#5 cylinder not firing

[David R.]

We have a 1979 Cessna 182RG with 1350 hours since overhaul. 6 weeks ago,
we began to notice the engine to be rough on the right magneto during
run-up. Over two weeks, it became increasingly difficult to burn it off by
leaning during the run-up, until one day when it became impossible. We
noticed on the engine monitor that the #5 cylinder head temp was cold during
the run-up. Our mechanic looked at it, and yep, it was a fouled spark plug
which was replaced. Now, about 15 hours later (and an annual), we have the
same problem with the #5 cylinder. It's going back to the shop today. Any
ideas? Why the same cylinder? What should we be looking for?

[Newps]

David R. wrote:

> We have a 1979 Cessna 182RG with 1350 hours since overhaul. 6 weeks ago,
> we began to notice the engine to be rough on the right magneto during
> run-up. Over two weeks, it became increasingly difficult to burn it off by
> leaning during the run-up, until one day when it became impossible. We
> noticed on the engine monitor that the #5 cylinder head temp was cold during
> the run-up. Our mechanic looked at it, and yep, it was a fouled spark plug
> which was replaced. Now, about 15 hours later (and an annual), we have the
> same problem with the #5 cylinder. It's going back to the shop today. Any
> ideas? Why the same cylinder? What should we be looking for?

Bad plug, bad mag or bad spark plug wire.

[Rich]

What was fouling it? Oil? Carbon? Lead?

Lots of different answers depending on what the cause was.

Rich

David R. wrote:
> We have a 1979 Cessna 182RG with 1350 hours since overhaul. 6 weeks ago,
> we began to notice the engine to be rough on the right magneto during
> run-up. Over two weeks, it became increasingly difficult to burn it off by
> leaning during the run-up, until one day when it became impossible. We
> noticed on the engine monitor that the #5 cylinder head temp was cold during
> the run-up. Our mechanic looked at it, and yep, it was a fouled spark plug
> which was replaced. Now, about 15 hours later (and an annual), we have the
> same problem with the #5 cylinder. It's going back to the shop today. Any
> ideas? Why the same cylinder? What should we be looking for?
>
>

[David]

I'm not sure, but i think he said it was carbon.

"Rich" > wrote in message
...
> What was fouling it? Oil? Carbon? Lead?
>
> Lots of different answers depending on what the cause was.
>
> Rich
>
> David R. wrote:
> > We have a 1979 Cessna 182RG with 1350 hours since overhaul. 6 weeks
ago,
> > we began to notice the engine to be rough on the right magneto during
> > run-up. Over two weeks, it became increasingly difficult to burn it off
by
> > leaning during the run-up, until one day when it became impossible. We
> > noticed on the engine monitor that the #5 cylinder head temp was cold
during
> > the run-up. Our mechanic looked at it, and yep, it was a fouled spark
plug
> > which was replaced. Now, about 15 hours later (and an annual), we have
the
> > same problem with the #5 cylinder. It's going back to the shop today.
Any
> > ideas? Why the same cylinder? What should we be looking for?
> >
> >
>

[jls]

"David R." > wrote in message
...
> We have a 1979 Cessna 182RG with 1350 hours since overhaul. 6 weeks ago,
> we began to notice the engine to be rough on the right magneto during
> run-up. Over two weeks, it became increasingly difficult to burn it off
by
> leaning during the run-up, until one day when it became impossible. We
> noticed on the engine monitor that the #5 cylinder head temp was cold
during
> the run-up. Our mechanic looked at it, and yep, it was a fouled spark
plug
> which was replaced. Now, about 15 hours later (and an annual), we have
the
> same problem with the #5 cylinder. It's going back to the shop today.
Any
> ideas? Why the same cylinder? What should we be looking for?

Bad cylinder, bad valve guides, bad plugs, bad wires -- all possibilities.

[Kevin Chandler]

We had a similar problem except the plug was getting fouled with oil. We
had a crack piston ring.

[G.R. Patterson III]

"David R." wrote:
>
> What should we be looking for?

Bad plug wire.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

[Michael]

"David" > wrote
> I'm not sure, but i think he said it was carbon.

You likely have a cylinder running too rich. First off, are you
leaning for taxi? You should be - and I mean leaning to the point
where you can't advance the throttle to runup power without killing
the engine.

Second - do you have a carbureted engine or an injected one? If
carbureted, not much you can do besides leaning, but if it's injected,
the injectors come in several sizes and you can go to a narrower bore
injector.

Of course it could be lots of other reasons as well. Bad plug, bad
contact in the mag, bad wire - but all those things cost money to fix.
Leaning costs nothing, so you should try that first.

Michael

[David R.]

Yes, we are aggressively leaning before taxi.

Thanks for the info.

"Michael" > wrote in message
m...
> "David" > wrote
> > I'm not sure, but i think he said it was carbon.
>
> You likely have a cylinder running too rich. First off, are you
> leaning for taxi? You should be - and I mean leaning to the point
> where you can't advance the throttle to runup power without killing
> the engine.
>
> Second - do you have a carbureted engine or an injected one? If
> carbureted, not much you can do besides leaning, but if it's injected,
> the injectors come in several sizes and you can go to a narrower bore
> injector.
>
> Of course it could be lots of other reasons as well. Bad plug, bad
> contact in the mag, bad wire - but all those things cost money to fix.
> Leaning costs nothing, so you should try that first.
>
> Michael

[David R.]

How do you diagnose a cracked piston ring? Scope? Compressions?


"Kevin Chandler" > wrote in message
...
> We had a similar problem except the plug was getting fouled with oil. We
> had a crack piston ring.
>
>

[David]

Update: Our mechanic found a bad spark plug lead wire. Thanks for all of
the replys.


"David R." > wrote in message
...
> We have a 1979 Cessna 182RG with 1350 hours since overhaul. 6 weeks ago,
> we began to notice the engine to be rough on the right magneto during
> run-up. Over two weeks, it became increasingly difficult to burn it off
by
> leaning during the run-up, until one day when it became impossible. We
> noticed on the engine monitor that the #5 cylinder head temp was cold
during
> the run-up. Our mechanic looked at it, and yep, it was a fouled spark
plug
> which was replaced. Now, about 15 hours later (and an annual), we have
the
> same problem with the #5 cylinder. It's going back to the shop today.
Any
> ideas? Why the same cylinder? What should we be looking for?
>
>

[Kevin Chandler]

I have no idea. I did not do it. The A&P made the call and got it right.
A new/used jug fixed it all.


"David R." > wrote in message
...
> How do you diagnose a cracked piston ring? Scope? Compressions?
>
>
> "Kevin Chandler" > wrote in message
> ...
> > We had a similar problem except the plug was getting fouled with oil.
We
> > had a crack piston ring.
> >
> >
>
>

[G.R. Patterson III]

"David R." wrote:
>
> How do you diagnose a cracked piston ring?

A cracked compression ring will show up as low compression. A cracked oil wiper
ring will show up in fouled plugs, oily deposits on the inside of the exhaust
pipes, and smoky exhaust.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

[Dennis O'Connor]

And a cracked wallet will show up soon after..

denny
"G.R. Patterson III" > wrote in message
...
>
>
> "David R." wrote:
> >
> > How do you diagnose a cracked piston ring?
>
> A cracked compression ring will show up as low compression. A cracked oil
wiper
> ring will show up in fouled plugs, oily deposits on the inside of the
exhaust
> pipes, and smoky exhaust.
>
> George Patterson
> A diplomat is a person who can tell you to go to hell in such a way
that
> you look forward to the trip.