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soldave

Bubbles in brake fluid reservoir

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I do seem to be able to make the simplest task into an absolute mission. Thought I'd just flush through the brake fluid in the Eclat as it'd been 2 1/2 years since I'd done it previously. I took charge of the nipples and the good wife was in charge of pedal control. Did the rear and that went fine. Then went to the front and whilst I was doing that I noticed bubbles coming up in the master cylinder reservoir. Wondered if lots of pumping had caused a couple of microbubbles to come back in through a nipple and that was it, but bleeding again. Left it 24 hours and then tried again. Once again, bubbles were forming when I was bleeding fluid, using either of the front two nipples.

All I can think is that one of the master cylinder seals has gone. Going to order a replacement kit and hope that sorts it. If not then I'm pretty much out of ideas.

 

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Do you get the same if not bleeding but just applying the brakes? If so then I'd say you are spot with the master cylinder seals. Think yourself lucky it's not like the problem I had on a neighbour's Nissan, turned out to be the fluid he'd used (still not sure whether it was too old and had absorbed air or just wasn't brake fluid), either way we got a never-ending lot of air, that would appear a few days after bleeding.

 

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Yeah, just applying the brakes is giving the bubbles too; that video was without any bleeding taking place. Brake fluid going in is brand new so I don't think it's that it's absorbed air or anything crazy like that.

Will get a kit ordered and hope SJ isn't in lockdown mode yet!

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Lotus ownership: never a dull moment, whether it be driving or working on. With the new set of seals in the post I decide to take apart the brake cylinder and see what's going on. The seal between reservoir and cylinder closest to the servo looked a little wet on the outside so hopefully that was my issue with bubbles in the reservoir, but the plot thickens!

Took the primary piston out with a bit of persuasion and then pulled the stop pin so the secondary piston and spring would come out. All good so I turned the cylinder so any more brake fluid would come out, and out popped the other part of the secondary spring!!!

I don't know what could have happened but now I need to find a secondary spring for this cylinder (Girling 74660374), and am having no luck at all. Any ideas, guys?

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I might have one Dave - I'll have a look in the man-cave later today.

Pete

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Hi Dave - yes I've got one.  However I'm barely leaving the house at the moment - how quickly do you need it?

Pete

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7 minutes ago, EXCEL V8 said:

Hi Dave - yes I've got one.  However I'm barely leaving the house at the moment - how quickly do you need it?

Pete

A smart man - nobody should be leaving the house too much!

No big rush for it given I'm not going to be driving the car until this thing all starts to get back to normal and we're allowed out. Will send you a message. :)

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Well thanks to the kindness of someone on Facebook (Pete - I'll message you shortly about this ) I got a replacement secondary spring for the brake master cylinder, along with a master cylinder seal kit from SJ. Fitted it all back together and immediately had a leak from primary piston rear seal (causing a bit of brake fluid to appear under the servo. Took it apart and realised I'd put one of the secondary piston seals in the wrong way around (according to the diagrams below from an Excel write-up online. Switched the seal and set to bleeding using my Sealey pressure bleeder. Got the bubbles out and went for a drive. Brakes felt... different. A smoother application of brakes with pedal pressure, and I could lock up wheels at speed. Came back and checked the servo area and once again found a drip of fluid. Unscrewed the master from the servo and it was wet once again. :(  
 
Not sure now if I buy another seal set and cross fingers, or just cut my losses and buy a new master cylinder with the vehicle tax refund I'll hopefully get in the next month.

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Dave - I've modified the inner wing slightly on my '74 car to take the larger servo as fitted to the later cars.  It's a Land Rover part.  The master cylinder to go with it, including the reservoir - also Land Rover - was £44 + VAT!  The brake line fittings are on the near side, but for me that didn't matter as I'm fitting new ones from scratch.  Worth considering for you car as well?

Pete

Edited by EXCEL V8
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21 minutes ago, EXCEL V8 said:

Dave - I've modified the inner wing slightly on my '74 car to take the larger servo as fitted to the later cars.  It's a Land Rover part.  The master cylinder to go with it, including the reservoir - also Land Rover - was £44 + VAT!  The brake line fittings are on the near side, but for me that didn't matter as I'm fitting new ones from scratch.  Worth considering for you car as well?

