engine hesitation/stumble

A forum to discuss the installation and maintenance of the O-320, O-360, & O-540 engines and their variants.
Post Reply
User avatar
hydroguy2
Class B
Posts: 1307
Joined: Mon Sep 10, 2007 11:13 pm
Location: Townsend, Montana

engine hesitation/stumble

Post by hydroguy2 »

Today during my brief flight today I felt a very slight stumble in the engine during my taxi. Run up was good, pulled hard on take off and ran flawless. Then while taxiing back to the nest, it definitely stumbled 2times. I was pretty much full rich, so pulled some mixture to see if any change. Nothing happened and never felt it again. Once at the hangar I ran it up to 2200rpm, did a mag check all ok, Leaned it out until it almost died. Restored mixture then shutdown Emag and leaned again. no problem, then did the same on the Pmag. again no issues.

I'm thinking I just had a overly rich mixture and maybe the plugs are loaded up.

Anyone else have this happen?
Brian
Townsend, MT

User avatar
cjensen
Whiskey Victor
Posts: 5275
Joined: Sat Apr 23, 2005 10:36 pm
Location: Green Bay, WI

Post by cjensen »

Mine has done just that, and I believe mine was loaded plugs. I've also had mine stumble in flight a time or two related to failing to push in the mixture on decent. My airplane is VERY sensitive to the red knob...
Chad Jensen
Missing my RV-7...
Vertical Power support
920.216.3699
http://verticalpower.com

john_r_graham
Class G
Posts: 13
Joined: Fri Jul 11, 2008 2:34 pm
Location: Alpharetta, GA, USA

Post by john_r_graham »

I always leaned my Cessna 170 (Continental O-300) for taxi to avoid the risk of an occasional extended run-up to clear the plugs. From talking to people on the airport, I got the impression that this was a pretty standard thing to do. No need to do anything fancy; just pull the mixture knob out a little bit.

- John

User avatar
cjensen
Whiskey Victor
Posts: 5275
Joined: Sat Apr 23, 2005 10:36 pm
Location: Green Bay, WI

Post by cjensen »

Yup, SOP for me too...tho I think the time I had a stumble on taxi was early in my test phase, and I still wasn't "in tune" with SOP's... :oops:
Chad Jensen
Missing my RV-7...
Vertical Power support
920.216.3699
http://verticalpower.com

User avatar
hydroguy2
Class B
Posts: 1307
Joined: Mon Sep 10, 2007 11:13 pm
Location: Townsend, Montana

Post by hydroguy2 »

cjensen wrote:.........early in my test phase, and I still wasn't "in tune" with SOP's... :oops:
I'm thinking that is my situation. Still hyper alert for issues and haven't flown much in the last few years. Leaning the 172 or Citabria was a reflex, not a thought.
Brian
Townsend, MT

User avatar
Brantel
Class B
Posts: 1029
Joined: Wed Aug 30, 2006 3:23 pm
Location: Newport, TN

Post by Brantel »

When I first started flying my newly rebuilt engine, it would oil foul the bottom plugs almost every flight. I would have to lean hard at runup and let it sit there and burn the crud off. Once I burned it off, mag check was fine unless I idled for a long time.

This started going away at around 50hrs and now I have no problems on long taxi's or delays. Most of the time I lean while on the ground as well. There is a fine line at low RPM between running and too lean. Go to far and it will quit dead fast.

I occassionally would get bumps after pulling power on downwind and final. Lately this seems to be gone as well. Might just be the cooler weather though.

I once had a weird event after pulling power on downwind that scared the crap out of me. The engine briefly sounded like a muffled "jake brake" for a couple seconds. I have no idea what that was. It did it again on final that flight. Has never happened again. Someone suggested that it might have been my noise canceling headphones creating this sound???
Brantel (Brian Chesteen),
RV12-IS, #121606, N912BC - Building Now!
RV10, #41942, N????? - Project Sold
RV-7/TU, #72823, N159SB - SOLD

Post Reply