Overheating engines

[Fen Enthusiast]

Hi all,

I recently attended the Low - ish Floor Running Day at Godstone last Sunday and there were a few buses that broke down or struggled with the heat that day. And this got me thinking - how does a commercial vehicle designed and built to cope with prolonged and intensive running succumb to heat related issues? What I'm also aware of is how much they are thrashed when accelerating up hill or when they're close to or at maximum speed if they have a low gear ratio. BX02YYZ made quite the racket at top speed. Drawing a comparison to cars now, a well maintained car in good condition never overheats on a very hot day, but then again, your car is never being thrashed at maximum RPM for prolonged periods of time unlike that of a bus. So what really causes heat related failures in buses? Are they working too hard in excessive heat, is it that if they're old are they simply knackered and a bit frail or is it other reasons including what I've mentioned?

 

[Geordie driver]

I had the misfortune to travel recently on a local Arriva service that had it's saloon heaters on during what has been the hotest day of the year so far, they do this in an attempt to keep the engine cool at the expense of passenger comfort.

Modern buses seem even more prone to overheating than buses built in the 1970s, from my direct experience as a driver.

The buses they buy are either not up to normal British summer weather (and we get a few hot days every year) or they are not maintained properly. I know our buses only had water in them most of the time, not proper engine coolant.

I have been suspended for refusing to drive a bus on a hot day with the saloon heaters jammed on during hot weather. Who on earth thinks that is a reasonable way to treat your customers?

 

[Busman84]

On some occasions buses overheating it could be a case it’s been topped up with water too much meaning coolant gets diluted more overtime. All depends though early Tridents overheated near enough everytime after a short stint on a dual carriageway or big hills

 

[Fen Enthusiast]

I can recall the driver of LN51KYY was checking the underneath of the bus under the engine in the latter part of the day.

 

[Flying Snail]

Low powered engines being thrashed just to haul the vehicle at all is a big part of the problem, also engines that in other applications cope getting stuffed into crapmped bays covered in heat shield designed to keep the saloon cool.

== Doublepost prevention - post automatically merged: 14 Jul 2022 ==

I had the misfortune to travel recently on a local Arriva service that had it's saloon heaters on during what has been the hotest day of the year so far, they do this in an attempt to keep the engine cool at the expense of passenger comfort.

Modern buses seem even more prone to overheating than buses built in the 1970s, my direct experience as a driver.

The buses they buy are either not up to normal British summer weather ( and we get a few hot days every year) or they are not maintained properly, I know our buses only had water in them most of the time, not proper engine coolant.

I have been suspended for refusing to drive a bus on a hot day with the saloon heaters jammed on during hot weather, who on earth thinks that is a reasonable way to treat your customers?

I always made sure to find out where the shut-off valves were so I never had a bus with heaters on in the summer, if it overheated then so be it.

 

[Stan Drews]

I recall plenty of Atlanteans, Ailsas and Olympians that overheated in hot weather, back in the 80s/90s, so it’s not a new phenomenon!

 

[Mikw]

There's been a couple of bus and coach fires round out way during the hot weather this week.

Also, i think calls to the AA for cars overheating balloon during periods of hot weather too.

 

[RJ]

Hi all,

I recently attended the Low - ish Floor Running Day at Godstone last Sunday and there were a few buses that broke down or struggled with the heat that day. And this got me thinking - how does a commercial vehicle designed and built to cope with prolonged and intensive running succumb to heat related issues? What I'm also aware of is how much they are thrashed when accelerating up hill or when they're close to or at maximum speed if they have a low gear ratio. BX02YYZ made quite the racket at top speed. Drawing a comparison to cars now, a well maintained car in good condition never overheats on a very hot day, but then again, your car is never being thrashed at maximum RPM for prolonged periods of time unlike that of a bus. So what really causes heat related failures in buses? Are they working too hard in excessive heat, is it that if they're old are they simply knackered and a bit frail or is it other reasons including what I've mentioned?

I had one of my fleet out at that event and it didn't overheat. The engine is cooled by way of intake of air through the engine grille/louvre and the fan in the bay. The coolant is also circulated through the system. Provided there are no leaks or airlocks and the header tank has an appropriate amount of fluid in it, there shouldn't be any problems.

The vehicle is intensively maintained - as part of the process, the intercooler and radiator are removed and any detritus collected is cleaned out. That is a threat the the efficient cooling of the engine, as is radiator damage, too much or too little coolant in the tank, use of the wrong fluid in the coolant tank and fans that don't spin quickly enough. The bus regularly does 50 miles runs at 50mph without breaking a sweat.

