One of my customers has reported total brake failure on his RM whilst abroad. Luckily no-one was injured. The failure happened while the bus was going down hill, no it wasn't brake fade, no pressure at all on the hydraulics at all.

Anyone with any ideas? Apparently it's had intermittent failure before, and it happened again 3 times yesterday.

Brake oil level is ok; handbrake works but needs adjusting again; brake pump is engine mounted; slack adjusters work.

Roy,
What Scania conversion was it?

Rob

My bus number (if any): RM1797

Don't know, I've heard that there,s 2 types of brake pump fitted. It's an ex Brixton bus. I don't want to reveal the identity of the bus at the moment.

Another learned regular on here has given some useful input; the verdict so far is that there's been a number of instances of brake failure on Scanias which has been the pump drive suffers intermittant failure, or the foot valve is by-passing.

hi roy. give me a call on 07881897945.
regards.
tim.

My bus number (if any): rm2023 2097 & RML2388

An update on this thread, the bus made its way back to the UK this weekend; the "other" roy and myself spent the day testing the hydraulics.

The top accumulator had very little pressure as the Schraeder valve had some foreign matter in the valve. that was changed, the sytem recharged and thoroughly tested. The cut-out was tested for cutting in and out; system checked for the number of apps. brake line pressures etc.

With the top accumulator down, we found the front brake pressure dropped quite quicly. We suspect that with the back brakes being out of adjustment, this probably caused the total brake failure in the first instance. The client was warned last year the bus needed new slack adjusters but they didn't appear to want to spend the money, despite the bus constantly touring Europe, doing probbaly 40,000 miles a year.

As for possible brake pump intermittant failure, we decided to leave that to a Scania dealer as neithe rof us have dealt with Scania RM engines and there may be a problem sourcing parts.

Having removed one of these tandem pumps in the past on a vehicle with much better access, it was decided to leave the problem to someone else. This is a heavy lump of ironwork with large bore, allegedly flexible pipes to reconnect at reassembly - all done at arms length and with some of the mounting bolts requiring mirrors to see. Vague memories of having battled with Scania oil coolers and water pumps in the past, allied to the potential for spending hours on the telephone attempting to find someone on the same planet from whom to acquire parts, means that there is no point in getting older if one doesn't get wiser. Let the main dealers earn their money for the 'book time' and as an added benefit, the customer a glimpse of main dealer rates.

I'd like to thank Roy for his help and input! I think we both got older a nd a bit wiser.

Havine had a better look under that bus, the exhaust is completely shot fro the cross pipe from the cataclysmic converter to the tailpipe! Lucky I have everything in stock except an adaptor to take something linke a 100mm pipe down to 68mm pipe!

I also have to change all the slack adjusters. Again, this was mentioned to the owner a couple of years ago but in their effort to cut costs decided not to get them done. The result was the above-mentioned total brake failure, which, luckily enough didn't end in multiple fatalities.

Why is it that bus owners in Europe (and to a degree here as well) seem to think these buses will do tens of thousands of miles at motorrway speeds with no preventative maintenance? Even the clevis pins on the back brake rodding were siezed solid! FFS, I'd oiled them last summer when I done a safety check!

Hi Roy out of interest did you put the clocks on? if you did, did you see any problems in building up pressure? or a very slow build up?
Tony

My bus number (if any): 1083

Yes, test gauges were used in every stage of testing. Pressure built up within the specified times at idling, fat idle and full revs.

Hello Tony,

This is one of those buses that is just itching to be a Coke can! It proved to be a pain to work on from start to finish. It had a Schrader valve that initially sealed but then commenced leaking after rechecking the pressure. Several attempts to tighten and reseal the core proved fruitless. Roy's new valves had decided that hide and seek was the name of the game and a new core was taken from a valve with a damaged cone to cure the seepage to allow work to continue. The bus had not given up however, since one of the accumulator test point connectors leaked constantly due to a damaged O ring. This proved to have a wall thickness that just isn't in four different boxes of assorted O rings. After testing the pressures and balance from the front boat (which were fine) a test point from there was substituted.

