Mercedes O305 Questions

New Users (or anyone else) is/are welcome to ask questions in here to which the answers might be obvious to most but you simply don't know yourself or are unsure where to find the answer. You can also ask questions about the working of the forum or anything else you may think of.

Moderator: MAN 16.242

Forum rules
### This section is a NO FLAMING ZONE! That means you cannot reply "harshly", abusively, sarcastically or in any negative manner to members. ###
Post Reply
User avatar
404wanderer
Posts: 0
Joined: Mon Aug 05, 2013 8:16 pm
Favourite Vehicle: Mercedes O305

Mercedes O305 Questions

Post by 404wanderer »

Hi all,

I've just acquired an ex Trans Adelaide Mercedes O305 and have some very newbie questions. Apologies in advance for the stupidity but I have an MR licence and am used to driving small manual trucks rather than buses.

So in no particular order -

1 - the airbags aren't inflating. There is a hissing noise like air escaping from underneath the bus but I can't seem to find where from. Is there a drain valve I need to close? Any other suggestions? Both air brake circuits seem ok but the airbag warning lights are on.

2 - since I pressed the alarm foot switch by mistake my bus now says emergency as the destination. How do I change it? The selector above the drivers seat doesn't seem to power up.

3 - ok, so the questions may be getting stupider. The dash has selectors for gears - 1,2,3,N,R. Now, how is the bus normally driven. Is it manually changed on the dash for each fear change or is that just the highest gear? I.e do I just put it in 3 and drive or do I need to keep using the buttons to change up and down

4 - there is a retarder switch on the dashboard. When do I use it?

5 - what is the procedure for long descents and ascents?

6 - when I'm parking up for a while do I need to do anything special or just switch off?

7 - thanks!
User avatar
Willie
Posts: 2501
Joined: Sun Mar 07, 2004 4:57 pm
Favourite Vehicle: Mercedes 0405NH

Re: Mercedes O305 Questions

Post by Willie »

Desto sign, with power on, select Dest A, enter a code, like 1, enter and it will change the sign.

Most retarder switches are disconnected.

Drive in highest gear, can select a lower gear for a long descent but they can be quite temperamental.

With the airbags not inflating, there is two air gauges on the dash, 8 bar is desired for both front and rear brake, what do they build up to? How long are you allowing for the air to build up?

From memory there is no master battery switch, just key out, though check around the battery box, I'm open to correction. Do you know it's old fleet number?
User avatar
Guy_Arab
Posts: 852
Joined: Sat Mar 06, 2004 10:11 pm
Favourite Vehicle: M.A.N Bus & Guy Arab
Location: Perth W.A.

Re: Mercedes O305 Questions

Post by Guy_Arab »

404wanderer wrote:Hi all,

I've just acquired an ex Trans Adelaide Mercedes O305 and have some very newbie questions. Apologies in advance for the stupidity but I have an MR licence and am used to driving small manual trucks rather than buses.

So in no particular order -

1 - the airbags aren't inflating. There is a hissing noise like air escaping from underneath the bus but I can't seem to find where from. Is there a drain valve I need to close? Any other suggestions? Both air brake circuits seem ok but the airbag warning lights are on.

2 - since I pressed the alarm foot switch by mistake my bus now says emergency as the destination. How do I change it? The selector above the drivers seat doesn't seem to power up.

3 - ok, so the questions may be getting stupider. The dash has selectors for gears - 1,2,3,N,R. Now, how is the bus normally driven. Is it manually changed on the dash for each fear change or is that just the highest gear? I.e do I just put it in 3 and drive or do I need to keep using the buttons to change up and down

4 - there is a retarder switch on the dashboard. When do I use it?

5 - what is the procedure for long descents and ascents?

6 - when I'm parking up for a while do I need to do anything special or just switch off?

7 - thanks!
I sent you some data that may help private email
Guy Arab
User avatar
404wanderer
Posts: 0
Joined: Mon Aug 05, 2013 8:16 pm
Favourite Vehicle: Mercedes O305

Re: Mercedes O305 Questions

Post by 404wanderer »

Thanks Guy and others,

In summary, I'm replacing the airbags anyway but I've been operating the parking / auxiliary brake incorrectly. I'll have a look at that and see if that stops the air escaping.

The emergency sign I haven't sorted as the destination selection panel is dead. I'm going to try and see where it gets its power from to see if I can resurrect it.