 

[Dai Corner]

I mistakenly sat in the seat above an auxiliary radiator on an E200 working the Stagecoach X15 Newport to Brynmawr, Wales' highest town, yesterday. I wouldn't have wanted to be there for the nearly 2 hour slog climbing from near sea level to about 1300 ft.

 

[mb88]

I had the misfortune to travel recently on a local Arriva service that had it's saloon heaters on during what has been the hotest day of the year so far, they do this in an attempt to keep the engine cool at the expense of passenger comfort.

I won’t name the operator but I was asked to do this one time when my bus was overheating. Turn the saloon heaters on full. On a hot summer’s day. I’m sure you can imagine what my response was.

 

[Volvodart]

It used to be fairly standard practice in warm weather with the Aberdeen Atlantans, although it is relatively rare to get a full warm day in Aberdeen when it would be really necessary, as it often clouds over around lunchtime in Summer.

 

[Geordie driver]

I won’t name the operator but I was asked to do this one time when my bus was overheating. Turn the saloon heaters on full. On a hot summer’s day. I’m sure you can imagine what my response was.

The one i was suspended for had the heater fixed so the driver couldn't switch them off, had you been caught trying to change this you would be in deep trouble.

How long would someone drive their car like that, yet it is ok for bus customers? Worse still, in the event of a passenger complaint, the company would claim the driver could switch them off, an outright lie.

Yes older buses used to boil over, but you just released the cap, jump back and gave it 5 minutes then off you went.

Modern buses seem to go into limp mode but are then left on the road. We has some buses that were in limp mode from the second you started.

When I was on the union I would get them "blacked", we would refuse to drive them, soon got them fixed.

 

[Snow1964]

Modern buses seem to go into limp mode but are then left on the road. We has some buses that were in limp mode from the second you started.

When I was on the union I would get them "blacked", we would refuse to drive them, soon got them fixed.

I think limp mode on start up usually happens because of failure to clean the filters and DPF (diesel particulate filter) so it is full of ash etc. So basically the engine management is saying no longer meeting euro6 emissions so take it to the maintenance bay. But some cowboy operators try and put it in service instead.

Similarly most overheating is usually due to poor coolant (water used instead), and obviously pure water boils at a lower temperature and isn’t very good at preventing rust, so unless the system is then regularly flushed gets partly blocked by the rusty particles. Guess what a partly blocked system isn’t as efficient at removing excess heat.

 

[jp4712]

I own two vintage buses and I’ve been involved in the restoration or maintenance of many more.

There‘s one thing you have to remember with old classic buses; they’re knackered. My AEC and my Bristol were both withdrawn after long service lives, no doubt because things had started to fail and it was getting harder to keep them on the road. No matter how immaculate a preserved bus, it’s not as good as new unless the owner has been lucky enough to procure one that was very unusually well kept.

Cooling problems in old buses are typically down to blocked pipes and radiators, generally due to silting up and/or scale. When I bought it, my Bristol RE had chronic overheating problems and it took some time to sort it. Let me tell you a story…

When I bought the Bristol, it wouldn’t go more than 20 miles without boiling despite having a front radiator which, in theory, is the best place. The water pump was full of clag, the centre bearing was shot and the vanes were worn, so that needed overhaul; and the pipes from front radiator to the rear engine needed a lot of flushing. Then attention turned to the radiator header tank; this header tank was okay BUT as well as the main connecting pipe to the radiator, there’s a small bore pipe from the top of the header to the top of the rad to prevent air locks. This small bore pipe was 100% blocked. The result of this was that water flow to the radiator was severely impacted, and this in turn led to sediment blocking about the bottom third of the radiator matrix. The breather pipe was renewed and the radiator rebuilt by a specialist contractor and bingo! All fixed and the bus now runs cool as a cucumber.

But with mine, the cooling system was so bad that I had to address it with an expensive campaign that took a summer to fix. If a preserved bus seems okayish, it’s tempting to leave it but that leaves it vulnerable to the first time it’s really working hard, or being used on a really hot day. Absolutely no criticism is intended, there are things on my buses that I’ve never touched on the not-broken-don’t-fix-it principle, but warmer weather or working hard does bring out vulnerabilities.

 

[fgwrich]

I mistakenly sat in the seat above an auxiliary radiator on an E200 working the Stagecoach X15 Newport to Brynmawr, Wales' highest town, yesterday. I wouldn't have wanted to be there for the nearly 2 hour slog climbing from near sea level to about 1300 ft.