Pete

Possibly. One other thing I noticed is that one corner of the bottom of the reservoir where the pin goes through is only hanging on by a very thin piece of plastic (less than the amount that should be there). It's still connected and the leak definitely wasn't from there, but I did notice it whilst doing some checks and putting it back together.

What kind of modding was needed?

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You might not need to do anything at all.  Measure your servo - the early ones are 7" diameter, the later ones are 8" (don't remember when they changed - perhaps with the 2.2?),  but the master cylinder will work on either.  I just wanted the extra servo action (going from 7" to 8" gives ~ 30% more as the effect is related to the area of the unit, not the diameter).

Pete

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1 hour ago, EXCEL V8 said:

You might not need to do anything at all.  Measure your servo - the early ones are 7" diameter, the later ones are 8" (don't remember when they changed - perhaps with the 2.2?),  but the master cylinder will work on either.  I just wanted the extra servo action (going from 7" to 8" gives ~ 30% more as the effect is related to the area of the unit, not the diameter).

Pete

Pete, does this one look like it's worth a punt? Looks like it comes with a reservoir too!
https://www.ebay.co.uk/itm/Land-Rover-Defender-110-Brake-Master-Cylinder-NRC8690/111147993591

My servo is an 8" I think :)

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Wrong bore - that's 1".  You need 7/8".  569671 is what you need.  The reservoir fastens on in a different way to yours - it's like the earlier master cylinders - but it has the correct bore and fitting flange.  I bought mine from Paddock's near Matlock - only about an hour from me.

Pete

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2 minutes ago, EXCEL V8 said:

Wrong bore - that's 1".  You need 7/8".  569671 is what you need.  The reservoir fastens on in a different way to yours - it's like the earlier master cylinders - but it has the correct bore and fitting flange.  I bought mine from Paddock's near Matlock - only about an hour from me.

Pete

Awesome knowledge. So it looks like it could be this one then instead: https://www.ebay.co.uk/itm/Brake-Master-Cylinder-Land-Rover-Series-SWB-Optional-Dual-line-System-569671/260948934251

Thanks for all of your help :)

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Yep - that's the same as the one I bought.  I bet you get yours fitted before I do!!  Don't forget to adjust the pushrod length on your servo to suit the master cyl piston position.

Pete

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Fitted yes, but I'll probably break something else in the meantime! Not that it matters as nobody should be going anywhere for a while ;)

I'd have never remembered to adjust the pushrod length - very good call.

Edited by soldave

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Yay - new Land Rover master cylinder arrived! Boooo - current brake pipes don't fit!

From what I've read, it seems like my Eclat ones are both M10x1, whereas the Land Rover ones are 3/8 and 7/16 (source: https://www.landyzone.co.uk/land-rover/dual-circuit-brake-fittings-sizes.352862/). I need to decide whether I'm going to try and just cut the flare off the original fittings and re-flare (could even do that whilst on the car), or make brand new brake lines from scratch. I think my lines are good so might just try the former for now.

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Sorry - I knew that - should have remembered to mention it.  I knew the holes were on a different side to some of the master cyls but forgot about the threads.  Apparently the different threads are to stop you reconnecting it incorrectly, although I can't see what difference it would make anyway.  You could just make a new front pipe - it's only short, and re-terminate the rear one.

Pete

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It's all good. Every day is a school day! tried to get the front pipe out of the 3-way fitting and the spanner was just slipping on the nut so am going to do that one in sit. The rear pipe actually goes down near the chassis in the engine bay and connects to another brake pipe so have removed that one and will change the fitting off the car.

Got fittings on order so hopefully next week I'll be able to get it together again and see were we stand :)

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Right, brake lines fitted with new unions and they seem to be holding pressure, which is quite surprising given my usual mechanical lack of skillz!. Bled a fair few bubbles out of the front although not too much from the read. Brakes feel alright but still a little spongy if I had to guess, even using a pressure bleeder. Think I'm gonna cut my losses and just find a garage close by when things reopen, give them my brake fluid and ask them to do a bleed. Then I know it's done properly. It's possible I've still got some air in the master cylinder (probably did a poor job of bleeding it)

 

I know, I shouldn't be allowed near a car if I can't bleed the brakes right, but I'd rather be safe than sorry here. On the positive side, I don't think the brakes are leaking any more.

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