Imposter!

[justnjoett]

Hi Everyone, I am a new member and own a 1967 Cessna 150g. I know this site is for 170 owners but i figured a lot of you once owned a 150 and that is why i am seeking your knowledge and experience regarding my Plane. I will try and keep this short...Did three touch and go this morning and while doing the 4th one my ( Continental 0200 ) engine began to run rough and lose power. RPM would not climb above 2200 and dropped to 2000 and ran rough..made an emergency landing on the opposite runway with no damage.The plane has just 3 days ago passed a 100 hr annual, all cylinders were in the upper 70s and with new plugs. Did a magneto check later at the run up area and mags did not drop more than 50rpm on both,also did a carb heat check also no problem however the engine would not go above 2200 on the ground and ran rough, it fluctuated between 2200 and 1900 and would not climb higher. All connections were checked today on all plugs and they are fine...It seems this problem developed quite quickly ie: my 4th touch and go climbout..Thanks to you all for any suggestions.
Cheeeeerz.. John H (N4035J) L70

[Robert Eilers]

Based on your description of the problem and the follow up checks you completed my first suggestion would be to suspect the fuel pump.

[W.J.Langholz]

how many hours? compression check?

W.

[ginbug92b]

Could be water in the tanks. go to http://www.sumpthis.com/cessna150andcessna152tanktest You will not believe how much water can be in the tanks and yet you can take a sample out of the tank drain and get pure fuel. Go to main tank test

[n2582d]

Based on your description of the problem and the follow up checks you completed my first suggestion would be to suspect the fuel pump.

On a C-150?

[GAHorn]

There is no fuel pump on a 150.
I suspect a restriction in the induction or a timing problem.
Inspect the carburetor air box and carb heat flapper.
What amount of drop do you see when you check carb heat?
Have you checked to see if you can kill the engine with the mag
Switch alone?(you might be running on only one mag and it
May be hot!

[flyguy]

Based on your description of the problem and the follow up checks you completed my first suggestion would be to suspect the fuel pump.

FIRSTEST TYEM ISA EVER HYEAR GRAVITIE CALL A FUEL PUMP. NOW SUCH AMINAL ON A C150.

Sounds like you have water in the gascolator and a failure in the drain valve. I've been there done that!

[johneeb]

Does the O-200 have the same flow devider that the O-300's have located above the carburator?

[Bruce Fenstermacher]

I suspect a stuck exhaust valve. I'll bet it stuck when you pulled the throttle for the third landing and the cylinders cooled. You wouldn't notice it until power is applied. It has happened to me just about as you describe.

I might have suspected carb ice but that would have passed. I might have suspected a mag problem but if you get the same mag drop on both mags it indicates both mags are working but of course we don't know if they are working correctly.

I would carefully with the mags OFF and all precautions taken that the engine might start, pull the prop through by hand. You should have compression on all four cylinders. If one compression stroke is missing, the valve is stuck open.

BTW I won "the diagnose the engine problem" bet the last time with a stuck valve diagnoses. Lets see if I go two for two.

[GAHorn]

I missed the rough running symptom......
Bruce caught it and has the best idea I think....
Pull the prop thru...AFTER you check for hot mag...
And see if you hear it HISS thru the exhaust during a
Weak cylinder.
After that is eliminated....try my other suggestions.

[flyguy]

Could be water in the tanks. You will not believe how much water can be in the tanks and yet you can take a sample out of the tank drain and get pure fuel. Go to main tank test

~@@~ The gist of the article focuses mostly on Cessnas with rubber bladders and not the majority of the Cessna fleet. Unless I am mistaken there are no Cessna 120, 140, 150, 170 or pre1975 172s with bladder fuel cells. The data list of accidents over the 6 year period did not specify why the "water" was in the fuel of bladdereless tanks. Most likely there was lack of sufficient preflight instead of "copious amounts of water remaining after sumping the tanks properly"

This is the main point in the Aviation Safety article " " "- - - the bladder-equipped Cessna singles do have a significantly greater rate of water-in-fuel accidents compared with the rest of the general aviation fleet. - - " " ".

So, IMHO, a normal preflight sumping will generally get "all" the water from a metal tank that is in a wing of a Cessna on level ground. And BTW the C170 was in the group that had the best rating of all the Cessnas listed in those tests.

[W.J.Langholz]

BTW I won "the diagnose the engine problem" bet the last time with a stuck valve diagnoses. Lets see if I go two for two.

holder there Buster Brown.......what do you suppose I was looking for on my compression test ...........
I just usually use my finger over the spark plug hole, if it's hard to hold it down on the up stroke and just about gets sucked in on the down stroke......you are good to go!!!!!



W.

chopper guys.....always want to be first

[Bruce Fenstermacher]

chopper guys.....always want to be first

Chopper guys ARE always first. I don't see anything wrong with that.

W., I think we are talking about a different diagnosis. The last time I diagnosed a stuck valve I seem to remember TWO stuck valves were actually discovered.

BTW I have a calibrated thumb, who needs a compression gauge. A new SB on compression check procedure will be forthcoming from Continental.

[justnjoett]

Imposter Update!!!!!!!!!!!!!!!!!!! Problem turned out to be a Stuck Exhaust Valve on #4... Thanks to you all for your help and suggestions that i checked thru all of them. Thanks again..Because of my limited mechanical skills i am sure i will be back... Cheeeeeerz.....John + N4035J. PS Have a wonderfull Memorial Day everyone.

[Bruce Fenstermacher]

WEEEEEELLLLL How about that W. A chopper pilot calls it correct again.

(Visualize a little victory dance here)

Two for two. Do I know my stuck valves or what.