I can imagine the racket it made - My ride to work last week was one of the local "Loan" Pointer Darts (GX56OGL) which arrived to us with the radiator stuck on. And I mean stuck on, to the point where you could hear it before you see it. Not as bad as some of the Volvo B7s though - get a stuck on radiator on one of those and you really know!

Something I do find a little odd though - the very cheep feeling E200s MMCs formerly used on the Kings City network in Winchester seem to have numerous small fans which make something of a racket when on full power full cooling mode.

 

[L401CJF]

Deleted

 

[Blindtraveler]

What a fascinating and interesting discussion. I won't name them but last year I took an operator that really is big enough and stupid enough to know better to task about this saloon heating jammed on, driver can turn them off complaint during warm weather and let's just say the bus operator came off significantly worse.

Basically I said, when they responded to me with the standard response, that I didn't believe a word they were saying and I was referring the case to my local trading standards officer. Said local trading standards department went off on one and eventually, after a couple of weeks of doing everything they could to get out of it, the bus company refuses to admit that I was right along with trading standards and and apologise. The only thing I didn't do was take it to the media as I was not in a good place mentally at the time and didn't want all the agro of the media then blowing it out of proportion or getting it wrong when it came to my side of the story. I hope a few more people do the same as this practice will then have to stop. As it was, I think they got what at the very least was a good talking to and possibly a fine. The health and safety boys got involved and said that cooking the passengers was totally unacceptable as the bus company be good then become liable in the event of someone 1B coming ill due to the extreme heat on board.

 

[E27007]

Hi all,

I recently attended the Low - ish Floor Running Day at Godstone last Sunday and there were a few buses that broke down or struggled with the heat that day. And this got me thinking - how does a commercial vehicle designed and built to cope with prolonged and intensive running succumb to heat related issues? What I'm also aware of is how much they are thrashed when accelerating up hill or when they're close to or at maximum speed if they have a low gear ratio. BX02YYZ made quite the racket at top speed. Drawing a comparison to cars now, a well maintained car in good condition never overheats on a very hot day, but then again, your car is never being thrashed at maximum RPM for prolonged periods of time unlike that of a bus. So what really causes heat related failures in buses? Are they working too hard in excessive heat, is it that if they're old are they simply knackered and a bit frail or is it other reasons including what I've mentioned?

Probable reason: the engine radiator is tired , worn out, has seen better days. We had similar problems with our diesel OTMs on the railway, engine compartment sensors reporting overheating, and engine fault alarms after hard running in warm weather, lots of experiments by technical staff including some far fetched schemes of fabrications to modify airflow through the engine compartment, common sense applied, a new radiator from the manufacturer! Problem solved! The 10+ year old radiators were worn out, when tested were found to be a good 20 to 25% down on heat dissipation compared to a replacement fresh from the manufacturer. It was clear the manufacturers had not skimped the specification, they had allowed plenty of margin for hot weather operation, but that capacity had eroded after 10+ years and many thousands of hours of operation of the OTM.

 

[Tom Gallacher]

I don't see it much nowadays as they generally are not service exchange now but years ago when I supplied radiators I was constantly amazed at the condition of the old unit being returned. With some of them there were so few cooling fins left all I was getting back was a bare shell. On some other units the fins were completely blocked with gunge. A quick blast with a power spray and the rad was completely serviceable. Why the workshops didn't do this I'll never know.

 

[Blindtraveler]

Calls into question just how well maintained or not many of the vehicles that we all travel on or drive on a daily basis are.

 

[341o2]

I recall plenty of Atlanteans, Ailsas and Olympians that overheated in hot weather, back in the 80s/90s, so it’s not a new phenomenon!

I have a photograph of a LT RT stopped outside a filling station at Green St Green due to low coolant levels, the driver went inside to get water, another incident occurred when the radiator was partially blocked by cardboard one cold winter's morning, so it would warm up faster, the bus stopped amid a cloud of steam en route having heated up more than the driver intended.

 

[TheGrandWazoo]

I have a photograph of a LT RT stopped outside a filling station at Green St Green due to low coolant levels, the driver went inside to get water, another incident occurred when the radiator was partially blocked by cardboard one cold winter's morning, so it would warm up faster, the bus stopped amid a cloud of steam en route having heated up more than the driver intended.

Something I'd forgotten about... the cardboard box to block the radiator! Was very common in Northern winters - photo from John Carter

 

[Ken H]

Leeds City Transport used to attach a metal sheet to the rad to stop overcooling in the winter. They were removed for the summer.