Good Idea Bad Idea? drive a civic with no compression on a cylinder

As mentioned in previous posts, my sister's 99 civic has a damaged valve on
cylinder 3 due to a timing belt breaking. The car is running, albeit poorly
due to no compression on cylinder 3. Once you rev it up, it sounds OK.

Would it be safe to drive the car across town to a different mechanic in this
condition? What are the risks? Or should it be towed?

The drive would be in the city, 50 km/h or less, and revved as low as
possible. Its about a 14km trip.

Please advise.

Thanks
Terry in Winnipeg

 

and by risks, i mean could we do further damage to the
cylinder/piston/valvetrain by driving with no compression and a damaged valve.


t

 

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I'd remove the spark plug wire from the plug and put an old 'dummy' plug
on the wire, with the metal part of the plug grounded, so it sparks
normally. Otherwise, I doubt anything bad could happen. (the high
tension needs to find it's way to ground or it will 'blaze a new trail"
inside the cap, or igniter)

'Curly'

 

Curly, not sure what you mean. How could I ground the 'dummy' plug? (IE
make it stay grounded while driving the car.)

Also, if the gas in the cylinder is not being burned off, wouldn't it cause
the oil on the cylinder wall to be washed away, causing potential damage to
the rings, and contamination of the engine oil? This is one of the big
concerns I have.

 

This brings me to what I would add - disconnect the injector. Injecting fuel
into that cylinder will come to no good.

Mike

 

yes,the unburned fuel will throw off the O2 sensor,and the ECU will
misadjust the other cylinders.

Better to just leave the spark plug the way it is,not provide a "dummy"
plug.

 

Thanks for everyones input! I will unplug the injector and leave everything
else as is. For a short trip, I doubt it will create any big problems.

t

 

I'm imagining the combustion chamber pooling up with unburned gas, or would
it just shoot out the exhaust valves anyway?

 

Is it really worth it to try? What will you save? $50 or less?

I wouldn't do it.

G-Man

 

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The other guys are more correct . . Unplug the injector. No worries
about any backfiring, but you might still generate a 'misfire' code, but
so what? At least it can't backfire if there's no fuel/air mixture
present.

I was referring to chassis ground, like any part that's steel. Doesn't
matter anyway, but it's worth remembering. Honda spark has to go
_somewhere_ or it will go to the wrong places.

'Curly'

 

14k's are no problem. it's just one or two valves a little open -
nothing different to a burnt valve. and don't worry about driving
normal speed - if anything it'll be better as you'll get less blowback
if it's on the intake side.

 

With one of these, http://tinyurl.com/cb9ky part number 2756 for HEI
systems.

Eric

 

Of course it would get pushed out the exhaust.The cylinder still remains an
air pump.A little leakage around a bent valve is not going to stop that.

The injectors atomize the liquid,so it will be a burnable fuel-air
mix,vapor,not a liquid.

 

Let it spark in the cylinder,it won't harm anything.
No fuel-air mix to burn with an injector disabled,but that does not matter.
Those engines(non-Honda) that share a coil between two cylinders do the
same thing;allowing a spark in a cylinder with no fuel-air mix.