2CV engine fighting back on Bastille Day!
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Thread: 2CV engine fighting back on Bastille Day!

  1. #1
    1000+ Posts pottsy's Avatar
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    Default 2CV engine fighting back on Bastille Day!

    At present Gaston's engine and gearbox are mounted in The Alleged Vehicle as a test bed. All was progressing well until recently. Allow me to elucidate.

    Symptoms: Starts and idles reasonably well. When accelerator pressed, motor will hesitate, misfire, sometimes spit back, and if it does wind up to some revs, the misfire is still noticeable and causes engine rocking. Maintianing a constant engine speed, when possible, results in the motor wobbling and the exhaust note popping as if the sparks were coming and going randomly.

    Car exhibited similar symptoms for a while last Saturday, but after it warmed up, and I glared at it for a while, it seemed to warm up and settle down and cruised happily homewards at 100kmh with no apparent problems. When I started it yesterday it idled OK as I rolled backwards down the drive. Filled out the logbook and proceeded to move off. "Non" quoth TAV as he coughed, sputtered and refused to accelerate. After a few choice words, expressed bi-lingually just in case it didn't properly understand, we lacked even the power to get back up my driveway! Checking everything and allowing it to warm up more only resulted in it taking a couple of goes just to finally struggle up the drive.

    First thoughts: It seemed to me to be possible fuel starvation, or maybe water in the tank. As detailed below, the ignition should be all OK.

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    So I checked, and changed anyway, the fuel filter. (It was dirty, but only a year old. Also drained about 5 litres of fuel out and replaced it with about 8 litres of fresh fuel. On spec I added some methylated spirits to the tank, even though there was no sign of water in the drained fuel. (Or in the carby bowl when I stripped it)

    No change.

    At this point I should perhaps list the things that Iíve done so far on this motor. The fuel pump and hoses are new, the points and condenser are new (Valeo kit) and set to open at the timing mark (8deg BTDC). Dwell checks out to within a tooth or two on the flywheel. Static points gap within a whisker of 16 thou and checking with the timing light puts the timing at maybe a tooth or so advanced on the mark. So today I vowed to wrestle it to the ground. Seemed appropriate as itís Bastille Day! First thing was to remove and re-check the points, then painstakingly reset the timing, check the dwell (open for 43 teeth +/- 1 or two teeth).

    No change.

    OK, I have a new coil in the box, so plugged that in.

    No change.

    A pair of new spark plugs and a pair of new ignition leads later:

    No change.

    Maybe itís an air leak, so while itís idling spray starter fluid around the inlet manifolds and carburettor base.

    No change.

    Off came the carby. Strip, clean, blow through all the passages with compressed air, remove and clean all jets, reset float level to exactly 18mm from centre float to gasket. Reinstall making sure all four bolts are tight.

    You guessed it, no change.

    So Iím hoping someone has a bright idea or two. Looking at some of the overseas sites suggests this is relatively common when either coils or condensers fail. Tried a new coil and the condenser is brand new out of the box.

    Busy tomorrow, but next time I tackle the beast I may re-install the original condenser on spec. Oh, and volts to the coil are a steady and constant 13.8 and the connectors to the coil are new.

    This is supposed to be a simple motor, so why do I feel like Iím losing the battle to it?
    Any input would be gratefully received.

    Cheers, Pottsy.
    Buvito Ergo Sum!

    The Fleet:

    2018 C3 Shine ("Oscar" Mrs P's)
    1974 D Special Manual Sedan ("Moby Dick")
    2006 C5 HDI Wagon Auto ("Mephistopheles")
    1982 2CV6 ("Gaston") On the road! (Woohoo!)
    1957 Slough 2CV ("Alphonse") Waiting in the wings
    1975 GS Pallas ("GiSelle") Also waiting in the wings
    And for Fun, 1968 Mini Deluxe ("The R & D'luxe" 1078cc, Grin Factor 100!)

  2. #2
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    Hi Pottsy,
    looks as though the only item not checked or removed, given a good 'talking to' and refitted was the capacitor.
    Unfortunately, more than a few of those have been found to be faulty 'out of the box' or not long afterwards, which is why I mount the capacitor remote from the points box nowadays.
    Quite a few of my customers use Boyer Bransden's points-assisted ID units or similar, so although in theory a capacitor isn't required, it's handy to have a functional one hooked up just in case the box of electronics ever did fail.
    .
    As regards diagnosis, if you run the engine with the fan and points box cover removed, check as to whether there's heavy sparking across the points.
    If there is, that would confirm that the capacitor has failed.

