Good evening all,

2719 has developed a fault in the charging system. All of a sudden the battery light has come on whilst driving, and after a day of using lights etc, the batteries have depleted. I have recharged the batteries and she will start but the battery light remains on.

My mechanical knowledge leads me to the Alternator/Dynamo. Can these be repaired or is it best to be replaced, if so anyone got one for sale?

If anyone thinks it is not the charging system, can they point me in the right direction please.

Thank you and regards

Chris

My bus number (if any): RML 2719

To save you a huge bill and possibly an unnecessary one, Check the belts on the alternator are not slack or failed.
Check all the cables in the connector are OK and not severed or disconnected.

Then depending on the alternator check the charging equipment or get a good auto electrician to check it out.

David Colin is an expert on this stuff and he regularly visits the site so see if one of his entries carries his email

How long is a piece of string? Before we can try to make all but the simplest diagnosis, what engine has it got? Ivecos have at least 3 types of alternator, AEC too many to mention, Cummins at least 2, don't know about Scania etc.

My bus number (if any): RML2532

sorry guys it is a Cummins C engine, i though they had Dynamo but perhaps it is an Alternator

Thanks
Chris

My bus number (if any): RML 2719

OK, check the isolator switch, work it a few times as the charging wire goes through there on a separate contact; same fault happens with Metrobuses, you don't know it's not charging until you lose gears.

Starter motor part no.S115-24-22-R £482.40 inc VAT; money back on the old unit when you return it. I had to replace mine last week with the same problem.

Put a volt meter across the batteries to see what the voltage is, should be 24-26v, up to 26.9 with the engine running. If under 24v, the low volt relay will cut out and prevent starting.

I was not aware of a battery light on the RMLs, but then they're all different, depending on who modified them.

My bus number (if any): RML2532

To ensure the battery switch is okay temporarily join together the two small cables on the isolator. These are part of the alternator field circuit. When the switch is operated the small contact opens momentarily before the main contacts. This is to ensure the alternator stops charging BEFORE the batteries are disconnected. Alternator damage will occur if the battery is disconnected while charging.

So firstly make sure the switch is fully on. I have been caught out several times by this mainly when someone else has switched the isolator on for me. The telltale sign is the charging light being on but the position on my bus is next to the start switch and not always noticable unless you turn and look.
Try Roys's suggestion of working it on and off a few times.
If this doesn't work switch the isolator off, disconnect the two small wires and join together (or leave connected and short together using a piece of wire with crocodile clips), switch the isolator on again and then start the engine and check the warning light.

There are many possible causes, wiring faults, charging relays, Altenator connections and of course alternator faults that can cause this problem.

I never had a Metrobus isolator fail during my LT time. It was almost always an alternator field fault. Non start from the front but starts okay from the rear was a tell tale sign of an alternator fault. (gold star if you can explain why Roy).

CAV isolators are ridiculously priced so try the breakers. Most 70's and 80's buses have one of these fitted. Perhaps we should all go and get a spare one.

This last paragraph is repeated on another post!

David

My bus number (if any): RML2276 M1001 T806

I too had a charging fault last month; it was one of the small wires off at the isolator switch, simples.

Metro isolators, I had one fail to move, lost all gears, on the A1 coming back from Scotland. I told the driver to kick the engine doors in case one of the door sensors had lost contact; no luck, so told him to switch the isolator off and on. Hey presto, all gears came back in and charge light went out. Had the same problem with my Reliance, it had a trip to the seaside and back, driver switched off outside a school, non-start due to flay batteries. The isolator had been turned off at the seaside and not switched back on properly, enough to start, but not enough to make the charge circuit.

My bus number (if any): RML2532

"I never had a Metrobus isolator fail during my LT time. It was almost always an alternator field fault. Non start from the front but starts okay from the rear was a tell tale sign of an alternator fault. (gold star if you can explain why Roy)."

My gold star? I'd guess that the feed for the rear start button is taken direct from the battery, whereas the driver's switch feed is taken via relays, switches, interlocks and all sorts of things. They will always start from the rear, even with all the doors open, providing the isolator is on and there's enough battery volts to turn the engine.

My bus number (if any): RML2532

Not quite as only the engine door interlocks are bypassed by the rear switch. All others are still in circuit (in gear, engine running, Londex delay etc). It is a bit more specific and odd than that

When you latch in the bus the charge warning light illuminates using the alternator field as a return. When the alternator charges of course that return becomes a positive and the lamps exstinguishes( and glowing will occur if the battery and alternator field voltage differs). At the same time the field also energises a relay to prevent the starter operating when the engine is running.

Now when field fault occurs you will find that when you latch in the lamp will glow dimly and you cannot start the bus. This is because the charge light return has disappeared and the only route available is via the interlock relay which energises thus preventing starting. The reason it will start from the rear is because the bus does not latch from the rear. If the bus is latched in then the rear starter button is operated it will not work but pressing "stop" (to delatch) and then "start" again will start the bus

David

My bus number (if any): RML2276 M1001 T806

A far more detailed explanation there, I'll keep that in the memory module.

One i had in Belgium last year, a Metro, not charging. Searched all over for the voltage regulator, the origianl alternator burnt out so they binned it. The bus had been heavily modified, so I supplied a recon alternator. that didn't work, so I supplied another one. That too didn't work. Next visit was spent searching for the regulator. No sign of it.

More phone calls reckoned it had a built in regulator. So, return with that type of alternator. Still no charge.. sitting in the cab with the engine off, pressed the gear buttons, click click as gears engaged with everything turned off. Funny. So checked the relay panel. Most had been by-passed with bits of wire. so, look under the gear selector buttons. There was loose wire or two. So, taking a gamble, I put a feed on the warning light. Presto, charging commenced.

What had happened was the usual cut-up, remove middle doors, rip out all wiring, by pass everything, burn out alternator, just to get the bloody thing working.

The fun of working on converted buses!

ps I don't have a Metro wiring diagram and don't profess to be a bus electrician! But I reckon my reasoning in the earlier thread was on the right lines.

My bus number (if any): RML2532

Thank you everyone for your input

I have had the isolator stripped down and cleaned, this appears to have solved the problem. Once again your knowledge and experience has excelled.

Thank you for your help, as always it is greatly appreciated

regards

Chris

My bus number (if any): RML 2719

Glad it's all sorted. I'm currently in Germany trying to change a fuel pump on a Lodekka. They should have all been scrapped years ago; a tractor chassis with a bus body. How anyone can ENJOY these heaps of crap is beyond me, they're a pig to work on!!

My bus number (if any): RML2532

Just seen this last re a Lodekka. Oh the joys of a Gardner 6LX cambox oil drain O ring and connection; I just love that job! What is so wonderful about Gardners is that nearly all the oil pipe bolts are the same length, all are 5/16, but some are Whitworth and some are BSF and you have to know what the thread in the hole you can't see is.