64 avanti M/C leak from cover

[steve remick]

Has anyone had this problem?  I have replaced gaskets and cover. Kept it 1/2" below top of reservoir to no avail.

 Click on photo to enlarge image, sorry for the rotation.   Any suggestions would be much appreciated..Thanks!

Steve
 

[Gunslinger]

I think it's a combination of too much fluid and a cap seal not sealing properly or possibly a warped cap.  Maybe poor machining or corrosion on the m/c rim itself.  

[mfg]

I agree with Gunslinger's thoughts on this....And may I add that this might be a good time to switch to a dual chamber master cylinder.....Mid 70's Chrysler products have the same four bolt mounting pattern, ....They are still available at your local auto parts dealer, are inexpensive, and most importantly a "split" braking system adds an extra measure of safety to your Avanti

I made this conversion to my own '63 Avanti 20 years ago, and 'have never looked back'!

[Rob Dudley]

When the brakes are released the fluid returns and squirts up against the top. There should be the gasket with a large flat washer below it held in place by an o-ring to deflect the fluid. The chamber is open to the atmosphere to prevent a vacuum condition in the reservoir, so there is an inherent tendency for a little seepage. Modern reservoirs use a rubber bellows to address this issue.

Rob

[steve remick]

On 7/13/2019 at 11:02 AM, Rob Dudley said:

When the brakes are released the fluid returns and squirts up against the top. There should be the gasket with a large flat washer below it held in place by an o-ring to deflect the fluid. The chamber is open to the atmosphere to prevent a vacuum condition in the reservoir, so there is an inherent tendency for a little seepage. Modern reservoirs use a rubber bellows to address this issue.

Rob

Thanks Rob.....but I’m not following. Is there somewhere to watch a visual on this or tell me if there’s another gasket, large flat washer and a o-ring, all of this under the cover?

thanks for your help!!

[Rob Dudley]

There is an exploded picture of the setup in the parts manual on plate # 11-2. Page 108 

[steve remick]

5 hours ago, Rob Dudley said:

There is an exploded picture of the setup in the parts manual on plate # 11-2. Page 108 

I see 1104-8 & 1104-5 that are" less No Rol"    I just have 1104-8 with "No Rol"   So...do I need "1104-5" also?

Thanks for your time and advice!

[Rob Dudley]

I think it helps but I have never had one that didn't seep some. It would be nice if it were sealed but that wasn't the design. 

Rob

[steve remick]

18 hours ago, Rob Dudley said:

I think it helps but I have never had one that didn't seep some. It would be nice if it were sealed but that wasn't the design. 

Rob

So Rob, have you had this problem on your Avanti?  And what you’re saying is just to put up with the seeping and keep a eye on it. 

Edited July 17, 2019 by steve remick

[JLBKY]

Replace it with a dual M.C. and be done with it..................not to mention a whole lot safer.

Your car, your money.

JB

[Rob Dudley]

On ‎7‎/‎17‎/‎2019 at 7:57 AM, steve remick said:

So Rob, have you had this problem on your Avanti?  And what you’re saying is just to put up with the seeping and keep a eye on it. 

That is what I do. Others will tell you to replace the master cyl. with a dual and others will say to replace the whole system with a modern kit. All are good valid suggestions. Whatever you do remember that stopping is your most important system. It must be maintained no matter which way you go. 

Rob

[steve remick]

Good advice!!  I want to keep it as original as possible....Thanks again Rob!!

[8 EYR]

If something in the brake system is dragging, it can cause the fluid to heat up (even boil) and cause a leak like this from the top of the master cylinder. No gasket will keep it from seeping until the drag is eliminated. Not saying this is what is happening with yours, but I know it can cause this problem, especially in single circuit M/Cs.