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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is not good
but not worth a tow
it is even possible to run without that combo valve,....
just make up a y to front and rear brakes
not the best answer but can work for a while
henderson is a good choice
good luck
gene
On Thu, Oct 24, 2013 at 6:18 PM, Michael Pisano <mapisano@gmail.com> wrote:
>
>
> This may be the last straw in our GMC journey. Just had our combo valve
> replaced and now there is substantial fluid dripping out of the brake line
> connection at the bottom of the valve. Pedal went to nothing overnight.
> In the middle of nowhere here in LaGrange, GA, where we'll hopefully find
> a mechanic daring enough to try to repair us. Otherwise we're looking at a
> 150 mile tow back up to Buford and Zeb Frady's shop.
>
> GRRRRRRR.
>
>
> Can't friggin believe this. New combo valve, new brake lines, and we're
> dead in the water WITH NO FRIGGIN BRAKES.
>
> Stay tuned. Last time we took this to a non GMC place we got a master
> cylinder that didn't fit under the hood!
>
> Wish us luck. :x
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #226954 is a reply to message #226939] |
Thu, 24 October 2013 22:50 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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OOPS,
I goofed, there is a fitting on the bottom and it goes to the front brakes.
Sorry,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Rob Mueller
Sent: Sunday, November 24, 2013 9:14 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange,GA
Michael,
As my sign off notes I'm pedantic!
To me there are fittings on the front, top, and back of the combination valve so when you say "at the bottom of the valve" I assume
the one that is leaking is the back (rearmost) fitting which feeds the rear brakes.
See the cross section here:
http://www.gmcmhphotos.com/photos/member-galleries/p37696-combination-valve-cros.html
I am starting to suspect a manufacturing problem with these valves as that is the fitting that leaked on mine and someone else
reported a leaking fitting on a combination valve.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Michael Pisano
Sent: Thursday, October 24, 2013 8:19 PM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA
This may be the last straw in our GMC journey. Just had our combo valve replaced and now there is substantial fluid dripping out of
the brake line connection at the bottom of the valve. Pedal went to nothing overnight. In the middle of nowhere here in LaGrange,
GA, where we'll hopefully find a mechanic daring enough to try to repair us. Otherwise we're looking at a 150 mile tow back up to
Buford and Zeb Frady's shop.
GRRRRRRR.
Can't friggin believe this. New combo valve, new brake lines, and we're dead in the water WITH NO FRIGGIN BRAKES.
Stay tuned. Last time we took this to a non GMC place we got a master cylinder that didn't fit under the hood!
Wish us luck. :x
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Combination valve leaking fluid, no brakes in LaGrange, GA [message #226963 is a reply to message #226929] |
Thu, 24 October 2013 23:23 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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OK,
Where do you need to get to?
You could do a work around that valve.
70% of your braking is done by the front wheels so those are the ones that need to definitely be operational.
As I understand your situation the front wheels are the line(s) that are leaking.
You could remove the two from the valve lines that operate the front wheels and plumb them together with a couple of couplings and a short piece of brake line. Bleed them fronts only and that should get you going down the road. It will save a tow and allow you to drive home or to a repair place of your choice.
The above eliminates the combo valve function which many people have done in the past when they install rear discs.
I wound take it easy and leave lots of room between you and the case in front of you and drive a slower speeds until you get it fixed correctly.
If you decide to go the fix it in place route, call JIM K. and have him overnight one to you. The US mail will allow shipping for pickup up at one of their post offices on Saturday. He could overnight it and you could pick it up at a local post office counter on Saturday. I did that one time with a GMC item. I mailed it here at 3PM in Indiana and the receiver picked it up at 10:30 AM the next day in Alaska.
I had a new one of those valves around here. If you telephone me and say you want it, I'll go look for it. My number is on the back list in Indiana. You can telephone me any time and I do mean any time including the middle of the night and I'll go look for it. Jim K also answers his phone at all hours and may still be around.
