Andy C Posted July 20, 2022 Share Posted July 20, 2022 I suspect as others have suggested the heating wasn't actually on, just the fans, circulating air. Yesterday the air was hot everywhere so the fans will have been blowing hot air around. Link to comment Share on other sites More sharing options...
Guest busdriver1 Posted July 20, 2022 Share Posted July 20, 2022 (edited) 9 hours ago, redruby said: That’s exactly what the driver said so I’m sure you’re right. It was absolutely boiling hot on there, respect to all the drivers out in that heat all day! Sorry but the heaters do not come on automatically when the engine temperature goes too high. First thing that happens is the fan cuts in, if that fails to lower the temperature the bus will then go into "limp mode" whereby its speed and engine speed will be severely reduced and if this was to haat fails it will shut itself down. At no point would the heaters be turned on. That is actually an impossibility. If a driver said it happens then he is misinformed, it cant.. If this was to happen, it would allow nominally cold water to enter a enter boiling engine and that would almost certainly have catastrophic consequences for the engine block. Edited July 20, 2022 by busdriver1 Link to comment Share on other sites More sharing options...
dutch Posted July 20, 2022 Share Posted July 20, 2022 3 hours ago, busdriver1 said: Sorry but the heaters do not come on automatically when the engine temperature goes too high. First thing that happens is the fan cuts in, if that fails to lower the temperature the bus will then go into "limp mode" whereby its speed and engine speed will be severely reduced and if this was to haat fails it will shut itself down. At no point would the heaters be turned on. That is actually an impossibility. If a driver said it happens then he is misinformed, it cant.. If this was to happen, it would allow nominally cold water to enter a enter boiling engine and that would almost certainly have catastrophic consequences for the engine block. I see buses go in limp mode even when going up moderate hills in Sheffield on a normal còol day. These fan are not good enough for a hot day like yesterday and my bus was crawling uphill but did fine on level areas. And you are very right about putting cold water in a hot engine be catastrophic therefore the cold water can get mixed with the hot coolant in the radiator before it reaches the engine. The buses I take do not use cabin heater in such emergency ways and go in limp mode or shut down or sometimes even never show up. Last time I ever put heater on to prevent overheating was 15 years ago on a long steep hill on a very hot day, modern vehicles control their heat much better now. 1 Link to comment Share on other sites More sharing options...
cgksheff Posted July 20, 2022 Share Posted July 20, 2022 Sometimes the fans come on and, because of the external temperature, they feel like heaters. Link to comment Share on other sites More sharing options...
redruby Posted July 20, 2022 Author Share Posted July 20, 2022 It was an older bus and the driver said that the engine was overheating going uphill and that’s why the heaters had come on. All I know is that hot air was blasting out around the seats and it was boiling hot. I’ve been on newer buses that don’t do this though. Link to comment Share on other sites More sharing options...
redruby Posted July 20, 2022 Author Share Posted July 20, 2022 (edited) It sounds like some buses do have the heaters on to stop the engine overheating https://www.railforums.co.uk/threads/buses-with-the-passenger-heaters-on-in-hot-weather.220362/ Edited July 20, 2022 by redruby Link to comment Share on other sites More sharing options...
Guest busdriver1 Posted July 20, 2022 Share Posted July 20, 2022 3 hours ago, dutch said: I see buses go in limp mode even when going up moderate hills in Sheffield on a normal còol day. These fan are not good enough for a hot day like yesterday and my bus was crawling uphill but did fine on level areas. And you are very right about putting cold water in a hot engine be catastrophic therefore the cold water can get mixed with the hot coolant in the radiator before it reaches the engine. The return from the heating system on any bus goes directly into the engine on all vehicles. Turning on the heating would release this cold water into the engine. Link to comment Share on other sites More sharing options...
dutch Posted July 21, 2022 Share Posted July 21, 2022 (edited) 8 hours ago, busdriver1 said: The return from the heating system on any bus goes directly into the engine on all vehicles. Turning on the heating would release this cold water into the engine. That will be a very bad design since like you mentioned earlier it's not advisable to suddenly shock a warm engine with cold coolant. If that heating system uses a heat exchanger to separate cabin heating and engine coolant fluids it will not matter and engine will be safe. All that is needed on modern bus is a decent fan by the coolant radiator but I suspect these radiator fan they have now are not good enough putting many busses in limp mode when they encounter one of Sheffield decent hills. By the way I rather see a bus crawl uphill in limp mode than be in position of topic poster Edited July 21, 2022 by dutch Link to comment Share on other sites More sharing options...
dutch Posted July 21, 2022 Share Posted July 21, 2022 (edited) https://www.bbc.co.uk/news/uk-england-derbyshire-36849648 Edited July 21, 2022 by dutch Link to comment Share on other sites More sharing options...
Guest busdriver1 Posted July 21, 2022 Share Posted July 21, 2022 3 hours ago, dutch said: https://www.bbc.co.uk/news/uk-england-derbyshire-36849648 Ironically, the company involved DO run air conditioned buses. Not all. 6 hours ago, dutch said: That will be a very bad design since like you mentioned earlier it's not advisable to suddenly shock a warm engine with cold coolant. If that heating system uses a heat exchanger to separate cabin heating and engine coolant fluids it will not matter and engine will be safe. Buses are much less advanced than you seem to think. There were some in the 80's with heat exchangers but they were removed and fitted with conventional systems. The actual design you call bad is standard in nearly every car, bus or lorry on the road and has been for many many years. Link to comment Share on other sites More sharing options...
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