o-200 stick valve ?

bobkiksass said:
what affect does the carb going from being a 2 piece venutri to one piece venturi ?

The one piece venturi I read runs richer than 2 piece ? Does it really affect performance that much ?

After they send the carb back, no big rise on idle mixture cutoff... but there is still some "morning sickness" type sound when idling. My mechanic isnt comfortable with reaming the valves, I think Im going to have someone else take a look at it. The mechanic says it has a "tinny" noise and is pretty convinced something is up with the valves.
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Some hydraulic units in the lifters take longer to pump up than others. Post a video of a cold stone start up because I feel your chasing something that isn't a problem. These aren't Japanese motorcycles.
 
bnt83 said:
Some hydraulic units in the lifters take longer to pump up than others. Post a video of a cold stone start up because I feel your chasing something that isn't a problem. These aren't Japanese motorcycles.
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Indeed they do....
 
bobkiksass said:
what affect does the carb going from being a 2 piece venutri to one piece venturi ?

The one piece venturi I read runs richer than 2 piece ? Does it really affect performance that much ?.
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99% of the carbs that changed venturis went from a 2 piece to a 1 piece and ran too rich after.

you got it backwards.
 
bnt83 said:
Some hydraulic units in the lifters take longer to pump up than others.
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they do not do this until the valve train is totaly worn out.
 
Tom-D said:
they do not do this until the valve train is totaly worn out.
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My point is that it could be a weak one that they are "hearing morning sickness" from. If you read this entire thread it looks like a shotgun approach overhauling magnetos and the carburetor, niether of which have solve the issues on a 300 SMOH engine
 
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Mine will show "morning sickness" on cold days, I blame the crap induction system not delivering the fuel well until warmed up.
 
bnt83 said:
My point is that it could be a weak one that they are "hearing morning sickness" from. If you read this entire thread it looks like a shotgun approach overhauling magnetos and the carburetor, niether of which have solve the issues on a 300 SMOH engine
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Morning sickness is not caused by a lifter, it is caused by a valve that is open when it should not be, like in stuck open and will not close all the way due to lead on the valve stem or in the valve guide.

0-200s are not known to have lifter problems, 2 strokes of the cam lobe will pump up the worst lifter.
 
Tom-D said:
Morning sickness is not caused by a lifter, it is caused by a valve that is open when it should not be, like in stuck open and will not close all the way due to lead on the valve stem or in the valve guide.

0-200s are not known to have lifter problems, 2 strokes of the cam lobe will pump up the worst lifter.
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Sometimes what one person defines as morning sickness is entirely different then what another defines as it.

My experience with an O-200 that actually has a stuck valve when cold is that it is extremely dramatic and not something that'd be of any difficulty to identify.

Quite possible what they mean by morning sickness is that "something sounds a bit funny when cold" which could be countless different things.
 
jesse said:
Sometimes what one person defines as morning sickness is entirely different then what another defines as it.

My experience with an O-200 that actually has a stuck valve when cold is that it is extremely dramatic and not something that'd be of any difficulty to identify.

Quite possible what they mean by morning sickness is that "something sounds a bit funny when cold" which could be countless different things.
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A stuck valve in a 0-200 is a big event. they usually won't unstick because the engine will be rough enough the pilot panicks and shuts it down. and if they don't the engine will bend a push rod then the valve will never open.

we simply do not hear about morning sickness in the 0-200/0-300 because when the valves stick open they will get hit by the piston and do much damage.

but most times the guides will wear the valve wobbles in the guide and we see a loss of compression, but due to dynamic compression the engine will run OK.

read Mike Bush's ramblings on the subject.
 
Tom-D said:
A stuck valve in a 0-200 is a big event. they usually won't unstick because the engine will be rough enough the pilot panicks and shuts it down. and if they don't the engine will bend a push rod then the valve will never open.

we simply do not hear about morning sickness in the 0-200/0-300 because when the valves stick open they will get hit by the piston and do much damage.

but most times the guides will wear the valve wobbles in the guide and we see a loss of compression, but due to dynamic compression the engine will run OK.

read Mike Bush's ramblings on the subject.
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I've seen morning sickness in a O-200 that was defiantly a stuck valve. It would clear itself once it warmed up but was rather exciting prior to that. I don't believe the valve was ever struck by the piston and believe the fix was just reaming - but don't remember precisely anymore.
 
