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07 D40 2.5 Brake Booster

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roscoe07

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There is not a lot on the forum regarding Brake Boosters as i suppose they rarely play up. The symptons i have are i apply the brakes and work ok. I might get a second pump but after that the pedal goes hard and and l am looking for an exit strategy with both feet on the pedal. Cars done 290k so i figure the booster is gone. Am i right? BTW pulled the vacuuum hose at the booster and have good vacuum. TIA
 

roscoe07

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I also hear a hiiss under dash when i let the pedal off.
 
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Old.Tony

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The only other thing that I can think of that could be leaking is the (rare) chance that the vacuum diaphragm in the brake booster has given up the ghost. If you get a new piece of hose (because I don't recommend putting an old piece in your mouth!) on the brake booster and suck on the other end, you SHOULD only be able to draw a certain amount in (unless you're Debbie from Dallas, in which case you should be able to make the car disappear). If you can continue to draw through the tube, the diaphgram is leaking.

Unfortunately, it's a rare problem that I've not experienced myself and cannot guide you further other than to say it may be worth considering either trying to disassemble it yourself if you feel a little mechanically-minded or contact a wrecker and see if they will part with one for less than your first-born (which is likely close to the price Nissan will charge).
 

Scuba Steve

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I have 2008 Navara with the same issue slight hissing noise when the brake pedal is in the off position. I have spoken to brake specialist and they say it the rear seal of the brake booster diaphragm that has failed. When the peddle has slight pressure the noise goes away. Brakes till work fine for a Navara. Navara brakes have always been crap. I did adjust my rear load sensing vale up tighter and the brake work much better. My Navara has a 2 inch lift. You can get reco brake booster but they are really expensive and a new booster is worth thousands.
 

roscoe07

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Thank you all for your replys. I bought a secondhand booster which had a master cylinder on it. I then changed it over noting that my brake fluid was half gone. Found it inside the booster. so replaced both booster and master with the secondhand one. Bled all the brakes until no air. Well its no better than it was. Still hard pedal and if you keep pushing it will go to floor. I have vacuum on it as there is an audible hiss when vacuum hose removed from booster. So i think the next thing is take it to a brake place. I am out of ideas.
P.S. the booster i got had 550 in pen on the back. Only differnce i could see is the firewall bolts are shorter on this booster than the old one. Also the brake pipes on the master have a larger thread so i bought adapters to fit the brake pipes on my car. Otherwise identical. Thoughts?
 

roscoe07

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Discount the pedal going to floor. Had a leak. Just took it for a drive. You get one application of the brakes and then goes hard. Same as before. I think losing vacuum. Will check all the pipes.
 

landmannnn

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It could be the non return valve. Worth buying a brake vacuum tester, not expensive, certainly cheaper than going to a garage.
 

Scuba Steve

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First you thing to remember is that you are fitting second hand parts and they could be faulty. Also brakes should be looked at by a licensed mechanic.

Brake basics are:
a. Hard brake pedal means lack of book booster lack of vacuum or broken brake booster diaphragm. To check booster switch motor off push brake pedal up and down a few times to the pedal is hard and all vacuum has been expelled from the booster. Leave you foot on the brake pedal start the car, the pedal should sink further down when there is vacuum applied from the engine to the booster.
b.Brake pedal sinking to the floor means brake fluid leak or fluid by passing in brake master cylinder. Visually check for fluid leaks if no fault found it will be by passing in the second hand master cylinder.
 

roscoe07

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I did test (a) above and its fine.
I then went looking for Lack of Vacuum even though the finger over end of hose showed it was good. I made a T and put in vac line to booster. The vac gauge shows 28 in/hg which is perfect by the manual. Not bad for a 290k vac pump.
Repeated operations of the brake pedal showed the vac pump holding the vac no probs.

I get 1 pump of good brakes and maybe another half pump and then the pedal goes rock solid.

So now i am looking elswehere.

Would the ABS system be causing the problem. Has anybody had the valves lock closed because it feels like no fluid pressure is getting to wheels. Its so hard the retardation is negligible even using 2 feet. It like system locked. I tried to disconnect the ABS pump but not sure how to do it???
Any Ideas.
 

roscoe07

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Somthing more to think about. I have done all the brake work on this car since i bought new in 07. When bleeding the brakes yesterday i had to have the engine running to get any fluid out. Now i dont remember having to do this before.
 

pol327

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These are the brakes you are talking about. In the words of Enzo Ferrari "Any body can make a car go fast. However, it takes a genius to make it stop".

The problems you are describing here could be a number of issues, leaking booster, faulty vacuum pump, seized or sticking calipers, the ABS system either hydraulically or its electronic control system, internally collapsed brake hoses, blocked brake lines etc etc etc.

DO NOT play the 'home mechanic' with what could ultimately kill you or even worse some other poor individual who was in your path.

Take your car to a brake specialist and have it diagnosed and repaired ........ could it cost you?....... of course it could. But that's a sad fact of owning older vehicles, nothing lasts forever. Manufacture's don't make cars to last otherwise they would not sell new cars.

I am a mechanic and I hear people complain time and time again about the cost of maintaining motor vehicles. What really gets under my skin is the people will spend thousands and thousands of dollars on a new TV, an overseas holiday or renovate the kitchen and bathroom. BUT ..... when they have to spend $500 on their car for someone to repair it they claim they are being ripped off.

A word of advise ..... These forums are OK for general chat and sharing experiences. However, every person commenting and giving advise here could be held to count if something should go wrong. What you put out there stays there for the authorities to look at.
 

roscoe07

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Yep thats all well and good. BUT the manual shows a check valve for the Petrol engine. It does not show for the diesel hence i dont think it has a check valve.
There is a check valve in the diesels. Wish i could buy one. Need one in bayside brisbane.
 

roscoe07

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These are the brakes you are talking about. In the words of Enzo Ferrari "Any body can make a car go fast. However, it takes a genius to make it stop".

The problems you are describing here could be a number of issues, leaking booster, faulty vacuum pump, seized or sticking calipers, the ABS system either hydraulically or its electronic control system, internally collapsed brake hoses, blocked brake lines etc etc etc.

DO NOT play the 'home mechanic' with what could ultimately kill you or even worse some other poor individual who was in your path.

Take your car to a brake specialist and have it diagnosed and repaired ........ could it cost you?....... of course it could. But that's a sad fact of owning older vehicles, nothing lasts forever. Manufacture's don't make cars to last otherwise they would not sell new cars.

I am a mechanic and I hear people complain time and time again about the cost of maintaining motor vehicles. What really gets under my skin is the people will spend thousands and thousands of dollars on a new TV, an overseas holiday or renovate the kitchen and bathroom. BUT ..... when they have to spend $500 on their car for someone to repair it they claim they are being ripped off.

A word of advise ..... These forums are OK for general chat and sharing experiences. However, every person commenting and giving advise here could be held to count if something should go wrong. What you put out there stays there for the authorities to look at.
Thanks for your reply. I appreciate all comments. Just a side note. I am 66 yo and have been working on vehicles for over 50 years. I understand the mechanics of how stuff works. This car i have had since new and its got 290k on it. It has only been to a mechanic to get timing chain done. I dont do anything or drive the car in an unsafe condition.
 

izzibri@gmail.com

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could it be sticking pistons in your callipers eg not returning quick enough during each pump, i seem to recal my 1998 nissan having trouble , the synthetic
pistons had swelled. and also the square section rubber rings were gunked up
 

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