90s MarkVIIs Brake Pedal Crackling?

T

Taurus90

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Hello!
As a new member of this forum immediately I've got a question:
As I drove last days a 1990 Mark VII LSC (want to buy that car) I've mentioned that there's some "crackling in the brake pedal" when starting the car. I think it was two times (each crackling was with a small declining of the pedal to the floor) until the engine was running.
Is this a fault or "normal"?
Hope that someone could help me.
Thanks!
 
Doesn't sound normal to me. The Mark VII are notorious for ABS problems. How many miles are on this car?!
 
Hi!
The Odometer reads around 58000 Mls.
I've to make clear, that I noticed no crackling when driving the car but only when starting the engine.
Would you explain which were the notoriuos problems with the VII's ABS?
Thanks!
 
Can you please define crackling some more... there are many issues with the brake master cylinders etc.

Sometimes it would cause the pedal to just sink to the flow without pressure.
 
maxmk8 said:
Can you please define crackling some more...
Click to expand...

Will try ...
When I turn the ignition key then I notice a noise (think it comes from somewhere around the brake pedal) that sounds like breaking a small perch away. At the same time the pedal wents some millimeters to the floor. Til engine is running this effect appeared two times I think. When driving the car, and braking, I havn't noticed the effect.
Should I notice that I have my foot on the brake pedal every time when starting the car?
Brake pedal travelling towards the floor when staring the engine I know from our Nissan Maxima - I think it's the brake booster which is activated when engine is running only. But with the Nissan there's no crackling ...
 
Oh got it... I don't know why you are keeping your foot on the brake while starting the car. But I would think that what is occuring is normal due to the vacuum building up and assisting the brakes. I would just try and use some WD 40 on the bushings of the brake pedal to alleviate some of that sound.
 
First off.....the LSC might not even have ABS, but it sounds like what is happening is your ABS pump is performing its NORMAL test cycle on the vehicle start up. It should do this when you first turn the key on also.

Basically what it will do is "pulse" the pump, which you can feel/see in the brake pedal, and after it performs this pulse, if it detects any failures your ABS light will come on.

Ok...just checked the AllData, these come with the VERY HIGH PRESSURE gas charged style ABS pump. It is normal for them to run on initial start up/key cycle to "charge" the system. Here is some info....

***The electric high-pressure pump, Fig. 3, runs for short periods to charge the hydraulic accumulator which supplies the service brake system.The accumulator, Fig. 4, is a gas filled pressure chamber which is part of the pump and motor assembly. The entire assembly is shock-mounted to the master cylinder and booster.

NOTE: If pump motor runs continuously for 20 minutes, a thermal safety switch (located in the motor) will shut motor off. A 2 to 10 minute cool-down is typical before operation can resume.***

You should be just fine. :D
 
Jesse all Mark VII's had ABS, they were very advanced cars for their time... kinda like the Mark

"The Mark VII was the first American vehicle with electronic 4-channel anti-lock brakes (November 1984, 6 months before the Corvette). It was also the first American vehicle with composite headlights."
 
I found that out d00d...didn't you read my post? :D After I saw a picture of that stupid gas "pod" I remembered how much of a pain the ABS systems are to work on, and remembered my neighbor changing his and having that gas "pod" blow off, dent his hood and shoot brake fluid in his face. :(
 
Taurus90 said:
Hello!
As a new member of this forum immediately I've got a question:
As I drove last days a 1990 Mark VII LSC (want to buy that car) I've mentioned that there's some "crackling in the brake pedal" when starting the car. I think it was two times (each crackling was with a small declining of the pedal to the floor) until the engine was running.
Is this a fault or "normal"?
Hope that someone could help me.
Thanks!
Click to expand...
This is normal on start up.
You may be mistaking the air spring compressor or the brake pump as a crackling sound. It's one of those things that you need a Lincoln Mark VII owner to listen to for you.

Once the engine is running, if the pedal is spongy or travels to the floor then there is a problem with fluid or pressure loss.

If the pedal is hard and travels only one to two inches then there may be a problem with the accumulator.

It's June ... have you bought the car? We hope so.

J said:
I found that out d00d...didn't you read my post? After I saw a picture of that stupid gas "pod" I remembered how much of a pain the ABS systems are to work on, and remembered my neighbor changing his and having that gas "pod" blow off, dent his hood and shoot brake fluid in his face.
Click to expand...
Once you know what the system is supposed to do, then working on them becomes easy. For an example, read this article.

http://www.thelincolnmarkviiclub.org/tech/brakeAccumulator.pdf
 
J said:
After I saw a picture of that stupid gas "pod" I remembered how much of a pain the ABS systems are to work on, and remembered my neighbor changing his and having that gas "pod" blow off, dent his hood and shoot brake fluid in his face. :(
Click to expand...

He's lucky that's all that happened.. The big warning label is there for a reason! The brake fluid in that accumulator is pressurized to ~2500 psi, which is enough to cause what's called a "hydraulic injection injury". 'Nuff said.

Anyway, I had a '88 T-Bird Turbo Coupe with the same ABS system. The 'clack' and slight pedal drop after startup is perfectly normal.

The only problem I had with that braking system was actually caused by Ford's crappy 1980s ignition switch design. Mine (which was the "improved" version replaced under recall) melted down and cut power to the pump. There's enough reserve pressure for a few stops. But after that you end up with not only no power assist, but NO rear brake pressure and only partial pressure to the fronts. The ABS light will come on to warn you that pressure is low, and when it gets really low the brake light will come on as well. So if you ever see those lights turn on, make sure you have a lot of room to stop.
 
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