ssuesMGB GT mpg issues
Discussion
Just bought my first MGBgt and apart from the expected niggles im pretty shocked by the mpg. From previous experience and heresay i was expecting somewhere around 28-30mpg, but the guzzler used nearly half a tank to cover less than 100 miles!! worse than my 110 landrover!
The other half has already nicknamed the car janis joplin, due to her drinking habits! Any ideas where to start first trying to improve the matter?
Cheers all!
The other half has already nicknamed the car janis joplin, due to her drinking habits! Any ideas where to start first trying to improve the matter?
Cheers all!
You should get 30MPG plus easily my old one would do 40s on a run without breaking a sweat.
Do a full service, check plug gap and clean, points gap and clean, tappets, then check timing, then mixture. Make sure it has the right needles and that the jets aren't worn, if the car is doing mainly stop start driving check the butterflies in the carbs aren't wobbly (worn spindles) if it's driving around though that won't make much effect. Make sure the air filters are clean.
If all else fails check you don't have any binding brakes (rear most common) check wheel bearings are free, check tracking, make sure engine has good compression, pulls cleanly and doesn't run too hot or cold, oil pressure?
It could just be a badly set up engine so don't worry too much, if so you will notice a big improvement on power too, my money is on some pleb having set the mixture too rich to "give more power".
I'm only here for a couple weeks longer but if you need any more help give me a yell.
Do a full service, check plug gap and clean, points gap and clean, tappets, then check timing, then mixture. Make sure it has the right needles and that the jets aren't worn, if the car is doing mainly stop start driving check the butterflies in the carbs aren't wobbly (worn spindles) if it's driving around though that won't make much effect. Make sure the air filters are clean.
If all else fails check you don't have any binding brakes (rear most common) check wheel bearings are free, check tracking, make sure engine has good compression, pulls cleanly and doesn't run too hot or cold, oil pressure?
It could just be a badly set up engine so don't worry too much, if so you will notice a big improvement on power too, my money is on some pleb having set the mixture too rich to "give more power".
I'm only here for a couple weeks longer but if you need any more help give me a yell.
Also check for fuel leaks, they can occur on the top of the fuel tank (check for dampness around the tank.
To check for fuel leaks put the key in the ignition and turn the ignition on (don't start the car) you should get a few seconds of clicking from the fuel pump and then when it's up to pressure the clicking will stop.
If you have a leak you will hear occasional clicking indicating that the pump is still running.
Check around the fuel pump -it hides in the rear drivers side wheel arch/battery area, the pipes to these can corrode and if the corrosion is on the fuel delivery side you will be loosing fuel.
Also check the carb overflows, on early carbs this is easy just remove the overflow pipes on the top of the carbs to see if fual is comming out. On later carbs it's not quite so easy but you may see fuel dripping from the overflows under the engine bay.
To check for fuel leaks put the key in the ignition and turn the ignition on (don't start the car) you should get a few seconds of clicking from the fuel pump and then when it's up to pressure the clicking will stop.
If you have a leak you will hear occasional clicking indicating that the pump is still running.
Check around the fuel pump -it hides in the rear drivers side wheel arch/battery area, the pipes to these can corrode and if the corrosion is on the fuel delivery side you will be loosing fuel.
Also check the carb overflows, on early carbs this is easy just remove the overflow pipes on the top of the carbs to see if fual is comming out. On later carbs it's not quite so easy but you may see fuel dripping from the overflows under the engine bay.
many thanks for all your replies!
Im on it, brakes where binding worse than i thought, sorted that but have booked it into a garage for the rest, the owner knows mgs! just for a tune up and health check!
Am planning on fitting a kenlowe fan when i get it back, seems to work well on my landrover, anyone any experience with em on mgs?
Im on it, brakes where binding worse than i thought, sorted that but have booked it into a garage for the rest, the owner knows mgs! just for a tune up and health check!
Am planning on fitting a kenlowe fan when i get it back, seems to work well on my landrover, anyone any experience with em on mgs?
I've experience with electric fans on classics including a B and it's a big thumbs up
Wire it in seperately and have it fused but don't worry if you do the job right it wont fail and will last many years
Next bits may upset some B owners (usually those that don't use their classic as an everyday car or think 1,500 miles is enough each year)
You don't need an overide switch, let the fan's thermostat do the work if your car doesn't overheat with the engine fan then it certainly wont with the electric
You also don't need an on-light for the fan, if you've wired it in correctly why keep checking it - you don't get that warning light in modern cars
I'd also suggest removing the engine fan (especialy if the rubber bushes are worn) as the engine fan is cooling the engine when it shouldn't (from cold and when the car is moving at speed) and not cooling it enough when it is really needed (running only slowly whilst stuck in traffic)
Plus removing the engine fan could make the engine seem a tiny bit quieter (especialy if the rubber bushes are worn) and you could gain an eight of a horsepower - why bother fitting an electric if you're leaving the engine fan in?
