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Re: [GMCnet] GMCNet Proportional Valve [message #328523] Tue, 23 January 2018 00:14 Go to next message
THOMAS R WHITTON is currently offline  THOMAS R WHITTON   United States
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Suggestions on removing the proportional valve. 
I have loosened the tubing nuts from the valve but all the nuts are frozen to the tubing.  I'm sure I would corkscrew the tubing if I try turning the nuts more than a quarter turn or so.  There is no sign of rust on the tubing or the nuts but, of course, I can't see between the parts.  How do you free the nuts loose from the tubing?  I don't relish the thought of ruining  and having to replace the brake lines.
This is a job I've never done and can use suggestions.
Tom Whitton26 foot upgraded GMCPaducah, Ky

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Re: [GMCnet] GMCNet Proportional Valve [message #328528 is a reply to message #328523] Tue, 23 January 2018 06:21 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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Patience, Patience, Patience.

Soak the nuts and tube with Kroil, once a day for 5 days. Then give it a try.

A little heat from a propane torch before soaking and then shooting the connections with Kroil to rapidly cool them sometimes helps speed up the process. Do not over heat them because there is brake fluid inside that can boil at somewhere over 300 degree F. Once you get one of them to move even slightly keep soaking and move then back and forth while soaking with more Kroil.

If you do not have Kroil, get some and in the interim use PB Blaster. It will just take you longer.

You can also mix up your own using a 50/50 mix acetone and Power Steering Fluid. I just unlocked a frozen 403 engine that had been sitting of 19 years. I soaked the cylinders for about 3 weeks with this mix before it broke loose.

Patience is a virtue. Give it plenty of time to work.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] GMCNet Proportional Valve [message #328530 is a reply to message #328523] Tue, 23 January 2018 07:50 Go to previous messageGo to next message
lqqkatjon is currently offline  lqqkatjon   United States
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Ken's advice is spot on. chances are you may twist and brake a line. Some are shorter and easier to replace(i broke off the one going up to master cylinder and was not bad). Otherwise you have the option of cutting and flaring and adding a union and small piece. That is not ideal.

Like ken said, lots of penetrant.


Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/
Re: [GMCnet] GMCNet Proportional Valve [message #328531 is a reply to message #328530] Tue, 23 January 2018 08:45 Go to previous messageGo to next message
Bullitthead is currently offline  Bullitthead   United States
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A crows foot 3/8 or 1/4 drive wrench and a small impact tool can send enough shock waves through the fasteners to break the nut free from the line after judicious application of penetrant. If not, I usually use the smallest torch tip I have and heat just the nut to expand it a smidgen to get them to separate. Same story on wheel cylinders but sometimes can't get the crows foot wrench on those. Don't forget to use a wrench on the block and put your turning force against that instead of relying on only the block mounting.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.
Re: [GMCnet] GMCNet Proportional Valve [message #328559 is a reply to message #328523] Tue, 23 January 2018 22:06 Go to previous messageGo to next message
Phantom2 is currently offline  Phantom2   United States
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A lot of folks swear by Kroil, but there was an "independent" article posted that indicated a 50/50 mix of trans fluid and acetone was the best. Here's a previous thread with some data: http://gmc.mybirdfeeder.net/GMCforum/index.php?t...

Larry Hopkins 75 Avion Springfield, IL
Re: [GMCnet] GMCNet Proportional Valve [message #328560 is a reply to message #328559] Wed, 24 January 2018 04:32 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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Phantom2 wrote on Tue, 23 January 2018 22:06
A lot of folks swear by Kroil, but there was an "independent" article posted that indicated a 50/50 mix of trans fluid and acetone was the best. Here's a previous thread with some data: http://gmc.mybirdfeeder.net/GMCforum/index.php?t...


That is what I used to free up this 403 engine. I used it because I needed a large quantity around 1/2 gallon to fill up the cylinders. It also was readily available locally and cheaper. I have been told that the acetone will evaporate off and leave just the oil.

We buy spray cans of Kroil around here by the case.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] GMCNet Proportional Valve [message #328562 is a reply to message #328560] Wed, 24 January 2018 08:47 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Ken Burton wrote on Wed, 24 January 2018 05:32
That is what I used to free up this 403 engine. I used it because I needed a large quantity around 1/2 gallon to fill up the cylinders. It also was readily available locally and cheaper. I have been told that the acetone will evaporate off and leave just the oil.

We buy spray cans of Kroil around here by the case.

