Ok, was slightly overdue for a service (so no negative arguments from Austria, thanks).

 

Noticed V hot osf brake disc and warm alloy after an unusual driving vibration, so after having to take the day off work got down to stripping the front brakes and thoroughly cleaning and re greasing (copper) and re ass embling. It was needed.

 

Anyway, the one thing that I forgot to do was remove the reservoir cap as I gently (with a g clamp) pushed the piston back. (comments / advice accepted).

 

It is however, still getting V hot. The others can be touched without worry, but the osf disc is hot enough to burn skin within seconds. Yes, ouch.

 

I do plan on doing the pistons again this weekend (bet it is pi55ing it down) but any other advice, similar situations you guys have / had? Cheers.

I expect the calliper is binding. I had one go on my mk5 golf. New calliper was required.

I had the same problem on my n/s/f & a new caliper fixed the problem.  

A new caliper will do the trick i had the same.

You need to strip the caliper piston and seals to clean properly and assess replacements otherwise any cleaning and lubing of exterior parts is just whizzin into the wind.

As well as cleaning and greasing the caliper make sure you have cleaned and lightly greased the floating pins too. Also worth a check is the pads themselves. My rear off side was binding and after cleaning it all up noticed one of the pads was tight to reinsert. The tab wasn't cleanly cut and removing the burrs (this was VW pads) with a file made a huge difference.  

I had this too on my 54 plate. Piston was sticking so had new OSF caliper fitted. 14 months later the NSF went the same way. Another 12 months later and the OSF started getting quite warm again. Stripped brakes down, cleaned, relubed etc. Piston wasn't sticking but still got warm. Garage advised brake disk was badly scored so possibly there was some friction causing the heat. Fitted new disks and pads. Problem reduced but this side still runs warmer than the other and produces more brake dust. No idea why as caliper seems fine.

 

Mystery! 

Cheers guys.

 

As stated, the brakes were thoroughly cleaned and copper greased including pins. And the piston pushed back very nicely / smooth.

 

I do not know how the calliper can bind, so the only logical solution left is as Micmac says. I guess it must be the piston.

 

This tallies with people replacing the whole calliper, although this being the expensive solution.

 

Further comments and advice on cleaning the piston / seals are welcome.

 

Thanks again.

 

I had this too on my 54 plate. Piston was sticking so had new OSF caliper fitted. 14 months later the NSF went the same way. Another 12 months later and the OSF started getting quite warm again. Stripped brakes down, cleaned, relubed etc. Piston wasn't sticking but still got warm. Garage advised brake disk was badly scored so possibly there was some friction causing the heat. Fitted new disks and pads. Problem reduced but this side still runs warmer than the other and produces more brake dust. No idea why as caliper seems fine.

 

Mystery! 

When you stripped and cleaned your brakes, did you pull the piston out also to clean??? I think this has to be my next step, unfortunately.

Tilt, mine was the same issue as Mike just described but mine was badly cut.

Hi Tilt, greeting from Austria, sorry I mean Yorkshire...................

 

This may sound a bit patronising, but believe me it is not intentional, just relating what I noticed with mine. What stands out here for me is you saying the piston was moving freely and smoothly.

 

My 54 plate got an advisory for a tight front brake and worn pads on one front corner, and found the wheel was hot. When I stripped the brakes down, I had to hammer the outboard pad really hard to remove it -- it had corroded into near enough a weld and it wasn't for shifting. 

 

I too cleaned everything up, or at least I thought I had, and copper greased everything (well, not the discs LOL) when reassembling, and found it was still getting too warm, so I stripped that side again, and noticed that the new pads were quite tight in the carrier, tighter than they should be. I suspect that was preventing the carrier moving on the pins as it should (the piston on mine was also moving quite freely). I ran a file along every area of contact where the pads met the carrier, and also ran that file over the carrier itself to get rid of every bit of corrosion that was on there, and since doing that, I haven't had any further issues, years down the line. It certainly is worth trying this, as it's at zero cost -- if it works, great, but at least you know you won't have forked out for another caliper when it wasn't needed.

