Home » Public Forums » GMCnet » [GMCnet] Brass Combination Valves
| [GMCnet] Brass Combination Valves [message #227198] |
Sun, 27 October 2013 10:38  |
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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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G'day,
Got to thinkin' about these valves and thought I'd send in a message to see if we could figger out how to do a cursory check before
they are installed.
If there is a machining problem with the brass valves we could thread one line and nut down into the valve finger tight which should
bring the flare in contact with the seat and the line should not move.
If the line moves the problem could be in the valve:
1) the inverted flare in the valve is not "tall" enough
2) the threads are keeping the nut from turning enough to force the line into contact with the inverted flare
3) the double flare on the line has been squashed so badly it won't reach the inverted flare
Anybody got any other ideas?
I would suggest the vendors check these valves before they ship them to customers.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
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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] Brass Combination Valves [message #227200 is a reply to message #227198] |
Sun, 27 October 2013 10:56  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| Robert Mueller wrote on Sun, 27 October 2013 10:38 |
G'day,
Got to thinkin' about these valves and thought I'd send in a message to see if we could figger out how to do a cursory check before
they are installed.
If there is a machining problem with the brass valves we could thread one line and nut down into the valve finger tight which should
bring the flare in contact with the seat and the line should not move.
If the line moves the problem could be in the valve:
1) the inverted flare in the valve is not "tall" enough
2) the threads are keeping the nut from turning enough to force the line into contact with the inverted flare
3) the double flare on the line has been squashed so badly it won't reach the inverted flare
Anybody got any other ideas?
I would suggest the vendors check these valves before they ship them to customers.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
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I do not understand why you do not just install some of those beveled copper washers into the connection and be done with the problem.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Brass Combination Valves [message #227206 is a reply to message #227202] |
Sun, 27 October 2013 11:34 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Yes they do come in all sizes. There was a hardware supply in Michigan on the Internet where I ordered a few of each size. So I have a whole collection of all sizes. Unfortunately I do not remember the name of the place. I looked back at my receipts for the name and did not find it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Brass Combination Valves [message #227214 is a reply to message #227198] |
Sun, 27 October 2013 12:41 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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here is where I purchased my "flare saver" or "flare washer"
http://dmpfasteners.com/shop/an-fittings-and-hose-1647/tubing-1003/copper-flare-saver-1005/
I have not used them, they are still in the box on my workbench.
this combo valve problem is a tough one to solve. there might be an issue with the manufacture, but there are so many variables in the installation. we have heard about some leaks, but there has to be plenty of installations that did not leak at all. I would think more of those then leaky installations.
there are so many different variables, condition and material of the brake line. conditions of the flares. I know if I have to make my own flares, I borrow a very expensive flare tool from work, I have not had luck with making my own flares with any other tool.
I would rather have a factory made flare line, and then joint it with fittings, then make my own brake flares. when i replaced the lines up to my master cylinder, I found brake lines that were the right length. when I did my dune buggy, I tried making my own lines, and have had some failures down the road on those flares.
the one thing consistency I see, is it seems to be people pointing down to the lower front connection. That connection in itself is tough, it is a sharp bend to the valve. would not take much to get that one out of line, and not have it seal right.
my own experience it was not the fitting at all, but the metering valve worked loose. or it was both, but I had already replaced the brake line. thinking that was it, before I checked and found that metering valve loose.
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] Brass Combination Valves [message #227265 is a reply to message #227198] |
Sun, 27 October 2013 19:12 |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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Senior Member |
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I have heard of the metering valve part of the brass Chinese combo valves leaking (not by other GMC'ers, by classic car guys). I don't know who made the brass combo valve you currently have but if I was a betting man I would say it was made by Tongshun, which makes the vast majority of them.
Since I have one of the Chinese brass combo valves on my GMC, in my toolbox I also carry a replacement metering valve as it's much easier and cheaper to replace just the leaky metering valve instead of the entire combo valve assembly. No need to remove brake lines, the metering valve unscrews from the front (as mounted in the GMC) of the combo valve.