The mag and the carb needed to be overhauled, they had 9+ years on them, the carb had loose butterfly and was dripping fuel. The mags had some crappy contacts. And the plane did seem to run better for a bit after doing this.

the mechanic wanted to borescope to inspect to see proper valve function at the annual 3-4 months ago because he suspected the valve was lagging. He found no evidence of any trouble then, but suggested the valve could just be a bit sticky.

Now he is convinced the valve is sticky. The roughness of the motor is only noticeable for the most part when idling, at full throttle not usually any roughness. On last flight it did "fart" a few times when wide open, and that was why I wanted to have him double check. Now I want a third opinion because Im not too confident on their abilities.

I understand that a "stuck valve" will cause serious trouble, I don't think its permanently stuck maybe just not quite working properly. Im having him check the oil to see if any metal, then Im going to take the plane down to a different mechanic who tells me hes dealt with sticky valves on o200 before. my current mechanic says mike bushs idea about dropping the valve in the cylinder and reaming the valve guide is a "sketchy" procedure that he wouldn't do.
 
bnt83 said:
My point is that it could be a weak one that they are "hearing morning sickness" from. If you read this entire thread it looks like a shotgun approach overhauling magnetos and the carburetor, niether of which have solve the issues on a 300 SMOH engine
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are you suggesting my valve train may be worn out ? what do you mean by that ?
 
bobkiksass said:
my current mechanic says mike bushs idea about dropping the valve in the cylinder and reaming the valve guide is a "sketchy" procedure that he wouldn't do.
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It's really not that difficult and is exactly what I'd be doing if I was having valve issues on a O-200 that was burning 100LL. I would ask your A&P what about it is exactly sketchy. As long as he is careful doing the reaming it's no biggie.

Directions (this is a Lycoming, but same idea):
http://www.theleftseat.net/stickyvalvereaming.html
 
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bobkiksass said:
my current mechanic says mike bushs idea about dropping the valve in the cylinder and reaming the valve guide is a "sketchy" procedure that he wouldn't do.
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Your Mechanic need to find a new profesion.

this routine is very common.
 
Tom-D said:
Your Mechanic need to find a new profesion.

this routine is very common.
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I think he is very inexperienced for sure, and based on this thread I'd find a new one.

Overhauling mags just because they were 9 years old? Points for mags are about $30-$50 a piece and grease the bearings if needed and thats about it if they are low time, but high calendar time. Impulse spring could need replacement too I guess.
 
jesse said:
Quite possible what they mean by morning sickness is that "something sounds a bit funny when cold" which could be countless different things.
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Been lots of that in this thread too.
 
jesse said:
Quite possible what they mean by morning sickness is that "something sounds a bit funny when cold" which could be countless different things.
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That's why I put morning sickness in quotes when I mentioned my "issue"

It isn't traditional morning sickness, but lots of folks call it that
 
bnt83 said:
Been lots of that in this thread too.
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its not so much noticeable when cold, but just low rpm. when the motor is run after flying for an hr or two, I still get a bit of stutter and roughness when at 1000 rpm or less
 
It happened to me a couple of years ago when I was ferrying a guys 150 to Oklahoma. In my case it definitely was not "morning sickness" as I had taken off early that day from Winslow Arizona, stopped for gas and lunch in Albuquerque and was on my second fuel stop on a hot mid-afternoon in Amarillo. I still had a pretty good leg ahead of me to just a bit past Tulsa and when I got to the departure end of the runway, just prior to taking off, it happened. Like Tom said - pretty big event when you lose a quarter of your power and it starts shaking. A departure on 35 from Tradewind Airport takes you right over dense residential areas and it was HOT so I'm darn glad that sucker did what it was going to do before I took off.

Anyway, I taxied back, shut down and found a maintenance shop that let me pull it in out of the sun and borrow some tools. It didn't take long to see by pulling the prop through that #3 cylinder was the culprit. I pulled the valve cover and tried to stake the stuck exhaust valve but all it did was go in further.

I was on vacation and doing this as a favor so I left it with the guys at Tradewind (who BTW did a good job and took care of my friend who eventually came down and picked it up) They gave me a ride to the big airport and I hopped on a SW flight home.

