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Sudden backfires and severe loss of power
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Rifai.Ad
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PostPosted: Fri Oct 22, 2021 9:43 am    Post subject: Sudden backfires and severe loss of power Reply with quote

A few days ago, a weird (but as of then insignificant) problem appeared: minor loss of power, windows of erratic idle, and extremely hard starting. These symptoms quickly developed and crippled my bug to the point that I can no longer trust to go into normal traffic with it. The symptoms I have right now are lots of backfires in very quick succession when accelerating, severe power loss (can barely get moving in 1st gear), and very hard idle. What is weirder is that these symptoms seem to diminish sometimes for a few minutes before coming back (usually when I have to start moving at a traffic light on the highway. Why do we have traffic lights on the highway, I have no clue Very Happy ). I have checked the valve clearance (adjustment was not due, but I did it anyways) and all of them were at 0.006 like I like them. I have made sure the HT leads are plugged correctly in the distributor and spark plugs, I made sure all wires to and from the coil are tight in their places, and I tried to spot sparking from the HT leads in the engine compartiment (although I did not look too hard). Starting is even harder than before, as the engine only sputters while cranking and hardly starts actually operating. The idle seems stable at first, but windows of severe instability appear during the stable idling, which sometimes causes the engine to die.
A very weird combo of symptoms. Does anyone know what could cause this?
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Matt Wilson
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PostPosted: Fri Oct 22, 2021 9:49 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

How is your ignition? Maybe points or something loose/wrong inside distributor.
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Rifai.Ad
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PostPosted: Fri Oct 22, 2021 10:03 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Matt Wilson wrote:
How is your ignition? Maybe points or something loose/wrong inside distributor.


Didn't open the distributor just yet (haven't reached that point of bug ownership Very Happy) but I'm sure it's just as easy as doing anything else on this car so I'll open it up tomorrow and check the gap, file down the points and perhaps spray a little WD-40 on the cap just in case it's got water in there somehow.
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Tim Donahoe
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PostPosted: Fri Oct 22, 2021 11:03 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Sounds like a bad condenser.
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busdaddy
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PostPosted: Fri Oct 22, 2021 12:37 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Look at the plastic block that rubs on the cam inside the distributor, if it snaps off it'll run as you describe.
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Rifai.Ad
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PostPosted: Fri Oct 22, 2021 12:39 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

busdaddy wrote:
Look at the plastic block that rubs on the cam inside the distributor, if it snaps off it'll run as you describe.


Will do, I'll keep you posted!

Tim Donahoe wrote:
Sounds like a bad condenser.


I've got one in the shopping cart ready in case the normal stuff doesn't work.
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KTPhil Premium Member
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PostPosted: Fri Oct 22, 2021 1:05 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Timing slipped?
Point hold down screw is loose?
Advance mechanism broken inside distributor?
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birddog1
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PostPosted: Fri Oct 22, 2021 2:03 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Could be several things but sounds reminiscent of when I'm starting my bug back up after a winter sleep. Usually it's junk in the jets of the carb and/or points need clean and re-gap. .
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Rifai.Ad
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PostPosted: Sat Oct 23, 2021 7:12 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Problem solved. Looks like the distributor cam worn off so much that the ignition breaker was not lifting at all. Literally no point gap. It's incredible how it ran like this so far.
Adjusted the gap to 0.016, adjusted the timing, and it now runs like new! I'll be sure to grease the cam a bit like the others around here have suggested.
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busdaddy
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PostPosted: Sat Oct 23, 2021 8:44 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Good job!, now check and set (if needed) your timing, altering the points gap changes the timing.
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Rifai.Ad
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PostPosted: Sat Oct 23, 2021 9:09 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

busdaddy wrote:
Good job!, now check and set (if needed) your timing, altering the points gap changes the timing.


I'm suspecting the timing slipped as well in the mean time since I had to turn the distributor a fair amount to get it set to...whatever angle the notch on my pulley is cut in at Smile .
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PostPosted: Sat Oct 23, 2021 10:18 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Rifai.Ad wrote:
Problem solved. Looks like the distributor cam worn off so much that the ignition breaker was not lifting at all. Literally no point gap. It's incredible how it ran like this so far.
Adjusted the gap to 0.016, adjusted the timing, and it now runs like new! I'll be sure to grease the cam a bit like the others around here have suggested.


Yes, wore down the rubbing block on the points. Always make sure to put a little dab of grease on the distributor cam where it contacts that rubbing block.

Folks neglect to do this, and end up like you experienced.
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viiking
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PostPosted: Sat Oct 23, 2021 7:28 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Cusser wrote:
Rifai.Ad wrote:
Problem solved. Looks like the distributor cam worn off so much that the ignition breaker was not lifting at all. Literally no point gap. It's incredible how it ran like this so far.
Adjusted the gap to 0.016, adjusted the timing, and it now runs like new! I'll be sure to grease the cam a bit like the others around here have suggested.


Yes, wore down the rubbing block on the points. Always make sure to put a little dab of grease on the distributor cam where it contacts that rubbing block.

Folks neglect to do this, and end up like you experienced.


And preferably high-temperature grease like disc brake grease as I was told as a kid.
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PostPosted: Sun Oct 24, 2021 10:07 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

Bosch makes a distributor grease that is unlike any other grease I have handled.. it is more waxy than sticky, if that makes sense.
https://vwnos.com/5-700-002-005-2
Or this
https://vwnos.com/5-700-005-005
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tasb
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PostPosted: Sun Oct 24, 2021 10:27 pm    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

When shopping for points and condenser consider buying NOS rather than brand new.
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PostPosted: Mon Oct 25, 2021 8:28 am    Post subject: Re: Sudden backfires and severe loss of power Reply with quote

I am a fan of old-fashioned point systems over electronic, but even German Bosch parts have had occasional quality problems with the rubbing block, all the way back to the '70s!

Always carry a spare. Cheap, easy to change.
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