Possibly your brake fluid leak is from the metering valve stem and the fluid is dripping down the body of the combo valve and making it appear to be leaking at the brake line that comes out of the bottom of the combo valve? Just a thought.
The replacement metering valve for the Tongshun combo valve is $10.00 from:
http://www.classicperform.com/Store2/Brakes/PVMVK-T.htm
Looking around the internet at GM-style combo valves there are many sellers selling what appear to be two different models of Chinese brass valves, the PV2 for disk/drum systems and the PV4 for disk/disk. Many sellers, the same two valves, both probably made by the same Chinese supplier (Tongshun).
Just thought I would add some more useless information to the list!
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: [GMCnet] Brass Combination Valves [message #227266 is a reply to message #227214] |
Sun, 27 October 2013 19:19 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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The place in Michigan I bought those flare seals from had them for only a cents each rather than dollars each. As I remember I ordered a dozen of each size and shared them with another GMCer. If I ever find the location again I'll post it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Brass Combination Valves [message #227310 is a reply to message #227284] |
Mon, 28 October 2013 00:38 |
jtblank
Messages: 237
Registered: June 2007
Location: Tulare, CA
Karma: 1
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Senior Member |
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Had to jump in here with a similar experience when changing my rear flex brake hoses. These are the braided ones I got from Jim B, the right side leaked slightly leaving a little puddle on top of the bogie fixture. I tightened as much as I thought the treads would take, I have a good set of Craftsman tubing wrenches so rounding of the shoulders was not of concern. I cleaned the puddle weekly and gave a little snugging weekly as well. Finally it stopped, it has been a couple of years since leaking and I haven't dared to touch it.... leave well enough alone. I have two theories; 1 is the seat of the flare finally formed to the housing or 2 enough microscopic gunk, corrosion or whatever in the brake fluid filled the leak. What ever the cause for it to stop, I'm not touching it...
John Blankenship
'76 Palm Beach
Tulare, CA
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| Re: [GMCnet] Brass Combination Valves [message #227437 is a reply to message #227198] |
Mon, 28 October 2013 18:18 |
Gail Marks Cruiser
Messages: 125
Registered: August 2009
Location: Gold Coast, Australia
Karma: 0
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G'day,
I installed a new brass proportioning valve last year and found I had to use more than usual force to seal the pipes. Then it leaked past the pin in the front, Another O ring fixed it.
>Now I am replacing the rear wheel cylinders and have found the pipes are needing too much effort to seal them. They were all cleaned with a wire brush before being re-installed.
>Checking the new slave cylinders, the threads were slightly longer than the old. A quick run over with a die cleared the threads on the pipe fittings, made them a lot easier to install, but not quite right, reversed the die to clear the thread to full depth, right up to the nut flats, perfect.
>30+ years of corrosion on the exposed portion of the threads. This is probably what made the proportioning valve difficult to install. I can see all new brake lines in the near future.
Mark Bennett
Gail & Mark's Cruiser
Gold Coast, Australia.
Motorhoming Lifestyle.com
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| Re: [GMCnet] Brass Combination Valves [message #227542 is a reply to message #227437] |
Tue, 29 October 2013 07:44 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
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Senior Member |
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Don't forget there are some original flare fittings attached to the new meter valve. I understand though that the leak is coming from the "bleed button" at the front of the new combo valve. If this is true, no amount of tighening a fitting or adding seal washers on the valve will stop the leak, the problem is internal.
I have seen a few new valves leak but it usually will happen immediatly. We watched the valve when it was installed for that. The valve was not leaking when it left and the brakes were pretty good as I remember. What can anyone say, things happen and new Chinese made parts (almost everything is anymore) must prove they are even as good as the old worn out parts. What can you say, it's the world we live in and there it is. The answer is not to reinvent that wheel but to replace the parts with good ones. I have already mailed a new meter valve to Zeb for you to replace the bad one, he does not stock these parts which will tell you how hard they are to find new. I will need the bad one back to send it back for replacement. If that fixes it great but in my experience, the valve may leak but it will usually not take out the entire brake system-- could I guess but I would look around at more pieces/parts of your brake system. There are
still many original parts in the system.