Anyway, just wanted to point out it doesn't have to be morning for it to happen.
 
bobkiksass said:
its not so much noticeable when cold, but just low rpm. when the motor is run after flying for an hr or two, I still get a bit of stutter and roughness when at 1000 rpm or less
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It should idle fine. Any chance you got carb ice building on taxi?

And you said that you do not see any RPM rise anymore as you very slowy pull the mixture out till it will barely run? Sounds like the idle mixture screw needs a twist in the "rich" direction and try running it again.
 
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bnt83 said:
It should idle fine. Any chance you got carb ice building on taxi?

And you said that you do not see any RPM rise anymore as you very slowy pull the mixture out till it will barely run? Sounds like the idle mixture screw needs a twist in the "rich" direction and try running it again.
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no carb ice, its warm out around here.

There is slight rise at idle mixture cutoff, but nothing more than 75-100 rpm ...

I talked to other mechanic on the field, he said the guy Im working with now is the most experienced in the area and he respects his opinions and 30+ years experience, but agrees having a second set of eyes check out the plane would be good. Im going to have this guy check it out in a few days. And he says he has dropped a valve in the cylinder before in a 150, and just cleaned and lubed the valve guide to fix a sticky valve before. Hes not convinced reaming the guide would be necessary
 
bobkiksass said:
no carb ice, its warm out around here....
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Depends on more than whether you're in short sleeves or not

carb_ice.gif


I just pulled a jug off my C90, removed both valves, cleaned and lapped them. Took no time at all. I really don't see any reason to try do this in-situ unless you're stuck out in the bush.
 
Re: o-200 sticky valve ?

bobkiksass said:
I have a cessna 150 with continental o-200.
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That means you probably have a Marvel-Schebler MA-3SPA carb.

These run rich, even more so since their AD mandating a new one-piece venturi.

They paid $38.6 MILLION dollars to two guys who were in a 150 that had engine failure due to their carb running rich ($1.5 million of that was a penalty for not having fixed the problem, despite 40 years' worth of complaints). This rich condition led to a stuck valve (from lead loading).

Given that history, I would suspect that your carb is running rich. Check for a "V" stamped on the number plate -- if it's there, you have the new venturi. If so, then go back through your logs for any reference to a new fuel tube (their kinda-fix for the problem). If it's there, that's all that can be done without changing to unleaded fuel (got the autogas STC?) or finding one of the two-piece venturis and reinstalling it.

They used to send the kinda-fix free to owners who requested it, but now Tempest (the current owners) want $158 for it (it's a tube and a couple of gaskets, about $10 worth of parts). Their attitude now is more or less "too bad for you that you have our carb -- gimme money!"

. . .which is why I'll never buy another Tempest product, except for oil filters and spark plugs . . .
 
Tom-D said:
I disagree Jim, you should be able to run a 0-200 full rich and not have any problems.
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The MS guys paid out $38.6 million to a couple of guys who went down because the design of the carb made it run rich (they had a valve stick open from lead fouling).

If you do a little looking around, you will find a lot of references to the MA-3SPA carb used on the O-200 running rich, especially since they got an AD pushed through in 1993 mandating a new (inadequately-tested) venturi. The problems caused by the AD led to that mandate being RESCINDED (how often does that happen?), but by then most of us had the new ratty venturi installed. The old ones were sent back and destroyed.

I'm at 4600 MSL here. I have to lean my O-200 before takeoff. Full rich DOES cause problems!
 
Re: o-200 sticky valve ?

SoloEqs said:
That means you probably have a Marvel-Schebler MA-3SPA carb.

These run rich, even more so since their AD mandating a new one-piece venturi.

They paid $38.6 MILLION dollars to two guys who were in a 150 that had engine failure due to their carb running rich ($1.5 million of that was a penalty for not having fixed the problem, despite 40 years' worth of complaints). This rich condition led to a stuck valve (from lead loading).

Given that history, I would suspect that your carb is running rich. Check for a "V" stamped on the number plate -- if it's there, you have the new venturi. If so, then go back through your logs for any reference to a new fuel tube (their kinda-fix for the problem). If it's there, that's all that can be done without changing to unleaded fuel (got the autogas STC?) or finding one of the two-piece venturis and reinstalling it.