    Note that by mounting the thing away from the points box, you're not tied to using Citroen/Valeo kit.
    Years ago, I picked up a box of NOS Datsun items which have worked very well.

    p.s. I'd recommend getting hold of a dwell meter and maybe a strobe, if you don't already have one.
    Strobes are so cheap nowadays and are the only way of checking that your ignition advance is correct at operating speeds.
    It doesn't matter too much if it's slightly off at tickover, whereas at full chat...
    < https://www.flickr.com/photos/301328...etaken-friend/ >
    Last edited by Ken H; 16th July 2017 at 03:33 AM.

  3. #3
    1000+ Posts pottsy's Avatar
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    Thanks Ken.
    First job in the morning is to check the points for arcing. Frankly I reckon the condenser is the only part left to check.

    It'll be disappointing if it is the faulty item, but satisfying if replacement fixes the fault.

    Stay tuned for an update.

    Cheers, Pottsy.
    Buvito Ergo Sum!

    The Fleet:

    2018 C3 Shine ("Oscar" Mrs P's)
    1974 D Special Manual Sedan ("Moby Dick")
    2006 C5 HDI Wagon Auto ("Mephistopheles")
    1982 2CV6 ("Gaston") On the road! (Woohoo!)
    1957 Slough 2CV ("Alphonse") Waiting in the wings
    1975 GS Pallas ("GiSelle") Also waiting in the wings
    And for Fun, 1968 Mini Deluxe ("The R & D'luxe" 1078cc, Grin Factor 100!)

  4. #4
    1000+ Posts gerrypro's Avatar
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    Had a similar condenser problem with the CX. I suspected all manner of other faults and even rebuilt the carbie twice, before changing the condenser over and of course the points the condenser had destroyed! The engine runs fine now but initially it would go OK then after a bout 100 yards( whoops Metres ) would begin to misfire , lack pick up and then stall.
    BTW is this engine rebuilt with parts from the one I gave you?
    Cheers Gerry

  5. #5
    1000+ Posts pottsy's Avatar
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    Can I get a YIPPEE!!!! from the assembled multitudes please?

    He's ALIVE! (again)

    A huge thanks to Ken and Gerry for steering me towards this problem. Yes, the brand new Valeo condenser is dead. (It's a stiff, bereft of life etc. You get the picture!)

    First task this morning was to remove all the bits between me and the points and then fire up the motor. After a few stutters it burst into life, albeit still with a miss.

    Observing the points was a revelation. I suspect Gaston's Engine was trying hard to celebrate Quatorze Juillet with the only fireworks it knew of. The sparking at the points was spectacular to say the least.

    I've taken a video of it but can't see any easy way of presenting a 4MB MP4 file to you all, so take my word for it, sparks were there in abundance.

    Replacement of the dodgy unit with the old one has resulted in a motor that starts and runs cleanly.

    Looking on the positive side, I now know way more than I did about tuning an M28/1 engine, and also can be sure that all the other bits that affect running are as spot on as I can make them.

    Thanks again, chaps, and let this be an object lesson to all of the others, like me, out there who are still on the almost vertical part of the 2CV learning curve.

    Oh, and Gerry. The 425cc bits to which you refer are waiting patiently in the wings until I get this young upstart fully fettled and ready to take on the Shaky Isles. Alphonse will be the next cab off the rank, but he just has to wait a bit longer. Since he was last on the road in 1969 I guess he's used to waiting!

    Cheers, and Thanks again, Pottsy.
    Last edited by pottsy; 17th July 2017 at 09:05 AM.
    GreenBlood, Ian/S and Shoji like this.
    Buvito Ergo Sum!

    The Fleet:

    2018 C3 Shine ("Oscar" Mrs P's)
    1974 D Special Manual Sedan ("Moby Dick")
    2006 C5 HDI Wagon Auto ("Mephistopheles")
    1982 2CV6 ("Gaston") On the road! (Woohoo!)
    1957 Slough 2CV ("Alphonse") Waiting in the wings
    1975 GS Pallas ("GiSelle") Also waiting in the wings
    And for Fun, 1968 Mini Deluxe ("The R & D'luxe" 1078cc, Grin Factor 100!)

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