0-200 intermittent loss of engine power

Mike5250

Mike5250

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Mike5250
We are trying to track down an engine problem on our 0-200. The (former) partner stated that after the annual the year before the engine would lose 200 +/- rpms for 10-20 seconds on takeoff and then loss of power would never return.

Fast forward a year... After annual, I get that same loss of power at 100 AGL- rpms dropped to 2200 and I landed straight ahead. Mechanics reinspect everything and the problem never occurs again.

Last annual/incident was about 5 months ago now... We had low compression on one cylinder and had it rebuilt by a shop with good reputation. While the plane was sitting we also drained the fuel completely to replace fuel switch o-ring (on/off valve). After a good run up, etc I do a static check and get 2450-2500 rpms and after about 15 seconds get the same drop to 2200 rpms. After a second static check it does the drop briefly and afterwards runs about 50 rpms higher during static check and the problem won't duplicate itself.
 
Mags, perhaps? Might be worth doing an inflight mag check next time that happens.
 
Brad Z said:
Mags, perhaps? Might be worth doing an inflight mag check next time that happens.
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Switched mags during roughness and it doesn't change anything. The weird part is it happens only after this major maintenance... Originally we thought this was a fuel contamination issue or water in carb heat duct work.
 
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Dan Thomas said:
None of the above. Go to this thread:

http://www.homebuiltairplanes.com/forums/firewall-forward-props-fuel-system/14992-o-200-problem.html

Or this one:

http://www.pilotsofamerica.com/forum/showthread.php?t=28123&highlight=O-200+lock-o-seal+washers

One other remote possibility: O-200s are prone to valve sticking if the guides aren't reamed enough. Since one cylinder was recently repaired...?

Dan
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That description from the homebuilders site is identical to my problem. Forgot to mention, but I think leaning it smoothed out the engine a bit when it was stumbling at 2200 rpms. The real confusing part is that this only happens right after annual or maintenance. I'm going to visit the mechanic tomorrow AM, plane is still in the shop.
 
Dan Thomas said:
One other remote possibility: O-200s are prone to valve sticking if the guides aren't reamed enough. Since one cylinder was recently repaired...?

Dan
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We were thinking another cyl may have a stick exhaust valve as well, because it happened previously. If I owned the plane, I think it would be getting 4 new cylinders, just don't want to spend $4,000 for parts and labor when its not my plane.

Mechanic looking at it today, I'll post an update.
 
I'm not a mechanic but have owned several small taildraggers with Stromberg carbs. Many times, these carbs. Are fiddled with by mechanics who are not very sharp concerning the float settings, etc. often times, when sent out to a good carb. Rebuilder it makes a great difference. The Stromberg is an excellent carb. But not really understood by many who work on them. Hope this helps.
 
Jimmy cooper said:
I'm not a mechanic but have owned several small taildraggers with Stromberg carbs. Many times, these carbs. Are fiddled with by mechanics who are not very sharp concerning the float settings, etc. often times, when sent out to a good carb. Rebuilder it makes a great difference. The Stromberg is an excellent carb. But not really understood by many who work on them. Hope this helps.
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:confused: A stromberg on an O-200?
 
Just curious, was this an off field landing? You said you landed straight ahead.
 
F01LA said:
Just curious, was this an off field landing? You said you landed straight ahead.
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I was at 100 agl and had about 1500 ft of runway left and was able to land on remaining runway. Thankfully not off field.
 
Check the exhaust valves for freedom of movement with the springs removed. Ream the guides on any tight ones -or better yet jsut ream all four. Not a big $deal. Last time I stuck one it was at 100' at the end of the runway. Grossed so it would not climb at all. Had to fly about 5 miles going around stuff to get back to the runway. Charlie Melot Zephyr Engines.
 
charlie said:
Check the exhaust valves for freedom of movement with the springs removed. Ream the guides on any tight ones -or better yet jsut ream all four. Not a big $deal. Last time I stuck one it was at 100' at the end of the runway. Grossed so it would not climb at all. Had to fly about 5 miles going around stuff to get back to the runway. Charlie Melot Zephyr Engines.
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This is the company that I've heard about on several occasions . Always excellent reports by those who have had work done there. Mooney and archer, two that I remember.
 
