Brake failure, no fluid in reservoir (early Rover 3 Litre)

[clive]

I'm a bit confused no know what has happened. The car has been driving perfectly for years, I check all the fluids on a regular basis and everything is as it should be...until a few days ago when I decided to fill up with petrol, reversing it out of the garage I noticed the Brake pedal went right down to the floor, total Brake failure. Luckily this was at slow speed and I was able to use the hand brake to stop the car.
I've since had a look and the reservoir is completely empty and looking about I cant see much oil anywhere, the Master cylinder is completely dry. I must admit I don't know much about the breaking system as it's always worked so well. There seems to be two cylinders, one that is activated by the foot pedal and another one similar looking but with a plastic cup on the top (a sort of breather filter housing.) Could it be one of these cylinders that has failed? or could it be more involved that just this?
Any advice would be most welcome, I hate not being able to use my car!

[Phil Nottingham]

Classic servo failure - the fluid will be inside the vac tank.

Do not bother fitting a recon Girling unit or doing it yourself as they are not as good as the Lockheed Type used on P5Bs which can be obtained from Wadhams and I think a kit to fit it.

[clive]

Oct 12, 2021 15:13:47 GMT Phil Nottingham said:

Classic servo failure - the fluid will be inside the vac tank.

Do not bother fitting a recon Girling unit or doing it yourself as they are not as good as the Lockheed Type used on P5Bs which can be obtained from Wadhams and I think a kit to fit it.

Thanks for the reply, if the fluid is inside the vac tank (pictured) is this the item that has failed and needs replacing?
or is there something else that's failed causing it to end up there? Sorry, I need to have this clear in my head so don't order parts that aren't needed.

[Phil Nottingham]

It could be inside that or most likely the vac tank which is part of the servo. As I said the servo most likely needs replacing not  The underwing vac tank is not required with a Lockheed servo. Do you know which you have fitted? Post a pic?

I strongly suggest you refer to the factory workshop manual before working on the brakes and doing any ordering - the P5 is a heavy vehicle to stop without brakes and servo failure is not uncommon on older cars of any make

[MK IA Norway Viking]

Good afternoon,
I have 2 MK IA Saloon, and the same has happened to me several times.

The fault is always the same; the brake fluid is passing from the chamber on the servo unit where the pipe from the brake fluid reservoir is connected to the servo, into the vacuum side which is the big bellow with a flat end about 25 cm across on the part of the servo that is closest to the front of the car.

It happens because the seal that is between the piston and the wall of the servo unit start leaking air.

Culprit is the vacuum induced into the servo by the engine which cause the brake fluid to travel to "the wrong side" of the servo.

JR Wadhams have a service kit. You can buy this and fit yourself or let a workshop for brakes do it for you. I've done it myself and time spent is 2-3 hours from start to finish.

Won't be necessary to bleed the brakes after this job, however it is a good idea / recommended, for the brake fluid in the pipes from the servo unit to each wheel ought to be replaced every 5th year (at least). Doing this job is an ideal opportunity for replacing the brake fluid in the pipelines.

Fitting a later type brake servo will work however NOT recommended for that makes your car not original anymore, and that means a lot to a purist (like me). Besides, getting a new unit of different type will cost about the same as the repair kit and money to the workshop-man.

[clive]

Thanks, My Rover is a Mk1 a, it's looking very much it's the Sevo, Speaking to my mechanic when this problem happened he suggested it was the Master cylinder, I'm not so sure now! I'll pass on your post to him, I don't feel competent doing it myself the Sevo looks in a very difficult spot to access.

[enigmas]

On a more serious note.
It's good that you've found the issue that caused total brake failure Clive BUT your P5s hydraulic brake system is single circuit. As such a failure at any point in the hydraulic system means total brake failure. I'm assuming that since it still runs the original brake servo then perhaps other components in the system may have never been reconditioned. If so the original brake seals are at least 50 years old and well past any safe service life.

