Leaking Brake Fluid?

[mrs.smith2012]

Morning all,
Following a helpful comment on YT, it occurred to me I hadn’t checked Nellie’s brake fluid levels since getting her in Jan

I checked over the weekend… judging by how much of a faff it was to get to the master cylinder (somebody had literally screwed the carpet down under the seat so couldn’t actually lift the carpet without unbolting the driver’s seat - is that normal?) and how seized up the bolt was - I suspect it hadn’t been checked in quite a while.

It was almost empty! I have topped up but am concerned that it’s possibly leaking somewhere… although having checked round behind the wheels I can see no evidence or any leaks.

Underneath it’s hard to tell as it’s all very mucky, there are a couple of oily looking ‘drips’ but I don’t think they are brake fluid… they have no smell to them. Also I’m embarrassed to admit, I’m not entirely sure if I’m looking at the right area? I don’t suppose someone has a clear photo of what the master cylinder looks like from underneath the car… google is mainly giving me photos of master cylinders on their own - not fitted to the car

If she is leaking, it’s not an obvious one… but I want to be sure!
Thank you

[myoldjalopy]

It is normal for the front seats to be bolted down through the carpet. Having said that, it should be easy to simply fold the carpet back from under the pedals to access topping up the MC. You cannot see the MC from under the car as it is contained within the chassis leg. Most likely place for leaks is from around the MC itself, or from around the slave cylinders at each wheel (pipe joins or cylinder itself). There is a little plate around the MC which can be removed after removing its screws so you can then see the MC itself.
If you cannot find a leak, check on the fluid level in the MC regularly and see if it drops again. It may be a recent leak, so don't drive very far before checking again and be sure you have a good, firm pedal. Obviously a bit worrying, and it may be that you ought to take it to a decent garage to have it checked over if you are not sure yourself about this.

[mrs.smith2012]

Thanks for the feedback.

Pedal feels fine, nice and firm, not sinking at all. I’ll check the level either today or tomorrow to make sure it’s not going down but this makes me realise I need to become competent at jacking the car up as the biggest issue I have is being able to do much under the car when she’s not lifted- I’m not big but it’s a very tight squeeze haha

When you say a little plate do you mean the one you can see from inside the car?

[myoldjalopy]

Yes, it covers the MC and has a hole in it to access the filler plug. It looks like this, but yours may not be so clean and shiny! https://www.morrisminorspares.com/brake ... te-p829370

[mrs.smith2012]

Yes, it covers the MC and has a hole in it to access the filler plug. It looks like this, but yours may not be so clean and shiny! https://www.morrisminorspares.com/brake ... te-p829370

Haha no, mine is absolutely grim!

Well once it stops raining I shall get Nell uncovered and take another look. If she’s definitely losing fluid and I don’t know from where I will take her to get looked at properly - but hard to know at the moment… fingers crossed it was just neglected!

Thank you!

[simmitc]

I'm really impressed by how quickly you have gone from never having sat in a Minor to being able to write knowledgeably about the brakes

On a standard Minor, there are two pipes coming from the MC, one exits to the rear of the log, through the cross member, heading for the rear axle. The other comes out of the left hand side of the leg near the gearbox support and then heads forwards. A leak could occur at any connection point, any cylinder, and the three flexible hoses. You can inspect the wheel cylinders by removing each wheel and brake drum. On a dry day, spread newspaper on the drive and secure. Park the car over the paper and leave it. Any drips will be obvious.

When working under the car, do not rely on a jack alone. The jack can raise the car, but the car should be supported on stands and the wheels chocked. A block of wood between the stand and the car can hgelp to spread the load. A trolley jack is better than a scissor jack or the standard Minor one.

Hopefully the low level was just lack of maintenance and all will be well. If the fluid is old, then it should be replaced. Yellow fluid is DOT4, purple is silicone. Silicone is much better, but cannot be mixed with DOT4, any change will require lots of replacement parts.

[mrs.smith2012]

Haha thanks, I’ve had lots of help from Google… and on here! I’m still fumbling my way through.

