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JayEstes

Advice on cleanup of vacuum booster

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We'll I've been having a rather horrible brake fluid leak going in my car recently.  I'm really not sure where things are leaking yet, but suffice it to say the master cylinder is a mess, and the vac boost has signs of oil after I removed the master cylinder. This is the original vac booster (bendix) that came with the car.  Even recently, this booster has seemed to be working fine, I have great brake pressure, and the brakes work just fine (at least when there is fluid in the lines!).

I'm wondering what to do with the vac booster.  At the least I need to remove it and cleanup and paint the housing, but since it's working, I am not sure I want to go thru rebuilding it.  Rebuilding it also kind of tears up the housing in some respects, since it was never meant to be rebuilt.  I can buy a rebuilt one $200, or just clean this one up.

How much of a problem can having brake fluid inside these be?  I've no idea how much - if any - fluid is in there, but the performance seems fine to me.  Is there anyway to just remove the booster, and then try to drain any fluid in there, before I clean up and paint the outside?  Or, would it be best to just buy a rebuilt one, and be done?

Looking for your recommendations.

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If the Master Cylinder piston leaked into the Booster then you may have a puddle of brake fluid in the booster?  With the MC removed I would use paper or cloth towels and  dab or wick the leaked brake fluid out of the bladder/diaphragm area.  Nothing further  needs to be done.  If you are not confidant/experienced enough to remove and replace the booster then go no further.  Clean the area, booster and firewall, with cleaner and towels and turn your attention to the MC.  Brian

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If it's a Bendix brake booster after the master cylinder is removed there is a seal in the front of the booster than can easily be replaced.  The brake fluid might have damaged it by now.  The piston rod will sometimes just slip out as well so don't worry if it does.  I've seen those seals on National Parts Depot's website.

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Yes, I wonder if the seal between the booster and master cylinder is a part of the problem - there wasn't one there.  I will make sure my new MC comes with one, or purchase one like you mention.  It is a bendix booster.

Regarding brake fluid in the booster, I watched some rebuilds of bendix vac boosters on youtube (this one is pretty damn funny, but quite relatable too https://youtu.be/otCsW-eKrw0 - its a different model than mine, and much easier to open, but it has what looks like brake fluid to me in there) Right now i can't know if there is any fluid in there.  When I get the vac booster off, I'll see if I can determine that, buy rolling it around or shaking it or something, I really don't want to open my original).

I'm not worried about taking it off the car, I had it off before, but somehow - even though I put a new MC on at the time, I've developed bad leaks in the system.  I don't know if it could be related to the MC to booster seal, but possibly.  The front of my booster has signs of leaking under the MC mount.  Thing I don't understand is why fluid should be in that small hole behind the MC - maybe the seal is to just hold any fluid that leaks in that space - I'm not sure.

My thinking right now is the MC is leaking into the volume in the front of the booster, and causing the majority of my problems.  However, I also noticed some fluid near my proportioning valve, so I have to get that out and have it a look at it also.

Anyway, thanks for the help.  I'll keep you posted on how things go.

 

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20 hours ago, 1969_Mach1 said:

Master cylinders do not include the front seal for the brake booster.  Here is a link to a kit that includes that seal.  There are more parts in it than you need, but it's the easiest way I know of to get that seal.  https://www.npdlink.com/product/boot-kit-power-brake-booster-repro-bendix-booster/205434/203210

Thank you very much - I went to NPD and looked for this but their search system isn't very good - pulled up tons of stuff and this was somehow either not there or lost in the pile - I couldn't find it.  So, I just got this kit.  It won't hurt to have new seals on the booster after I clean it up.  It's a little pricey, but having the right parts matters a lot.

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Okay, well I've removed and checked the booster, and it seems just fine.  I decided to repaint it because it was already getting surface rust from where the brake fluid had cut the paint, and it had begun to rust.  I stripped it, and got it in good shape, but I wanted to kill the rust so I hit it with Osphor.  Well it looked terrible after that stuff had dried on there, so I began brushing it, and then found that a wire brush made the thing shine:

57673306613__205009AF-2667-452A-BCD2-7E24904708AB.thumb.JPG.b09ee88296689dc7848ad84f0547327a.JPG

IMG_3947.thumb.JPG.e424bd03cd7ffdf5e66d1515fa17bb2c.JPG

IMG_3960.thumb.JPG.a7a0f545f7bf8b63193fd26c16c345e4.JPG

IMG_3959.thumb.JPG.d9edf655f38d2f8b2ca10bcd58eeb9b0.JPG

I have been thinking I was going to use engine paint, but I had been considering using a two part epoxy (brake fluid proof) to cover the paint and protect it from the brake fluid, but NOW, looking it how this came out, I am wondering if just painting clear 2-part epoxy on here is a good idea to just preserve the buffed metal look.  

 

I'm looking for your thoughts on this.  The part doesn't get overly hot, and it's not in the UV much.  The 2-part gloss clear I have is crystal clear and marine grade.  Am I crazy to think I could coat it as is, and preserve this bare metal finish?  No, it's not concourse, but it is original, and looks  pretty great if you ask me!  Give me your opinions!

Thanks,

Jay

Edited by JayEstes
clarity

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Yes, paint it black with a satin or semi gloss finish.  Don't use an engine enamel.  Engine enamel lays on with a heaver film thickness and will not leave as nice of a finish on smooth parts.  When using spray cans Duplicolor brand dries fast but is not very durable.  I use to use that brand but now do my best to avoid it.

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Thanks for thoughts guys - I will let you know which way I go.  In the mean-time, I found that west coast classic cougar has the front seal for a bendix booster by itself (repro) for $10: https://secure.cougarpartscatalog.com/16984/30151/front-seal-bendix-brake-booster-repro-1969-1970-mercury-cougar-/-1969-1970-ford-mustang.html?attribs=80  I bought the whole kit at NPD, but this is a good option if you just want a new front seal.

I was looking for a new push rod - mine is kind of pitted, but nobody sells the kind I have anymore.  They gave me a good contact for a place to rebuild boosters who was helpful.  "Booster Steve" in Washington state I believe.  Their business info is:

Power Brake Booster Exchange
503-238-8882

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