Ken,

The acetone does leave fast in an open can, but I keep it in a pretty tight pump oil can and it stays pretty well. But I can't carry it in the coach.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] GMCNet Proportional Valve [message #328567 is a reply to message #328523] Wed, 24 January 2018 13:17 Go to previous messageGo to next message
Russell K. is currently offline  Russell K.   United States
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Tom,
I recently replaced the proportioning valve on our GMC. The 50/50 mix of acetone and ATF (as recommended to me on this forum) worked very well for me. What I did first was scrub the fittings and the tubing with the 50/50 mix and a toothbrush. I also purchased the vice-grip locking wrench (also recommended here) that grabbed the fittings tighter than the flare nut wrench. After tightening the wrench on the fitting, I would tap it with a small hammer while applying pressure to loosen the fitting. It worked successfully on all the fittings, but I did replace some of the brake lines anyway, since I had previously purchased the stainless steel brake line kit.

valve before cleaning
http://www.gmcmhphotos.com/photos/data/7010/20170102_074927.jpg

after cleaning
http://www.gmcmhphotos.com/photos/data/7010/20171230_092718.jpg

New valve in place
http://www.gmcmhphotos.com/photos/data/7010/New_Proportioning_Valve_Installed1.jpg


1978 Eleganza II, Dunedin, Florida
Re: [GMCnet] GMCNet Proportional Valve [message #328588 is a reply to message #328523] Thu, 25 January 2018 13:20 Go to previous messageGo to next message
THOMAS R WHITTON is currently offline  THOMAS R WHITTON   United States
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Russell, Ken Jim and others...
Thanks everyone for excellent advise.  Here's where I stand on the project... 
This will be the third day to spray the acetone/ATF 50-50 mix on the proportional valve fittings.  So far, I have resisted the urge to get out a wrench, hammer and torch.  I'll try a wrench tomorrow.  By the way, as far as I know, my proportional valve and brake lines are original.  Amazingly, they show zero rust.  I guess that may have something t do with keeping the coach garaged most of its life.  Russell, if you were able to free up your lines I may have a fighting chance.
I'll report whatever happens.
Thanks,
Tom Whitton26 foot updated GMCTom Whitton
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Re: [GMCnet] GMCNet Proportional Valve [message #328593 is a reply to message #328588] Thu, 25 January 2018 15:05 Go to previous messageGo to next message
NextGenGMC is currently offline  NextGenGMC   United States
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Tom,
If you do end up busting any of the brake lines (or just want to change them), I have a complete set of stainless steel brake lines for 26 footer available if you are interested.


Vadim Jitkov '76 Glenbrook 26' Pullman, WA
Re: [GMCnet] GMCNet Proportional Valve [message #328602 is a reply to message #328588] Thu, 25 January 2018 18:56 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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Tom, Get a little butane pencil torch and heat the just the nut. Then shock cool it with your penetrating oil and let it soak. The heat and uneven shock cooling lets the oil penetrate quicker.

TSC has the torches for a couple of dollars and you fill them with butane lighter fluid.

Here is an example:

https://www.ebay.com/itm/Set-of-2-Butane-MINI-PENCIL-TORCHES-Refillable-Welding-Soldering-Jewerly-Repair/312036072984?epid=1340428883&hash=item48a 6cc9e18:g:BDcAAOSw-RFaYSS8



Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] GMCNet Proportional Valve [message #328607 is a reply to message #328602] Thu, 25 January 2018 20:55 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
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Tom, et al,

While you're at it, if you haven't already, get these:

http://www.irwin.com/tools/locking-tools/the-original-locking-wrenches

At least the 4" & 7" ones.

FAR superior to flare nut wrenches for tight nuts -- they won't spread.

Ken H.

On Thu, Jan 25, 2018 at 7:56 PM, Ken Burton wrote:

> Tom, Get a little butane pencil torch and heat the just the nut. Then
> shock cool it with your penetrating oil and let it soak. The heat and
> uneven
> shock cooling lets the oil penetrate quicker.
>
> TSC has the torches for a couple of dollars and you fill them with butane
> lighter fluid.
>
> Here is an example:
>
> https://www.ebay.com/itm/Set-of-2-Butane-MINI-PENCIL-
> TORCHES-Refillable-Welding-Soldering-Jewerly-Repair/
> 312036072984?epid=1340428883&hash=item48a6cc9e18:g:BDcAAOSw-RFaYSS8
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: [GMCnet] GMCNet Proportional Valve [message #328619 is a reply to message #328607] Fri, 26 January 2018 08:21 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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Ken Henderson wrote on Thu, 25 January 2018 21:55
Tom, et al,

While you're at it, if you haven't already, get these:

http://www.irwin.com/tools/locking-tools/the-original-locking-wrenches

At least the 4" & 7" ones.

FAR superior to flare nut wrenches for tight nuts -- they won't spread.

Ken H.

As you all have to know, I love mine, but they are a little tough to get on the master cylinder lines at the combination valve. One I could just enough to break the line loose, but not the other and I don't remember which.

With the 7", you can actually get on a line nut at a wheel cylinder with enough torque to shear the line nut and it won't slip. Not Mine, not even a GMC, but fortunately wheel cylinders are cheap and the line had to be replaced anyway. (You know this was not a good day.)

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] GMCNet Proportional Valve [message #328620 is a reply to message #328619] Fri, 26 January 2018 08:32 Go to previous message
hdforge is currently offline  hdforge   United States
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Don't worry about the effect of heat on fluid, you will be replacing all the old fluid anyway once the new valve is in.
And from my experience heat/cold is more important than any specific concoction of penetrating fluid. Be patient, any movement at all should be used with more fluid and heat.
Eventually it will break loose, but it can take time. I spent a half hour on one fitting this summer. But did the prop valve and all 4 wheel cylinders without a single broken line.
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