MC Question

James Fischer

James Fischer

PCS Member
Ok,so my mechanic is installing the master cylinder that was original to the 70 Cadillac Rescuer,(after being rebuilt by a local shop).....he called this morning saying that after securing the 2 bolts,there seems to be a small leak...he seems to think that there is/was a small "o"ring or small bushing that is supposed to go on also ??

I advised him that I will ask the experts...sooooo...can anyone confirm that there is supposed to be a bushing,0 ring ,washer etc on the end of the mc before being mounted ??
Any info would be greatly appreciated !!:thumbsup:

I have looked in the 70 Cad service manual and it does NOT show anything ..other then the inner workings of the mc....
 
M/Cyl

Ok,so my mechanic is installing the master cylinder that was original to the 70 Cadillac Rescuer,(after being rebuilt by a local shop).....he called this morning saying that after securing the 2 bolts,there seems to be a small leak...he seems to think that there is/was a small "o"ring or small bushing that is supposed to go on also ??

I advised him that I will ask the experts...sooooo...can anyone confirm that there is supposed to be a bushing,0 ring ,washer etc on the end of the mc before being mounted ??
Any info would be greatly appreciated !!

I have looked in the 70 Cad service manual and it does NOT show anything ..other then the inner workings of the mc....
__________________
Click to expand...

Some had a small felt washer ,but that was just a dirt /dust seal . If it was rebuilt correctly nothing should be leaking by the master cylinder piston and out the back.
 
Your 1970 is the same as my 1969, and there is no "O" ring in the master cylinder. If it is leaking, then the cylinder bore might be damage with rust pits. Did you have it re-sleeved? If not, then you should. Also, if the person that rebuilt it didn't do it right, then it will also leak.
 
OK

Paul Steinberg said:
Your 1970 is the same as my 1969, and there is no "O" ring in the master cylinder. If it is leaking, then the cylinder bore might be damage with rust pits. Did you have it re-sleeved? If not, then you should. Also, if the person that rebuilt it didn't do it right, then it will also leak.
Click to expand...

Thank you Paul,
I specifically asked them to see if it needs to be re-sleeved,when they were rebuilding it..the answer was NO..it was fine and did not need it(I was a bit surprised as this shop loves to charge for every little item they can)...
I will be going over to the mechanic Monday AM just to see what he is talking about....I will take a copy of your and Daniel's reply with me..:)
 
After 40 years, I haven't seen many that didn't need to be re-sleeed. I like the brass sleeve, since it doesn't move like the stainless steel units. I am doing one presently for another member, and it is out being sleeved now, and when it comes back, I will reassemble and send it home.
 
Update

Went over to the shop this morning to see the issues...

The MC is mounted and functioning,however there is a "leak" with a hissing noise coming from the area a ?....the engine stalls a bit at times....mechanic seems to think it may be something with the hydraulics inside the diaphragm,perhaps a vacuum seal or check valve issue..?:rolleyes:

any thoughts or suggestions..?
 
From your description it sounds like there is a problem with the booster and not the master cylinder. Some noise is acceptable from it when the pedal is depressed but stalling is not, possibly a diaphragm leak in the booster.

Whatever, do NOT try to dissasemble the booster yourself. There is a large spring under tension which will decompress when the two halves of the booster are taken apart. Getting a mouthful of booster shell and spring will ruin your day.
 
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