plug fouling...

J

jd winchester

Filing Flight Plan
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jd winchester
I have cherokee 180 w 0-360-A4A
Can I do any more to reduce plug fouling????

Start Procedure: crank up full rich after 3 pumps.... fires....as soon as I get good oil pressure I immediatly throttle up to 1000 rpm..... pull back lean as far back (lean) as possible without causing a miss. I try to never idle under 1000 rpm......... but I still foul plug from time to time.

Is this typical of this engine?? Or can I do more?
 
(You don't mention, but I presume you lean in flight, too, right?)

Yes..... Mostly referring to plug foul pre-take off.
 
Also leaning after landing as you taxi back in. Also you can do a Mag check before shut down to confirm they are not fouled.

Brian
 
dmccormack said:
How do you know? Do you pull the plugs after idling a bit? :dunno:
Click to expand...
That's a good idea actually.

I assume that he does a quick mag check at 1000 RPM before takeoff and notices roughness. I also assume a bit of high rpm well leaned clears the problem.

Lots of assumptions, I know but that's how I would deduce plug fouling.

Since you are doing the ground anti-fouling procedures, I'd ask:

  1. How long after youpull and clean the plugs does it take to become fouled?
  2. Are the plugs wet (oily), coated with soot, or lead deposits?
  3. You are using 100LL right?
There are more things than a lean mixture that cause plugs to foul.
 
I once had the same problem, not matter how much I leaned it ran too rich and often fouled plugs. In my case the carb float went bad and absorbed fluid making it too heavy. This cased the carb to run very rich. I overhauled since then but I do like the fine wire plugs in the O-360, never had a problem since.
 
taters said:
I once had the same problem, not matter how much I leaned it ran too rich and often fouled plugs. In my case the carb float went bad and absorbed fluid making it too heavy. This cased the carb to run very rich. I overhauled since then but I do like the fine wire plugs in the O-360, never had a problem since.
Click to expand...

If you lean it far enough it cannot be "too rich". Now it is possible that the mixture distribution is so bad that the engine runs rough if you lean it far enough to prevent fouling, perhaps that's what you meant.
 
After you troubleshoot and determine everything else is well but still fouling, I believe you have some choices in plug heat range - what plug is in there? Check out this SL
 
A misfire or rough running at low rpm could be something other than a fouled plug.

An induction air leak comes to mind...
 
I have a PA28-180F that also has an O-360-A4A, and it has always been prone to plug fouling.

I idle/taxi at 1200RPM, and lean very aggressively during ground ops. I also advance the throttle a bit during my pretakeoff checklist (prior to the runup portion). Even with these precautions, if I have a lengthy taxi (say a mile or so), 50% of the time - the plugs are fouled by the time I get to the runup. Also, during descents, I try to keep the power over 50% and the engine leaned as much as possible. If not - the plugs will slightly foul making them more likely to foul on the next start/taxi.



jd winchester said:
I have cherokee 180 w 0-360-A4A
Can I do any more to reduce plug fouling????

Start Procedure: crank up full rich after 3 pumps.... fires....as soon as I get good oil pressure I immediatly throttle up to 1000 rpm..... pull back lean as far back (lean) as possible without causing a miss. I try to never idle under 1000 rpm......... but I still foul plug from time to time.

Is this typical of this engine?? Or can I do more?
Click to expand...
 
You cannot over lean an engine in ground operations (warm up, taxi)...
Pull the mixture until it shudders and shakes like a wet dog...
IF you can get to half throttle before it stalls out you are running way too rich on the ground...
On my engines I have to advance the mixture to do the run up or they will just die when I give it some throttle... Same thing on taxi after landing... I never have plug fouling...
 
The way I recognized the fouling is during run-up... OK in flight... And I always lean below 1200 rpm or high DA

Denny, I thought I was doing extreme precautions but you do a bit more leaner and higher extremes than I... thanks ! I guess you can NOT over lean w/ low rpms.

Nathan , we have the same engine and sounds like these are notorioust for not handling rich lead.. thanks

Thanks to everyone for your input..... great forum

jd
 
Some engines, depending on wear and head configuration, will suck oil when cold and that oil runs into the bottom plugs and shorts them. Small Continentals are famous for this. Once the engine heats up and clearances tighten, the oil stays in the case where it belongs and the plugs don't foul so quick during post-landing taxiing. The Lycoming has one mag firing the bottom plugs on the left side and the top plugs on the other, while the other mag fires the rest, so fouled bottom plugs show up on both L & R checks. The Continental has one mag firing all the top plugs and the other all the bottom, and that latter mag will show a big drop or shake and the other will be fine.