Good tip about the newspaper… it’s soaking wet out at the moment but once it dries up I’ll be sure to do that. When the rain does let up and I can get Nell’s cover off I’ll check to see if the levels have dropped… if they HAVE then further investigation is required! Very hard to pinpoint links when everything is soaking

Judging by the little bit of fluid that was left it looked yellowish in colour so I assume it’s DOT4 - hope so anyway

[mrs.smith2012]

Well happy to report, I checked the brake fluid again today and it has not moved… so IF there is any sort of leak, it’s not a big one. I will of course keep an eye on it.

I did intend on removing the metal cover to have a look at the master cylinder but the carpet underlay made that pretty much impossible… a previous owner has basically stuck the underlay round the edges so it’s all sealed down, with a little flap cut in so you can get to the bolt and check the fluid level. You would have to rip the underlay out to actually remove the plate… not a job I want to do unless it was necessary… ie I have evidence to suggest she is definitely losing fluid

I’ll check the fluid level again in the next week perhaps although I’ll keep an eye out for any signs of actual leaking… so far I haven’t seen anything so…. All good I hope!

[mobylette]

Nobody has mentioned that the fluid level will drop as the brake shoes wear. But with brakes you cannot be too careful/vigilant.

[mrs.smith2012]

Nobody has mentioned that the fluid level will drop as the brake shoes wear. But with brakes you cannot be too careful/vigilant.

Oh really, well that’s something to keep in mind too! Thank you

[Bill_qaz]

I don't no about standard but I have recently fitted replacement carpets and only the rear section has the seat bolts passing through it. The front section stops at the seat frame, so can be just rolled forward to access the master cylinder filler plug.

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[Chief]

a previous owner has basically stuck the underlay round the edges so it’s all sealed down,

If it's the original underlay it should have a bitumen ("classic latex") backing so it may peel up without destroying it (with care):
https://www.martrim.co.uk/car-trimming- ... e-felt.php
Presuming that side is facing down of course

[Bill_qaz]

a previous owner has basically stuck the underlay round the edges so it’s all sealed down,

If it's the original underlay it should have a bitumen ("classic latex") backing so it may peel up without destroying it (with care):
https://www.martrim.co.uk/car-trimming- ... e-felt.php
Presuming that side is facing down of course

If the underlay is stuck to the floor but not the carpet you could just cut an access hole in the underlay, to save pulling it up.
I used modern sound deadening which sticks to the floor and just cut a hole for topping up brake fluid and same on passenger side to fill gearbox oil.

20260124_140304.jpg (1.39 MiB) Viewed 18096 times

[mrs.smith2012]

I don't no about standard but I have recently fitted replacement carpets and only the rear section has the seat bolts passing through it. The front section stops at the seat frame, so can be just rolled forward to access the master cylinder filler plug.
IMG-20260131-WA0005.jpg

Funny because the passenger seat isn’t bolted through the carpet, you can just take that one out, but the driver’s side is. It was also VERY awkward trying to manoeuvre the carpet off the pedals. I’ll probably look at replacing the front carpets at some stage, I like the fact they are probably original but they are in pretty poor shape.

[mrs.smith2012]

a previous owner has basically stuck the underlay round the edges so it’s all sealed down,

If it's the original underlay it should have a bitumen ("classic latex") backing so it may peel up without destroying it (with care):
https://www.martrim.co.uk/car-trimming- ... e-felt.php
Presuming that side is facing down of course

If the underlay is stuck to the floor but not the carpet you could just cut an access hole in the underlay, to save pulling it up.
I used modern sound deadening which sticks to the floor and just cut a hole for topping up brake fluid and same on passenger side to fill gearbox oil.
20260124_140304.jpg

That’s a good idea. A previous owner has cut a flap in the underlay but it’s only big enough to allow you access to top up the brake fluid, not access and remove the plate should you need to. But yes I could make the hole wider!

[mrs.smith2012]

That’s a point… gearbox oil… another thing I hadn’t thought of!

Should that be part of my weekly checks?

