Front caliper failure in 280 SE, next in a litany of continuing faults!

[carl888]

I don't know how you people are all going with your W116, but I can seriously say that my W116 is the worst car I've ever owned.  That it's one of the best to drive makes ownership all the more frustrating.  Here's a list of what been done to it since 2007 and 92,000 kms.  Now it's only done 109,000 kms.

-head gasket replaced
-water pump replaced
-rear brake calipers replaced
-brake hoses replaced
-exhaust "Y" piece welded three times
-replaced lower ball joints in front suspension
-replaced drag link
-replaced transmission selector rod bushes
-removed interior and re-fitted poorly fitted radio and wiring
-re-dyed centre console
-replaced firewall grommets (due again)
-replaced all fuel hoses including engine bay
-replaced all water/cooling/heating hoses
-adjusted heater flaps
-adjusted transmission modulation unit and control rod
-repaired faulty indicator stalk four times
-adjusted stiff drivers side window regulator
-replaced hood liner twice
-about to replace very noisy differential
-cold starting issue remains unresolved.

The above is in addition to the maintenance schedule which I do completely by the book.  And I haven't included items such as the Michelin XWXs and all the genuine parts that have gone into it.  Nightmare this car.

So the next thing to go wrong with this shit heap is a failure of the front braking circuit.  A fairly hard stop from about 30 km/h. Pedal goes almost to the floor, rear wheels lock almost immediately, fronts ineffective from then on!  What happened was the bore in the caliper just proud of the seal recess broke off. The result being the broken metal and the seal was blown out of the caliper and retained by the dust boot.

Brake fluid had been changed annually from purchase in 2007 but before then, I suspect the work performed didn't exactly correspond to what appeared on the invoice.  Last image shows the piston and evidence of corrosion sitting proud of the surface. I suspect it had just corroded to the bore and I'd just been pottering around and not noticed until a panic stop.














And here is what a good caliper should look like:






On the bench:




As you can imagine I've flipped with this car, so I just went straight out and bought a new master cylinder since that will probably shit itself next.  Thanks to robertD,  he's found me some rebuildable front calipers.  I've done the hoses and rear calipers when I bought the car.  Sigh, more work!!




Starting from the master cylinder, I was able to paint the discoloured lower section of the booster, no doubt due of a previous failure of the master cylinder, so I suppose that's a plus, as well as the top of the spring tower under the master cylinder.










There was a significant amount of crud in the bottom of the brake fluid reservoir but it cleaned up nicely. 




One item I am yet to source are the two small rubber grommets that anchor the contact for the low brake fluid warning lamp to the float, a close up appears in the second image below.  I haven't tried ATE as yet however the ones I removed aren't really useable, they've gone all soft and crumbly.





And so the work continues...........

[carl888]

One thing I should mention, the replacement master cylinder doesn't come with the "O" ring that's designed to seal the body of the master cylinder against the brake booster housing.  This is imperative for the vacuum to hold.  For some reason, and imperial R29 fitted perfectly.

[daantjie]

Hang tough brother! Yup I call mine "the Mistress ", it really is a love/hate kind of thing

[carl888]

Hang tough brother! Yup I call mine "the Mistress ", it really is a love/hate kind of thing

Thanks Daniel

[robertd]

Faarg Carl,

You, ve had a bad run with this low mileage concourse winning car.
Goes to prove that its critical to have regular services done right.
Unfortunately we can, t know how well they are performed, even when the service books are fully stamped by a main dealer?

I, ve been lucky with most of my fleet, but I do usually perform pre-emptive work such as front brakes and bearing on my new arrivals.
Don, t give up on it Carl, it usually darkest just before the dawn.

Cheers
Rob

[s class]

Carl, that brake caliper is a shocker, and I see lots of wierd stuff coming into the workshop. 

I notice that the pads are very thin.  What can happen when the pads are thin, is that the pad's steel backing starts to contact on the retainer spring, preventing further travel on that side of the pad.  Under harsh braking, this results in the pads only being able to move on their inboard side, and the pistons skew in the caliper bores.  I've often seen this result in cracking of that lip in the caliper, but I've never seen it go so far as to break out a piece, but I spsiect this is the reason for what has happened to your caliper. 

Interestingly, my 280SE has 565 000km, so obviously Ive had to do more regular maintenance than you, but honsetly, I've had fewer actual component failures. 

[oversize]

If you're that infuriated by you car why don't you sell it??  Seems to defeat the purpose of owning one if it doesn't make you happy.

Hey what brand was the caliper??

[carl888]

S-Class:

Yes, I ran the pads down to the last 2mm of material but there was still some clearance with the backing plate (Although it was close).  I've seen pads worn down to the point where the caliper won't function like you say.  Interestingly, I had a really good look at the caliper after cleaning it, and the piece that's broken off has been cracked for some time.  Along the break, it's rusty, no clean metal at all, so the fracture had been there for some time.  Thanks for the tip.

Oversize:

Don't get me wrong, I really like this car, but as it stands, it's salesproof the way it is currently.  Even with the brakes done, I still have to contend with the differential screaming its tits off!  My theory is that hopefully I'm on the cusp of getting it sorted.  Will that be my famous last words?  Once the brakes, differential, exhaust and starting issues are sorted I should be able to drive it more regularly.  Should!  Caliper is ATE.

[robertd]

Sorry we didn, t get to catch up yesterday Carl,
Ready when you are.cheers

[carl888]

Update:

Thank to RobertD I have rebuilt two nice looking calipers today.  They cleaned up well, I'll post some pics when they're uploaded.

Question:  the piston dust boots don't like staying put.  Anyone else had this issue?  When you press them onto the ring around the outside of the caliper body they just don't stay on.  The inner part, the section that fits over the piston is no problem.

Very annoying!  Any ideas?

[koan]

Question:  the piston dust boots don't like staying put.  Anyone else had this issue?  When you press them onto the ring around the outside of the caliper body they just don't stay on.  The inner part, the section that fits over the piston is no problem.

Isn't there supposed to be a thin metal retaining ring - or am I thinking of something else?

[carl888]

Ken yes, but that's for the Bendix calipers, not ATE.

[carl888]

Well, I'd just like to say I managed to get the old shit box back together after almost 9 months waiting for parts lol.

The brakes feel fantastic, which is a relief.  Interesting that the replacement level senders for the master cylinder is now a modified design that has eliminated the disintegrating rubber grommets in the top of the floats.

Some pics...







Now on to job 467!!

[s class]

Nice Carl, keep the faith, they are awesome cars to drive, and mostly, to own and maintain IMHO.