REM37BY plugs have extended electrodes that resist fouling. Might try a set.

Dan
 
Steve said:
A misfire or rough running at low rpm could be something other than a fouled plug.

An induction air leak comes to mind...
Click to expand...

Everyone with a Marvel Schebler MA-3A, MA-3PA, MA-3SPA, MA-4SPA, MA-4-5, MA-4-5AA, or MA-6AA carburetor who isn't aware of this service bulletin (I wasn't) should check the bowl assembly gasket and security screws. A few weeks ago I was stung by this issue and found that the bowl was loose and fuel was leaking from it. Symptoms were AVGAS smell, blue stains on bottom cowling, rough running, sooted plugs and inability to cut engine using mixture control.
 
ChrisS said:
Everyone with a Marvel Schebler MA-3A, MA-3PA, MA-3SPA, MA-4SPA, MA-4-5, MA-4-5AA, or MA-6AA carburetor who isn't aware of this service bulletin (I wasn't) should check the bowl assembly gasket and security screws. A few weeks ago I was stung by this issue and found that the bowl was loose and fuel was leaking from it. Symptoms were AVGAS smell, blue stains on bottom cowling, rough running, sooted plugs and inability to cut engine using mixture control.
Click to expand...

Had one of those, returned for warranty, got another one that did the same thing.

There's another service bulletin, this time from Tempest who are now building these things, issued October 14, less than two weeks ago. It involves the HA-6 carbs, and has to do with the internal mixture control sleeve coming loose and cutting off the fuel flow. It applies to the machined-from-billet carbs, not the sandcast units. Typically found on the 182RG, like ours. New carb is around C$8400.
http://www.tempestplus.com/pdfs/SB-18 MFB HA-6 Mixture Sleeve Security 10-14-2010 FINAL.pdf

Dan
 
My Tiger always seemed to run rich. I would agressively lean on the ground.
In addition I always leaned for takeoff and would get a few more RPM in
the process. As soon as I went full throttle I'd lean for max RPMs. I still do that now with the VW conversion I'm running. Keep an eye on the CHT's
though. I think full rich can often be too rich, especially with a high density altitude. Following an agressive leaning habit at all times cut the plug fowling.

RT
 
Dan Thomas said:
REM37BY plugs have extended electrodes that resist fouling.
Click to expand...


I installed these in my Tiger a few years ago and have not had any fouling issues. I also lean very aggressively on the ground and in the air, plus perform a leaned out runup prior to engine shutdown.
 
jd winchester said:
I have cherokee 180 w 0-360-A4A
Can I do any more to reduce plug fouling????

Start Procedure: crank up full rich after 3 pumps.... fires....as soon as I get good oil pressure I immediatly throttle up to 1000 rpm..... pull back lean as far back (lean) as possible without causing a miss. I try to never idle under 1000 rpm......... but I still foul plug from time to time.

Is this typical of this engine?? Or can I do more?
Click to expand...


Why do you go to 1000 RPM ?
 
Dan Thomas said:
Had one of those, returned for warranty, got another one that did the same thing.

There's another service bulletin, this time from Tempest who are now building these things, issued October 14, less than two weeks ago. It involves the HA-6 carbs, and has to do with the internal mixture control sleeve coming loose and cutting off the fuel flow. It applies to the machined-from-billet carbs, not the sandcast units. Typically found on the 182RG, like ours. New carb is around C$8400.
http://www.tempestplus.com/pdfs/SB-18 MFB HA-6 Mixture Sleeve Security 10-14-2010 FINAL.pdf

Dan
Click to expand...

8400.00 for just the carb ??? Holy crap ..:hairraise::hairraise::hairraise:
 
Answering somewhat on behalf of the OP... The handbook on the PA28-180F says (paraphrasing):


  • After start, go to 800 RPM
  • Wait a bit and check for oil pressure.
  • Once oil pressure is confirmed, idle between 800 and 1200.
  • For extended periods of idle, it says to use 1200RPM.
I presume the latter bit is to help with plug fouling.


Tom-D said:
Why do you go to 1000 RPM ?
Click to expand...
 
nyoung said:
Answering somewhat on behalf of the OP... The handbook on the PA28-180F says (paraphrasing):


  • After start, go to 800 RPM
  • Wait a bit and check for oil pressure.
  • Once oil pressure is confirmed, idle between 800 and 1200.
  • For extended periods of idle, it says to use 1200RPM.
I presume the latter bit is to help with plug fouling.
Click to expand...

Or engine cooling. When I was checked out in a T182 in Phoenix, they wanted 1200RPM, and said it was for engine cooling, but in Chicago the recommendation was 1000RPM, which is what the POH calls for, IIRC.
 
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