They used to send the kinda-fix free to owners who requested it, but now Tempest (the current owners) want $158 for it (it's a tube and a couple of gaskets, about $10 worth of parts). Their attitude now is more or less "too bad for you that you have our carb -- gimme money!"

. . .which is why I'll never buy another Tempest product, except for oil filters and spark plugs . . .
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carb was just overhauled and has the one piece venturi, I think it had the once piece venturi when I sent it to them. It was overhauled by aero accessories, not tempest. Is it safe to assume it has this "kinda fix" fuel line for the one piece venturi installed from aero accessories ?
 
I gotta ask this: how does a carburetor with a manual mixture control "run too rich"?

SoloEqs said:
I'm at 4600 MSL here. I have to lean my O-200 before takeoff. Full rich DOES cause problems!
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We were specifically talking about standard temperature and pressure.
 
jesse said:
Sometimes what one person defines as morning sickness is entirely different then what another defines as it.

My experience with an O-200 that actually has a stuck valve when cold is that it is extremely dramatic and not something that'd be of any difficulty to identify.

Quite possible what they mean by morning sickness is that "something sounds a bit funny when cold" which could be countless different things.
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that's a problem, everybody has their own defination of the same symptoms.
 
Silvaire said:
I gotta ask this: how does a carburetor with a manual mixture control "run too rich"?
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Because the pilots won't use the mixture or they don't understand what they are doing.
 
Silvaire said:
I gotta ask this: how does a carburetor with a manual mixture control "run too rich"?
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The carb doesn't just meter fuel, it also has to mix it with air. The MA-3 with the new venturi doesn't vaporize fuel well or consistently. The optimum would be a "fog" of fuel vapor in the intake, but what you get are relatively thick streams of fuel, which somewhat randomly flow into the intake spider, surrounded by very lean streams of air.
 
Re: o-200 sticky valve ?

bobkiksass said:
carb was just overhauled and has the one piece venturi, I think it had the once piece venturi when I sent it to them. It was overhauled by aero accessories, not tempest. Is it safe to assume it has this "kinda fix" fuel line for the one piece venturi installed from aero accessories ?
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The AD came out in 1993, so you probably got the new venturi then.

The fix is a replacement for the brass fuel nozzle inside the carb. If you saw the nozzle and it had holes in the side near the venturi end, you have the new nozzle. The original nozzle only has the big hole in the end.

Go check AD 98-01-06 and Marvel-Schebler's SB MSA-7

Symptoms of problems are "engine richness, roughness or hesitation."
 
Bob,

Did you get your issue resolved? I'm curious to know what it was because I've experienced a stumble during climb out similar to what you explained in a previous post. I have a 150G and it's occurred twice in the last dozen take offs. I'm pretty confused as I haven't changed anything on the engine and never noticed the problem before. I thought it was carb ice, but I'm not sure after reading this thread.
 
after months of troubleshooting and moments of terror while my motor vibrated like it wanted to quit... we found too short of push rods installed in the motor. The gap between the rocker and top of the valves was out of spec on all 8 valves. Two intake valves had been beat up, and one lifter body broke. long story short is, motors getting torn down to fix the lifter body, and longer pushrods will be installed.
 
SoloEqs said:
The MS guys paid out $38.6 million to a couple of guys who went down because the design of the carb made it run rich (they had a valve stick open from lead fouling).

If you do a little looking around, you will find a lot of references to the MA-3SPA carb used on the O-200 running rich, especially since they got an AD pushed through in 1993 mandating a new (inadequately-tested) venturi. The problems caused by the AD led to that mandate being RESCINDED (how often does that happen?), but by then most of us had the new ratty venturi installed. The old ones were sent back and destroyed.

I'm at 4600 MSL here. I have to lean my O-200 before takeoff. Full rich DOES cause problems!
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you missed my point, the 0-200 / MA3 should run fine full rich, but won't after all the Precision modifications, they did run fine for well one 35 years as designed.
 
bobkiksass said:
after months of troubleshooting and moments of terror while my motor vibrated like it wanted to quit... we found too short of push rods installed in the motor. The gap between the rocker and top of the valves was out of spec on all 8 valves. Two intake valves had been beat up, and one lifter body broke. long story short is, motors getting torn down to fix the lifter body, and longer pushrods will be installed.
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Be sure to tell us who built that engine.
 
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