Hi, interesting problem with my 1973 e-type, one brake reservoir level drops and the other increases to overflowing. Reservoir for master on the firewall is dropping, reservoir down below next to washer bottle is overflowing. I suspect the servo (slave?) that the overflowing reservoir is attached to has leaky seals allowing hydraulic pressure to run up the filler tube to the reservoir ?
Thanks all,
Steve
This is a bad seal in the servo cylinder. The seal stops fluid from going from one circuit to the other
I will find a diagram and post
Dennis 69 OTS
Bad seal has blue pointing to it. Or the cylinder is badly scored
See photo with colour mark pointing to seal L
Dennis 69 OTS
Hi Dennis, thanks for the reply, yes I guess I’m pumping fluid from one reservoir to the other with a leaky seal in the servo cylinder. I couldn’t see any color in your diagram but I can see where the seal is at L on the piston. Do you know any good online suppliers of a rebuilt cylinder or rebuild kit that ship to Canada ?
Thanks again for your help !
Steve
I buy from XKs unlimited in California and they ship to Canada. Shipping is expensive!
I am not aware of any Canadian suppliers.
You may need to sleeve your service cylinder depending on its condition
I (in Vancouver) am not aware of any reliable Canadian machine shops so I sent my servo cylinder last year to a US company to be resleeved. I had the same problem you have
My servo cylinder was original and had erosion pits due to moisture that allowed fluid to go from one brake circuit to another.
If you want the name of the US reslerving company, contact me offline
Dennis
69 OTS
Before you despair, two things that might help or at least reduce the problem:-
1/ Move the slave reservoir up to the same height as the master reservoir. This means that if the link between the two circuits perpetuates, you won’t lose all of your brake fluid overnight. There will be less head of liquid to gravity feed the wrong way.
At the moment you are only pumping a small amount of liquid from one circuit past this seal to the other every time you operate the brakes, as the piston in the slave doesn’t move forward and back exactly proportionately 1:1 and the seal sticks a bit before it travels with the piston. It can get worse if that link becomes permanent.
2/ Bleed the brakes and as the fluid from the reservoir drains, pack it with red grease and then top up and fully flush through. You may be lucky and find that lubricating the piston/seal will solve the problem. If you do this to one brake circuit first, then you may see the confirmatory red colour in the wrong circuit.
kind regards
Marek
Hi,
Thanks again Dennis (I’m originally from Vancouver, now on Van Isle) and Marek, very interesting ideas raising the reservoir and the packing with red grease to lubricate the seal. I’ll start by shopping around for a new cylinder. Thank you both so much for your time and expertise !
Very appreciated !
Cheers,
Steve
It might be that your existing servo can be fixed with a light honing of the cylinder bore and a rubber parts rebuild kit. But one can’t determine this until it is taken out after which you run a hone inside it and see if the bore is clean or pitted badly
If I can help, do Private Message me
Dennis 69 OTS
Steve,
I have spare servo whose cylinder needs resleeving and a new rubber parts kit that I think is pretty complete so if any of this is of use at no charge, do private message me!
Dennis 69 OTS
Marek, I would not think this to be the best approach. Clearly, there is an issue somewhere, probably in the servo. These seals do not typically fix themselves, it will only get worse. And as a brake issue, I would much rather see the issue resolved, not masked. And it would probably be more work to move the reservoir than to simply fix the problem. IMO.
Tom
I’m not suggesting you mask the problem. It’s a good idea to move that reservoir irrespective of whether you have a problem or not, as it eliminates one of the failure modes which could leave you with no brake fluid.
There isn’t actually a braking problem here. The problem is that the seal between the circuits doesn’t move 100% smoothly along the piston/bore all of the time, but “burps” a tiny amount of fluid past the seal every time the brakes either start to be applied, or start to be released. That’s what needs to be cured and it either needs a new seal on the shuttle and/or smoother bore/piston for the seal to run along.
If this small movement of brake fluid becomes a greater problem leading to a permanent path between the two circuits, then you risk losing all of your brake master fluid as it’ll simply gravity feed the lower reservoir as you lose the entire primary circuit. Moving the slave reservoir upwards is simply a sensible thing to do as the worst case scenario becomes much less worse, irrespective of whether you have a leak or not. It’s just a better design.
kind regards
Marek
It sounds to me that you are describing a braking problem. One of fluid getting past a seal to where it should not. In this case, instead of the fluid ending up on the ground, it ends up in the other reservoir. If/when this seal would fail totally, and I know fortunately most brake seals do not fail all at once, but as it fails, either front or rear brakes will fail, I believe on later cars, the fronts. And that will be very noticed. Also, and maybe I am incorrect, you mention the seal issue as one occurring as the piston moves. I thought some owners said the issue of fluid transfer was overnight, when the brakes were not being used. You make somewhat of a point of the fluid loss staying in the system. IMO, that is not worth moving the reservoir. One could make the case that by losing the fluid and turning on the light, the real problem will be fixed sooner than later. But to me, that is a mute point.
Either way, the owner may do as he pleases. I just personally do not see moving the reservoir as part of a solution.
Tom
I predict that a cylinder hone and a new seal will sort the problem. Unless there is pitting that cannot be removed in which case a re-sleeve or new servo is needed.
I am sending Steve some seals and an old servo so I think he will be reporting when it is all apart!!
Dennis 69 OTS