I strongly advise, given what could have occurred with a total brake failure scenario (a car without brakes is a lethal projectile) is to have the complete hydraulic system checked over or more to the point reconditioned.

If you don't have relatively recent receipts with regard to either maintenance or servicing of the brake system (including the brake fluid) a full system check and evaluation needs to be carried out if not for your preservation then for any other road users/pedestrians.

[clive]

Oct 13, 2021 11:28:03 GMT enigmas said:

On a more serious note.
It's good that you've found the issue that caused total brake failure Clive BUT your P5s hydraulic brake system is single circuit. As such a failure at any point in the hydraulic system means total brake failure. I'm assuming that since it still runs the original brake servo then perhaps other components in the system may have never been reconditioned. If so the original brake seals are at least 50 years old and well past any safe service life.

I strongly advise, given what could have occurred with a total brake failure scenario (a car without brakes is a lethal projectile) is to have the complete hydraulic system checked over or more to the point reconditioned.

If you don't have relatively recent receipts with regard to either maintenance or servicing of the brake system (including the brake fluid) a full system check and evaluation needs to be carried out if not for your preservation then for any other road users/pedestrians.

Yes, this is indeed a wakeup call and I'm going to get it all looked at. I realise it's single circuit system so it would be complacent of me to just carry on as usual especially as I use the car a lot.

[MK IA Norway Viking]

Hello Clive,
on an earlier failure that I had, I too thought it was the brake master cylinder.

Turned out, it was not - so now I have a new spare item plus a fully functional second hand one in the parts bin.

It's very easy to ascertain whether the servo is faulty - without building it out, simply loosen a few turns ALL the screws on the flat plate on the back of the servo. It is the foremost part of the servo unit, facing forward in the engine bay. 

Objective of that plate is to keep the big piston on the vacuum side in place. The piston, and the rod fitted to it, can move 2-3 mm further out without anything coming out of alignment.

If drops of fluid comes out, you have established where the fault is.

If it is hard to get access to the screws, build out the servo. It takes 15-30 minutes for an experienced person. 1 hour for the un-practiced DIY mechanic.

As Enigmas said, the brake system is single circuit. Little you can do about that, for making it a two-circuit system requires one extra output line for brake fluid off the servo plus re-piping all the brake lines. Big job considering that should a leakage occur after you've mended the current fault you will always notice during driving if there is loss of brake fluid by the manner in which the brakepedal feels. That's because it takes time for the fluid to be "consumed" or lost. If the car is parked for enough time for the fluid to disappear you'll notice the same as reported today.

Normally, the issue with the servo presents itself if the car has not been used for a while. A daily driver will nto develop the issues you've reported.

Happy Rovering !
Best regards, Christopher "from the Viking-Land of the ancient Rovers"

[percy]

Clive. A fully functioning handbrake is also essential on the P5. This is your back up and, if working properly, it will stop the car in an emergency. It is a very good handbrake but often incorrectly set up.

[clive]

Thanks again for all the comments, I've just ordered a servo kit from Wadhams and booked the car in for an extensive (and probably expensive) Braking system overhaul. A good garage I've used before that do a lot of work on older cars, some years ago they managed fixed my power steering that other garages gave up on!
Percy, yes the Handbrake is working very well, always holds the car of a steep incline.

[djm16]

I second Phil in recommending ditching the Girling MkII servo in favour of a Lockheed unit. I had several goes at rebuilding mine. Getting it in and out is not trivial given that the inlet manifold for the head is in the way.

[clive]

Oct 14, 2021 15:18:15 GMT djm16 said:

I second Phil in recommending ditching the Girling MkII servo in favour of a Lockheed unit. I had several goes at rebuilding mine. Getting it in and out is not trivial given that the inlet manifold for the head is in the way.

