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  1. #1
    Fellow Frogger! andrewj's Avatar
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    Default Guzzling GS

    Ok clever GS people,
    My GS sedan is doing all the things it should do, ie. plenty of power, rev's like crazy and occasionally puffs smoke when starting hot.
    Only problem is that it is using around 12.5L/100k, which seems way too much. Any idea's on what could be causing it?

    Cheers,
    Andrew

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    Driving - '90 XM, '85 CX IE Auto, 406 Coupe, 405 srdt wagon, '78 dyane, Resting (or Rusting): '73 Birotor '82 CX Presitige, '81 CX Break IE, GS X2, GS1015 Wagon, GS 1300 5sp Wagon, '76 GS 1220 Wagon, '75 GS Wagon, '58 2CV, '58 Vauxhall Velox

  2. #2
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by andrewj
    Ok clever GS people,
    My GS sedan is doing all the things it should do, ie. plenty of power, rev's like crazy and occasionally puffs smoke when starting hot.
    Only problem is that it is using around 12.5L/100k, which seems way too much. Any idea's on what could be causing it?

    Cheers,
    Andrew
    Heavy traffic, many cold starts and rarely gets upto operating temperature Under these circumstances I found the GS uses as much petrol (nearly) as a CX doing the same thing.

    Check the basics first:

    --choke patially on
    --blocked air cleaner ...

    You know the really simple things.

    seeya,
    Shane L.
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    Fellow Frogger! Trixie's Avatar
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    Cold weather, urban trips of 15 mins and our GS would be lucky to better 12l/100km, even when in the best of health. Air-cooled, relatively heavy body and high torque peak/low gearing I suppose.
    John

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    Fellow Frogger! chris's Avatar
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    Puffs of smoke from a hot engine are bad news. Probably means the rings are on their way out. Sorry.

    As others have said, cold running is murder on economy for a GS. I've given up working out my round-town fuel economy; if I do a lot of stop-start driving I'm lucky to crack 25 mpg (yes, I know, I should get with the whole metric thing).

    Make sure that all your preheater/heat exchanger doo-dackies are hooked up and working so that the engine warms up fast. Also check on the condition of your ignition system (plugs, HT leads, etc).

    On the other hand if that's your open-road economy something is badly wrong


    Chris
    GS 1220 break. Beige cars go faster

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    Quote Originally Posted by andrewj
    Ok clever GS people,
    My GS sedan is doing all the things it should do, ie. plenty of power, rev's like crazy and occasionally puffs smoke when starting hot.
    Only problem is that it is using around 12.5L/100k, which seems way too much. Any idea's on what could be causing it?

    Cheers,
    Andrew
    Andrew - I'm driving 4 cars at the moment and although I've not done any controlled testing to prove it, I find the GS around town gets about the same economy as the R12, R8 and Pug 204 - but on the highway it outshines them easily. The best for around town is the 204 - magic little thing it is.

  6. #6
    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by chris
    Puffs of smoke from a hot engine are bad news. Probably means the rings are on their way out. Sorry.

    As others have said, cold running is murder on economy for a GS. I've given up working out my round-town fuel economy; if I do a lot of stop-start driving I'm lucky to crack 25 mpg (yes, I know, I should get with the whole metric thing).

    Make sure that all your preheater/heat exchanger doo-dackies are hooked up and working so that the engine warms up fast. Also check on the condition of your ignition system (plugs, HT leads, etc).

    On the other hand if that's your open-road economy something is badly wrong


    Chris
    GS's are designed to leak oil into the combustion chamber when resting... Most likely one of the reasons they last so well. When they were brand new on the showroom floor they would blow a nice cloud of smoke on startup.

    As long as there not blowing smoke once they have been running for a few minutes, you should be ok !!

    seeya,
    Shane L.
    PS: Chris, watch your exhaust one morning when you start it ... You going to be in for a surprise
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  7. #7
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    Hi Andrew,
    My GS is averaging about 10ltr/100 kms, that is cold start, drive to work in 20 mins, then home again. It does much better in summer and on long runs. Check the tube that takes warm air from the exhaust to the air cleaner is OK.

