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Points and Condensers Failing

Discussion in 'Engine & Transmission' started by Mr Beckstar, Apr 23, 2019.

  1. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    Yes, has to be a reason. I'll have to get some alligator clips to fit the multimeter so I can clip them on the points and then wiggle the wires around to see if there's an intermittent issue.
     
    oldman likes this.
  2. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,775
    Location:
    Penna, Hobart
    Ok, I have tested the suspect condenser and the new one with some test equipment and both are .20 uF and show no leakage at 500 volt DC, so that would indicate it is the points, as that is the only other thing we changed. I was expecting the suspect one to have some leakage but it is quite happy to hold the voltage.

    Adrian
     
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  3. grumble

    grumble Well-Known Member

    Messages:
    982
    Location:
    Taree
    Scratching at straws, as the new coil came from VVDub I would say it was correct. ...so...Another possibility is that the preservative wax applied to prevent rust on the point surfaces may have been inadverently left on them and when they warmed up melted, insulating the points and consequently stopping the vehicle. I have seen this happen many times over the years.
     
  4. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    I must admit I didn’t make an effort to clean the wax off, but it worked fine for something like 2,000 km and I’d suspect the failure you’re suggesting should happen after the first time it’s warmed up... o_O
     
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  5. grumble

    grumble Well-Known Member

    Messages:
    982
    Location:
    Taree
    Not always the wax may burn or melt but the contact can be intermittent, or non existant. -Murphy's Law often works on motor vehicles and leaves you scratching your head for months trying to make sense of it.
     
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  6. cbus

    cbus Well-Known Member

    Messages:
    11,601
    Location:
    sunshine coast
    I have a practice of wiping thru points with a rag dipped in thinners or petrol due to this issue.
    Doesn't always occur but agree that symptoms can be intermittent miss or no start.

    Another trap used to be points where the insulator on the moveable arm was two part or secured with a nut.
    Was easy to have a misalignment of insulator and arm contact pin which caused an earth in the points.
    Haven't seen such types for a long time tho.
     
  7. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    Pictures of suspicious points:

    2305CA6D-FC1F-417A-B625-68E9A5AAE56E.jpeg 0A6DFFF1-747D-4454-B71F-E1C0D38D938D.jpeg 4D030E6F-DD61-4D57-A29F-2D095C378DB7.jpeg 19CB7655-06FF-4AD6-9A7B-1EBA1308A7ED.jpeg
     
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  8. tintop

    tintop Well-Known Member

    Messages:
    423
    Location:
    Canberra
    mmm, coming in on an angle - cheap set?
     
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  9. cbus

    cbus Well-Known Member

    Messages:
    11,601
    Location:
    sunshine coast
    Is the mark in insulator in last photo a moulding mark or possibly arcing thru insulator?

    Looks similar to arcing thru a spark lead cap?
     
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  10. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    I always try to buy good quality. They’re Bosch, but I guess that doesn’t guarantee quality these days.
     
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  11. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    There’s a mark on the contact surface in the last photo. I’m holding the contacts wide open. I can’t see a mark on the insulator. It’s only 12V through that circuit so unlikely to get arcing like a spark lead cap.
     
  12. tintop

    tintop Well-Known Member

    Messages:
    423
    Location:
    Canberra
    yeah you'd hope bosch would be good but this example appear to have a twist to them (first photo) so they ended up with point contact and have been arcing and pitting
     
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  13. Grantus

    Grantus Well-Known Member

    Messages:
    15,471
    Location:
    Southern ACT
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  14. David H

    David H Well-Known Member

    Messages:
    4,402
    Location:
    newcastle
    I'm with the rest. Pic one says it all:(. Not only not parallel to the contact but also not square to centre of contact. If it was..... that arc point would be in the middle.
    Learning curve for me is check all points that I buy for this.
    So the gap was closed with the Mt Vesuvius;). Good work Adrian checking the condenser:).
    Cheers
     
    Last edited: May 16, 2019
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  15. cbus

    cbus Well-Known Member

    Messages:
    11,601
    Location:
    sunshine coast
    My bad.
    Cross eyed interpretation of photo.
    Thought it was strange:eek: :rolleyes:
     
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  16. cbus

    cbus Well-Known Member

    Messages:
    11,601
    Location:
    sunshine coast
    I'll risk another chasing rainbows:D

    Seems a bad and quite pronounced deposit on the points face.
    I assume dwell and/ or timing was checked before swapping/ adjusting original set and showed up ok ?
     
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  17. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    That's the weird thing. The gap wasn't closed. :confused: The blemish on the contact is only a very small height. As you can see in the third photo, it is almost undetectable to the naked eye.

    And, like I've said, the dwell was measured to be perfectly set at 48 degrees (checked only two days before with only about 50km driving after that) :cool:. As you would know, dwell is a dynamic measurement of the angle over which the points remain closed. As such, dwell is a direct verification that the points gap is correct. If points gap is incorrect, the measured dwell angle will be incorrect. In fact, dwell angle is more reliable because it bypasses the inaccuracies of measuring points gap (e.g. points contacts not flat) and confirms what setting you actually have through accurate electronic measurement.

    Anyway, I'm pretty sure the points gap was one of the first things that was checked when Harry's fire went out by the side of the road, but can't remember for sure :oops:. So lets assume something weird happened during that 50 km which resulted in the points gap closing up. Well, I still know it's not the issue because, when Mordred and I put my distributor back in with the new condenser and he still wouldn't go, we double checked the points gap was correct, which it was, but still no go! We had to change the points to get Harry to go again even though the gap was correct.o_O
     
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  18. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    True, it's not a good look. But I've seen points in far worse condition with much larger mountains than this providing reliable spark to an engine. The build up on the positive side is actually quite negligible; it looks far worse in the photo than in reality.
     
  19. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    It's perhaps a little strange in it's shape so I wonder whether there is any "wax effect", but in reality the size of the blemish is quite negligible as explained above. And the points measure 0.2 Ohm with a multimeter when closed so it appears to be making good contact.

    But, thinking out loud, perhaps the actual contact area available for flow of current across the points contact faces is very small due to the misaligned faces. This could cause a large voltage drop across the points when current flows, which is perhaps starving the coil of the voltage/current it needs to operate properly.

    An ohmmeter tends to supply a very, very small amount of current when it measures resistance, so it wouldn't detect the above issue. Further, the current flowing through the small contact area would heat up the contact area; a well know means of causing increased electrical resistance (a hot spot) which would also not show up when I'm measuring the points resistance cold.
     
    Last edited: May 17, 2019
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  20. Mr Beckstar

    Mr Beckstar Well-Known Member

    Messages:
    917
    Location:
    Bateau Bay, NSW
    Gee I'd like to install those points again as is and confirm they're still causing an issue. And then, without filing the faces, give them a bend so the contact faces are parallel and see what that does.

    Anyway, the lesson here is to make sure the contact surfaces are centred and parallel, and to clean off the protective wax, before installing. Probably should know that already, but who would have though the contact faces would come from Bosch so misaligned!!
     
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