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Old 09-12-2017, 01:16 PM   #1
NeoJuice
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Brake Bleeder Thread Sealant?

Folks,

I finally got back from holidays and had some time to work on the truck. I got the hole cut in the floor and my brother helped me bleed the brakes.

Here is a link to my old thread about the residual valve mounting.

http://67-72chevytrucks.com/vboard/s...d.php?t=743831

Bleeding went smoothly and got all the air out and all nice clear fluid with no bubbles on each corner which I was very happy about and no leaks in any of the brake lines I fabricated.

Now onto the problem. All my bleeder screws are tightened up but they're leaking fluid out around the threads (I believe) on all four corners of the truck and down onto the caliper and onto the ground. WTF? I need to verify closer if it is coming from around the threads or out through the bleeder hole.

I'm worried that air might be getting sucked back into the system. The rear calipers are brand new and the front MII front calipers have never had brake fluid in them (brand new).

Should I get new bleeders? like speed bleeders? Researching online people are pro/against Teflon tape. I don't need to be going buying four new calipers.

Thank you for your time.

What are your thoughts?
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Old 09-12-2017, 02:09 PM   #2
mongocanfly
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Re: Brake Bleeder Thread Sealant?

odd that all 4 are leaking...i assume youve checked to make sure theyre all tight..I'd replace the bleeders to start...they work like a needle and seat..the threads don't really seal...make sure there's no trash/dirt in the bleeder hole that could have gotten behind the bleeders...
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Old 09-12-2017, 02:56 PM   #3
mr48chev
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Re: Brake Bleeder Thread Sealant?

As Mongocanfly said the threads don't seal anything. It is the seat in the cylinder and the tapered tip of the bleeder screw that do the sealing.
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Old 09-12-2017, 04:14 PM   #4
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Re: Brake Bleeder Thread Sealant?

I'll pull the bleeders out and take a closer look for any damage or debris. I didn't really bother checking them before I started to bleed the brakes except to make sure they were all tight.

They were already installed with the calipers so I figured that they would be fine. I wrenched on them hard and they are all tight so I'm not sure why there leaking.

I'll post an update once I have a chance to take a closer look and someone to help me re-bleed the brakes.

I'll also get some new bleeders to rule that out of the equation.

Anyone ever use any kind of sealer? like Permatex 59214 high temp thread sealant?
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Old 09-12-2017, 09:38 PM   #5
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Re: Brake Bleeder Thread Sealant?

never had a need to use sealant on the threads...like stated above the threads don't seal...its a needle/seat kind of action. ..
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Old 09-12-2017, 10:09 PM   #6
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Re: Brake Bleeder Thread Sealant?

The taper on the end of the bleeder screw seals against the corresponding taper in the caliper / wheel cylinder casting. Replacing the bleeder screws is the easiest and least expensive option, I would try that first...
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Old 09-12-2017, 10:33 PM   #7
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Re: Brake Bleeder Thread Sealant?

Quote:
Originally Posted by Black_Sheep View Post
The taper on the end of the bleeder screw seals against the corresponding taper in the caliper / wheel cylinder casting. Replacing the bleeder screws is the easiest and least expensive option, I would try that first...
I'll replace the bleeders in the next couple days. I also found this link.


http://www.mityvac.com/pages/info_faq.asp

Just a fyi.
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Old 09-12-2017, 10:43 PM   #8
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Re: Brake Bleeder Thread Sealant?

what they're doing is using a vacuum bleeder ...the teflon tape is being used to prevent getting air in the system from around the bleeder screw threads whike the system is under vacuum..the tapes not being used to seal the threads after bleeding. .
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Old 09-13-2017, 09:49 AM   #9
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Re: Brake Bleeder Thread Sealant?

if the fluid is, in fact, coming from around the threads then I would remove the bleeders one at a time and take a look at the tapered seat area on the end of the screw. it should have a nice uniform taper on the end with no grooves or nicks etc. if they are all good then next check the seat area in the bleeder screw hole on the calipers and wheel cylinders. that is a bit more difficult but can be done easier with a small syringe to suck a bit of fluid out of the hole. you gotta be fast here because the system will automatically gravity bleed so more fluid is going to be coming as soon as you suck a bit out. new bleeder screws are cheap so maybe just replace the screws first and see what happens.
some guys will put teflon tape everything simply because they think it helps seal and they may not know any better. like said earlier, bleeders screws seal on the taper and brake lines are classified as an inverted flare fitting so the seal comes from the tapered flare, not the threads. I have heard of a few guys that wrap the threads on brake fittings because it makes them easier to tighten up and get off after a few years, stops rust is the thought.
start by cleaning the area well with brake clean and compressed air (safety glasses) then include a couple of pics of the leak if it is still there. you could try a small piece of clear tubing attached to the bleeder port of the screw, then if it leaks from the bleeder portion it will show up in the hose. if it leaks from the threads it will be apparent and the hose will be dry on the inside.
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Old 09-13-2017, 05:52 PM   #10
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Re: Brake Bleeder Thread Sealant?

As so many have already stated, reading that all 4 bleeders are leaking tells me something ain't right with the bleeders-threads-or seating area?? Never had to use any sealant to seat those I've worked on, but I had ONCE over tightened a bleeder and cracked the threaded area. I changed the bleeder 2 times before finding out it was cracked. As dsraven said, check (1) at a time and I would definitely buy the ones recommended for your application and replace (1) at a time. Keep us posted.
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Old 09-14-2017, 01:32 PM   #11
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Re: Brake Bleeder Thread Sealant?