    Cheers, Andrew.


    Quote Originally Posted by andrewj
    Ok clever GS people,
    My GS sedan is doing all the things it should do, ie. plenty of power, rev's like crazy and occasionally puffs smoke when starting hot.
    Only problem is that it is using around 12.5L/100k, which seems way too much. Any idea's on what could be causing it?

    Cheers,
    Andrew
    Cheers Andrew

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    Andrew,

    has the car's economy changed recently, or has this been typical since you've had it? And what sort of fuel are you running it on? (ULP, PULP or LRP?)

    It's very easy to check the float level with either Solex or Weber carbs fitted to these cars, so unless you've done this recently, might be worth whipping the top cover off and inspecting the float needle valve while you're at it too.

    If the temperature is much below 10 degrees C do not be afraid of fitting the grill muff. I know that a lot of people will say that these cars run OK at colder temperatures without the muff fitted, and this is true, however the engines warm up quicker and run smoother during short trips in cold weather with it fitted. Less choke = better economy. The fact the heater works better too, is a bonus.

    Chris's remarks about the pre-heater components are also worth addressing. Whilst I have a car with the exhaust pre-heater box disconnected that runs perfectly without it, the thermo valve that feeds warm air to the air cleaner intake until the motor is warm, on the other hand, has a significant impact on engine tractability when cold. Having said all of this, 12.5L/100km, whilst not brilliant, isn't that surprising for shorter trips in cold weather. Longer trips should be better though.

    Puffing smoke occasionally may not necessarily indicate worn top end components. Does it tend to puff more often when parked up or down a hill, for example? As Shane has pointed out, these engines would puff smoke from brand new. In fact, if you open the "Road Tests" page of AF, you will find a copy of a 1975 test of the GS Estate by Wheels, where the writer describes exactly this behaviour. This results (in part at least) from the piston ring gaps in one or more cylinders lining up near the "six o' clock" position on engine shutdown, allowing oil to trickle into the combustion chamber. Interestingly, later GS/GSA engines incorporated pegged piston ring grooves, in order to prevent the rings from rotating during engine operation, in an effort to address this problem, less common in four stroke engines than in two strokes (although for different reasons).

    I'm now living in Hobart, so if you need a hand with the carb check send me a PM,

    Regards,
    Brett

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    Fellow Frogger! chris's Avatar
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    Quote Originally Posted by DoubleChevron
    PS: Chris, watch your exhaust one morning when you start it ... You going to be in for a surprise
    If my car's been sitting for a week you could land a troop plane behind it without anyone seeing But only when it's cold. Hot, even after sitting a few hours, it blows no smoke...

    Chris
    GS 1220 break. Beige cars go faster

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    Fellow Frogger! andrewj's Avatar
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    Thanks everyone for your advice.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o:p></o:p>

    <o:p></o:p>

    OK, progress so far.....<o:p></o:p>

    <o:p></o:p>

    Washed air filter in petrol. <o:p></o:p>

    Petrol went green/grey from oil that had splattered up from crank case ventilation.<o:p></o:p>

    Checked float level- seems ok.<o:p></o:p>

    Checked choke- opens fully.<o:p></o:p>

    Checked manifold heating tubes- Not there<?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"> <v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 16.5pt; HEIGHT: 14.25pt" type="#_x0000_t75" alt=""><v:imagedata o:href="http://www.aussiefrogs.com/forum/smilies/nownow.gif" src="file:///C:/DOCUME~1/ac-jones/LOCALS~1/Temp/msoclip1/01/clip_image001.gif"></v:imagedata></v:shape><o:p></o:p>

    Checked air- inlet heater- Not there<v:shape id=_x0000_i1026 style="WIDTH: 16.5pt; HEIGHT: 14.25pt" type="#_x0000_t75" alt=""> <v:imagedata o:href="http://www.aussiefrogs.com/forum/smilies/nownow.gif" src="file:///C:/DOCUME~1/ac-jones/LOCALS~1/Temp/msoclip1/01/clip_image001.gif"></v:imagedata></v:shape><o:p></o:p>