Sorted how I use the gear selector!
Not sure why the retarder would be disconnected but I need to have a play to see if it is.
Parking brake operates with a twist to drain water form air tanks.

One other thing I haven't been able to find out is how the engine start and engine stop buttons work. They're not mentioned in the manuals so may be a fleet addition. The stop button doesn't actually work at present and the only way I can stop the engine is to pull up the accelerator pedal with my boot, which eventually stops the engine. Does anybody have and idea how the engine stop buttons normally work? What do they do to the engine; is it air or fuel they cut off, or something else?

Thank you all for your patience with a newbie :-)
User avatar
Willie
Posts: 2501
Joined: Sun Mar 07, 2004 4:57 pm
Favourite Vehicle: Mercedes 0405NH

Re: Mercedes O305 Questions

Post by Willie »

With the stop button, your generally to have 6-8 bar in each tank for it operate.
Pulling up the accelerator pedal but be careful not to wear it out!

Does the Desto have a flick switch on it at all?
User avatar
404wanderer
Posts: 0
Joined: Mon Aug 05, 2013 8:16 pm
Favourite Vehicle: Mercedes O305

Re: Mercedes O305 Questions

Post by 404wanderer »

Ah, ok, I was wondering how it operates.

What's a flick switch?
User avatar
404wanderer
Posts: 0
Joined: Mon Aug 05, 2013 8:16 pm
Favourite Vehicle: Mercedes O305

Re: Mercedes O305 Questions

Post by 404wanderer »

Is there a better way of stopping the engine if the stop button doesn't work? I had both brake circuits up to pressure but the bags weren't inflating. That could be why there wasn't pressure to the stop circuit.
User avatar
404wanderer
Posts: 0
Joined: Mon Aug 05, 2013 8:16 pm
Favourite Vehicle: Mercedes O305

Re: Mercedes O305 Questions

Post by 404wanderer »

Just found the large handle in the engine marked "Engine Stop". Once I'd cleaned the dirt off the label that is :-)
User avatar
R-C
Posts: 1559
Joined: Wed Nov 10, 2004 12:31 am

Re: Mercedes O305 Questions

Post by R-C »

On the right hand side of the accelerator on the floor is there a black button?
Press that to see if it turns bus off
User avatar
boronia
Posts: 21566
Joined: Sat Mar 06, 2004 6:18 am
Favourite Vehicle: Ahrens Fox; GMC PD4107
Location: Sydney NSW

Re: Mercedes O305 Questions

Post by boronia »

I'm not familiar with this model Merc, but usually the STOP button operates a solenoid on the fuel pump
Preserving fire service history
@ The Museum of Fire.
User avatar
Andrew
Administrator
Posts: 6960
Joined: Sun Feb 29, 2004 6:02 pm
Location: The People's Republic of Campbelltown

Re: Mercedes O305 Questions

Post by Andrew »

O305s I have driven you have to lift the accelerator pedal up towards you to shut the engine down - I assumed it was lifting something by cable in the air intake of the engine to starve it and thus cause a shutdown.
.
Job done.
User avatar
boronia
Posts: 21566
Joined: Sat Mar 06, 2004 6:18 am
Favourite Vehicle: Ahrens Fox; GMC PD4107
Location: Sydney NSW

Re: Mercedes O305 Questions

Post by boronia »

Usually lifting the accel pedal simply pulls the injector pump rack back beyond the idle position, shutting off fuel to the engine. THis is how it worked on the older AECs

The third method, simply turning off with "ignition" key, requires the pump solenoid to be powered to open the pump. One downside of this is you can't clutch start the vehicle if it has a flat battery.
Preserving fire service history
@ The Museum of Fire.
User avatar
DiAmOnD T
Posts: 976
Joined: Thu Oct 07, 2004 2:11 pm
Favourite Vehicle: AEC Mandator Ex Browns no7
Location: under the subway at 'the main

Re: Mercedes O305 Questions

Post by DiAmOnD T »

If your air bags don't inflate and the engine stop is not working - Do the doors work??
If they don't then you are not getting an air supply into your auxiliary tank for these items, which would suggest your 4 way protection valve is sticking/faulty.

