DS21 running on
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Thread: DS21 running on

  1. #1
    Tadpole dherrick's Avatar
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    Default DS21 running on

    Dear brains trust:

    I've got an issue with my 1970 DS21 Pallas with the engine running on.

    Some background to the car is:
    - I've had it for over a year and am slowly fettling it to excellent health. The car is basically in very good condition.
    - The original DX2 engine and 4 speed manual was replaced with DX2 engine and 5 speed from a D Super 5 prior to me owning it.
    - The replacement engine has done about 100k.
    - 123 ignition fitted for me by the mechanic. This slightly lessened the running on.
    - Car fully serviced.
    - It apparently has always run on with this engine. This is from speaking to the mechanic who restored the car and replaced the engine 6 years ago and now works on it. He's stumped to what the cause is, short of pulling the head to have a look (which will be expensive).
    - Compression is fine, is within 10% between all cylinders (1= 138, 2= 145, 3= 138, 4=143, all psi).
    - I've had the carbie rebuilt, this lessened the running on but did not cure it. I’m pretty certain its base plate was machined flat.
    - The car runs hot, to the point that if parked after a run and left for 5 min, fuel will vapourize in the mechanical fuel pump and then vapour lock the carb. I'm now running an electric fuel pump to prevent this happening.
    - Thermostat is working.
    - The heater works very well.
    - Repairing the air intake tunnel helped make it run a little cooler, the temp warning light no longer comes on in traffic or a very hot day. The car hadn't got a temperature gauge yet.
    - When the car is very hot and I accelerate hard up a hill in 2nd or 3rd with the revs over 4000 at full throttle, the engine stumbles like it's starved of fuel.
    - I've run a de-carboning foam through the carb/engine, other than producing spectacular clouds of white smoke this didn't change anything.
    - The car doesn't run on when the engine is cold.
    - I currently use 4th gear and the clutch to stop the engine.
    - I'm going to de-scale the cooling system, replace the coolant, fit an Engine Guardian temperature gauge and likely an electric fan behind the radiator (will be taking the nose tip off the fan to fit the electric fan in).

    My questions are:
    - Could this be to do with the timing scale changing from the DX2 engine fitted to a 1970 DS21 to the DX2 engine fitted to a 1972 onwards D Super 5? - therefore the car is still set up with the timing for the earlier engine (NB: setting timing is something I would need a mechanic to do for me).
    - Could it be electrical?
    - Is it simply carboned up?
    - Or, should I be checking for something different / doing something different?

    I want to avoid pulling the head (which may be within my skill level) or taking other expensive action, hence the information dump, so all help is appreciated!

    Some photos of the car are also below.

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    Many thanks

    David

    DS21 running on-img_3257.jpgDS21 running on-img_3258.jpgDS21 running on-img_3260.jpgDS21 running on-img_3264.jpg

  2. #2
    Fellow Frogger
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    An attractive DS you have there. Have you read the existing thread on an overheating 21 in Adelaide? You may share some root problems.
    More ds woes

    Is the ignition actually switching off? You could try pulling the wire from the spade terminals on the coil and see if stops, which might suggest some electrical fault, perhaps the ignition switch. That's unlikely, but not impossible.

    I assume it currently has a Weber carby??? You might check the carby setup, specifically, that the float valve shuts off the fuel flow and that the primary throat butterfly has the correct closed opening.

    Operation D210.0 in Vol 1 of the factory manual shows a change in the static timing flywheel pegging arrangement from 7/71. Earlier cars had the peg lock the flywheel at 12 degrees BTDC, while later versions lock it at TDC. If your car has has an engine swap, this could be an overlooked contributor, although it affects the static timing and it may have been adjusted subsequently using a timing light. D Super 5 was a designation used from 1972, while your car is 1970. You should certainly investigate this as a possibility.

    If you don't have the factory manuals, which are far, far better than the alternatives for many important adjustments, download the PDF versions here: https://sites.google.com/site/citroenpublicationslist/

  3. #3
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    David,

    With any engine timing should really be done dynamically - i.e. with a timing light. Specifications for the various engines/years is in 814. The use of the timing 'pin' is only to get a rough position to get the engine started. As the timing scale (your car should have one) is gauged via the cam shaft pulley the actual 'value' on the scale will be 1/2 the advance if the reading(s) were done at the crank shaft - which are the values given in 814. *If you get yourself a decent timing light and inexpensive tachometer - setting timing is an easy procedure.


    That the engine was rebuilt and the problem did not go away really does tend to eliminate 'carboning' of the combustion chamber(s) being a source of the problem. Although the carb was rebuilt - I doubt who ever did it actually checked to ensure that the needle valve is really shutting off fuel flow. An easy way to check is to get the car to the point where it will 'run on' - then with the engine at idle pull the air supply hose to the carb and look into the top with a small flash light and see if you detect any 'wetness' on top of the throttle plates. If you do - fuel is leaking past the needle seat. Also double check the 'heat range' of your spark plugs. It is also possible that the plugs you have are the wrong heat range for the engine. There are any number of internet sites that will explain this and how to check your plugs. If you have problems, let me know and will point you in the right direction.