    Put a tank of petrol through- Still exactly 12l/100km. <o:p></o:p>

    <o:p></o:p>

    Iím driving to work, which is around 25km each way, mostly on the open road. So I would expect around 10l/km like Artisan is getting... Iím running on PULP, so Iím thinking maybe try and advance the timing a bit.<o:p></o:p>

    <o:p></o:p>

    On the weekend I borrowed the air inlet heating gear out one for the wagons, and it now heats up much faster (will idle with choke fully in after around 30seconds driving, compared with around 5min previously). <o:p></o:p>

    <o:p></o:p>

    Itís cold, wet and snowy down here at the moment, so Iíll be driving the nice warm CX Ďtill it clears up a bit. <o:p></o:p>

    <o:p></o:p>

    Cheers,<o:p></o:p>

    Andrew

    Driving - '90 XM, '85 CX IE Auto, 406 Coupe, 405 srdt wagon, '78 dyane, Resting (or Rusting): '73 Birotor '82 CX Presitige, '81 CX Break IE, GS X2, GS1015 Wagon, GS 1300 5sp Wagon, '76 GS 1220 Wagon, '75 GS Wagon, '58 2CV, '58 Vauxhall Velox

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    Fellow Frogger! chris's Avatar
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    OK, so even if it will idle with the choke in, the car probably isn't coming up to operating temperature at all in weather that cold. Your comment about the CX being warmer rather confirms that -- the heater in a GS is pretty good if the engine is getting warm.

    I know some say you can get away without the exhaust heat-exchanger pipes, but I don't agree. Sucking warm air into the carby will help, but if the intake manifold isn't warm the fuel won't vaporise properly and will burn poorly -- leading to the poor economy you're experiencing. Basically the two systems (intake preheater and heat exchanger) are complementary, not interchangeable, and if the engine runs cold your economy will definitely suffer.

    To illustrate, my car was missing those pipes when I got it, and it took me quite a while to fit them. The best economy I ever got in that state was 33mpg, on a very warm day and a good flat run. With the heat exchanger fitted I get 34.5mpg in those circumstances. Not to mention the car is much nicer to drive around town on cold nights and warms up about 10 times as fast in the morning.

    Cheers,
    Chris

    PS: And as Brett says, if you're running around in near-freezing conditions don't be afraid to cover some of the grill. For snow-lying-around weather I use duct tape and cover the top half of the grill plus a strip down each side.
    Last edited by chris; 12th September 2005 at 02:51 PM.
    GS 1220 break. Beige cars go faster

  12. #12
    Tadpole
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    I have the same problem with my gs.
    But mine is drinking 15l/100km!!!!
    If you find out whatīs the problem please share it in this thread.
    Iīm starting cold too (īround 5ļC) and driving short city distances. Now trying to avoid +2500rpm and fast accellerations.


