TR7 brake servo reservoir level going down

[UKPhilTR7]

Some time ago, I thought that the level in my brake servo reservoir was going down (be it very slowly). This was combined with small drips discovered under the car over the last couple of months. The drips are only small and appear to be coming from the rear of the engine/start of the gearbox. I am just hopinbg that it is not the Crankshaft seal that needs replacing. However, this would not explain the servo reservoir level going down though and they are not oil. Great, that bullet has been dodged lol.

I have followed the break lines as far as I can and I cannot see any damage or signs of leaks. Nothing that would be falling on the engine and resulting in the drip marks where they are. However, as it can be seen from the picture below the right hand side of the tap shows where the level was a few months ago compared to the level now. There is no sign of liquid near the breaks or anyhting.

Has anyone come across anything like this before and any ideas where to look?

[Cobber]

As your brake pads & shoes wear, the caliper and slave cylinder pistons move out to take up the slack, the fluid fills this void, thus lowering the level in the reservoir.
When you change pads and or shoes you push the pistons back to allow for the extra thickness and this will push the fluid back in the reservoir, up to the original level.

[FI Spyder]

Are you saying the drips under the car are not oil? If not, are they brake fluid or coolant (the only two other choices).

That's not a lot of brake fluid as the slope of the top of the reservoir magnifies the level it's down. Slight leaking at rear cylinders? You would have to peel back the edges of the dust boot to see if it is wet and not necessarily see a puddle by the rear tire.

[skertonman]

Slight weepage from the master cylinder into the servo unit itself. Sometimes it can show as paint contamination on the outside of the servo under the bottom of the master cylinder where it bolts onto the servo.

Are you able to mark the level on the resovoir, and check it in a few days to see if it is going down, if it's leaking then it will go down slightly.

[UKPhilTR7]

Thought of the pads wearing and forcing the level to go down a bit, but then I wondered about the drips on the floor. I am having real trouble trying to track down where they are coming from. Another day under the car I think. Good job my trolley has been fixed.

I have to take of the back wheels soon to figure out why the passenger side is jamming. Should tell me if there is a leak there or not.

[Hasbeen]

How old are your brake hoses? The passenger rear wheel cylinder is fed via the drivers side. If there is any restriction in the hose that feeds fluid to the rear axle it causes the pressure applied by booster pressure to be very slow to be returned by the shoe springs. As the passengers side is at the end of the line, it will bind more than the drivers side.

I found the hoses on 7s were deteriorating about a dozen years or more ago, with the inside of the hose combining with the brake fluid to form a substance like thick toothpaste. This stuff is hard to force back towards the master cylinder, holding line pressure, & causing high brake drag & temperature.

Try cracking the bleed nipple on that wheel, to see if any fluid actually squirts out, indicating it is under pressure. If that frees the brake, you have a partial blockage in the system, most likely in the hose.

Of course due to the angle of the wheel cylinder that do tend to get water in them & rust. Most of the 7s I have bought have had one or both wheel cylinders rusted solid when I got them.

Hasbeen

[saabfast]

It may be coincidence. The brake fluid level will drop with pad wear as noted but, if the fluid on the floor is brake fluid, the slight leak could be from the clutch slave around the area you note. The other favourite place for a small leak is the rear wheel cylinders. Would not explain the drips around the trans but may contribute to the brake fluid loss. Peel back the cylinder rubbers and see if it is wet inside there.

[UKPhilTR7]

Went down to the garage the weekend and the level still seems to be going down slightly. Now it is towards the writing on the right hand side of the picture. I have not had chance to take the rear wheels off yet but it is on the list of jobs to do.

[busheytrader]

As per Saabfast's experience. Drips underneath the rear of the engine / gearbox happened to mine last year, due to the clutch slave cylinder leaking. It was the original factory fitted item that was carried over to the V8 conversion, at 36 years old it had done pretty well.

Ive also gone through several brake drum slave cylinders which have corroded and then leaked as well. One pair of brake shoes became contaminated which eventually caused the lining of one to brake free and lock the wheel up in reverse.

Adam

[dursleyman]

Don't forget most brake fluid is very aggressive on your paintwork and will strip it off pretty effectively so if its leaking inside the car best to fix it asap.

[UKPhilTR7]

Oh yes it is next on the list. The level keeps on going down, so the rear wheels have to come off soon.

If it was the clutch would that not result in the clutch level going down, not the break level?

[dursleyman]

Yes the clutch is a completely separate system to the brakes. Check the level in the master cylinder, if the slave cylinder is leaking you will see a pool below it on the floor. If the clutch master is leaking you will see something like this one on my car. There was also a little dip appearing on the floor mat.