Help! I've just started my bus (it's garaged) and the starter switch was beeping and the left hand light flashing every 4 seconds. I also noticed that water was dripping from just forward of the near side rear wheel. On looking underneath, the water is coming from a drain hole that would seem to be from the lower saloon heater, but I'm not sure about this.

Suspecting the two were connected, I switched off, checked the coolant header tank and filled it up - it took a lot of water. I also turned off the heater tap behind the flap above the engine.

On restarting, the warning beeper had stopped, as had the dripping, until suddenly the dripping turned to a gush of steaming hot water, and the warning beeper went mad!

1. I'm not sure what has happened. Could something have frozen and burst?

2. Other than the saloon heater, I don't understand why the vent point is towards the rear of the bus.

3. Is there a way of sealing off the heater - beyond what I've done already?

Any suggestions most welcome. I have 'The New Routemaster Maintenance Manual', but it's not helping in this case!

Thanks in anticiption.

My bus number (if any): RML2352

Hi Jeremy,
Assuming that your RM is a refurbed bus with the radiaters in the saloons downstairs and upstairs , it does sound like you have a burst pipe or loose connection ( some pipes are push fit , so worth checking joins) . You can completely isolate the heaters by closing the heater control valve in the cab (near handbrake) There is also a second return valve to completely isolate the system . This is situated in the canopy above the engine bonnet . there is a little hatch that drops down locked with a 'T' key , inside you will find the 2nd valve .
After shutting them both off refill the system and check for leaks anywhere else . I think it sounds like you need to check the strength of the antifreeze , needs to be about 50%.
Leaks can be a pain to sort , i've chased them around 2391 everytime you fix one another springs up further along !!
hope this helps

mark

My bus number (if any): RML2391

The flashing lights you mention , there is one for oil pressure which should illuminate before the engine fires up and will then go out when the engine is running , the other is the coolant light which should allways be out , unless as you've found out is low and you get a buzzer sounding as well . Very important to make sure the buzzer is funtioning from time to time , could save your engine ! I've seen come RM's with this disconnected , not advisable !
I think when you first liven the system up with the starting bullet the coolant light briefly flashes to prove its working , will have to check next time I visit RML2391

Mark

My bus number (if any): RML2391

I do not have the oil pressure warning light that Mark mentions on my RML with Cummins engine, only the ignition warning light. Following an intermittent fault with the coolant warning device which made the light and buzzer come on at frequent intervals I disconnected it. The heating system in the refurb RML's can be a pain, it has been known for mice to chew their way through the push fit 22mm elbows. In my elimination mode after finding one of the copper heating pipes nearly worn through I decided to bypass the system completely in favour of not having any saloon heating at all. Now you may think that this is a bit extreme, but as most use of the vehicle is in the warmer months anyway I considered it unnecessary, after all most RT's never had saloon heating. If I could offer any other advantage of doing this, it would be that the engine warms up a little bit more quickly with less water in the system.

My bus number (if any): RML2335

Many thanks Mark & Ed - much appreciated. I'll try this next weekend, but closing down the heating system would seem to be the answer. Fingers crossed!

Cheers. Jeremy

My bus number (if any): RML2352

All this illustrates the fact that the original fresh air heating system was the most relible and trouble free if not the most efficient (it only delivers warmth when the bus is moving). I have a decent heater matrix in 1001 and a neatly fitting door on the platform. The result is a warm cosy bus as the heat doesn't escape through the back end. The bonus is there are no moving parts and no eletrics to go wrong. The only possibly dodgy component is the ranko valve inside the front canopy which shuts the waterflow from the engine on and off. I always thought the ranko unit was a bit on the flimsy side, but have to admit that mine hasn't gone wrong in 25 years!

My bus number (if any): rm1001

All sorted. Heater system isolated, engine header tank topped up with antifreeze and water.

My thanks to you all.

Jeremy

My bus number (if any): RML2352