Thank you 'DsRaven' and 'My56ChevyTruck' for the information. I'm going to get new bleeders tomorrow and will do as you recommend.

I will then re-bleed the brakes and see what happens. I will update the thread when I have chance.
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Old 09-17-2017, 11:36 AM   #12
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Re: Brake Bleeder Thread Sealant?

how did it turn neo? do they still leak?
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Old 09-18-2017, 11:26 AM   #13
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Re: Brake Bleeder Thread Sealant?

I picked up some new bleeders screws and got them installed in the front because the ones that were in there were grooved on the screw seat and inside the caliper hole looked clean. So that's why it was probably leaking up through the threads on the front.

After doing some bleeding I ended up taking the rear calipers back to Napa for warranty on the weekend because they were leaking out the bleeder screws as well.

The problem with the rears was they were both remanufactured and must have had rusted bleeder screw holes so they sleeved them and then used a smaller bleeder screw. So they were leaking out around the sleeve they put in during remanufacturing which made me so mad.

So I got the new rear calipers and there ready to be installed with the proper size bleeder screws. What I'm now fighting with again is trying to get the ebrake bracket adjusted properly. The drivers side is done but I'm really fighting with the passenger side.

This is what I'm trying to do at about the 9 minute mark. The drivers side lined up quick but I'm having a hell of a time with the passenger side.

https://www.youtube.com/watch?v=opjdu8DdVeA

So that's the update lol. Thought I was moving forward but I will update once I have more information and I'll upload some pictures.
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Old 09-18-2017, 12:06 PM   #14
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Re: Brake Bleeder Thread Sealant?

man that sucks about the rebuilt bleeder screws. I buy quite a few parts from napa and haven't had that problem before. just your luck I guess. trying your patience. seems to have worked, haha. (I assume there is no caliper or wrenches embedded in your garage walls....)
ya, been there with those +#@! calipers. a pain but once you get it done they work, usually.
you don'y have to pull the piston out if you are confident they have the right stuff inside. just do a bench test like the video and make sure the rebuilder got the proper piston and bolt in there for the side of the vehicle you are working on. otherwise they are backwards.
pics would be nice when you get a chance.
good luck
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Old 09-18-2017, 01:00 PM   #15
NeoJuice
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Re: Brake Bleeder Thread Sealant?

Quote:
Originally Posted by dsraven View Post
man that sucks about the rebuilt bleeder screws. I buy quite a few parts from napa and haven't had that problem before. just your luck I guess. trying your patience. seems to have worked, haha. (I assume there is no caliper or wrenches embedded in your garage walls....)
ya, been there with those +#@! calipers. a pain but once you get it done they work, usually.
you don'y have to pull the piston out if you are confident they have the right stuff inside. just do a bench test like the video and make sure the rebuilder got the proper piston and bolt in there for the side of the vehicle you are working on. otherwise they are backwards.
pics would be nice when you get a chance.
good luck
.

I'll take a closer look at the passenger side tonight. I'm doing it like just in the video and with the drivers side I was done in like two minutes. But for some reason if I recall when turning the piston in either direction for the passenger rear it came out instead of going in/out. I spent a couple hours fighting with it yesterday and just needed to walk away LOL.
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Old 09-18-2017, 01:36 PM   #16
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Re: Brake Bleeder Thread Sealant?

glad you figured out them bleeders...that sucks for sure
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Old 09-18-2017, 04:10 PM   #17
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Re: Brake Bleeder Thread Sealant?

That is an absolute new one on me. Sleeved bleeder screws, who would have ever thought about that but the rebuilders probably don't throw much away unless it is totally destroyed.
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Old 09-19-2017, 02:00 PM   #18
NeoJuice
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Re: Brake Bleeder Thread Sealant?

I got the pictures of the old bleeders for you front and rear. Silver are rear gold are front. (see attached). As you can see one of the rear silver ones was smaller. As I mentioned in the other post how one of the rear calipers was sleeved. The other rear was the correct size but also grooved and leaking.

I've installed new bleeders in the front calipers and rear calipers so hopefully I don't have any leaks when I bleed the brakes again.

Last night I finally got the adjustment of the passenger side rear ebrake caliper done. So now both of them have 1/4" pull before engagement. I still need to hookup my rear brake lines and tighten up the calipers before bleeding again.

I will update the thread after my next bleeding session.
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Old 09-22-2017, 07:50 PM   #19
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Re: Brake Bleeder Thread Sealant?

One of two things come to mind, both bad.

1. There isn't a way to "sleeve" the caliper (or rotor) for the bleeder. It might have an insert like a Heli-Coil(R) for the smaller threads. I don't ever recall using a Heli-Coil(R) in a hydraulic system, and I wouldn't want to try. The system is tested to 2000 psi at the factory, and I don't think that they are meant for that application.

2. The smaller bleeder screw isn't necessarily going to get the same seal as the big one, due to possibly even missing the inner edge of the taper. I seriously doubt that they would seal at panic stop pressures.

That's a pretty hack fix, AFAIAC.
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Old 09-22-2017, 08:47 PM   #20
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Re: Brake Bleeder Thread Sealant?

There are two way to repair a bleeder screw hole as far as I know, one is very similar to an insert that's screwed in and sealed then a bleeder is screwed into that, the other is you tap out the bleeder hole to 1/8 NPT and install a brass screw in bleeder assembly.

Dorman makes the brass one in various sizes. The other I see used on Motorcycles mostly
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Old 09-22-2017, 11:57 PM   #21
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Re: Brake Bleeder Thread Sealant?

that's amazing, to have all 4 bleeders leaking. glad you got it fixed, now on to the driving!!!
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