If you can get underneath the bus you should find a couple of long air tanks side by side, one will have a square valve mounted off it, which in a way looks like the bottom of an egg carton. If you find it give it a belt with a hammer and try building air again to see what happens
The Diesel Guy
- Mobile heavy vehicle repairs serving Sydney to Newcastle -

dieselguynsw@gmail.com
Drewwarner

Re: Mercedes O305 Questions

Post by Drewwarner »

Guy_Arab wrote:
404wanderer wrote:Hi all,

I've just acquired an ex Trans Adelaide Mercedes O305 and have some very newbie questions. Apologies in advance for the stupidity but I have an MR licence and am used to driving small manual trucks rather than buses.

So in no particular order -

1 - the airbags aren't inflating. There is a hissing noise like air escaping from underneath the bus but I can't seem to find where from. Is there a drain valve I need to close? Any other suggestions? Both air brake circuits seem ok but the airbag warning lights are on.

2 - since I pressed the alarm foot switch by mistake my bus now says emergency as the destination. How do I change it? The selector above the drivers seat doesn't seem to power up.

3 - ok, so the questions may be getting stupider. The dash has selectors for gears - 1,2,3,N,R. Now, how is the bus normally driven. Is it manually changed on the dash for each fear change or is that just the highest gear? I.e do I just put it in 3 and drive or do I need to keep using the buttons to change up and down

4 - there is a retarder switch on the dashboard. When do I use it?

5 - what is the procedure for long descents and ascents?

6 - when I'm parking up for a while do I need to do anything special or just switch off?

7 - thanks!
I sent you some data that may help private email
Guy Arab
Hey Guy,

Do you still have a manual for a MB O305 for sale? I am in need of one.

Thanks!

Drew
DRIVEN1
Posts: 7
Joined: Thu Mar 09, 2017 6:55 pm

Re: Mercedes O305 Questions

Post by DRIVEN1 »

Hi All,

I just failed an annual inspection for my recently purchased 0305.
One of the things I have told to rectify is the oil light coming on with the other warning lights after the "battery connect" button is pushed, prior to starting the engine.
I have replaced the bulb for the oil light but still no luck. Is this a common fault? Any help would be appreciated.

Kind Regards

Driven1
User avatar
Bus-1809
Posts: 3140
Joined: Wed Mar 08, 2006 4:40 pm
Favourite Vehicle: As long as it's not a B7...

Re: Mercedes O305 Questions

Post by Bus-1809 »

Adelaide O305's are different to the Perth and Sydney ones.

Stop button is on the dash. No battery isolator as they have a Battery Connect button.

To fix the desto:

1. Press Enter
2. Enter the code "0002"
3. Press Enter
4. Enter the code "0002 again
5. Press Enter
6. Press Destination A button.

Drive with 3 selected on the gear selector. Use 1 and 2 for long ascents or descents. Leave retarder switch on. Retarded works on First stage of brake pedal.
If it's not a ZF, take it back!

Holder of W.A's largest transport sound recording collection. Over 1,300 recordings of vehicles and constantly expanding for the enjoyment of future generations.
User avatar
busrider
Administrator
Posts: 2388
Joined: Fri Jun 20, 2008 11:35 pm
Favourite Vehicle: Maybe not my car...
Location: Not in the Gutta

Re: Mercedes O305 Questions

Post by busrider »

Good of you to answer the questions, but this thread is 5 years old now, and the person who asked the questions hasn't been on here in the past 2.5 years...
User avatar
Bus-1809
Posts: 3140
Joined: Wed Mar 08, 2006 4:40 pm
Favourite Vehicle: As long as it's not a B7...

Re: Mercedes O305 Questions

Post by Bus-1809 »

busrider wrote:Good of you to answer the questions, but this thread is 5 years old now, and the person who asked the questions hasn't been on here in the past 2.5 years...
I realised this after I made the post. You are welcome to delete the post if you see fit as a moderator.
If it's not a ZF, take it back!

Holder of W.A's largest transport sound recording collection. Over 1,300 recordings of vehicles and constantly expanding for the enjoyment of future generations.
Benmerc
Posts: 0
Joined: Tue Mar 14, 2023 6:24 pm

Re: Mercedes O305 Questions

Post by Benmerc »

I am in need of a manual ??
Any one have one or know where to get
User avatar
Guy_Arab
Posts: 852
Joined: Sat Mar 06, 2004 10:11 pm
Favourite Vehicle: M.A.N Bus & Guy Arab
Location: Perth W.A.

Re: Mercedes O305 Questions

Post by Guy_Arab »

YES CONTACT ME I AVE ONE FOR SALE
GUY ARAB
Post Reply

Return to “New Users/Ask a Simple Question”