[mobylette]

"There is a checklist on this very club website under the tech tips section:- http://www.mmoc.org.uk/index.php?page=330

WEEKLY CHECKS:

1. CHECK TYRE PRESSURES.

2. CHECK ENGINE OIL WITH DIPSTICK

3. CHECK BRAKE FLUID LEVEL (reservoir is under the carpet where your left heal goes)

4. CHECK WINDSCREEN WASHER LEVEL

5.CHECK RADIATOR LEVEL AND REFILL WITH A MIXTURE OF ANTI FREEZE AND WATER.

6. CHECK ALL BULBS WORK ESPECIALLY THE BRAKE LIGHTS


EVERY 3000 MILES:

Top up the dash pot on the carb. This unscrews by hand. Add a small amount of thin oil until it is 1/2 inch above the interior lip. If you overdo it will escape from the little hole in the top.

Tighten the fanbelt as necessary I try to turn the generator pulley by hand If I succeed easily the belt needs tightening. Do not overdo this as it will wear out the water pump bearings

Grease all the grease points. There are two on each leg, one on each steering arm ball joint, one on each handbrake cable, two on the propshaft and one on the steering rack. This last one only requires oil not grease. It is possible that the handbrake cables and the propshaft do not have the nipples any longer as new parts often have these deleted.

Adjust the brakes. While the front wheels are off for the greasing, you can get at the brakes. Look through the hole in each drum with a torch. You will see two screw head adjusters in each of the front drums. Turn each clockwise until it locks and then come back one click. If you reach the end of the adjustment but you can still turn the drum the shoes need replacement.

The rear brakes are adjusted in the same way but there is only one adjuster per side. This is at the front of each drum. Do this with the handbrake off and make sure the cables do slack when the handle is down.

The Clutchshould have 1 1/2 inches of play on the pedal (3/4 on non 1098 models). If not, then the adjuster is between the gearbox and the chassis leg. Be careful as there is a locknut on the end off the rod as well as the adjusting nut. Lubricate all the joints while you are under there.

Oils: Check the gearbox oil level. The filler is accessed from inside the car. Lift the carpet on the passenger side and remove the filler plug. The oil should be to the bottom of the filler hole. Use engine oil to fill it except on the MMs which require EP 90. Also check the axle level. Remove the filler plug and the oil should be to the bottom of the hole. Use EP 90 on all models.

[geoberni]

That’s a point… gearbox oil… another thing I hadn’t thought of!

Should that be part of my weekly checks?

This is a scan of the Lubrication Chart in the SII Operation Manual I have, what they then called the glovebox Owners Manual that would have come with every car; I don't believe much if anything changed for the S3 and 5.

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[Bill_qaz]

I don't no about standard but I have recently fitted replacement carpets and only the rear section has the seat bolts passing through it. The front section stops at the seat frame, so can be just rolled forward to access the master cylinder filler plug.
IMG-20260131-WA0005.jpg

Funny because the passenger seat isn’t bolted through the carpet, you can just take that one out, but the driver’s side is. It was also VERY awkward trying to manoeuvre the carpet off the pedals. I’ll probably look at replacing the front carpets at some stage, I like the fact they are probably original but they are in pretty poor shape.

Yes i think mine were original but very tatty and someone had cut the driver mat probably for the same reason. I was lucky to come across someone selling a complete unused quality set in the correct colour and snapped them up at a very good price. Once fitted around the pedals they no longer have to be disturbed. I did cheat and cut a slit to the steering column hole to save removing the column. You have to make holes for the seat bolts and seat belts if you have them. If you use a soldering iron to melt the hole it stops any fraying.
Part way through fitting

20260126_143041.jpg (1.59 MiB) Viewed 17219 times

[mrs.smith2012]

Wow thank you everyone for such helpful feedback, those checklists will be incredibly useful, I’m still learning what I need to do and when. Greasing is on my list. She was greased shortly before I got her so she should be good for some time but it’s something I want to learn how to do soon!

Those carpets look smart… wow the list of things I want to do and learn for Nell is endless! It’s so fun though!