I've noticed that some RM's have the Cummins B6 5.9 engine fitted, I am guess ing that these ones are the turbocharged ones from lorries?

Does anyone know what fluid flywheel was used on these engines?

Or if the engine with turbo would fit in a refurbished RM engine bay?

The 130 hp output is roughly in line with a 9.6 AEC engine

My bus had a Cummins engine before it was removed so it seems the sensible option to put one back in.

My bus number (if any): RML 2547

Don't go there. This is a major operation, which took Marshalls, Cummins and Alison some time to not get right and the vehicles were withdrawn before all the problems were tackled. The list of required substitutions would include the gearbox, the Power steering arrangemonts , ditto brake hydraulics, the radiator, the exhaust system and the list goes on...

Thanks Roy, I do have a C6 for the bus but it needs a rebuild, thought this might be an easier route

Matt

My bus number (if any): RML 2547

Roy you are spot on, there were on going mods that were never completed & from what I've seen the same mods were different on each bus. Paul.

Chris Sullivan commented that some of the work done on the bus looked a bit unique!

My bus number (if any): RML 2547

I'm sure you are right about this not being a recommended course of action Roy, if all this stuff has to be sourced and reaplced, but there were any number of RMLs re-engined with a Cummins engine plonked in basically on the original AEC set up including the original gearbox. We had one, RML 2667. There were of course some electrical changes done on the RMLs to facilitate the Cummins engine but certainly no requirement to change anything like was done on the Marshall's RMs. Is it the engine used in the refurb'd RMs or proposed by Matt as opposed to that used on the RMLs that causes all these problems?

My bus number (if any): RTL 960 RMC 1458 RM 1585 and several RTs

Hi Brian,

When my bus had a Cummins C6 it had cab wiring panels changed and all the usual changes like the automatic gear changer circuitry, so for simplicity, it seemed easiest to go back to a Cummins engine.

The only drawback is the fluid flywheel is missing off the spare seized up engine I have, I have the bowl but not the voith coupling.

IF spacewise a 5.9 with the turbo would fit as itis somewhat smaller than a C6 physically, all I would need to change is to a fluid flywheel I can see?

Matt

My bus number (if any): RML 2547

All of the RMs or RMLs that were fitted with the smaller B-series engine had an Allison gearbox fitted directly to the rear of the engine under the old flywheel covers. The larger Cummins C-series engine as fitted in the earlier late 1980's / early 1990's engine conversions retained the original centrally fitted gearbox (with standard compressor and brake pump set ups) but had various different flywheels fitted in place of the standard J156 RM flywheel unit.

As far as I know, a Cummins B-series engine has never been fitted with a flywheel in an RM transmission installation.

My bus number (if any): RM1368

To the best of my knowledge there were two main reasons why the Cummins 6BT (5.9l) required a different gearbox. The engine idles too fast for a fluid flywheel to be able to work as designed. ie the bus is trying to move away when it is idling, this would result in very fierce gear engagement when stationary or the flywheel overheating if left in gear. The Wilson type gearboxes were considered to have come to the end of their lives and were not deemed capable of running in service for the further proposed 10 years.

I am sure if I ask very nicely,Paul will easily be able to quote from the list of problems with the power steering and brake hydraulics arising when these and Scania engines were installed.

Hi Andrew

Presumably these B6 engines with auto boxes would have had fluid flywheels?

I believe that a Leyland fluid flywheel may fit the C6 engine

Mind you, if the prop was lengthened I can't see why using a B6 with a fluid flywheel isn't possible, as long as the ancillaries of the C6 and B6 were adequate?

Maybe they decided the b6 wasn't as good with a loaded up bus, however mine is only going to be a class 5 and non psv (less than 8 passengers carried) so the b6 should be ok.

My bus number (if any): RML 2547

Ok Roy, so looks like I will have to go with the C6 engine after all.

Which explains why they had a different auto box for the B6!

Thanks for the info, now I know which route to go down for sure

Matt

My bus number (if any): RML 2547