Oil Drop on the disk brakes tank cap

Lorenzo · Jul 21, 2015

dear all,
I am keeping having a small drop coming out on the top of the tank cap of the front disk brakes.

I already did a full service to the front brakes re-sleeving the piston, adding a stainless brake line and refurbising the caliper. It is working very wall and it is very effective, but since few times I am keeping having this drop from the small hole of the cap.

do you have suggestions? what is it?

daveparry · Jul 21, 2015

Is the rubber seal in place under the cap?

Lorenzo · Jul 21, 2015

daveparry said:
Is the rubber seal in place under the cap?

.. gosh.. yes.. it should be there..

peter12 · Jul 21, 2015

I have the same, haven't liked into it yet.

1up3down · Jul 21, 2015

my guess is that there is too much brake fluid in the cylinder

easy to overfill unless one takes into account that the rubber seal raises the level considerably when the cap is screwed back on

Lorenzo · Jul 21, 2015

1up3down said:
my guess is that there is too much brake fluid in the cylinder

easy to overfill unless one takes into account that the rubber seal raises the level considerably when the cap is screwed back on

thank you for your kind help

if the seal was just fitted and the oil was just filled, than it would make sense
on the contrary it seems that the oil brake was not just filled and I have it there since a bit less than a couple of year
it seems this is just happening now and it was working ok until a couple of weeks ago..

Nater_Potater · Jul 21, 2015

Lorenzo said:
it seems this is just happening now and it was working ok until a couple of weeks ago..

I'm thinking item #9 (http://www.oldbritts.com/nor_comm_73_22.html) may be torn. This is bad, not so much from a leakage standpoint, but that water is now getting into your brake fluid. If it is in fact torn, be sure to flush the system with plenty of new fluid once you have the replacement parts in hand.

Nathan

L.A.B. · Jul 21, 2015

All original bellows diaphragms should have been replaced with the later 3818-747 diaphragm by now?

The later type diaphragm increases the reservoir fluid capacity.
Note that the 3818-747 diaphragm should be folded before the cap is refitted, do not replace the cap with the diaphragm extended.

The later plastic reservoir caps also have a paper gasket between the diaphragm and cap.

Oil Drop on the disk brakes tank cap

Lorenzo

daveparry

Lorenzo

peter12

1up3down

Lorenzo

Nater_Potater

L.A.B.

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