Brake pedal is solid as a rock

[timothyr]

Okay, I am new to this party, and after searching could not find an answer that would solve my problem. Today I purchased a 94 Q45 with 140k on the clock, in perfect condition except for one item (kind of major)...the brakes.I do all of my own maintenance and service on all my cars but have never owned a nissan product and figured ask before tearing into it.Long story short the brake pedal is hard as a rock...you can make it stop, but initial pedal travel feels like it is about 2 inches, then it feels like you are pushing through the floor and then you can feel the brakes actually engage. Stand on it and you can hustle it down from speed, but there is no way you could ever engage the ABS. From my initial inspection the master cylinder, booster and abs pump all look like thery have been replaced very recently, fluid is full and pads are at about 50% all around. Nonw of the calipers are dragging, and the emergency brake hold fine. I have not blead the system out, but honestly I have never felt an air bubble in a system act like this...it literally feels like there is no pressure.Another symptom that seemed odd is when you are at a stop applying enough pressure to hold the car you can hear what sounds like a vaccuum leak..it sounds like it is coming from under the dash and its level of intensity is directly related to how hard you push on the pedal (the harder you press the more air it sounds like is escaping). Checked the line going from the manifold to the booster and it looked good....is there something I am missing? for some reason I am thinking it is related to the ABS system, but I have absolutly nothing to base this on.

Please help.

[Q451990]

The air under the dash noise sure sounds like the brake booster. They very rarely fail, but it's possible. What you're describing doesn't sound familiar at all...

Do you have the FSM (factory service manual) for the car? If not, I would download it at http://www.nicoclub.com/FSM/Q45

Welceom to NICO!

Heath

[Q45tech]

"94 Q45 with 140k on the clock, in perfect condition except for one item (kind of major)...the brakes."

As far as you currently are aware of, however experience in dealing with thousands has proven that every used 19 to 13 year old Q 45 needs at least $3,000* in repairs to return every system to near new functioning condition.

Probably a bad master cylinder from lack of mainteance also check to make sure vacuum line from booster to plenum and one way check valve is functioning.

* We constantly see new used [90-96] owners who present perfect Q in need of $3,000 to $10,000 in repairs [at $85/hr + MSRP parts]. WE always keep smelling salts at the ready.

Does it have Traction Control?

[timothyr]

Q45tech - Dont put me in a league with the average joe...Last time one of my cars saw a mechanic was about 13 years ago when I lost a transmission almost 700 miles from home. I dont mind spending some time and change when you consider the condition the car is in and what I got it for (less than a set of cheap 15" tires) What I was really hunting for was if there was a common weak link that might save me some time trouble shooting. I will go through the FSM tonight and see if anything raises a flag.

Q451990 - thanks for the link...it will become tonights reading; from past experience I am thinking brake booster as well, but figured ask as maybe there was something prone to failure and someone would say "oh that problem again"

[Q451990]

Q451990 - thanks for the link...it will become tonights reading; from past experience I am thinking brake booster as well, but figured ask as maybe there was something prone to failure and someone would say "oh that problem again"

Glad I could help. Sadly, this doesn't sound like a common problem... there are plenty, but this isn't one of them. Good luck and please let us know what it ends up being!

Heath

[Q45tech]

"Q45tech - Dont put me in a league with the average joe"

Why I speced the way I calculated expenses: $85 an hour amd MSRP parts.

Most know that MSRP parts are 55-60% of bill so $3,000 is at least $1200 in $85/hr labor..............~~~ 14-15 hours by a trained experienced technican who works on your year model EVERY WEEK.

Personally I ALWAYS PAY someone else to work on my Q [sure I do the trouble shooting] but when it comes to changing anything more than an electronic module, fuse, or sensor, I PAY a trained technican. I may ohm my injectors or R and R a spare rail with injectors but the actual work is always done with me just supervising.

I ONLY ENJOY THE MENTAL DIAGNOSIS not the physical labor..........at 61 my back cannot tolerate the bending.

[timothyr]

Didn't mean to comm off like an @$$...sorry.at this point I still enjoy the physical labor; I think at the end of the day I have had one too many dealerships "forget" something or have the one problem leads to another. My view has kinda become if it breaks after I work on it I can blame myself; if there was a shortcut taken I will know where, both of there will give me insight to future problem resolution...if it breaks after someone else works on it all I can do is get pissed off and call a tow truck......or start the whole process all over myself.

I think I have trust issues, at any rate everything else on the car seems to prove out fine; from the look of it the previoous owner has spent a ton going the "dealer maintenance" route

[Q45tech]

During the first 100k I spent $7,000 going the dealer route, The next 40K cost me $8,000 for things the dealer didn't attend to - at T3 prices which were as low as $45 per hour back before 2000.

A ton of systems just wore out just after 100k, luckily many were upgraded in 1994 models so no ABS, master cylinder, drive shaft, speedometer.

Watch out for HVAC system fans [2] and compressor/dryerInjectors, radiator, fuel pump, differential, brake calipers and flex hoses, kingpin bearings, suspension components and everything rubber isolated, shocks, wheel bearings, inner and outer tie rod ends, transmission and rack mounts, engine mounts, rear diff mounts and rear subframe.Transmission [140k is not the problem but 15 years is].

I am a stickler for perfect oem brakes and tire radial force balancing so I spent a bit extra keeping every vibration supressed and quiver free since my clients were paying by the mile.

[timothyr]

the story behind the car goes omething like this...the PO spent close to 8K over the last year on it (complete AC system, injectors & fuel pump, trans rebuild, MC & ABS pump etc)..I just found reciepts in the spare tire well...he said he had a ton of work done to it; Then the brake system started acting up...he had an appt to get it checked out and thought it should be covered based on the other work, but he was rear ended before he got the car in The dealer quoted close to $2500 to repair, and he has a $1k deductable....he was fed up and just wanted out....after inspecting the car (and discovering that majority of the damage was cosmetic to the trunk lid and bumper) I talked him down to $350; by shear coincidence I had notice an identical colored Q hit from the front sitting in the bone yard 2 days earlier. The replacement parts went on the car no problem and match perfect.

I guess when I meant perfect it was more like totally manageable =)

I am still happy...it goes like hell, and is wonderfully smooth; I now realize why I liked them so much when I test drove a new one in 92...truly a drivers car, glad I didnt buy one then, but am sure I will enjoy it now.

Noow I just need to make it stop...new booster going in this afternoon...all things are pointing to it.

[Q451990]

Sounds like the nicest $350 Q ever... you should post pictures

Heath

[timothyr]

will do in the next day or so