    Cheers


    Agustin

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    Moderator Alan S's Avatar
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    My knowledge of GS's would fit on the back of a postage stamp, so bear with me on this suggestion.
    My first BX a 1.6 litre, used to do V8 consumption figures when I first bought it. It also was owned by a well known Cit specialist so you would have to expect it to have been set up correctly and that was a problem, trying to find out what he'd done and which I found was mainly things most of them seem to do which was dispose of many of the parts associated with the fuel/air intake side of the engine. Usually done I feel in stages firstly possibly due to slack workmanship which creates a problem, then from there downhill all the way as they 'modify' things rather than restore them trying to sort it.
    Amongst the things I restored on it was the idle jet which when checked was found to be a 70 when a 45 was the original size. The main and compensater jets were fitted assabout, the float level was too high and the most important piece of handywork to be discarded was the hose from the hotbox on the exhaust that fitted to a 3 way thermo flap controlled diverter that was designed to allow the heat from the exhaust manifold to be drawn into the intake but which thermostatically was diverted once the air in the box hit a certain temp. The manifold to diverter hose was missing, the flap in it was held wide open allowing ambient temp air, regardless of ambient temperature, to flow into the throat of the carby.
    A condensed version of what I did was this: Fitted a 45 idle jet, reversed the main and compensator, set the float height so it would idle and rev out when hot (cold engines are only that way for 1 % of running so who cares if it's rough when cold) by trial and error rather than pre determined measurements, reconnected the hotbox to the diverter, removed the screw jamming the flap so it again became thermostatically controlled.
    The reason the latter was so important as I discovered, was that when I accessed a service manual on this Weber carb (and I have no doubt this would apply to others) it seems the initial settings on them are done in a rather strange way. There is a setting done that is proportionate to ambient temperature. Technically speaking, this will not change dramatically if an artificial ambient temperature is established via the hotbox to thermo flapped diverter is used, however, when the "Australian conditions" mentality clicks in that tells these guys that 30 degrees here is different to 30 degrees they get overseas, this gets all discarded. At this point, the setting within the carby (and no, I'm not now talking about automatic chokes before anyone asks) compensates for the temperature difference by bringing into play what they refer to as an "enrichment device" possibly controlled by a bi-metal strip, that richens the mixture to allow for what it thinks is cold driving conditions. If the carby is retuned and this 'throttle' as it is referred to is reset to allow for the lower ambient temperature, then this may not be quite as big a problem, but whilst ever the hotbox and diverter are disconnected, this enrichment device will play a constant part in affecting fuel consumption. When mentioned on an overseas board, it seems that even over there, the average greasemonkey discarded the hotbox hose sometimes even under warranty with resultant fuel consumption problems.
    When my car was sold, the new owner was rapt in the performance and consumption but a few weeks later rang to have a whinge saying it had been taken to a different but equally well known specialist who gave them a right old sermon about the tuning of the car including showing them how he'd "modified" the air intake, reset the float and put the jets back the correct way around, but didn't know what I'd done because he couldn't get it to run or idle as smooth and the fuel consumption had almost doubled to what they were getting when they bought the car at first.
    I didn't waste any breath trying to explain. Just referred them back to the expert.

    The point I am making, is that if the original set up was a similar set up to this BX, then this may be one avenue that hasn't been explored and might be the answer you are looking for but slipped through the net if the removal of these pipes from the hotbox is as common on GS's as it was on the carby BX.
    Being an air cooled engine, these kinds of things I would imagine could play a critical part of correct tuning and overall operation.


    Alan S
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    Fellow Frogger! chris's Avatar
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    Quote Originally Posted by Alan S

    The point I am making, is that if the original set up was a similar set up to this BX, then this may be one avenue that hasn't been explored and might be the answer you are looking for but slipped through the net if the removal of these pipes from the hotbox is as common on GS's as it was on the carby BX.
    Alan,

    It's actually worse than that. Not only does the GS have one of those thermostatic flapper jobbies (double whammy as these stop working in old age -- I had a go at mine but it's still not perfect), they have a heat exchanger under the carb. There's an small exhaust tube running from the left-hand manifold, through a hot-box under the centre of the intake manifold, and back down to the right-hand front pipe, just behind the engine.

    Replacing the right-hand side of that pipe is time-consuming and rather fiddly, especially as it's often the actual exhaust front pipe that rusts through (even less fun). At this point dodgy mechanics and backyard bodgers alike seem to decide that as it's occasionally hot in Australia, Citroen's elaborate and carefully worked out preheating systems are completely un-necessary As a consequence the engine takes forever to warm up, and won't warm up at all in cold weather. The fuel doesn't vapourise properly, doesn't burn properly and flies merrily out the exhaust pipe in that state

    You could say I have a bee in my bonnet about this

    There isn't a temperature compensator inside the carb though, to the best of my knowledge. The driver has to enrich the mixture with his foot

    btw, I bet I can guess who put that screw in your BX's intake flapper -- my car was the same, except it was sucking half-hot/half-cold all the time and finally refused to run on a hot day until I pulled the screw out

    Chris
    GS 1220 break. Beige cars go faster

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    Fellow Frogger! Paul Smith's Avatar
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    Andrew's car, being an early 1015 doesn't have the exhaust preheater - it uses an oil heat exchanger under the carby - which they got rid of - maybe because it did not work so well?