I'm a bit of a stickler for originality with my car so I'll stay with the Girling, I've just received the MkII Repair Kit. I agree it looks like a monster of a job getting that sevo out but I feel confident the garage will be up for the job.
I've owned my car 35 years and in all that time I'd say the braking system has been incredibly reliable and long lasting. Looking back, I had the Master cylinder/ pads done soon after acquiring the car and the front discs replaced 5 years ago and the brake fluid changed every few years, I don't think it was much more than that!

[clive]

The Car goes to the garage on Friday.
In the meantime I thought I'd try something out for my own curiosity to perhaps see were it's going. I topped up the fluid, It didn't need much and with the engine running I pumped the brake pedal and managed to get a reasonable amount for brake power back. I looked under the car, absolutely no sign of fluid anywhere on the drive.
Then something unusual happened, the car started smoking really badly with white smoke bellowing out. All I can think is the fluid is getting into the engine via the servo. Any thoughts on this?
Thanks.

[enigmas]

Leave the repairs to your brake specialist/mechanic Clive...and certainly don't drive the car in its present state. The brake fluid is being drawn into the inlet manifold via the vacuum hose to the brake booster. From there it is being burnt in the engine's combustion chamber and exiting the exhaust as white smoke.

I note that you previously stated that the brake master cyl and some brake components were overhauled 30 years ago. That's definitely a red flag issue to any professional mechanic. I'd also hazard a guess that the flexible hydraulic hoses are probably 60 years old. Any one faulty area can initiate a total brake failure on a single circuit system, so do have the whole system properly evaluated and restored.

[clive]

Oct 24, 2021 12:36:42 GMT enigmas said:

Leave the repairs to your brake specialist/mechanic Clive...and certainly don't drive the car in its present state. The brake fluid is being drawn into the inlet manifold via the vacuum hose to the brake booster. From there it is being burnt in the engine's combustion chamber and exiting the exhaust as white smoke.

Thanks for the warning and info, I wasn't planning to drive it, just to try and find were the fluid was going, I now know!
The car is going to be put on a trailer and taken to the garage and the whole braking system looked at.

[djm16]

White smoke in the exhaust after operating the brake is a standard servo failure mode. When you strip the servo, you will likely find scoring on the servo piston and cylinder.

Do you still have the filter present in the reservoir (to keep grit out)?

[clive]

Oct 24, 2021 14:05:30 GMT djm16 said:

White smoke in the exhaust after operating the brake is a standard servo failure mode. When you strip the servo, you will likely find scoring on the servo piston and cylinder.

Do you still have the filter present in the reservoir (to keep grit out)?

Doing this work myself is beyond my capability/space so the garage will undertake the work, yes the filter is still there and all looks good.

[djm16]

I realised you were having someone else do the work. Consider though that if there is damage to the control piston, either grit got in through the reservoir on refilling, or corrosion in the reservoir or downpipe caused it. So reservoir and downpipe might beneficially be replaced.

[clive]

Unfortunately My garage is having problem's with the Servo, they have replace all the components from the repair kit but the brake fluid is still getting into the Servo. I spoke to the garage and I get the impression the kit I supplied isn't very good.
I bought it on ebay but it looks identical and around the same price as the one J Wadhams supplies and from other places.
I feel sorry for the garage they're spending a lot of time on the internet trying to sort this out for me. It's looking like they might have to give up on the old unit and replace it with a modified one.
I had a feeling this was going to be a bit of a nightmare, even reading the posts here the problem isn't straightforward!
Any suggestions I could pass on would be gratefully received!

[MK IA Norway Viking]

Hello Clive,
I've done this myself and found it to be straightforward. 

I bought a genuine set from Wadhams and it worked very well for me. 

Ebay (aka Fleabay) is not necessarily reliable, for you might get overaged items or unoriginal kits which do not possess the quality you require.