    High speed miss. Normally this is an indication of fuel starvation and should happen regardless of engine temperature. However it could also be caused by insulation breakdown inside the plug tubes in the head. This tends to happen more when the engine is hot. Make sure that you have no oil build up inside the spark plug wells. Additionally check the end of the fiber insulating tubes (should not show any evidence of carbonizing - being burnt) as well as the overall condition of the ignition leads. They should be soft/flexible with no sign of harding or increased electrical resistance.

    Good luck with the "detective" work and let us know what you find out.

    Steve

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    Tadpole dherrick's Avatar
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    Hi Steve and David,

    Thanks for the replies. I have been following the overheating thread referred to. I'll start working through the things you suggest and let you know how I get on.

    Steve - the replacement engine actually hasn't been rebuilt, it was used to re-engine the DS when it was restored, and the engine is supposed to only have done around 100,000k's. I guess this would mean carbon build up could be a possibility?

    Thanks

    David

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    David,
    beautiful looking DS.
    It's worth checking the curve setting of your "123". Settings dial on the underside of the 123 body ( it's facing the ground ) If you have a small mirror, do a quick check to confirm it is set on "9". Otherwise remove to see, either way a simple thing to eliminate.

    I just read your post again and you say the motor may be post 72 in which case the setting should be
    set to "C".

    Best of luck.
    Attached Thumbnails Attached Thumbnails DS21 running on-123-curve-settings.jpg  
    Last edited by mberry; 17th January 2014 at 10:14 AM.

  6. #6
    1000+ Posts Greg C's Avatar
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    When investigating the overheating I would caution against running out and buying aftermarket improvements. The system should work quite well in standard setup. If it doesn't, find the cause and only then make improvements and only if really needed. I would doubt you would need to if everything is OK. First basics like a new radiator core, reconditioned water pump, new thermostat. Then see how you go. I will lay odds the overheating is related to incorrect timing, another basic setup you have to get right before going out and buying extra fans etc.
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    David,

    Doubt that is the problem. Had a 68 ID19B that had the same problem from new - well after about 15,000 miles or so. Being a US car with*pollution control the problem came back to a duffed solenoid on the POS Solex carb . Think you may well find the problem is just related to engine timing and/or the heat range of the plugs. Also possible that the needle/seat is not actually cutting off fuel flow the way it should.

    Steve*

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    Greg,

    Re a*reconditioned*water pump - only really needed if one has A/C. Best bet is to just one of the new 2 groove pumps from Spain. Cheap and well made. The trick with the pumps is to make sure the impeller is in good shape. It is a bit scary how much wear can occur with those impellers. The other thing to check is that there is a thermostat and it is working correctly. The system will not cool properly if the thermostat is missing. A lot of us in the US use a 7 psi relief cap instead of the 4 psi the cars came with. Raises the boil over temp*significantly and the system will handle the extra pressure with no problem.

    Steve

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    1000+ Posts daffyduck's Avatar
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    Got a factory installed auxiliary fan on a crossflow radiator? Are the electrical connections mismatched and the fan is running backwards?
    Run on is caused by too much spark advance, carbon deposits, or too much idle air.
    Barring success after setting timing and idle speeds properly there isn't much that can be done. If the cylinder head has been shaved beyond minimum thickness, run on is a common side effect.

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  10. #10
    Real cars have hydraulics DoubleChevron's Avatar
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    My old CX2400 used to always run on in hot weather. Try running the highest octane fuel you can find. The main reason later carby cars run on is the anti-diesel solenoid on them died decades ago....

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    Default Thanks Wally

    Quote Originally Posted by daffyduck View Post
    Got a factory installed auxiliary fan on a crossflow radiator? Are the electrical connections mismatched and the fan is running backwards?
    Run on is caused by too much spark advance, carbon deposits, or too much idle air.
    Barring success after setting timing and idle speeds properly there isn't much that can be done. If the cylinder head has been shaved beyond minimum thickness, run on is a common side effect.

    Via the aussiefrogs App
    For the simplest, yet most comprehensible answer to the question posed.

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    Tadpole dherrick's Avatar
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    Hi Everyone - thank you so much for all your advice, I'll start working through the now extensive list and report back!

    Thanks

    David

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    Well, I've started working through the list of things that could be causing the car to run hot/run on, and first on the list had been making sure the front brake pads can be wiggled.

    They can't be wiggled, both sides are tight in the calipers. The LHS is pictured. I have pulled on them very hard, but they won't budge. I'm not sure if I should lever them to the side with a block of wood to loosen them, or try something else.

