Brakes Locked On

[Lukas]

Okeydokey,

The remaining thing preventing me from going for a little drive is the fact that my brakes are locked on. This is regular brake, not park brake.

History: The car has not been driven for approx 15 years. Lukas knows very little about braking system maintenance.

Previous owner said that when the brakes were applied, they locked on, and then released a few days later. This time they have been locked for about a week at least. When I try to drive it, the back of the car squats as I apply the juice, but no forward motion ensues.

Brake fluid reservoir level looks good, fluid is a greenish colour, which I take to mean un-contaminated. Brake lines + hoses seem find from what I've seen, and no visible leaks anywhere.

Suggestions please.

I'm guessing I should do a fluid change - any tips? Have not done one before, so trawled the www for howtos. Found a nice PDF guide from PBR. Have found nothing specific to 116s - even the handbook just says "bleed the brakes".

Anything else likely to require replacement or refurbishment?

Recommendations for brake fluid types / makes?

How much brake fluid is required?

Obviously I want to get this right - if the engine dies only I get inconvenienced (probably), if the brakes go.....

Ta

Lukas

 

[abl567]

Chances are the pistons are seized in the calipers or the rubber brake lines have perished and swollen internally restricting the return flow of fluid.

Lift it up on stands and try and rotate all 4 wheels to determine which ones are seized and remove the brake line from the caliper carefully, if the hose is blocked the fluid may be under pressure.

If releasing the fluid frees up the caliper things are looking better but for a car that has not been driven for 15 years I'd be a little uncomfortable driving very far at all without new hoses and slave and master cylinder seals at the very least.

 

[WGB]

If no wheels rotate it will be a master cylinder problem.

If it is only the rear make sure the handbrake cables haven't rusted internally with the handbrake applied - this usually happens to the left hand handbrake because it runs over the exhaust and the plastic coating on this one goes first.

Bill

 

[Styria]

Hi Lukas, I'll second everything that abl567 and WGB have suggested to be the source of your problems.

First, you will need to ditch ALL of your brake hoses - with the car jacked up, determine which brakes are locked on. Then undo the flexible brake hose to any wheel that may be locked up. If, after you have loosened each flexible brake line, you can then turn the wheel, it's time to replace the flexible hose.

Personally, I doubt if that would be your only problem. I tend to think that each caliper should be re-kitted, assuming of course, that the pistons are not rusted nor pitted.

Once you have new hoses and re-kitted calipers, take stock of the situation and pay some attention to the handbrake cables. As WGB infers, the cables can seize. However, once you know that the hydraulics are right, it's easy to determine the mechanical condition. That's for starters - then endeavour to drive the car and observe operation of brake cylinder and/or servo unit. Bear in mind that it is best to purchase Master Cylinder new as they do not lend themselves readily for reconditioning. Regards Styria

 

[s class]

A W116 master cylinder at the agents costs about 30% more than a M/C seal kit, and is DEFINATELY the preferable route.

 

[Lukas]

Thanks all for the advice.

Agree that the brake system is not somewhere to scrimp and save, so have asked MBSpares for pricing and availability of all the rubber brake lines. Had also asked for the master cylinder seals, but will change that to the whole master cylinder. Turns out the car does move (very slowly) if you really put your foot down, but obviously there is something jamming somewhere.

Had not occurred to me to try rotating all the wheels (iot does now seem obvious), so will try that while doing the hoses.

Park brake operates fine from the "pulling the handle" perspective, but that doesn't of course mean it's working at the other end. However, I am led to believe that the car was stored with the park brake disengaged. Will pay attention to that too next weekend.

Few more questions:

* Brake fluid - any DOT4 fluid is OK?

* How do I dispose of the old brake fluid?

* Pulling all the hoses off will no doubt introduce air to the brake system - I take this is removed by essentially the same method as a regular brake bleed?

 

[SELfor50]

Thanks all for the advice.

Agree that the brake system is not somewhere to scrimp and save, so have asked MBSpares for pricing and availability of all the rubber brake lines. Had also asked for the master cylinder seals, but will change that to the whole master cylinder. Turns out the car does move (very slowly) if you really put your foot down, but obviously there is something jamming somewhere.

Had not occurred to me to try rotating all the wheels (iot does now seem obvious), so will try that while doing the hoses.

Park brake operates fine from the "pulling the handle" perspective, but that doesn't of course mean it's working at the other end. However, I am led to believe that the car was stored with the park brake disengaged. Will pay attention to that too next weekend.

Few more questions:

* Brake fluid - any DOT4 fluid is OK?

* How do I dispose of the old brake fluid?

* Pulling all the hoses off will no doubt introduce air to the brake system - I take this is removed by essentially the same method as a regular brake bleed?

Hey Dude,

Tell ya what, if you want I can drop round on Saturday to give you a hand?? The park brake is lever / spring operated so would be un-related to the calipers... (I think, someone correct me if i'm wrong)

Disposal of the brake fluid? Do you have any surfaces that need cleaning? Maybe a garage floor with oil on it? Just poor it on that and scrub...

If you need to strip any paint, this is also great!

 

[John S]

It's good that brake fluid is so easily miscible with water.

 

[Lukas]

Hi Cam,

Have already lined up an assistant for the brake surgery, but thanks for the offer regardless. Am also still waiting on brake bits. Wonder if the brake fluid will remove the funny stains left on my driveway by the rust converter?

Lukas

 

[SELfor50]

Hi Cam,

Have already lined up an assistant for the brake surgery, but thanks for the offer regardless. Am also still waiting on brake bits. Wonder if the brake fluid will remove the funny stains left on my driveway by the rust converter?

Lukas

No worries mate... Not sure bout the rust converter stuff, maybe.

Are you getting a new master cylinder? If so, how much is a new one if you don't mind me asking? I have a very good 2nd hand one I ripped of ol' smokey.... contemplating a brand new one though.

Cam

 

[Lukas]

New one was $171.00 or so from MBSpares - good deal I'm told.

 

[SELfor50]

New one was $171.00 or so from MBSpares - good deal I'm told.

That's a pretty good price!

 

[Styria]

Hi Lukas, the only way to go Master Cylinder wise. Regards Styria

N>B> Althouigh changing it is unlikely to solve what I think are other problems.

 

[John S]

Someone mentioned it earlier, but normally the brakes locking on and taking a day or so to release, the back end squatting etc indicates rear brake hoses having deteriated and blocked.