Finally see if there is anyone on the Black list in the area. Colonel Ken is down there in Georgia somewhere but Georgia is a BIG state and he may be hundreds of mines away from you. Look on the Black list.
I wish you had left a telephone number in your posting. I would have telephoned you.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Thu, 24 October 2013 23:29] Report message to a moderator |
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| Re: Combination valve leaking fluid, no brakes in LaGrange, GA [message #226998 is a reply to message #226963] |
Fri, 25 October 2013 09:48 |
MichaelP
Messages: 65
Registered: October 2012
Location: Ohio
Karma: 0
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Thanks, Ken. You always have the best information. We may have found a mechanic who will look at our problem today, and I'll mention the workaround method. Also, yes, Jim B will be my first call if we need a new combo valve, since that's where we got it installed a couple months ago.
I got in touch with Ken Henderson, but he's a little far away for us right now.
Right now we're looking at getting towed to Buford, near the limit of our AAA free tow distance, and Zeb Frady has a spot reserved for us on Monday. Last time we got towed 45 miles to the Co-op it took AAA three tries and 24 hours to come up with the right truck, so if we get started on it now maybe they'll get one by Monday!
And thanks for the driving tip! As you know (you helped us out about a year ago with our brake problem!) I'm becoming an expert NO BRAKES driver! This will be Brake Repair, Round 3 in less than a year. Last time we drove from Winslow, AZ to Tom Hampton's place with low pressure, but a lot more pedal, so this time I'm going to defer to AAA, unless we can get some pedal back today. I'm not trying to mess with Atlanta traffic without brakes, which is a much higher skill level than the nighttime highways between St. Louis and Marysville, OH we did the last time.
We've made it to a driveway in LaGrange for now where we're regrouping and getting our options in order, but here's my number regardless: 216.403.4336
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #227002 is a reply to message #227001] |
Fri, 25 October 2013 10:10 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Michael -
I'm about 20 miles N of Frady's off I 85. I have a new brass valve (P 30 style) I can lend you if that's the problem and he doesn't have one on hand.
--johnny
4zero4seventwofive6one2zero.
--------------------------------------------
On Fri, 10/25/13, Michael Pisano <mapisano@gmail.com> wrote:
Subject: Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA
To: gmclist@temp.gmcnet.org
Date: Friday, October 25, 2013, 3:05 PM
And yes, Jim B. is always my first call, We spent 2
months at the Co-op this summer. We probably have the
running record for number of showers at the co-op, and we
are now edified in a number of Daily Pose posts, where he
nicknamed our coach MR. RUSTY before they did some frame
rail surgery on it this summer! Looks like Zeb Frady will be
the latest on our tour of GMC specialists of the USA!
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #227047 is a reply to message #227023] |
Fri, 25 October 2013 19:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Michael,
You might be OK permanently. The fitting that was leaking at the back of my brass combination valve fixed itself. I tightened the
crap out of it before I put Double Trouble in storage and when I returned the next year to fix it properly it didn't leak and that
was three years ago! I did not take it apart to see how / why it fixed itself I just left it alone.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Michael Pisano
Good (well, good-er) news. Still leaking fluid from the combo valve area, but after giving a good wrench to the metering valve nut
and another to the lower "front" brake connector, then bleeding the passenger and driver side front we have the best brakes since we
left Tom Hampton's place a year ago. Understood that there is still a fail waiting to happen in the combo valve, but may be able to
risk the drive from LaGrange to Buford now on Monday without having to play the AAA lottery and wait for a tow.
Not able to find a mechanic here in LaGrange willing to do even the most minor work/diagnostic on our coach (I woulda thunk I
could've found a good old boy up for the challenge!), our fate will be in Zeb Frady's hands on Monday.
Hope she holds until we get past Atlanta!
