Master cylinder
Thread Starter
Instructor
Joined: Mar 2012
Posts: 177
Likes: 0
From: MISSISSAUGA ONTARIO
Master cylinder
I have had to replace the master cylinder on my 1974 L48 automatic twice in the past 8 years. This last time I went through three different ones to get one that actually worked. And it failed after about 3 months driving. I have now ordered one from Summit and hope that's more successful. Anyone else have this issue? Could it be a bad booster maybe. I replaced that about 6 years ago. Thanks.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
The booster is strictly an assist, so you can lock up all four with a pinky toe.
However, if someone put the wrong booster on or the wrong booster rod, (too long) it could have damaged the MC.
First, stick with Delco MC instead of an aftermarket. Then you will know it fits properly and the critical gap between booster rod and the MC piston is spot on.
How are you bench bleeding these MCs? You might be damaging the piston seals if done improperly.
Click on my profile > photo album > bleeding, for some tips.
However, if someone put the wrong booster on or the wrong booster rod, (too long) it could have damaged the MC.
First, stick with Delco MC instead of an aftermarket. Then you will know it fits properly and the critical gap between booster rod and the MC piston is spot on.
How are you bench bleeding these MCs? You might be damaging the piston seals if done improperly.
Click on my profile > photo album > bleeding, for some tips.
Last edited by HeadsU.P.; Jul 30, 2020 at 03:43 PM.
Le Mans Master
Joined: Aug 2005
Posts: 6,539
Likes: 1,972
From: Temple Terrace Florida
Consider having the M/C sleeved in stainless steel. I think Whites is still doing them. If after the sleeve is installed, and a rubber seal fails, a rebuild kit is very inexpensive and easy to install. Jerry