Wire it in seperately and have it fused but don't worry if you do the job right it wont fail and will last many years
Next bits may upset some B owners (usually those that don't use their classic as an everyday car or think 1,500 miles is enough each year)
You don't need an overide switch, let the fan's thermostat do the work if your car doesn't overheat with the engine fan then it certainly wont with the electric
You also don't need an on-light for the fan, if you've wired it in correctly why keep checking it - you don't get that warning light in modern cars
I'd also suggest removing the engine fan (especialy if the rubber bushes are worn) as the engine fan is cooling the engine when it shouldn't (from cold and when the car is moving at speed) and not cooling it enough when it is really needed (running only slowly whilst stuck in traffic)
Plus removing the engine fan could make the engine seem a tiny bit quieter (especialy if the rubber bushes are worn) and you could gain an eight of a horsepower - why bother fitting an electric if you're leaving the engine fan in?
Kentish said:
Good advice, my viscous fan is going at some point for replacement with an electric fan.
I am going to wire mine to a permanent supply so that it can run on after the car is switched off.
Absolutely no need for a permant supply to the electric fan especially in a standard B, plus you're bound to get a flat battery from it at some time I am going to wire mine to a permanent supply so that it can run on after the car is switched off.
O/T
Kentish you must talk to more people who actually use their classic MGs and less to those fair weather users and show queens
Spend more of your money now, on petrol - drive your car, save a bit of money for FULL regular servicing (and repairs) and replace and "improve" later next year
A BGT - you should be driving it from now until, well, you sell the car
SB - Nigel said:
Kentish said:
Good advice, my viscous fan is going at some point for replacement with an electric fan.
I am going to wire mine to a permanent supply so that it can run on after the car is switched off.
Absolutely no need for a permant supply to the electric fan especially in a standard B, plus you're bound to get a flat battery from it at some time I am going to wire mine to a permanent supply so that it can run on after the car is switched off.
O/T
Kentish you must talk to more people who actually use their classic MGs and less to those fair weather users and show queens
Spend more of your money now, on petrol - drive your car, save a bit of money for FULL regular servicing (and repairs) and replace and "improve" later next year
A BGT - you should be driving it from now until, well, you sell the car
Ah well, I like to be able to lock the car up and leave the fan to cool everything down and there's no reason why it should flatten the battery as long as the the microswitch is working correctly.
I don't want to hijack this thread so have taken the O/T bits back to my MGB thread.
Kentish said:
Hi Nigel;
Ah well, I like to be able to lock the car up and leave the fan to cool everything down and there's no reason why it should flatten the battery as long as the the microswitch is working correctly.
I don't want to hijack this thread so have taken the O/T bits back to my MGB thread.
yeah sorry I slightly got the wrong end of the stick there Ah well, I like to be able to lock the car up and leave the fan to cool everything down and there's no reason why it should flatten the battery as long as the the microswitch is working correctly.
I don't want to hijack this thread so have taken the O/T bits back to my MGB thread.
Still think it's unecessary and you will at some stage flatten your battery unless you've got really on top of the car's electrical "conectivity", charging and storeage
Edited by SB - Nigel on Friday 8th May 12:42
As long as the temp is not set too low it should not run for ages after switching off the engine and of course it'll only run on hot days too.
I've given the battery a bit of a hammering with the current starting issue and it is holding up quite well so I think the charging is all OK, a new alternator has been fitted and I have a 12v system too. Fan motors take a fair amount of current at start up but not too bad once running, it would take quite a few hours of use to flatten a battery which is only an issue if the temp switch isn't working as it should.
I could always fit an inexpensive timer too, allowing the fan to run for say 3 mins after the ingnition is switched off but also depending on the engine temp. Nice and reliable, safe and quite cheap to do.
I've given the battery a bit of a hammering with the current starting issue and it is holding up quite well so I think the charging is all OK, a new alternator has been fitted and I have a 12v system too. Fan motors take a fair amount of current at start up but not too bad once running, it would take quite a few hours of use to flatten a battery which is only an issue if the temp switch isn't working as it should.
