This is my brake servo.
I removed it from the car as part of the "refurbish the brakes" subproject of the "financially ruinous Rover P5" project. It's a separate unit from the pedal-activated cylinder unlike it is on almost any other car, because Rover loved overcomplicating things back then.
The vacuum chamber (the large cylinder on the right) was half-full with brake fluid. As the name "vacuum" implies, there is not meant to be any fluid in there at all. That was quite the surprise when I took it apart, and also a surprise which caused me to lose a full set of clothing. There was little way the servo could have been functioning, and I suspect that aeration of the brake fluid would have caused the braking system to be minimally-functional even without the servo's assistance.
I suspected this seal may have been the problem:
But, the unit was so ugly that I cannot say for sure that any single component was at fault. The photos you see here were after a blast of electrical contact cleaner (which is great for cleaning up anything that isn't an electrical contact).
I take a lot of photos in the course of doing things as reference for how things need to go back together. In the above one, you can see quite a lot of mank in the servo's internals.
Under other circumstances, I would have considered giving it a wire brush on the outside, a soak in petrol and a skim with very mild abrasives to clean the cylinders. But while I was ordering an electroplating kit for the various fasteners I have removed from the car, it seemed a good idea to order an electrolytic cleaning kit` as an experiment! As if I didn't have enough new things to learn...
Electrolytic cleaning is, in my head, electroplating in reverse. Rather than using an electric current to attract material onto a thing you want to plate, you operate it in reverse so an electric current attracts material away from a thing you want to clean.
It works quite well. In the process of working quite well, it turns the electrolyte (this is water mixed with powdered sodium carbonate) into the only thing I would like to drink less than brake fluid or Foster's.
The exterior of the servo still required some love from a wire brush on the outside after the cleaning. The two bores feel very nice after the cleaning, so I will leave them be.
And the part that makes me happiest, is that the Girling wordmark is now visible!
And that...means that after two weekends I am half-way through rebuilding one of the components of one of the sub-projects of the P5.
rip small hammer always in are hearts xxx
And that, kids, is where your P38 comes from!
This was not an act of wanton destruction and savagery. I would be lying if I said I didn't enjoy it, but it was necessary, because my brother's 1963 Land Rover had, as my brother sagely observed, a lot of filler.
Some time before my brother bought this Land Rover in 2008, someone had tried to make its bodywork a bit smarter, with a lot of filler. I cannot say that this was a terrible idea, because it held up as well as a monstrous amount of filler could reasonably hold up.
It took my brother rolling the car onto its side some years ago to crack it severely, with some help from daily driving for years, three road trips to Africa, and one gentle road trip to China via Kazakhstan and Mongolia. Even then, as ugly as it was, it was not an MOT failure, until someone picked off some bits of it, and then it was an MOT failure because of an exposed sharp edge.
So, with a lot of filler removed, and some help from a blowtorch, soap, and a selection of percussive persuasion tools, we had a straight panel again. I say "straight", though I actually mean "straight enough to be presentable on a battered Land Rover". I made sure that Alex was out of arms reach and did not have any power tools to hand when I said "that's straight enough, but do you know how we could make that panel absolutely perfect? If we got a lot of filler..."
Many other things were completed over the weekend, thanks to Alex's superhuman motivation. And also his ability to talk people out of whatever else they wanted to do and into helping him.
I had other things to do with my current project-within-a-project on the P5 (more on this soon-ish), but after the filler-mining was complete of course I stayed up much longer than I was expecting to stay up, helping him wire in a pair of new horrifically-bright LED light bars, because Alex can talk toothpaste back into the tube...
...which took us into the early hours of the morning, and all of that was definitely a good way to spend 14 hours!
Thanks to Alex for the video and a couple of the pictures in this post.
 With very thin aluminium such as that of a Land Rover body panel, you mark the area you want to with ordinary soap. Heat that area with a blowtorch. When the soap turns black, it is at a temperature that is more-or-less optimal for percussive reshaping. :)
I love good documentation.
The Rover P5's workshop manual - the original one written by the engineers at Rover - is the best manual I have ever used. I especially enjoy that the manual sets out exactly what tools you will need including the sizes of spanners in the preface. This is the only workshop manual I have seen that does this, and it makes every job a tiny bit faster and a tiny bit more fun.
How many times did I work on the Mazda and read through a 20-step walkthrough and then in step 19 it says "use special tool, part number F-U, which is obviously completely unavailable for any amount of money to remove this delicate thing that will definitely break if you try to use cruder methods to remove it"?
Good documentation is important, and I believe in thanking people for good work even if I am late to their particular party. So, thank you, Rover engineers from 60 years ago. You did a fantastic job.