SuperP
I have a 1974 super beetle with a 1776cc rebuilt engine (about 8 years back), that used to run perfectly. It was garaged for a few years, but my parents have been driving it off and on for the past few months, and it didn't have any issues. On a recent trip, it started smoking really bad and was soon retired to a parking lot. I just had it trucked back home, and upon inspection it looks like it is not running on all 4 cylinders.

If i pull the plug wire for the drivers hand cylinders, it doesn't appear to affect idling much or even at all. It doesn't really smoke at idle anymore, but my dad (who was driving when the problems started), told me that it seemed like it was overheating, and just smoked when it was pushed.

I noticed that if i pull the oil filler cap off, there is a decent amount of exhaust that comes out of the filler tube. Does this mean that my rings are shot on at least a few cylinders, or could it be something else?

I've done a lot of work on the car myself (tune-ups, maintenance, etc), but I am no mechanic... Does anyone have any troubleshooting tips for me? Or thoughts of what could be wrong?
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MY72BUG
Start with some quick tests.  Are the plugs all oil-fouled?  What are the compression readings for all four cylinders?   Drain the oil - is there any debris in the oil screen?  Was the incident accompanied by any knocking?  You could be looking at some serious trouble depending on your answers to the above.   M72BUG
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
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SuperP
I just got the car back in town today, so i haven't had a chance to check it out.  My plan was to do pretty much what you said.

- Pull/replace the plugs
- Do a compression test (need to pick up a gauge though)
- Change the oil (and inspect it)

There wasn't any knocking when it started smoking.  From what I have been told, I think they pushed it too hard (with too much cargo) up over a pass, and it overheated.  Seems that it just went down from there.  I was hoping that it just overheated, and plugs got fowled really bad, and I could get it running again without a huge cost/effort...  But I wanted to see if the symptoms immediately meant something bad.

Thanks for your comments, and I'll post back my findings once I get time to check it out (will be out of town over the weekend...).

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MY72BUG
If it was a case of overheating, look for other simple things like stuff dragged into the cooling fan.  One bug owner I know up here had an overheating problem cured when I pulled the remains of a plastic bag and an oil wiping rag out of his fan.  Very loose generator belts and jammed oil pressure control gizmos are other places to look before you embark on engine surgery.  May your problem be a simple and cheap one.  MY72BUG
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.
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SuperP
I pulled the plugs today, and found that one of them (Cylinder 3) was oily and quite gummed up (more to follow).  The other 3 were fairly carboned up, with the cylinder 1 in the best shape. 

I replaced them, adjusted the points (they were a smidge off), put in a new distributor cap/roter (current ones were in bad shape, and i had spares). 

I then pulled the valve covers off and checked the clearances.  I was amazed to find that there was no clearance for cylinders 3 & 4 at TDC.  I loosened these to spec.

After these adjustments the car ran much better.  Previously it seemed to only be running on cylinders 1&2 (and a little bit of 4), but now pulling the plug wires for 3&4 caused the engine to stumble more, and it ran much smoother now.  It however still seemed a little bit off.  It stumbles now and then...

I had to wait till after 6pm to change the oil, as I'm not supposed to do it at my apartment building (that's when their office hours end).  Upon dumping the oil out, I discovered silver metal flakes/grit in the oil, mostly around the filter screen and in the last bit of oil that drained after I pulled off the screen. 

I'm assuming this means at least one of my rings are torn up?  I don't get my compression gauge in the mail till probably later this week, but I can bet the problem is on cylinder 3 due to the oily/fouled plug.

One thing that makes me wonder though...  If the rings were burnt up, wouldn't the engine smoke all the time?  I don't get any smoke at idle, and it doesn't even seem like i'm getting any noticeable smoke when i get on the gas.  I however never let the engine fully warm up (just ran for a few minutes at a time), so maybe thats why?

What do you think?  Are my rings screwed, or did something else burn up?

Thanks!

-
SuperP




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OldPunk

I unfortunately have experience with multiple engine failures and I have NEVER known or heard of any reason for the oil filler to be spouting gas (whether smokey or not) other than one of more rings having blown. If you take off the filler cap and there's a rush of pressure coming out that's similar to what you feel at the exhaust tip(s), in my experience there's no question that one or more of the rings have gone to mechanical heaven. It sounds like no. 3's spark plug is consistent with that, as well. This is not to say you should not do a compression test or other tests to confirm; I just think you may as well start adjusting the budget for pulling off at least the heads and cylinders.

OldPunk
_______
Keep yer hands on the road and yer eyes upon the wheel.
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ainokea
Besides a ring problem, you might have a burned piston. At any length, you'll
need to pull the heads, the jugs, and the pistons, to pinpoint the exact problem. While the heads are off, it would be in your best intrest to replace the exhaust valves with new. Check the guides and renew or knurl if necessary. The intake valves can be refaced and reused, and the seats should be given a 3 angle cut. With all of that done, replace the pistons and jugs, you should be good to go with a top half rebuild. If you don't have the
the equipment or skills to get the head work done, any machine shop that
does VW work should be able to accomodate you.
Ainokea
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