Bus - Rough Running Engine

ruckman101 · Post by **ruckman101** » Mon Jul 23, 2007 12:29 pm

I check, I check, seems doubly, yet somehow I am an idiot.

I go out to take another crack at resolving Bertha's issues and notice that my dead cylinder is actually #4, not #2.

I'm checking my valvetrain by turning the engine over by hand and making sure things are opening and closing, they were, and the lure of the open engine hatch lures my neighbor over. Collapsed valve spring he ponders? In all our discussion, he asserts, yep, there's your trouble, your dead cylinder, toasted valve, etc. Yet the compression is 120, and when I had the spark plug out, it looked fine.

So, push comes to shove and I pull that spark plug again. Ouch, black and oily this time, and......hey, there is no gap at all, it's bent completely closed and touching the anode (?). Bertha seems happy now, but I'm more confused than ever. How did it get bent? I re-checked the gap before putting it back in, and didn't touch the plugs while on the road.

It had to have been my distributor is my conclusion. The plate the points are mounted to was definitely flexing up, closing my point gap, but it didn't show on my dwell meter that I recall.

Ach!

I'm counting my blessings at this point, licking my bruised vw mechanic credentials.

neal

Post by **Amskeptic** » Mon Jul 23, 2007 4:15 pm

ruckman101 wrote:
I pull that spark plug again. there is no gap at all,

When you pulled it the first time, what was the engine doing?

You can dislodge a huge chunk of carbon that will happily bash the electrode (I had a piece of carbon crush the corner of a piston). Shouldn't have too much carbon in your engine though with the recent disasemblies though, right?

Check that plug again at some point to see if it has cleaned up as far as oil around the inner perimeter of the shell. If still oily wet around the perimeter, or heck even the insulator, then a mechanical event occurred that has damaged the cylinder wall likely as not.
Colin

Hippie · Post by **Hippie** » Tue Jul 24, 2007 5:13 am

Sure you have the right plugs, too, right?...Not too much reach into the cylinder?
I've mashed the electrodes a little before when putting them in.
I dunno.

Rob

ruckman101 · Post by **ruckman101** » Wed Jul 25, 2007 11:46 am

The engine was running very rough, but smoother at high rpms, enough to get us home. All the plugs looked good in terms of color and I checked the gaps and none needed adjusting. So it had to have been when I did a compression check that I bumped or dropped or something to bend over that plug.

The same plugs have been in for a spell, so I don't think they are too long.

Bertha ran fine all Monday, to the Lab and back, errands, like a gasket set for the oil strainer. It's been awhile for the strainer and I hope I don't find scary bits of metal all over it.

Keeping my fingers crossed,

neal

Hippie · Post by **Hippie** » Wed Jul 25, 2007 6:35 pm

ruckman101 wrote:...It's been awhile for the strainer and I hope I don't find scary bits of metal all over it.

Keeping my fingers crossed,

neal

Hopefully not, but I find scary bits of metal in mine every time. Several thousand miles later, I just quit worrying about it.

Rob

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Bus - Rough Running Engine