DB maintenance: reduction?

Cookie_Monster

Have DB cut back on maintenance in recent months at all?

I've noticed a lot more buses in recent times belching out huge clouds of black smoke whenever the driver presses the loud pedal. Always used to see it on the odd bus but seems to me to be a lot more common and noticeable recently

variety of buses too: midi's, tri axles and AVs so not like it only the older ones...

Or maybe they're simply using Tesco diesel now :pac:

Drimnagh Road

What's the story with the AVs and some of the original VTs that roar / make hoover noise?

Christ the noise of them! It's like someone has removed a silencer or something.

I got off one on Drimnagh Road there off the nightlink not so long ago and I could hear the bus booting up Walkinstown for ages, it was comparable to an 071

L1011

Been told its wear from hilly routes, e.g. up the mountains or the 66 (Lucan and Leixlip both require some hill-fun, at both ends in Lucan's case) that causes the engine roar. Not sure how true that is, though. Especially seeing as I mostly hear 66s!

Cookie_Monster

Is that roar not something to do with the fans rather than the engine itself, i'm pretty sure someone mentioned that on here way back...

LXFlyer

Correct.

Run_to_da_hills

Cookie_Monster wrote: »

Have DB cut back on maintenance in recent months at all?

I've noticed a lot more buses in recent times belching out huge clouds of black smoke whenever the driver presses the loud pedal. Always used to see it on the odd bus but seems to me to be a lot more common and noticeable recently

variety of buses too: midi's, tri axles and AVs so not like it only the older ones...

Or maybe they're simply using Tesco diesel now :pac:

I started a thread on this subject almost three years ago.

Could our public transit system decay with cut backs during the recession?

The Skulls

I think i might be able to shed some light on this; i also noticed this over the last while,plumes of black smoke, bus vibrating like mad, engines roaring etc. One of my wifes cousins works for DB maintenance, it seem that maintenance were told to adjust the revs of the engines of the buses whilst the engine is idling e.g. in traffic. The revs have been lowered to the bare minimum needed to keep the engine ticking over thus restricting the amount of diesel being consumed (in theory), however when the bus moves off again especially up an incline the engine must work harder to propel the bus hence the noise & smoke etc. It seems this has been started about 2 months ago citywide on their whole fleet. I personally can't see it producing any significant fuel saving but then again i'm neither a mechanic nor an accountant.

The_Wrecker

Its also warm at the moment, so the cooling system is working overtime.

You should hear the machines in Lisbon.

GTE

Cookie_Monster wrote: »

Is that roar not something to do with the fans rather than the engine itself, i'm pretty sure someone mentioned that on here way back...

Its for cooling.
From what I have read on other forums (fori? ) the DB buses are a bit underpowered and get hot and bothered with speed bumps :rolleyes:

In all seriousness it is to stop the engines from overheating, the reason for this overheating is something I dont know for sure but allegedly the sensors responsible for this extra loud cooling can fail and they can be on for no reason what so ever.

In the one and a half years I used DB regularly it would be in the Summer that the Alexanders Volvos from 00+ would roar regularly and very rarely would the Alexander Volvos <99 give out at all.

When you get a quiet 00 era Alexander Volvo I can really like the bus to travel on. Once they roar I just wish for a 99 era chariot.

My RA, RH and AX and which one is which knowledge is very bad so Ill stick with my eras

GTE

The Skulls wrote: »

I think i might be able to shed some light on this; i also noticed this over the last while,plumes of black smoke, bus vibrating like mad, engines roaring etc. One of my wifes cousins works for DB maintenance, it seem that maintenance were told to adjust the revs of the engines of the buses whilst the engine is idling e.g. in traffic. The revs have been lowered to the bare minimum needed to keep the engine ticking over thus restricting the amount of diesel being consumed (in theory), however when the bus moves off again especially up an incline the engine must work harder to propel the bus hence the noise & smoke etc. It seems this has been started about 2 months ago citywide on their whole fleet. I personally can't see it producing any significant fuel saving but then again i'm neither a mechanic nor an accountant.

I can see why they would lower the idle revs but I dont know how that could cause any difference in how the engine works once you raise it off idle. In my mind I would think that the idle rev count only affects the engine when no loud pedal is used.

Though maybe with lower starting revs the gearbox is committing the engine to movement lower in the rev band? That could make it harder for the engine to get it moving initially.

The_Wrecker

bbk wrote: »

Its for cooling.
From what I have read on other forums (fori? ) the DB buses are a bit underpowered and get hot and bothered with speed bumps :rolleyes:

In all seriousness it is to stop the engines from overheating, the reason for this overheating is something I dont know for sure but allegedly the sensors responsible for this extra loud cooling can fail and they can be on for no reason what so ever.

In the one and a half years I used DB regularly it would be in the Summer that the Alexanders Volvos from 00+ would roar regularly and very rarely would the Alexander Volvos <99 give out at all.

When you get a quiet 00 era Alexander Volvo I can really like the bus to travel on. Once they roar I just wish for a 99 era chariot.

My RA, RH and AX and which one is which knowledge is very bad so Ill stick with my eras

Guys its summer, the machinary is doing whats its designed to do. Cool the engine.

Cookie_Monster

The_Wrecker wrote: »

Guys its summer, the machinary is doing whats its designed to do. Cool the engine.

It's hardly that hot though, coldest July in 50 years :P

Anyway I know about the fans and that's not really what I was looking for an answer for.

I suppose if the idle is really low then I wonder is there sufficient air and pressure through the engine to burn all the fuel completely and "properly", residue collecting throughout the engine and exhaust system and leading to excessive smoke as it's burned out on acceleration...

dfx-

There has to be some in the very high decibel range, there has also been some who have been loud for several years and in the odd case, ever since they were in the fleet:eek:

AV20 and AV385 and AV386 have roared ever since I first seen them. AV13 is VERY loud. AV19 has roared badly for about 2-3 years. A lot of AV70-90 roar as do AV130-150. The 2004 buses, AV363-398, are awful for it too.

Baron de Robeck

The noise is caused by the termostat settings on the cooling fans either going haywire or in some cases being set too low so that they stay on practically all the time.

As the post above reveals this tends to run in batches of buses the reason being of course that it depends on what garage the bus is allocated to. Phibsboro and Ringsend are the worst for screaming AV's and it seems no attempt is made to rectify them and Donnybrook is not far behind. On the opposite end you have Conyngham Road and you will have to search to find a screamer here and if you do locate one it is guaranteed to have been cured if you check back a few days later!

Red Alert

Some of them are louder than the old Bombardier double deckers.

GTE

The_Wrecker wrote: »

Guys its summer, the machinary is doing whats its designed to do. Cool the engine.

Never was that ever in dispute I think. Though, temperature sensor condition was raised as being an issue.

Chiming in on dfx, I am a sound engineer myself and I was totally shocked at the volume. The dB count would have been fairly high I'd say.

My concern with the design is from what is said here:

When they are roaring, is this the only setting they have? On and off or are the sensors so out of whack that they are going to 100% ear blowing immediately thinking the engine is about to melt?