Bad master cylinder cap/gasket?
#1
Supreme Member
Thread Starter
Join Date: Apr 2017
Location: Northern NY
Posts: 1,116
Received 401 Likes
on
314 Posts
Car: 1988 Trans Am GTA
Engine: 5.7 L98
Transmission: 700r4
Axle/Gears: Borg Warner 9 bolt 3.27
Bad master cylinder cap/gasket?
I have an 88’ GTA with 4 wheel discs and noticed that when you press the middle of the master cylinder reservoir cap I can hear air escaping or coming in, almost like its pushing air out?
The brakes work great, firm pedal and are not leaking anywhere including around the master cylinder. I even double checked that the cap gasket was on and seated correct.
The only thing I can think is the cap gasket may be worn out???
I just find it odd that it makes that noise. Also I really hate that design, the cap that the later cars have is much better.
The brakes work great, firm pedal and are not leaking anywhere including around the master cylinder. I even double checked that the cap gasket was on and seated correct.
The only thing I can think is the cap gasket may be worn out???
I just find it odd that it makes that noise. Also I really hate that design, the cap that the later cars have is much better.
Last edited by Reddragon88gta; 04-16-2023 at 11:19 PM.
#2
Supreme Member
Thread Starter
Join Date: Apr 2017
Location: Northern NY
Posts: 1,116
Received 401 Likes
on
314 Posts
Car: 1988 Trans Am GTA
Engine: 5.7 L98
Transmission: 700r4
Axle/Gears: Borg Warner 9 bolt 3.27
Re: Bad master cylinder cap/gasket?
I looked at it further tonight, the air noise is coming only from the back of the plastic cap pointing to the firewall. There is no noise in the front.
#3
Supreme Member
Thread Starter
Join Date: Apr 2017
Location: Northern NY
Posts: 1,116
Received 401 Likes
on
314 Posts
Car: 1988 Trans Am GTA
Engine: 5.7 L98
Transmission: 700r4
Axle/Gears: Borg Warner 9 bolt 3.27
Re: Bad master cylinder cap/gasket?
Did some more with it and tried a different MC cap I had lying around and a new gasket. Still the sound persists so I went with the new gasket and old cap.
At this point I will assume it’s normal as brakes work great etc.
At this point I will assume it’s normal as brakes work great etc.
#4
Supreme Member
Join Date: Jun 2015
Location: Austin, TX
Posts: 1,920
Received 176 Likes
on
135 Posts
Car: 90 Formula / T-tops
Engine: 305 TPI
Transmission: MD8
Re: Bad master cylinder cap/gasket?
that doesnt "sound" right. pardon the pun. if air get out, air get in. air has moisture, not good for brake fluid or brake lines. last I checked, they had exact replacement gaskets at rockauto and elsewhere.
#5
Supreme Member
Thread Starter
Join Date: Apr 2017
Location: Northern NY
Posts: 1,116
Received 401 Likes
on
314 Posts
Car: 1988 Trans Am GTA
Engine: 5.7 L98
Transmission: 700r4
Axle/Gears: Borg Warner 9 bolt 3.27
Re: Bad master cylinder cap/gasket?
#6
Supreme Member
Join Date: Jun 2015
Location: Austin, TX
Posts: 1,920
Received 176 Likes
on
135 Posts
Car: 90 Formula / T-tops
Engine: 305 TPI
Transmission: MD8
Re: Bad master cylinder cap/gasket?
ya man, I dunno. I'll try to check mine if I think of it. maybe you can put your hand back there and see if you can determine where it comes from. or push down on cap and see if noise goes away.
someone around here mentioned about DOT2 brake fluid in a post, they had a 90 or newer. I wanted to tell them there cap should say DOT3 on it, but cant find the post.
someone around here mentioned about DOT2 brake fluid in a post, they had a 90 or newer. I wanted to tell them there cap should say DOT3 on it, but cant find the post.
#7
Supreme Member
Thread Starter
Join Date: Apr 2017
Location: Northern NY
Posts: 1,116
Received 401 Likes
on
314 Posts
Car: 1988 Trans Am GTA
Engine: 5.7 L98
Transmission: 700r4
Axle/Gears: Borg Warner 9 bolt 3.27
Re: Bad master cylinder cap/gasket?
ya man, I dunno. I'll try to check mine if I think of it. maybe you can put your hand back there and see if you can determine where it comes from. or push down on cap and see if noise goes away.
someone around here mentioned about DOT2 brake fluid in a post, they had a 90 or newer. I wanted to tell them there cap should say DOT3 on it, but cant find the post.
someone around here mentioned about DOT2 brake fluid in a post, they had a 90 or newer. I wanted to tell them there cap should say DOT3 on it, but cant find the post.
Thread
Thread Starter
Forum
Replies
Last Post