 

As a follow up to this, I also did this as a planned maintenance exercise on the other car shortly after I got it, and found the corrosion of the pads an issue here as well. But after the same treatment, all is well here as well.

 

I might be wrong, and the voice from Austria will no doubt tell me I am, but I am convinced that the major problem was using a high pressure jet wash on the wheels, a very easy way to wash away any grease that is there, and being water, this is a perfect recipe for rust to form. I never, ever power wash wheels now, I just use a sponge and swill with a watering can. Maybe/probably/probably not/definitely (take your pick) I'm sure this has done wonders in the last few years to prevent a recurrence of the hot brake syndrome.

 

Mike

Cheers Mike, glad someone got the link to Austria. Some people, eh!

 

Anyway, your reply - not patronising at all as well informed information from a reliable source is always welcomed. :yes: .

 

As said though,I thoroughly cleaned disc's and pad's and that was with a fine file. I took note of the main three points of contact of each corner of the pads to the calliper and paid extra attention to these, and made sure they were through to (mostly) shiny metal, without going too far obviously.

 

Although the Skoda is mainly a work vehicle, I never have used a jet wash. Sponge wash only for my vehicles. :p .

And new disc's and pad's were fitted a few years ago, I do not brake heavily very often so both still in very good condition.

 

Going to check them again but probably (?) going to have to look into stripping the piston. Not done this before, so pointers anyone???

 

Thanks all.

As I used a clamp to push the piston back, using the clamps thread, this could have made it seem free and smooth. Need to re-check but logically this is the only other thing I can think of.

As said, gonna re-check though asap.

Is it normal practice just to remove the reservoir cap to push the piston back, and should it cause any other issues if I forgot to remove this when I did it?????

Removing the cap prevents pressure build build up which can flip the seals. Only seen this once when some extra used a drill to wind the clamp in so I doubt you will den any damage by hand.

If you want to do a full caliper strip then clamp the hose, remove the caliper and drain the fluid out of it. To pop the piston out put a rag in the opening. Apply air pressure through the hole were the hose went and the piston and dust seal will pop out. The rag stops it flying across your garage. Air compressor is great but you use a foot pump to do the same using the tapered adaptor for blowing up air beds etc.

Use a pick to remove the piston seal. Remove any deposits from the caliper inner and piston with a fine wet & dry then thoroughly clean out with ispopryl alcohol and air dry. Apply a little red grease to the seal and fit into the caliper and ease the piston back in. Refit the dust seal if not damaged and your good to go again after bleeding the caliper.

Rear calipers are a more complicated due to the handbrake mechanism but the same principle.

My rear caliper was getting really hot, Needed a new one as it was seized, Don't do what i did and continue driving the car thinking i''ll replace it some time soon, As i was continuing to drive the car the heat produced from the seized caliper was gently frying my ABS sensor, Which yes also now needs replacing........We live and learn,,,    some of us..

Edited 25 March, 201610 yr by Doofy

Forgot to add, the pins were soaked in white spirit and cleaned to a sparkle. Ok, no sparkle but you know what I mean, then greased.

 

I do not have any paraffin, but white spirit worked fine.

Agree with Mike. Try taking some more off the tabs. If your not comfortable with that remove the clips. They'll rattle and squeal but if they don't bind you know it's the tabs.

You need to strip the caliper piston and seals to clean properly and assess replacements otherwise any cleaning and lubing of exterior parts is just whizzin into the wind.

Sorry Micmac. Changed my mind on this one - Not necessarily true, if it is just the pads that are seized.

No worries.

Do the job twice and see how you get on.

If you want a job done fully there's only one way to assess a sticky piston and that's to remove it so you can see rust/pitting/corrosion fur/dirt.

Many times I've refurbished less than ideal looking parts with no problems, depends how thoroughly you clean and finish items.

Slightly off topic, but relevant for anyone planning to take the pistons out of their calipers.

 

The front calipers are easy enough to reassemble as they just push in, but remember that the rear calipers need the pistons SCREWING in rather than pressing.

 

@ Tilt -- I really do suggest taking the pads out again and filing a bit more off them to make sure they are free in the carriers. It doesn't take a lot of corrosion or excess burring to get them sticking, especially when they expand as they get warm.