Jimmy cooper said:
This is the company that I've heard about on several occasions . Always excellent reports by those who have had work done there. Mooney and archer, two that I remember.
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You can add a Baron to that. Charlie's shop does excellent work and we're lucky he shares his expertise here.
 
charlie said:
Check the exhaust valves for freedom of movement with the springs removed. Ream the guides on any tight ones -or better yet jsut ream all four. Not a big $deal. Last time I stuck one it was at 100' at the end of the runway. Grossed so it would not climb at all. Had to fly about 5 miles going around stuff to get back to the runway. Charlie Melot Zephyr Engines.
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Charlie,


Sounds like a good idea. I think we are going to regrind the other three exhaust valves too. Our mechanic has experience doing this without removing the cyl head.

Do you recommend any any fuel or oil additives?
 
charlie said:
Check the exhaust valves for freedom of movement with the springs removed. Ream the guides on any tight ones -or better yet jsut ream all four. Not a big $deal. Last time I stuck one it was at 100' at the end of the runway. Grossed so it would not climb at all. Had to fly about 5 miles going around stuff to get back to the runway. Charlie Melot Zephyr Engines.
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Help me out here Charlie, reaming a hole and checking it with a go / no go gage pin isn't rocket science, what am I missing here?
 
Just listen to Charlie. The odds are high that is the issue - like 99%. It is easy to do and almost cheap.
Use a rope and drop the valve into the cylinder, hand turn the reamer, you will find one or more guides are warped.
BTDT more than once.
 
Dr. O said:
Just listen to Charlie. The odds are high that is the issue - like 99%. It is easy to do and almost cheap.
Use a rope and drop the valve into the cylinder, hand turn the reamer, you will find one or more guides are warped.
BTDT more than once.
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Plan on having that done, good advice.

The only other thought is something with the Carb because this problem happens everytime after annual or when all of the fuel is drained. Thinking maybe the carb is running out of fuel until a good runup or two. Maybe air in the line or float level is too high causing the fuel mixture to be too rich. When the rpms dropped to 2200 leaning a little helped it gain rpms and smooth out.

Anyway, should have an update this weekend once we address a few things.
 
Found solid washers where "lock-o-seal" washers should have been installed. Hopefully thats our fix.
 
Dan Thomas said:
None of the above. Go to this thread:

http://www.homebuiltairplanes.com/forums/firewall-forward-props-fuel-system/14992-o-200-problem.html

Or this one:

http://www.pilotsofamerica.com/forum/showthread.php?t=28123&highlight=O-200+lock-o-seal+washers

One other remote possibility: O-200s are prone to valve sticking if the guides aren't reamed enough. Since one cylinder was recently repaired...?

Dan
Click to expand...

Thanks Dan! Replaced the torqued down crush washers with o-rings and running smoother than ever and problem didn't reproduce after flight today.
 
Mike5250 said:
Thanks Dan! Replaced the torqued down crush washers with o-rings and running smoother than ever and problem didn't reproduce after flight today.
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Good. Was that the only change, or were the valves also done?

Dan
 
Dan Thomas said:
Good. Was that the only change, or were the valves also done?

Dan
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Valves will get done with the rope method. The rpm drop was fixed with the o-ring washers and replacing the crushed intake hose. I also cleaned the spark plugs on the cylinder with the bad intake hose. The other 3 hoses are getting ordered as a precaution. They only had one set in stock at the shop.
 
Jimmy cooper said:
Carb. Needs rebuilding while your at it.......by someone capable.
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The carb has always seemed to be set about perfect. Starts first turn, idles nice, smooth at full power, etc. I'll see if it has the stromberg carb like you mentioned above.

Thanks for the ideas.
 
Great article about Strombergs a few years back by a fellow who overhauls them. Said 1 out of five were not machined correctly from the factory allowing the float to be set wrong. In some cases running rich or too lean . Went on to say while you may think it's performing correctly it's very possible your not running at optimum.( He repairs them and charges a pretty hefty fee) I mentioned this as he said people often change carbs. To another manuf. when in fact it's a matter of overhaul and proper setting.
 
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