When brake fluid enters, it is most likely to the vacuum chamber. There is a piston in there, which is about 20-25 cm diameter. That piston has a soft seal against the wall of the chamber and on the other side is vacuum, which is fed by the engine. If you can test whether the fluid enters the vacuum side of the piston it will be convenient to learn of same. If it stays outside the vacuum chamber, the matter is much easier to deal with.

Brake fluid enters the servo unit from the fluid reservoir via pipelines. In between the reservoir and the servo is the brake master pump. 

What probably happens is that the brake master pump exerts pressure on the brake fluid. This in turn exerts pressure on the long and thin rod (approx 10 cm long, 5 mm diameter if my memory serve me right) on the piston which is sitting inside the housing of the servo, where the brake fluid inlet and outlet is.


Fluid can leak along this long thin rod into the vacuum chamber. If the soft seal aroudn the piston/vacuum chamber wall is holding, then brake fluid will accumulate on one side of the piston. If the soft seal is not holding, brake fluid will travel past it and enter the vacuum line to the manifold, into the cylinders and out with the exhaust.

I recommend to get a genuine set from Wadhams and fit those parts instead of the ebay products. The workshop / garage to gently clean/remove build-up of "old brake fluid" and old deposits that could prevent seals from doing their job properly.

I hope the above will help you to get a fully functional brakeservo.

[MK IA Norway Viking]

Clive,
I like to add that vacuum must not be allowed to travel between the wall in the vacuum chamber and the piston. The soft seal is meant to prevent this from happening. If vacuum is allowed to travel between the piston and the vacuumchamber wall, it will suck brake fluid into the vacuum chamber. 

Therefore, the wall of the vacuum chamber must be totally clean and the soft seal have a perfect fit. Cleaning might be required in case of deposits from the brake fluid that has been in there (emptied out when the servo was serviced). 

[lagain]

If it is possible to buy a new servo that is suitable I would do that.
If it is the original it could be that the bores are very slightly corroded and the new rubbers are not a snug fit.

About 25 years ago I used a servo repair kit on the original servo, when I changed to silicone fluid but the servo did not work properly afterwards and I had to buy a new one. Since then I have replaced the seals several times with no problems.

Best to buy rubber seals from Wadhams as he probably has a good turn over and the rubber should be fairly fresh. Rubber has a fairly short shelf life.

[MK IA Norway Viking]

Nov 5, 2021 16:42:44 GMT lagain said:

If it is possible to buy a new servo that is suitable I would do that.
If it is the original it could be that the bores are very slightly corroded and the new rubbers are not a snug fit.

About 25 years ago I used a servo repair kit on the original servo, when I changed to silicone fluid but the servo did not work properly afterwards and I had to buy a new one. Since then I have replaced the seals several times with no problems.

Best to buy rubber seals from Wadhams as he probably has a good turn over and the rubber should be fairly fresh. Rubber has a fairly short shelf life.

I again has some valid points. My view is that the wetted parts of the servo are the ones that are presently giving a problem. As they have been wetted they are unlikely to corrode. Rather it is a question of either old rubber from ebay, which is overaged and not sealing properly, or the walls of the vacuum chamber have deposits that must be cleaned. 

Surely, a brake workshop will know how to do this.

So, my conclusion is "try again", only this time with parts that are more likely to perform according to design.

[clive]

Nov 5, 2021 16:18:55 GMT MK IA Norway Viking said:

I bought a genuine set from Wadhams and it worked very well for me. 

Ebay (aka Fleabay) is not necessarily reliable, for you might get overaged items or unoriginal kits which do not possess the quality you require.

Thanks for your input, I'm not so critical of "Fleabay" I've made many a worthwhile purchase from there.
The servo kit I purchased on ebay looks identical to the Wadhams kit going by the picture comparison. so I could have been in the same situation.
As recommended here and a suggestion from the garage I've now decided to go for a new Lockheed unit as used on the later V8 cars.
I'll let you know how I get on, again thanks for all the posts. I've certainly learnt a lot.