Caliper piston Boot Torn - Replace caliper?
 

Rear Caliper boot tear- see pic.

Doing rear pads, rear discs, and emergency brake shoes on the 85 and came across this tear/wear in my caliper. Caliper itself works fine. This is on the 'outside' - opposite of the side the fluid comes in.

Does it need to be replaced immediately?

Thanks
dd

Your call; I do not think anyone knows how long you could drive like that before it causes another problem.
I think you already know Rust and Dirt will eventually cause the Caliper Piston to stick; and, maybe the Caliper to leak.

How hard is it to rebuild a non-stuck caliper myself?

Its an original unit and all the seals are brittle.

I have had bad luck with purchasing rebuilt calipers, they make me nervous.

Rebuild for an otherwise good caliper is straightforward. A compressor/pump is useful for popping out the pistons after the caliper is pulled.

There's a bit of fussiness involved to get the outer seals, like your torn one, situated. It's like trying to stretch the too-small rubber band around the groove.

In Boston, assuming standard wet roads, etc. I'd recommend sooner rather than later. You "might" be able to just replace the outer boot, but I think the procedure for getting the folds and the seals the right way round calls for putting the outer boot on the piston first, then inserting the piston, then snapping the boot onto the caliper. I'm going from memory and could be wrong. If correct, that technique seats the inner seal from the boot to the piston correctly without too much finagling. The other way may also be possible, just with more finessing the boot into the ring.

Here is my pictorial of a caliper reseal.

http://www.peachparts.com/shopforum/diesel-discussion/284342-resealing-w123-126-calipers.html



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Not hard. Just do not disassemble the caliper halves.

I have done that with every Car that I own that has had disc Brakes.

I cannot remember ever having any problem with them after they were done.

Installing the Piston, Seal and Boot far harder than unbolting the Caliper Halves.

There is an issue that the cutouts on the Face of the Caliper Pisto have to be oriented correctly; but, that has nothing to do with splitting the Calipers.

The MB FSM strongly cautions against the practice. 'Nuff said.

I'd look into rebuilding but because of your area be prepared to buy a replacement caliper.

Condition is crucial: Pitting / scoring / corrosion are probably a sign it is time to give up and buy a replacement.

Even so I encourage you to have a look - you never know you might catch the deterioration just in time.


(Sorry to be all doom and gloom but it is often the way in climates like yours and mine)

Most of the calipers I've had to replace seized up because the outer boot let moisture in and the outer half inch of the piston bore rusted.

Unfortunately, once the boot is broken, rust can get started in that crucial area even if the boot is replaced. At that point it's a crapshoot. You might get by with replacing just the boot, maybe not.

I've always wanted to try this experiment: lay the caliper so the piston is face up, pry the boot off and pour a small amount of a rust converter like Oxy-Solv into the space between the piston and bore and let it work overnight. It sure would be easier than removing the piston and cleaning up the rust by hand.

You might - just might - kill the rust that way but there is no way you'll clean it out. You'll be leaving junk in there that would most likely score or damage the piston and caliper surfaces accelerating the demise of the caliper.

A bit of fun for a Sunday - sure - but don't fit it to a car.

This is not an argument but an observation:

The MB FSM also shows a bunch of Special Tools (mostly for the Boots and Heat Shields) being used to rebuild the Caliper.

If a person was to go strictly by the Manual they would not attempt to do the job without the Special Tools.

The job can be done without the special tools. And it can also be done without separating the caliper halves.

Not having the special tools makes the job a bit less convenient and makes it take longer, but it doesn't change the end result. Failing to heed warnings can lead to a life-changing event.

That is true but it is also true that your job can be made easier by splitting the Calipers and that it has never caused me any issues; and I do not consider myself to be a lucky person.

I did the same thing when I assembled my Caliper halves that that who ever does the rebuilding these days would do when the assemble a Factory Rebuilt Caliper; with the very big exception that I trust My own work more.
Over on Benzworld someone has found a source of the Square Crossectiond O-ring that goes between the Caliper halves.
Unforunately I cannot find my notes on the Link.

For any Europeans who might be tuning in - these people stock 'em

http://www.ccparts.nl/