I could always fit an inexpensive timer too, allowing the fan to run for say 3 mins after the ingnition is switched off but also depending on the engine temp. Nice and reliable, safe and quite cheap to do.
Kentish said:
As long as the temp is not set too low it should not run for ages after switching off the engine and of course it'll only run on hot days too.
I've given the battery a bit of a hammering with the current starting issue and it is holding up quite well so I think the charging is all OK, a new alternator has been fitted and I have a 12v system too. Fan motors take a fair amount of current at start up but not too bad once running, it would take quite a few hours of use to flatten a battery which is only an issue if the temp switch isn't working as it should.
quite right if electric system is good and nothing else has drained battery (like difficulty starting) then you will be ok - all electric motors put a reasonable drain on a battery - windscreen wipers, cassette/8-track, heater fan (electric windows) and electric engine fan(s) I've given the battery a bit of a hammering with the current starting issue and it is holding up quite well so I think the charging is all OK, a new alternator has been fitted and I have a 12v system too. Fan motors take a fair amount of current at start up but not too bad once running, it would take quite a few hours of use to flatten a battery which is only an issue if the temp switch isn't working as it should.
Kentish said:
I could always fit an inexpensive timer too, allowing the fan to run for say 3 mins after the ingnition is switched off but also depending on the engine temp. Nice and reliable, safe and quite cheap to do.
fair enough then I'm with you - always bearing in mind that this is in addition to (and not instead of) having a correctly set up and completely fully functioning cooling system that is fully and regularly serviced in the first place (yes I know you'll do all that but some don't)Most Bs already have an oil cooler as standard or added, that's another thing I don't understand, if the car's used for towing a good load or in a very hot country or racing but not on a standard road going B in the UK
Have to agree on the chap saying spend money on petrol and frequent servicing. Cooling should be fine if your radiator is it good nick - maybe apart from long traffic jams on really hot days.
The only thing I recommend getting without the old one breaking first is electronic ingition - the type that replaces the rotor arm (three minites to fit). A nice strong spark delivered on time every time.
Then save for when things need replacing and improve them then - if your car is anything like the majority of them when you start to drive it with gusto on longer journeys you'll soon find out what really does need work. Unless you are rich or course, in which case go ahead. It will absorb thousands if you wish. Despite the simplicity there can be a huge number of hidden woes.
The only thing I recommend getting without the old one breaking first is electronic ingition - the type that replaces the rotor arm (three minites to fit). A nice strong spark delivered on time every time.
Then save for when things need replacing and improve them then - if your car is anything like the majority of them when you start to drive it with gusto on longer journeys you'll soon find out what really does need work. Unless you are rich or course, in which case go ahead. It will absorb thousands if you wish. Despite the simplicity there can be a huge number of hidden woes.
Edited by cml on Wednesday 13th May 20:05
I don't agree with spending money if it's not needed either.
The standard ignition is pefectly fine as long as everything is working. A new set of points and a condensor and the odd dissy cap are peanuts compared with the cost of a lumenition kit or electronic style dissy.
Just keep it serviced and all the ignition parts clean or renew the consumable parts for about £15 every 2 or 3 years. As you say, why waste the money!
My running issues are down to the pump; I have gone modern to replace that. It's an electronic pump without points and is plastic bodied so does not corrode under the car and it's half the price of the original type of (less reliable) pump!
If something fails then I'll look to improve that part but otherwise I'd prefer to spend the money on getting the interior nice and keeping the bodywork in good condition.
The standard ignition is pefectly fine as long as everything is working. A new set of points and a condensor and the odd dissy cap are peanuts compared with the cost of a lumenition kit or electronic style dissy.
Just keep it serviced and all the ignition parts clean or renew the consumable parts for about £15 every 2 or 3 years. As you say, why waste the money!
My running issues are down to the pump; I have gone modern to replace that. It's an electronic pump without points and is plastic bodied so does not corrode under the car and it's half the price of the original type of (less reliable) pump!
If something fails then I'll look to improve that part but otherwise I'd prefer to spend the money on getting the interior nice and keeping the bodywork in good condition.
Have to agree with the advice here ~ provided the rest of the engine is in good shape, prime suspect would be worn SU carbs and their parts. Those can make even a new engine appear very thirsty...
By the way, one or two comments suggest driving slowly to save fuel. Smooth driving with good anticipation is the real fuel saver which is not the same as driving slowly, far from it....in any car ... if you get my drift....
By the way, one or two comments suggest driving slowly to save fuel. Smooth driving with good anticipation is the real fuel saver which is not the same as driving slowly, far from it....in any car ... if you get my drift....
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