 

Mike

Going to try this firstly, Mike. Cheers. I do not have the new seals to hand if it proves to be the piston.

 

Agree with Mike. Try taking some more off the tabs. If your not comfortable with that remove the clips. They'll rattle and squeal but if they don't bind you know it's the tabs.

I do not think they have clips Bud, only on the back of one pad??? Going to try what you guys say, firstly though. Cheers.

No worries.

Do the job twice and see how you get on.

If you want a job done fully there's only one way to assess a sticky piston and that's to remove it so you can see rust/pitting/corrosion fur/dirt.

Many times I've refurbished less than ideal looking parts with no problems, depends how thoroughly you clean and finish items.

That is the thing here Bud. If I knew it was the piston then I would agree with you, undoubtedly.

 

I wouldn't muck about - I would buy new seals etc and get the job done.

 

The pads definitely were sticking however, so this was the logical place to start. The piston may not be sticking at all and if this is the case I do not want to waste my time doing it unnecessarily.

 there's only one way to assess a sticky piston and that's to remove it so you can see rust/pitting/corrosion fur/dirt.

Totally agree with you on this statement, and appreciate your replies.

 

I'm just addressing the easiest option first and hoping this is the cause.

 

Cheers.

Edited 26 March, 201610 yr by Tilt

I have taken a file to the lugs on the pads now and will find out the result on Tuesday.

 

They are Greenstuff pads and were originally fitted a few years ago, along with new disc's with no problems up until recently though. Not a lot of mileage or heavy braking as stated, both in vgc.

 

Other than the brakes, are there any other possible causes???

 

I ask this as I noticed a small split in the rubber boot behind the disc. The split is just beside the (jubilee type) clip on the smaller side. There doesn't seem to be much grease leaked out (assuming it is greased) but not sure. I have wound some self amalgamating tape around at least for the short term. Could there be a possibility of a link here, to the very hot disc if the grease has dried up or leaked???

 

Thanks.

You need to get the CV boot changed before it costs you a new CV joint or wheel bearing. A failed wheel bearing would produce heat but to get to that stage you would have heard and felt it by now.

As well as cleaning and greasing the caliper make sure you have cleaned and lightly greased the floating pins too. Also worth a check is the pads themselves. My rear off side was binding and after cleaning it all up noticed one of the pads was tight to reinsert. The tab wasn't cleanly cut and removing the burrs (this was VW pads) with a file made a huge difference.  

 

 

I really do suggest taking the pads out again and filing a bit more off them to make sure they are free in the carriers. It doesn't take a lot of corrosion or excess burring to get them sticking, especially when they expand as they get warm.

 

Mike

 

 

Agree with Mike. Try taking some more off the tabs.

Spot on, Guys.

 

I did a good job of the holder on the calliper the first time but only gently cleaned the pads.

 

After taking a fairly coarse file to the points of contact on the pads (taking the 'greenstuff' paint off too) and slightly rounding them, It seems to have sorted the problem.

 I have now done a mixture of travelling and even arrived in Leicester (with very little braking required) with cold brakes all around.

 

No maintenance was carried out on the piston at this time.

 

I will keep an eye on them for a while just in case, but pretty sure sorted, and for anyone slightly sceptical of this solution, so was I.

 

Cheers guys.

I had this too on my 54 plate. Piston was sticking so had new OSF caliper fitted. 14 months later the NSF went the same way. Another 12 months later and the OSF started getting quite warm again. Stripped brakes down, cleaned, relubed etc. Piston wasn't sticking but still got warm. Garage advised brake disk was badly scored so possibly there was some friction causing the heat. Fitted new disks and pads. Problem reduced but this side still runs warmer than the other and produces more brake dust. No idea why as caliper seems fine.

 

Mystery! 

Try the above solution, bud. Worked for mine.

Try the above solution, bud. Worked for mine.

 

My pads were very free and smooth in the contact areas so no amount of filing was needed.

 

I've a niggly feeling that something else is applying some pressure to the caliper whilst the car is in motion.