W202 - clamping brake hose

[teddyk]

Hi,

I have a seized driver's side caliper on my 1999 w202 C230K.
I can see lots of corrosion on the end of the piston. I can also see that the boot is torn.
I was hoping to have a go at refurbing it myself and have ordered a suitable kit with seals, boots etc.
I had a go at removing the caliper a couple of nights ago, but came upon an issue which caused me to abandon until I could ask for some help here.
The issue is as follows:
When I went to clamp the (rubber) brake hose, the hose seemed quite firm and my clamp did not seem to compress it much. I was afraid to continue in case removing the hose from the caliper would lead to a torrent of brake fluid and the risk to emptying the master cylinder.
Do I need to clamp off the brake hose? And if so, what is the best way of doing so without damaging the internals of the hose? I plan on doing a complete brake fluid change after the caliper has been replaced.

All help much appreciated,

Thanks.

 

[television]

If you have the new calliper to hand, then you can remove the old one and unscrew it from the pipe and screw it into the new with very little fluid loss, then bolt it back on and just bleed that line

 

[teddyk]

Hi Malcolm,
Thanks for the quick reply.

Unfortunately I don't have a replacement caliper. I'm hoping to refurb the one that's seized on the car. Have seen a tip that involves unscrewing the cap on the brake fluid resevoir, placing some cling-film over the top, and rescrewing the top back on over the cling-film. Claims to lessen fluid loss.
The Haynes manual I have ( for w202 C180, C200, C220, C230 and C250 but excluding C230K ) suggests clamping the hose - I'm just afraid of damaging the internals of the hose - I would need to use a vicegrips to get enough force to clamp it I think.

I'm hoping to refurb as any online places that I have seen replacement calipers for sale are looking for nearly the same price again for shipping to Ireland.

 

[EmilysDad]

.....
The issue is as follows:
When I went to clamp the (rubber) brake hose, the hose seemed quite firm and my clamp did not seem to compress it much. I was afraid to continue in case removing the hose from the caliper would lead to a torrent of brake fluid and the risk to emptying the master cylinder.
Do I need to clamp off the brake hose? And if so, what is the best way of doing so without damaging the internals of the hose? I plan on doing a complete brake fluid change after the caliper has been replaced.

All help much appreciated,

Thanks.

Don't forget that the bore of the flexi hose isn't that big, so you don't need much to compress it enough to stop the brake fluid escaping. Using a proper hose clamp is best, Molegrips run the risk of damaging the hose. What also helps the fluid from escaping is to remove the master cylinder cap, cover it with a piece of polythene & replace the cap. Don't let the system empty via the caliper hose otherwise you'll have to get the system bled using something that can exercise the ABS pump (assuming of course your car has it) You would only get a 'torrent of brake fluid' out of the hose if someone pressed the pedal.

 

[grober]

I recommend these Sealey clamps http://www.sealey.co.uk/PLPageBuilder.asp?id=20&method=mViewProduct&productid=8705
Very neat for awkward places and if they aren't tight enough you can just give em a tweak in situ.

 

[teddyk]

Thanks EmilysDad and grober.

Have ordered some of the pipe clamps as suggested above.
Will let you know how I get on.

Thanks.

 

[kth286]

do consider that the hose may already be damaged internally and causing
a one way valve effect, thus not allowing the brake to release.

I would be replacing the brake hose for that age car.

 

[Silver_Star]

No need for a special clamp, you can clamp it with a pair of mole grips with a socket on each of the jaws.

 

[spock500]

I would use this as a good opportunity to replace the brake fluid altogether.

This time of the year there's plenty of moisture in the air. Brake fluid is hygroscopic which means it absorbs water from the air.

Good practice is to change every 24 months anyway, which I think MB recommend too.

 

[Frontstep]

I would just get your caliper up and running first, change fluid at some other time a stripped and honed out caliper with new seals should be fine.
I used to have a honing tool that fitted on an electric drill for such a thing.
The reconditioners blast the outside to get them looking good I used to block the holes and leave them in vinegar overnight.