You have had your saga "cross country" at least partly because you left California with so many old parts holding hands. The frame was pointed out to be badly rusted but you were told there wasn't much you could do. Trying to put the coach on out left the frasme colapsed and broke one of our 6 ton stands and almost hit the ground The reality is you should not even have taken off as bad as the undercarriage of your coach was! It stinks but you didn;t know what to look for and the previous owner, if he knew, did not point out the fact that your coach was mechanically rusted to the hilt. You really need to get to a place and have the drive train, chassis and suspension totally reworked. The "patches" everyone is trying to accommodate you with is not going you yeild in the end a relaible travel machine, you are simply postponing the inevitable.
I am sorry to post this tough love comment but brother everyone is trying their best to keep you on the road, you must understand the vehicle you have and what needs to happen to it. It's not the design of the coach, it's not the competance of the techs that have worked on it and it's not even the less reliable new parts that we would hope them to be-- it's the total volume of the reapirs needed to the coach. These issues will contiue as you try to turn your coach into a silk purse one stitch at a time. You were not informed or treated properly when you purchased the coach--- what is the Latin phrase... which is why I am not a dealer and want nothing from the sale of any coach because Brother-- they all have problems after 30+ years!
Jim Bounds
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On Monday, October 28, 2013 7:18 PM, Mark Bennett <mark.bennett.58@gmail.com> wrote:
G'day,
I installed a new brass proportioning valve last year and found I had to use more than usual force to seal the pipes. Then it leaked past the pin in the front, Another O ring fixed it.
>Now I am replacing the rear wheel cylinders and have found the pipes are needing too much effort to seal them. They were all cleaned with a wire brush before being re-installed.
>Checking the new slave cylinders, the threads were slightly longer than the old. A quick run over with a die cleared the threads on the pipe fittings, made them a lot easier to install, but not quite right, reversed the die to clear the thread to full depth, right up to the nut flats, perfect.
>30+ years of corrosion on the exposed portion of the threads. This is probably what made the proportioning valve difficult to install. I can see all new brake lines in the near future.
--
Mark Bennett
Gail & Mark's Cruiser
Gold Coast, Australia.
Motorhoming Lifestyle.com
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| Re: [GMCnet] Brass Combination Valves [message #227603 is a reply to message #227542] |
Tue, 29 October 2013 13:41 |
MichaelP
Messages: 65
Registered: October 2012
Location: Ohio
Karma: 0
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Jim, thanks for the "tough love" in your post, and of course I don't fault the competency of the mechanic for a failed part -- and thank you for the replacement; I will of course send you the failed valve when we get it switched out tomorrow.
I think you may have mistaken my criticism of different parts: asked why the metering valve nut on the combo valve was even necessary if it could fail this way, NOT the combination valve itself. If this is what you are calling a bleed button, then I guess that partially answers my question: that it must serve as a bleeding function of some kind.
Regarding all the frame rust comments: not sure why the frame repair has come into this thread, but thanks for the work you did on that as well as all the other work you did on it. But it is a separate issue entirely, and one we hope has been remedied.
Regarding the brakes and the combo valve: One thing I was adamant about when we did all that brake work was to get the entire system solid, and that's why we put the work into it. It's a little frustrating at this point that we've been stranded due to a faulty part. (Since my business is to sell the CNC machinery that makes these parts--machines that need to hold certain tight tolerances so this kind of thing doesn't happen--I do know the difference between the competency of the manufacturer and the competency of the mechanic.) In this case, to be perfectly clear, it seems to be an engineering or machining fail, and having nothing at all to do with frame rust or anything else addressed at the Co-op. We do appreciate everything you've done to keep us on the road, as we do everyone who has worked on our coach.
What I've realized, after this latest issue, is I need to get myself a collection of brake fittings so I can do these repairs on the road myself; there are so few people around who will even look at our coaches, even for a simple fix like this one.
-Michael
[Updated on: Tue, 29 October 2013 14:01] Report message to a moderator |
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