Stuck callipers..

[Shaunm41]

Good evening,

I have a 2003 CLK 270 diesel and I’m having some brake problems..

The front N/S brakes were sticking on and overheating so I decided to replace the front disks and pads as there was also shaking through the steering when braking..

While replacing the disks and pads, the brake callipers wouldn’t return all the way in and I struggled to get them over the new disks..

Now the brakes on both sides are sticking as the callipers won’t fully retract and it’s un drivable.. the wheels didn’t turn freely after the brakes were pressed..

Can the callipers be repaired? Or any other suggestions I could try to get things moving again?

I’ve changed disks and pads before but never had problems like this..

Any advise would be much appreciated

Thanks

Shaun


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[Blobcat]

It’s the pistons sticking in the callipers. They will need a rebuild / cleaned up / new seals

 

[Shaunm41]

It’s the pistons sticking in the callipers. They will need a rebuild / cleaned up / new seals

Thanks, is that a straightforward job?


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[robin.large]

Just checking that you slacked off the brake bleed nut to release any stored pressure as you try to push the pistons back into the calipers?

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[Shaunm41]

Just checking that you slacked off the brake bleed nut to release any stored pressure as you try to push the pistons back into the calipers?

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Ohh that’s a good point...... no I didn’t do that... I’ll give that a shot tomorrow


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[onefortheroad]

Thanks, is that a straightforward job?


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Did you use a piston push back tool or leverage ?

 

[Shaunm41]

Did you use a piston push back tool or leverage ?

I picked up a push back tool from euro.. had to use quite a bit of force with a ratchet on it and ended up bending the plate that comes with the tool


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[joderest]

Normally, pushing the pistons back would just increase the level in the master cylinder, and as long as the top is off and it is monitored should be no problem, unless someone has topped it up when pads were worn, it may well then spill out.
HOWEVER
It does sound like you have seized pistons in both sides, which will mean removal of the callipers, you can overhaul them yourself if you have the tools and knowledge, but if the pistons are rusted, which is often the case, may be better to have reconditioned callipers, which would make the job quicker. The seals are available, i rebuilt my rear ones on the W163 last year for this problem, right hand side was sticking causing a brake issue.
I would look on ebay or check a site like Eurocarparts for prices, or if you have a garage near you that would perform the overhaul for you.

Good luck

 

[onefortheroad]

I picked up a push back tool from euro.. had to use quite a bit of force with a ratchet on it and ended up bending the plate that comes with the tool


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That shouldn't happen. Try cracking the nipple and try again.

 

[Shaunm41]

That shouldn't happen. Try cracking the nipple and try again.

Thanks will give that a try tomorrow and maybe pump and wind it a few times see if it’s free..


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[Shaunm41]

Normally, pushing the pistons back would just increase the level in the master cylinder, and as long as the top is off and it is monitored should be no problem, unless someone has topped it up when pads were worn, it may well then spill out.
HOWEVER
It does sound like you have seized pistons in both sides, which will mean removal of the callipers, you can overhaul them yourself if you have the tools and knowledge, but if the pistons are rusted, which is often the case, may be better to have reconditioned callipers, which would make the job quicker. The seals are available, i rebuilt my rear ones on the W163 last year for this problem, right hand side was sticking causing a brake issue.
I would look on ebay or check a site like Eurocarparts for prices, or if you have a garage near you that would perform the overhaul for you.

Good luck

Thanks for your reply, I’m hoping it’s not as serious as that, but will see tomorrow


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[Wighty]

This was my caliper journey
https://forums.mercedesclub.org.uk/...-brake-caliper-overhaul-question-help.181200/

 

[AMGeed]

If the worst happens and you do need a caliper refurb, this company are well recommended.

http://www.biggred.co.uk/brake-calipers

 

[onefortheroad]

Thanks will give that a try tomorrow and maybe pump and wind it a few times see if it’s free..


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Don't pump too much your piston may pop out

Brakes International do really good refub calipers with a part exchange option.

 

[Shaunm41]

Don't pump too much your piston may pop out

Brakes International do really good refub calipers with a part exchange option.

well atleast it won’t be stuck then


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[Shaunm41]

So I’ve slackened the bleed nipple off and managed to get the pistons all the way in, fitted the new pads and the wheels turned freely.. went out for a drive and they got pretty hot and one produced a little smoke which I believe is normal.. I think I may just sent the callipers away to be refurbished..

Thanks


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[Blobcat]

Pushing the pistons back in if they’re seized is a bad idea. The rust on the outside of the pistons (what causes the seizing) will likely damage the seals as it’s forced past them.
I’d get them refurbed pronto.

 

[joderest]

It does sound like the pistons are not retracting correctly.
Be aware that the hose connection can be very tight into the calliper, and you cannot use heat to free it off, for reasons that do not need explaining !!!.
I used a freeze spray, which worked very well, you must have a decent tight fitting spanner.
Good Luck

 

[onefortheroad]

So I’ve slackened the bleed nipple off and managed to get the pistons all the way in, fitted the new pads and the wheels turned freely.. went out for a drive and they got pretty hot and one produced a little smoke which I believe is normal.. I think I may just sent the callipers away to be refurbished..

Thanks


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Brakes international will sell you 2 calipers and give you money back when they receive your old ones.

 

[ajlsl600]

Ohh that’s a good point...... no I didn’t do that... I’ll give that a shot tomorrow


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Leave one pad in use Tyre lever, gently force piston back, watch level in mcyl does not go up such that b/fluid goes al over the place, many make mistake of topping up as pads wear down. After getting one back fit pad, repeat for other side
If piston does not move freely I have fitted grease nipple and pumped them out for resealing.