 

[teddyk]

Thanks everyone for the replies.

I removed the caliper tonight (very little brake fluid loss ).
The dust boot was torn and the piston is fairly corroded, though most of it came off with a bit of 600 grade wet+dry paper.
See pictures below - in a pretty bad state.

Started to remove some of the crud from the housing and bracket with my Dremel, but was tedious and dusty. Might see if I can get it sandblasted locally tomorrow.

New seal kit arriving on Saturday. Depending on the cost of the blasting, I may get the other front one done too. It can't be far off seizing given the condition of the seized one.
Do I need to prime and paint the caliper after the sandblasting?

Thanks.

 

[television]

I always paint mine up just for the appearance but you do not have to

 

[spock500]

I would just get your caliper up and running first, change fluid at some other time a stripped and honed out caliper with new seals should be fine.
I used to have a honing tool that fitted on an electric drill for such a thing.
The reconditioners blast the outside to get them looking good I used to block the holes and leave them in vinegar overnight.

Pagid DOT 4 is £3.12 a litre (after forum discount ) delivered.

Makes sense especially as you will have to bleed system anyway.

 

[teddyk]

Job done.

A few things to note -
1. Even working outdoors, wearing a dust mask and goggles, using a wire wheel to clean up the calipers, I can feel the dust in my chest a couple of days later.
2. Had to unscrew the caliper from the brake line by loosening the nut and then turning the caliper itself - nearly had me stumped.
3. Easily managed to rip one of the two replacement dust boots when trying to get one of the pistons back into the bore. Luckily the original boot on one of the calipers was still in good condition so I was able to reuse it. The repair kit I used was ordered from Bigg Red - www.biggred.co.uk.

Don't think I would bother repainting if I have to do it again. It was time-consuming with not a lot to show for it. I used Hammerite high temp matt black paint which dried dark grey. Needed 2 cans for 4/5 coats on each of the 2 calipers and mounting brackets.
An air compressor with air gun was very useful for removing the pistons from the bores - would have struggled without it.
Followed up refitting with a full brake fluid flush. I used a manual pressure bleeder for this - Laser 4832 Manual Brake Bleeder. Only took a few minutes per wheel.
Started raining immediately after a test drive so will have to wait for a dry day to be able to check for leaks.

Thanks again for all the help.

 

[yorkshire1]

piston

Job done.

A few things to note -
1. Even working outdoors, wearing a dust mask and goggles, using a wire wheel to clean up the calipers, I can feel the dust in my chest a couple of days later.
2. Had to unscrew the caliper from the brake line by loosening the nut and then turning the caliper itself - nearly had me stumped.
3. Easily managed to rip one of the two replacement dust boots when trying to get one of the pistons back into the bore. Luckily the original boot on one of the calipers was still in good condition so I was able to reuse it. The repair kit I used was ordered from Bigg Red - www.biggred.co.uk.

Don't think I would bother repainting if I have to do it again. It was time-consuming with not a lot to show for it. I used Hammerite high temp matt black paint which dried dark grey. Needed 2 cans for 4/5 coats on each of the 2 calipers and mounting brackets.
An air compressor with air gun was very useful for removing the pistons from the bores - would have struggled without it.
Followed up refitting with a full brake fluid flush. I used a manual pressure bleeder for this - Laser 4832 Manual Brake Bleeder. Only took a few minutes per wheel.
Started raining immediately after a test drive so will have to wait for a dry day to be able to check for leaks.

Thanks again for all the help.

Even though asbestos for linings is now banned and the dust could get you back up to 40 years later no dust is good dust
Good luck with the piston the problem with corrosion where you show it is that now the bad area is right where the seal is located in the cylinder and with new pads the piston will stay there for quite some time could leak might have been better to replace piston see how you go