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Captain Avgas

Well Known Member
I've attached a photo of the plastic fitting that Vans supplies for the RV7A brake fluid reservoir. It has a 1/8" NPT male thread that goes into the reservoir. It's a T fitting that diverts brake fluid to the two master brake cylinders.

A friend of mine claims he could never stop this plastic fitting from weeping brake fluid at the NPT thread into the reservoir. He said it annoyed him intensely....not just the little drops of oil on his carpet, but on a hot day when he first opened the canopy the smell of brake fluid was terrible.

In the end he changed over to a brass fitting and had no further problems.

I'd like to ask those who are flying with this plastic fitting if they have had similar problems. In reality there is no pressure in the lines from the brake fluid reservoir to the master cylinders so you'd think that it shouldn't have a tendency to leak.

Has anyone found it leaked and solved the problem by using a Teflon pipe thread paste.

What have others found about this particular fitting. Left click on image to enlarge if required.

 
Threads...

Bob... it looks like there is molding flash on the threads in the left hand portion of the pic.

If this is the case, it will be really difficult to get a seal, even with Teflon tape...

Is there flash on those threads, or is it an artifact of the photo?

gil A
 
Captain Avgas said:
I've attached a photo of the plastic fitting that Vans supplies for the RV7A brake fluid reservoir. It has a 1/8" NPT male thread that goes into the reservoir. It's a T fitting that diverts brake fluid to the two master brake cylinders.

A friend of mine claims he could never stop this plastic fitting from weeping brake fluid at the NPT thread into the reservoir. He said it annoyed him intensely....not just the little drops of oil on his carpet, but on a hot day when he first opened the canopy the smell of brake fluid was terrible.

In the end he changed over to a brass fitting and had no further problems.

I'd like to ask those who are flying with this plastic fitting if they have had similar problems. In reality there is no pressure in the lines from the brake fluid reservoir to the master cylinders so you'd think that it shouldn't have a tendency to leak.
Click to expand...

Mine leaks, even after tightening it a couple of times.

Matter of fact, after a while I just never bothered to refill the reservoir. I can look at the brake pedals and if there is fluid in the nylon stand pipes, I'm good to go.

But....since I am in the process of replacing the aluminum brake lines running down the gear legs with stainless-braided teflon lines, I'm gonna take the time to fix the reservoir once and for all. Probably will use a brass fitting.
 
az_gila said:
Bob... it looks like there is molding flash on the threads in the left hand portion of the pic.

If this is the case, it will be really difficult to get a seal, even with Teflon tape...

Is there flash on those threads, or is it an artifact of the photo?

gil A
Click to expand...

Gil ma boy, there's nothing wrong with your eyesight. A very astute observation. I put the fittings under my trusty microscope. Yep, there's moulding flash on ALL of the threads. In fact I'd be confident in saying that probably every one of these type of plastic fittings has moulding flash on them. I'd say none of them are machined after moulding. That might explain the poor seal on the pipe threads.

I'm going to toss this fitting and go brass.
 
Use brass fittings.

My 15 year old -6 has plastic lines from reservoir, to master cylinders and on to the firewall. No problems ever. However all the fittings are brass!
 
Where do I get one of the brass fittings then?

O.k.

I have the same leak with two of the same fittings on two occasions. I too am very frustrated with this. I spoke with Vans and they mentioned that they got around this (as they had it too) but putting jbweld on the thread of the plastic fitting and letting it set up. Personally, I would rather use a brass fitting the match the one at the top of the thread. Anyone got any ideas where I could find one of these.

Much appreciated.
 
I used the plastic fitting. No leaks after 200 hrs - I used a bit of permatex thread sealant.
 
I never had any leakage problems on any of the brake lines. Everything was put in per plans. I used teflon sealant on any metal pipe (NPT) connections, but no sealant on plastic or the other fittings. I do remember the flashing on my plastic tee and I did clean it up with a thread file before assembling it.

Roberta
 
I bought a brass replacement at McMaster Carr. Sorry, don't have the part number but a little searching should find it.

Bob
RV-10 #40105
 
Mine leaks too! I thought it might be cracked, since I was able to tighten it several times after I thought I had it screwed in pretty good. If someone has a part number for a brass replacement it sounds like many of us would appreciate it...
 
I used an 1/8" npt x 1/8" flare x 1/8" flare aluminum AN tee, but I used braided brake lines throughout...nothing leaks. plus I can't see any bubbles to lose sleep over either;)
 
Alternate Leak Fix

Another nice fix is to purchase the little individual res. canisters from AC Spruce that attach directly to the master cyulinders.

Randy C
 
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