Brake booster/master cylinder issue - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

BFever · 06-15-2018, 03:20 PM

Yesterday I did a boost, and vacuum test on my 97 with a s13 sr swap and found that I'm leak air somewhere maybe between the booster and master cylinder. I have been doing some researching and found that normally when this happens it's the booster that's bad. I have been noticing that my brake pedal feel has been iffy since I got the car, but just never put the two idea together. I'm just curious if there is something I'm missing or someone with better knowledge with the issue could help me with. If it helps the car was originally auto so it has the larger brake booster.

Also to be noted I could my vacuum line running to the booster does not have the check valve installed so I'm curious if that could also be part of the issue.

Thanks in advance
Ben

Kingtal0n · 06-19-2018, 12:38 PM

Yeah you definitely need a check valve in there. Get that on then go from there

dbeiler · 06-19-2018, 05:25 PM

Brake boosters do fail occasionally. My dual diaphragm S14 booster failed several months ago. It started running lean and adding fuel to the trims whenever I stepped on the brake pedal. Eventually it failed to the point where I lost all power brake assist and the engine would stall out when I hit the brake pedal.

You should definitely install the check valve in the booster line. It's intended to keep a small safety supply of vacuum in the booster in the event of an engine stallout. It will also keep positive boost pressure from entering the booster.

Here's what happened to my booster. The rubber diaphragm tore and created a huge air leak.

06-15-2018, 03:20 PM	#1
BFever Join Date: Jun 2016 Location: Minot, ND Age: 35 Posts: 6 Trader Rating: (0) Feedback Score: 0 reviews	Brake booster/master cylinder issue Yesterday I did a boost, and vacuum test on my 97 with a s13 sr swap and found that I'm leak air somewhere maybe between the booster and master cylinder. I have been doing some researching and found that normally when this happens it's the booster that's bad. I have been noticing that my brake pedal feel has been iffy since I got the car, but just never put the two idea together. I'm just curious if there is something I'm missing or someone with better knowledge with the issue could help me with. If it helps the car was originally auto so it has the larger brake booster. Also to be noted I could my vacuum line running to the booster does not have the check valve installed so I'm curious if that could also be part of the issue. Thanks in advance Ben

06-19-2018, 12:38 PM	#2
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	Yeah you definitely need a check valve in there. Get that on then go from there

06-19-2018, 05:25 PM	#3
dbeiler Zilvia Junkie Join Date: Jun 2012 Location: Lancaster county, PA Age: 33 Posts: 465 Trader Rating: (4) Feedback Score: 4 reviews	Brake boosters do fail occasionally. My dual diaphragm S14 booster failed several months ago. It started running lean and adding fuel to the trims whenever I stepped on the brake pedal. Eventually it failed to the point where I lost all power brake assist and the engine would stall out when I hit the brake pedal. You should definitely install the check valve in the booster line. It's intended to keep a small safety supply of vacuum in the booster in the event of an engine stallout. It will also keep positive boost pressure from entering the booster. Here's what happened to my booster. The rubber diaphragm tore and created a huge air leak.