    I agree about the air intake thingy Chris - I went through a pile of wrecks to find one of the wax pellet thermostats that stil worked - AFAIK mine is still going, but taking it apart to check is as usual, not fun. Also many cars don't actually have the hot air intake hose still there - it is left off when people reassemble them.

    Even in Sydney, on short runs in what we laughingly call winter I use a grill muff - it makes an enormous difference to the running of the car - the GS is very over-cooled for winter. (and with the muff on you can actually get something approaching heat out of the heater). I can imagine that in a proper cold climate you would need it on a lot more.

    In tropical countries the preheaters are often disconnected completely - I remember an Indonesian guy on the GS list, with a car with A/C that kept overheating - that was the first thing I checked - and they were never connected over there.

    The other reason they are removed is that the alloy preheater plate corrodes inside, so you get exhaust leaking back and vice versa - so people often just blank them off. As well as slow warm up you also run the risk of the carby icing up on a fast run without any preheat.

    Paul
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    Paul,

    it is interesting that you've mentioned the car Andrew has a problem with is an early 1015 as I have 1015 and 1220 estates. My own experience has been that the 1015 is quite a bit thirstier than the 1220 around town. I put it down to the fact that it is geared lower, is much less tractable and hence has to be revved more than the 1220. It needs more warming up too. I could usually manage about 10km a litre in the 1220 (about 30mpg) but around town the 1015 stuggles to make 9. The 1015 however closes the gap a bit when on the open road.

    The other thing is that if the car is actually an early 1015 with the oil heating system then by definition it would have a Solex carburettor fitted, as the arrival of Weber carbs on GSs co-incided with the introduction of the exhaust heated intake system.

    A while ago I had to replace a Weber because it developed a terminal air leak around the throttle spindle. This made the car a pig to drive at low rpm, even when it was warm. Driving at 80-100kph wasn't too bad.

    Might be a silly question, but is all the fuel coming out of the tank actually getting into the carburettor? Another chap here in Tas found a leak in the fuel hose near the filter at the front of the tank...

    Regards,
    Brett

  17. #17
    Fellow Frogger! chris's Avatar
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    Andrew has a 1015? Brett also has 1015... How many of those cars do we have here anyway? Are they all beige? Who am I again?

    Ahem. As a wee aside, the flapper thing actually has two potential failure modes. It's powered by a bi-metallic spring, which pushes against a coil spring, and another (heavier) coil spring returns the system to the "cold" position when the bi-metallic spring relaxes. The two springs are held together by a bit of plastic that disintegrates (completely -- the biggest bit I found was about 1mm long). The bimetallic spring also wears out, and doesn't extend as far as it should. I have no idea if you can buy new ones...

    Oh, and the breather hoses often leak too -- the joint is under that plate in the floor of the boot.

    Chris
    GS 1220 break. Beige cars go faster

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    Moderator Alan S's Avatar
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    Quote Originally Posted by Chris
    There isn't a temperature compensator inside the carb though, to the best of my knowledge. The driver has to enrich the mixture with his foot
    It's a setting done on an intitial setting up on the BX (and possibly CXs) and isn't one of those things you would normally touch in the tuning of the carby.
    Most are set at a 20 degree ambient temperature but the adjustment is + or - by a few thou on each degree the ambient temperature is increased or decreased and when you think about it, how many times at going to work time would the ambient be above 20 degrees. The cowboys seem to think everything is worked around a 35 degree day and as a result, they throw the entire calibration out of whack when they disembowel them.
    If someone took the time or had the ability and instruments to make the necessary adjustment, it might be an interesting exercise to see what the end result might be, but methinks that possibly returning the system of using an approximate pre determined temperature which I feel is the intention using these hot box systems, might be a lot simpler, more effective and give better results.



    Alan S
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

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