-Michael
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #227051 is a reply to message #227047] |
Fri, 25 October 2013 19:35 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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One thing I have experienced over many years of working with double flared
tubing is that it takes a hell of a lot of pressure to tighten them down
leak free the very first time after they are formed. I have also noticed
that if you tighten them very well, and then come back several hours or
days later and retighten them, you will find that the nuts will move. I
attribute this to a slow compressibility on the part of the materials
involved. If you have one that just will not stop leaking, take the line
off and cut the flared end off and reflare it. It is probably cracked or
deformed so much that it can't be used. Tubing is cheap.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Oct 25, 2013 5:21 PM, "Rob Mueller" <robmueller@iinet.net.au> wrote:
> Michael,
>
> You might be OK permanently. The fitting that was leaking at the back of
> my brass combination valve fixed itself. I tightened the
> crap out of it before I put Double Trouble in storage and when I returned
> the next year to fix it properly it didn't leak and that
> was three years ago! I did not take it apart to see how / why it fixed
> itself I just left it alone.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: Michael Pisano
>
> Good (well, good-er) news. Still leaking fluid from the combo valve area,
> but after giving a good wrench to the metering valve nut
> and another to the lower "front" brake connector, then bleeding the
> passenger and driver side front we have the best brakes since we
> left Tom Hampton's place a year ago. Understood that there is still a
> fail waiting to happen in the combo valve, but may be able to
> risk the drive from LaGrange to Buford now on Monday without having to
> play the AAA lottery and wait for a tow.
>
> Not able to find a mechanic here in LaGrange willing to do even the most
> minor work/diagnostic on our coach (I woulda thunk I
> could've found a good old boy up for the challenge!), our fate will be in
> Zeb Frady's hands on Monday.
>
> Hope she holds until we get past Atlanta!
>
> -Michael
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Combination valve leaking fluid, no brakes in LaGrange, GA [message #227055 is a reply to message #227051] |
Fri, 25 October 2013 20:05 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Jim,
That's what I figger'd happened to the leak that fixed itself! I had installed new SS tubing which is even stiffer than the normal
steel.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: James Hupy
One thing I have experienced over many years of working with double flared
tubing is that it takes a hell of a lot of pressure to tighten them down
leak free the very first time after they are formed. I have also noticed
that if you tighten them very well, and then come back several hours or
days later and retighten them, you will find that the nuts will move. I
attribute this to a slow compressibility on the part of the materials
involved. If you have one that just will not stop leaking, take the line
off and cut the flared end off and reflare it. It is probably cracked or
deformed so much that it can't be used. Tubing is cheap.
Jim Hupy
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Combination valve leaking fluid, no brakes in LaGrange, GA [message #227107 is a reply to message #226929] |
Sat, 26 October 2013 13:11 |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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Senior Member |
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I tend to agree with a previous poster who suggested a design or manufacturing problem in the brass combination valves. My history:
After I bought my GMC in 2010 I replaces many brake components - hoses, MC, booster, wheel cylinders, etc, and Combination Valve.
On my first vacation the Combination Valve, at the fitting for the front brakes started leaking. I tried tightening it to no avail and rounded the nut. In Moab, UT, a truck shop suggested the connecting tube was bad, not an unreasonable conclusion since the nut was round. $200 later they had replaced the connecting tube. By the time I got back to CA it was leaking again.
I concluded the Combination Valve was bad and Jim K agreed to give me a new Combination Valve. $200 labor later I was on my way. His mechanic, Alonzo, suggested the valve was OK and the fitting wasn't tight enough. By the time I got home, guess what, leaking again from the same front brake tube connection.
By this time I knew to use a vicegrip on the tubing wrench to prevent rounding the tube nut. So, I've tightened it a couple of times over the past year as leaks continually appear. On my way home from the Coos Bay rally it's leaking again.
It's now impossible to tighten the nut any further. Even with the vicegrip on the tubing wrench the nut is starting to round.
So, I've got $400 in useless repairs into fixing this problem. What's next?? Advice please.
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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