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 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.

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?
>
>

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?
> >
> >
>

"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.

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

"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.

"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

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

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.
>
>

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?
>
>

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.
> >
> >
>
>

"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.

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.