Why do buses overheat?

[royalemember]

Is it because of poor maintenance or is it because there isn't enough water in the system?(surely they must be topped up every day?) Or could it be that engine could be struggling under a full load for example.

[Matty]

Because of the weather, all the heat just makes the engine hotter and drink more coolant.

[leedstom]

I can understand this, but I live abroad in the Middle East where temperatures are regular well in to the 40's. But the buses never seem to overheat over here, even with the extra work of the Air Conditioning unit.

Will the buses over here have larger coolant tanks?

[Matty]

More than likely yes or different cooling systems.

[Father Dougal McGuire]

Or if it is hilly the engines can overheat. If there are not many hills the engine wont over heat.

[Danny]

Our Volvo B7RLEs overheat all the time in hot weather.

[Matty]

Don't forget Solo's

[Father Dougal McGuire]

66762 Screeches in winter never mind when it's hot lol. 66780 gets too hot at times, more than say 66754 which doesn't suffer as much as 66762/80 - seems strange.

[lbaspotter]

FTR's always overheated.

[wibble]

Buses shouldnt overheat if everythings working properly of course. The hot weather puts more pressure on the coolant system though to keep it cool meaning radiators/water pumps/hoses etc are at full pressure for long periods of time creating a failure

[kendall17]

May 27, 2012 18:13:56 GMT 1 Matty said:

Because of the weather, all the heat just makes the engine hotter and drink more coolant.

They shouldn't "drink" coolant. The coolant is pumped around the engine and if there is any coolant loss, then it is down to there being a leak in the system. There should be very little coolant loss over a number of years.

[angrycommuter]

Buses don't seem to have adequate radiators any more. The older models used to have a large radiator grill at the front so the air flowed straight into the vehicle (like a car) but now buses have plated up fronts with tiny grills at the back side or even none at all.

You do see more overheated vehicles nowadays - is this a design flaw?

[Father Dougal McGuire]

May 29, 2012 13:08:13 GMT 1 angrycommuter said:

Buses don't seem to have adequate radiators any more. The older models used to have a large radiator grill at the front so the air flowed straight into the vehicle (like a car) but now buses have plated up fronts with tiny grills at the back side or even none at all.

You do see more overheated vehicles nowadays - is this a design flaw?

Quite a good point is that. We can't put radiators at the front anymore because low floor buses can't because most, if not all buses manufactured now are low floor. Volvo Olympians & the Leyland ones were very good at staying cool, large radiator at the front.

Take the B7TL Wright Eclipse Gemini, it needs 2 cooling fans to keep the engine cool as one doesn't cool it quickly and efficiently. Older buses seem to have been built with more thought, but it would of been easier back then as the DDA rules wasnt as stringent as the are now so they could have a radiator at the front.

[timelesstable]

May 29, 2012 16:31:42 GMT 1 Father Dougal McGuire said:

We can't put radiators at the front anymore because low floor buses can't because most, if not all buses manufactured now are low floor .

We could if we went back to the Cave Brown Cave system

[Deleted]

Enviro400s and Volvos (especially the B7TLs and the FTRs) seem to be worst including some B9TL Olympuses.

[Father Dougal McGuire]

May 29, 2012 18:17:02 GMT 1 @duobus30 said:

Enviro400s and Volvos (especially the B7TLs and the FTRs) seem to be worst including some B9TL Olympuses.

yeah, the B7TL & Fail To Runs seem to be bad as they have a problem with over revving. I don't actually know what causes the over revving.

[jake31804]

I think instead of the side engine grills pointing towards the rear to allow heat to escape, they should face the front so the air flows into the engne compartment & out the bonnet grill. This wold be more efficient, especially when the bus moves fast. All anyone has to do is turn the grill inside out or upside down to reverse the direction of the "blades" or whatever they're called. Cold air flowing into the bus would be better than hot air escaping as it cools as it flows.

[dwarfer1979]

I think part of the problem is modern engines run much hotter than older engines were. Smaller, higher reving engines need to work harder and so increase heat and the need to meet emissions regs leading to more burn also has an impact. From reports (and first pictures) the next generation of buses to meet the forthcoming Euro 6 emissions regs have a vastly increased cooling requirement and have a number of extra new radiators to assist in this cooling.

Older buses used to overheat regularly as well but with simpler engineering all the crews needed to do was let it cool for a short while and top up with more water and carry on. Modern electronics and engine management systems mean that plodding on till it boils over and then topping up will no longer work without damaging the engine, plus modern engines don't just use water in the cooling systems, the glycerine mix used now boils at a much higher temperature but is much more dangerous to deal with when hot - it takes at least half an hour for the system to cool enough to safely open the coolant tank to top it up before you can carry on so just opening the radiator cap and standing back as a fountain of hot water & steams geysers out is incredibly dangerous to bystanders as well as whoever is doing it.

[busman3]

dwarfer1979 as it more of less spot on high reving engines especally turbocharged ones are more prone especialy if you have reduced the number of times you flush the system out this can get clogged . especcially if the bus is working on areas where there is a large amount of mud on road ie farming areas or where there is lots of construction sites.