Microswitch pressures, cut out/in, pressure drop at rest, drop with engine running and finally drop brakes applied were all within spec. Build up at tickover gave the impression of being slow, but this Scania had a very low idling speed - even so it managed to cut out within time. All tests were repeated several times. Since these tests proved OK no further testing involving pipe disconnection were done.

Speaking to my namesake Roy last night, the Scania dealer has been advised to expect the vehicle shortly with instructions to remove and inspect the drive coupling. Roy now has a raft of other defects to rectify before it can be driven there.

What was very clear was that the vehicle had covered a lot of mileage since it had last seen any routine proactive attention.

All of which goes to emphasise the point of regular safety checks and preventative maintenance!

The entire exhaust system from behind the cat box has had to be replaced!

Our trucks are modern and up to the minute but they do huge weekly mileages and are still checked very regulary with a very thorough check before and after any long booked or international trip.

We cannot take chances with people drivers or the cargo. So we don't.

This is why it still bothers me that so many want to use Routemasters for a purpose that they were not built or equipped to do.

Private hires and such are fine as long as the regime in maintenance and upkeep is adhered to.

Driving and indeed conductor/attendant standards need to be as good as possible..or better.

Of course they are well built and can do more than they are designed for but not without a full schedule of checks and maintenance that addresses it's useage.

One day something really bad will happen and I suspect it will lead to everyone getting tarred with the same brush.

It really pays to be tougher than the rules require.

very interesting Roy and Roythebus, the scania Bn conversion didn't really work from day one, it was a complete waste of money time and effort,it was badly fitted, not thought out and done on the cheap. We had problem after problem when they came back from scania. a few problems like blowing brake lines, no power, harsh gear changes, oil leaks, after about 3 weeks into service .the rear x member where fracturing,it was a complete nightmare, I remember a conversation with my foreman at the time saying to him. Why are we doing all this work when scania should be doing it. his answer was it was done on the cheap and none of the buses that had the conversion done had any warranty, unless the engine blew up, I'm glad you have it sorted, shame though it's in pretty dyer condition

My bus number (if any): 1083

ON paper the conversion of this type of Scania should have been very good but it seems the execution was not so good and the slide rule was not really used properly.

I would guess that a few good engineers getting thier heads together and witha good understanding of the whole of the Routemaster could had (or still could ) eliminate the flaws and come up with a good solid drivetrain and power unit.

Word was that it was all done in a cheap rushed fashion not even allowing for a full testbed and proper drawings.

Pity really.

very true Jack, if your look at the new cross scania conversion there where differences.possibly one big factor they left the compressor and brake pump on the gearbox, getting rid of that was a good idea at the time since most of the common brake downs was either compressor problems or quill drive failure, but as you say it wasn't thought out, also cutting away the firewall was a complete bodge, why o why didn't they just put the engine on a slight tilt like the new cross conversion? also on the BN scanias the gearbox control panel wasn't adjusted like the new cross ones..BN scanias feel like they are going to smash the gearbox to bits every time they change gear where the newcross ones are very smooth. just a bit more thought would of made a good unit...shame

My bus number (if any): 1083

The LG conversion was thought through far more and to be honest modifying a BN conversion to the NX set up is probably a better and cheaper option than trying to get a bad execution ironed out.

This particular bus has quite a wierd gearchange; the auto stopped working in Italy about 4 weeks ago and was by=-passed to provide manul only. However,the gears seem to engage on a reduced air pressure, then "bite", almost as though the brake bands are slipping but the adjusters show little signs of excess wear.

Agreed, with a bit more thought this could have been an excellent conversion. the fact that this bus trots round Europe year in, year out without a murmur from the engine says a lot for the engine. that the rest of the bus gives trouble is in my view down to the owners failure to leave enough time for maintenance. I would guess it does about 60,000 miles a year!

The Scania engine is probably the best quality engine that has ever been fitted in these buses. It is indeed a shame that the installation and compatibility is such a cod's.

In conversation with another southern engineer yesterday, his description of the RM was, I thought, not only spot on; but brilliant:

"I have never met such a hormonal bus."