[Francesko35oZ]

hello.i am working on an nissan 350z.i am dealing with some brake issues the pedal is too spongy, i changed the master cylinder due to pressure loss and after installing the new one the brakes worked perfectly and after 3 days the pedal was spongy again.i bleeded the brakes again and the pedal was on top again.but every 3 days the pedal is spongy again.it has no leaks.can anybody help me?

 

[dkmura]

I'll try to help. First, what kind of brake bleeding system are you using? What type of brake fluid?

In general, if the brakes continue to get spongy, there's some type of leak in the system that you'll need to find. What are the condition of the bleed nipples on all four corners? Have you checked the main seals on the calipers?

 

[Francesko35oZ]

I'll try to help. First, what kind of brake bleeding system are you using? What type of brake fluid?

In general, if the brakes continue to get spongy, there's some type of leak in the system that you'll need to find. What are the condition of the bleed nipples on all four corners? Have you checked the main seals on the calipers?

i'm not using an vacum bleeder.all the nipples and seals are in good conditions.but can the brake booster cause this problem?

 

[dkmura]

i'm not using an vacum bleeder.all the nipples and seals are in good conditions.but can the brake booster cause this problem?

If the brake booster has an internal leak, than yes, that could be the source of your problem. How many miles are on your Z?

 

[Francesko35oZ]

If the brake booster has an internal leak, than yes, that could be the source of your problem. How many miles are on your Z?

55,000km its brand new😅

 

[dkmura]

55,000km its brand new😅

Not sure what you're saying- do you mean the car has 55K km, and you changed the brake booster as well as the brake master?

 

[Francesko35oZ]

Not sure what you're saying- do you mean the car has 55K km, and you changed the brake booster as well as the brake master?

yes

 

[Francesko35oZ]

yes

but the car was drowned one time

 

[dkmura]

Sheesh-

but the car was drowned one time

That would have been a critical fact that should've been mentioned in post #1. Perhaps you could mention how long ago this flood happened and what the circumstances were. Sheesh...

 

[Francesko35oZ]

Sheesh-

That would have been a critical fact that should've been mentioned in post #1. Perhaps you could mention how long ago this flood happened and what the circumstances were. Sheesh...

so should i check the brake booster?

 

[dkmura]

so should i check the brake booster?

No, first you should tell us why, how and when this Z was flooded. Next, how did you determine which parts should be replaced?

Without accurate background information, it's impossible to make any realistic suggestions.

 

[Francesko35oZ]

No, first you should tell us why, how and when this Z was flooded. Next, how did you determine which parts should be replaced?

Without accurate background information, it's impossible to make any realistic suggestions.

so it was flooded 6 years ago.we fixed it and the car runs and drives perfectly but i have only the brake problem.when pressing the brake pedal the engine rpm drops a little bit and when i relese it's ok

 

[dkmura]

so it was flooded 6 years ago.we fixed it and the car runs and drives perfectly but i have only the brake problem.when pressing the brake pedal the engine rpm drops a little bit and when i relese it's ok

So the car had NO brake problems for the past six years after being fixed? Did the spongy brakes just crop up recently? Are we talking about a manual or auto tranny?

 

[Francesko35oZ]

So the car had NO brake problems for the past six years after being fixed? Did the spongy brakes just crop up recently? Are we talking about a manual or auto tranny?

manual trans and the problem was there for 2-3years but the car was used as a weekend car it could go out only 2-3 times a month

 

[dkmura]

What I hear you saying is that this brake problem may have always been there since it was driven very little. That's a problem with a flooded car. Was the car completely under water, or was it only partially submerged?

BTW- engine revs should drop slightly when you apply the brakes. That's normal. With the clutch connected to the driveline, any brake use will drop the revs a bit.

 

[Francesko35oZ]

What I hear you saying is that this brake problem may have always been there since it was driven very little. That's a problem with a flooded car. Was the car completely under water, or was it only partially submerged?

BTW- engine revs should drop slightly when you apply the brakes. That's normal. With the clutch connected to the driveline, any brake use will drop the revs a bit.

the car was under water.so what do you suggest to check?

 

[dkmura]

If this Z was actually submerged, you could have water stuck anywhere in the system. It's why flood cars are totaled and can be purchased cheaply. How many times have you performed a full four wheel brake bleed? I'd suggest using a hydraulic brake bleeder to move a lot of old brake fluid out of all the lines.

 

[Francesko35oZ]

If this Z was actually submerged, you could have water stuck anywhere in the system. It's why flood cars are totaled and can be purchased cheaply. How many times have you performed a full four wheel brake bleed? I'd suggest using a hydraulic brake bleeder to move a lot of old brake fluid out of all the lines.

but how is it possible when i bleed the brakes only right front it bleeds a lot of air

 

[Francesko35oZ]

If this Z was actually submerged, you could have water stuck anywhere in the system. It's why flood cars are totaled and can be purchased cheaply. How many times have you performed a full four wheel brake bleed? I'd suggest using a hydraulic brake bleeder to move a lot of old brake fluid out of all the lines.

i've asked around and they say me that is the brake booster fault but it makes no sense

 

[dkmura]

but how is it possible when i bleed the brakes only right front it bleeds a lot of air

If you're finding ONLY the RF is leaking after a four-wheel bleed, check the hard line for cracks and consider the caliper and/or seals as being suspect.
Are you doing this brake assessment, or are you using a trained technician?