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Brake Hydraulic system cleansing

We have had problems with an overfilled hydraulic system on a bus we have just bought back.
We assume there is a filter in the hydraulic tank, but where is it, and do we have to dismount the tank to get at it. Any advice welcome.
It is a Lockheed system.

Thanks in advance.

My bus number (if any): RTL 960, RM 1585, RML 2667 and several RTs

Re: Brake Hydraulic system cleansing

I am about to renew a footbrake valve so I have just removed the tank to flush it out. That is not the easiest thing to do, but hey-ho everything on an RM takes five minutes because that's how the legend goes.

There is a filter, but the tank will overflow all over the floor if you try to remove it without draining most of the fluid out first. Open the door on the o/s of the bus ahead of the fuel filler. On the front vertical surface of the tank you will find the drain plug, drain out about 10 litres. Remove the filler plug beside the sightglass and check to see if the level is below the bottom of the cover with no hydraulic pressure in the accumulators.. If it is remove the six bolts and cover, if not drain the tank. Visible will be a 5/16 BSF hexagon undo the bolt and remove the filter. Cut it open to see if it is blocked. Do not remove the horseshoe clip, it is exceedingly difficult to get back in place again. Renew filter and reverse procedure.

Tank removal if required is a matter of draining completely and disconnecting pipes. Remove as much dirt as possible. Clean carefully around all pipe connections to be disturbed and blank off pipes to keep out dirt. It is quite heavy and awkward to handle and manoeuvre. It comes out relatively easily it does not go back the same. It is important that the pipes are not strained when the tank straps are all tight. Clean the outside thoroughly. Remove the relief valve and Wash out the tank with fuel and drain thoroughly. Then add at least five to ten litres of brake cleaner and slosh around to remove all traces of the fuel. Drain thoroughly and let it dry. Clean the refief valve. When everything has been refitted and is tight make sure that the relief valve is not fouling the underside of the floor.

Prime the Plessey pump before starting the engine.

The level is correct when the oil is in line with the mark with fully OIL charged accumulators. When hydraulic pressure is nil then the level will be above the mark.

Re: Brake Hydraulic system cleansing

Thanks for that Roy, much appreciated.

My bus number (if any): RTL 960, RM 1585, RML 2667 and several RTs

Re: Brake Hydraulic system cleansing

Hello Brian,

Your copy of the Lockheed braking system Service Manual
Section 2 page 8 gives all the information required
to overhaul the hydraulic supply reservoir and it's contents.

Lockheed recommended that the filter be changed at intervals of not more than 50,000 miles.

The filter in question are common to all Routemasters irrespective
off the engine type fitted.

Filter Particulars are:-

1) OE Part No ALH 311A
FCL Ref No :- FCL 7474

Filtration Control Ltd
Filtration House
Units B/C
Longman Court
Skettby Close
Northamptonshire.NN4 7PL
Phone:- 01604 707750

2) Fleetguard Filters LTD

Part No LF563 stocked by

Filter Services (UK) Ltd @

Chesterfield UK 01246 802822
Leeds UK 0113 2451643
Leicester UK 0116 2601233

My bus number (if any): Ex LTE Bus Engineering. AMIRTE. CPC-HGV

Re: Brake Hydraulic system cleansing

Thanks Michael I had forgotten we had that!! I'll alert Philippe...
One thing I am not clear about, and manuals do not often cover, is little tips like Roy's advice about not removing the horseshoe clip as it is very hard to get back in place again.

What I was wondering Roy, and I have not looked at it, is how do we replace the filter with the clip in situ. Apologies if it obvious if you look at it!

My bus number (if any): RTL 960, RM 1585, RML 2667 and several RTs

Re: Brake Hydraulic system cleansing

The clip is underneath the filter holding the bottom filter locating plate in place. IIRC there is either a spring or a spacer under this plate. If NOT removing the tank one would be tempted to remove the clip to make cleaning in the filter cavity slightly easier.

Fleetguard filters should be obtainable throughout Europe from the Cummins dealer network.

Re: Brake Hydraulic system cleansing

Thanks for that Roy, Philippe was worried about how he got the filter out without disturbing the clip.
Thanks also Michael and Roy for the filter details>

My bus number (if any): RTL 960, RM 1585, RML 2667 and several RTs