Brake Pedal Manifold leaks... - Printable Version

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+--- Thread: Brake Pedal Manifold leaks... (/showthread.php?tid=6476)

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Brake Pedal Manifold leaks... - Wanderman - 11-30-2021

So while going through the air leak detection process, in addition to the diff lock solenoid I found last week. I have found several line under the dash at the brake pedal manifold/valve body that are leaking.

I am attaching a photo, if someone could tell me how many fittings total, what size to buy and what tubing diameter (1/4" for the white ones and 1/2" for the black ones??) I will refit the entire assembly. They seem to be leaking from around the plastic locking collars so it may just be bad/hard tubing... but I may as well use better fitting if I am already there!

Thanks in advance!

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RE: Brake Pedal Manifold leaks... - Tf175 - 12-01-2021

Those are push connect fittings and should be replaced.  They don't appear to be DOT type , which is a better part . You might look at going with compression fittings , preferred by many here on the forum . Sizing and hose type should be shown on the hoses themselves. 
McMaster Carr or truck parts house for sourcing .
Someone familiar with your vintage can probably shed more light on what you need . PTFE paste on the threads , keep out of insides of course .
Chris

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RE: Brake Pedal Manifold leaks... - Richard - 12-01-2021

Everything Chris said. I use McMaster Carr for all my fittings.

In addition you will find a couple more tidbits. You need to snip with tubing cutters, about 3/8 off each airline if going back with push ons. The problem is that the collet inside the airline leaves a dimple in the tubing which eventually leaks. Second, i replaced most of mine with compression fittings a long time ago, but I remember one was only available DOT version in plastic and push on.

You might try trimming the tubing and reinserting before replacing the fittings IF Newell left enough slack to do that.

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RE: Brake Pedal Manifold leaks... - Wanderman - 12-01-2021

I agree with Richard (after reading so many excellent posts from him) regarding DOT compression fittings. I have a tubing cutter on the way, and, as a stop gap) will attempt to trim the tubing back and reinsert. In any case, I would like to confirm the sizes.

It appears that ALL the fittings on this manifold are 1/4 NPT threads into the manifold,but several sizes exiting. Looks like 1/4", 3/8" and 1/2"

Am I close??

I'd really like to just order the correct bits and install them all.

Thanks!

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RE: Brake Pedal Manifold leaks... - folivier - 12-01-2021

It's nice to have an assortment of fittings when you have problems on the road.

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RE: Brake Pedal Manifold leaks... - Wanderman - 12-01-2021

Foliver,
I agree... but I would need to know what assortment to carry!

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RE: Brake Pedal Manifold leaks... - encantotom - 12-01-2021

i call the parker store the 100 dollar store. when i go in, i just get an assortment. and when i work on something i keep track of what i might need the next time. so you really are not going to get a shopping list. just look at fittings and go buy some. i have two partioned cases of fittings. and brake tubing as well. including plugs to put in push in unions to use as temporary caps.

tom

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RE: Brake Pedal Manifold leaks... - folivier - 12-01-2021

I'd get a couple of each of the following: 1/4", 3/8" tubing x 1/4", 1/2" male NPT straights & 90º ells, plus a bushing 1/4-3/8" and like Tom said get a couple tubing caps for 1/4" & 3/8" tubing. Plus about 20' of 1/4" and 3/8" tubing. All DOT rated. And 1/2" if you have any that size tubing.
That should get you back on the road. Or help a friend.

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RE: Brake Pedal Manifold leaks... - kyleb - 12-01-2021

We use a lot of "push to connect" fittings at work - not because they are the best or even good - - - we use them because they are cheap, easy to install, & good enough (We don't care if the air leaks down since the air compressors are provided by others . . . )
We also use fittings with pre-applied sealant when available. We use a paste sealant instead of tape as the tape can cause more problems if it gets inside the air system.

Inside the "push to connect" fitting is a rubber "o-ring". As they dry due to age, they shrink & crack. That is why I use compression fittings on my Newell.

The DOT fittings provide more support for the air line for a longer lasting leak free connection (a vibrating line can wear out the o-ring seal or allow the tube to crack.)

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RE: Brake Pedal Manifold leaks... - Richard - 12-01-2021

Rick,

You will spend a LOT of time replacing fittings on the coach over time.

I keep forgetting that most people haven’t had a need to identify pipe and tube by sight. You now have that need. Go to Lowes/HD and buy your self an assortment of pipe plugs for 1/8, 1/4, 3/8, and 1/2 NPT. Drill a hole in each and put them on a cable. By using that you will soon develop the ability to identify by sight NPT threads. Do the same for 1/4, 3/8, and 1/2 tubing. You need some DOT of those sizes anyway.

Once you know the sizes, you can cruise the DOT fittings on the McMaster site.

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