    What other things should I be trying to get the pads out?

    Thanks

    David
    DS21 running on-imageuploadedbyaussiefrogs1390295461.161299.jpg

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    Quote Originally Posted by dherrick View Post
    Well, I've started working through the list of things that could be causing the car to run hot/run on, and first on the list had been making sure the front brake pads can be wiggled.

    They can't be wiggled, both sides are tight in the calipers. The LHS is pictured. I have pulled on them very hard, but they won't budge. I'm not sure if I should lever them to the side with a block of wood to loosen them, or try something else.

    What other things should I be trying to get the pads out?

    Thanks

    David
    Click image for larger version. 

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    David,

    With the front of the car on stands, can you easily turn the front wheels by hand or is there some to a lot of resistance? If you can manually rotate the front wheels with out trouble then your pads are not dragging.

    To actually release the front pads you need to attach a drain tube to each of the calipers drain nipples - location will depend on model of car. Open up the caliper drain nipples a 1/2 to a full turn - with them open you will be able to move the pistons back in to allow a 'wiggling' or removal of the pads. With them shut you should not be able to force the pistons inwards.

    Steve
    Last edited by Citroenfan; 22nd January 2014 at 09:07 AM.

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    Tadpole dherrick's Avatar
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    Hi Steve,

    Thanks for the advice. Both front wheels rotate relatively easily, so there's no longer any need to remove the brake pads.

    That's a good tip on bleeding the brakes to release the pads, I hadn't seen that before.

    Thanks

    David

  16. #16
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    Hi All,

    Just updating you on where I've got to with the hot engine / running on in the DS.

    The hot engine was fixed by replacing the water pump. The one that was there was completely stuffed and not circulating much water. The block and radiator were flushed at the same time, and have checked out fine. The car feels heaps cooler, no longer smells of coolant when hot, and the temp gauge I fitted in the weekend shows it's running at 80 degrees when up to temp.

    Saying this, the car is still running on...

    Other things checked were:
    - the timing was out by 4 degrees, which apparently isn't enough to cause running on. It's properly set up now.
    - the 123 is on the correct curve.
    - spark plugs/insulators/leads are fine.
    - there are no air leaks and the vacuum is fine.
    - carb has been checked over and adjusted.

    The only outstanding thing is the hot idle is too high. The hot adjustment screw is at it's maximum and the hot idle is still at approx 1000rpm. To get this fixed the carb needs to go back to the Weber specialist. This apparently is contributing to the running on.

    In summary I'm resigned to live with the running on for a while longer, then get the carb looked at in the future.

    Unless of course anyone has suggestions for more adjustment range at hot idle?

    Thanks

    David

  17. #17
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    David,

    Having the idle that high when the engine is warm and not being able to drop is an indication, if all else is OK with the carb, that the base adjustment on the carb is faulty. With the two barrel Webers used on the D's all idle adjustment is done with the secondary throttle. This is where the actual idle circuit in the carb body is located. The throttle stop of the primary barrel is set so that its edge has between 0.003" and 0.005" clearance to the venturi wall. Additionally when set correctly the first progression hole drilled in that venturi wall will just be completely covered by the primary throttle stop - one may need the use of a magnifying glass to verify that setting. This is done with the unit removed from the car. Once set a lock nut is used to secure the primary throttles adjustment screw so that it cannot be moved out of adjustment. Then all idle mixture strength and air flow is done via the idle mixture screw on the base of the carb along with the secondary throttle stop adjustment screw. The primary is not touched at all. Under normal circumstances the idle mixture screw will be between 1.5 to 2 turns out from its gently seated position. If not then the secondary throttle's secondary jet (so called idle jet) may be either to large or to small depending on the position of the mixture screw. Also possible that the mixture screw's taper is damaged. Additionally any excess air getting into the intake manifold via the carb base will also cause it to run fast at hot idle. A quick way to check for this condition is to gently spray the base of the carburetor with carb cleaner from a pressurized can. You want to spray just the joints between the carb base, the phenolic heat shield, and intake manifold. If engine speed increases when you do this you have an air leak in that area.

    Steve

  18. #18
    1000+ Posts daffyduck's Avatar
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    Or the other idle jet is plugged and somebody monkeyed with the first side to overcome the issue. Not all carbs have two jets but some do. Look for the simple things first.

    Doing the Daffyduck dance via the AussieFrogs app.

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    Quote Originally Posted by daffyduck View Post
    Or the other idle jet is plugged and somebody monkeyed with the first side to overcome the issue. Not all carbs have two jets but some do. Look for the simple things first.

    Doing the Daffyduck dance via the AussieFrogs app.
    ALL progressive Weber carbs used on the D's have 2 main and 2 secondary jets - as does his.

    Steve

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