Tapping rocker arms

[greatamericanwest]

Annual finished today on my C150, Cont O200A. Cyl 4 stuck a couple months ago, did the rope trick, cleaned and reamed and flying fine for a couple hours since. Flew it 40 nm to annual no issue. Compression test time. The same Cyl 4 making 32 psi/80. Could hear air rushing but I don’t know from where. Mechanic tapped the rocker arm and it rose to 72/80. Was told it was likely carbon or debris.

Flew it home without issue, but Cyl 4 CHT never rose above about 310F. Related? Maybe it’s post annual jitters but it didn’t help. Other than that, it was routine.

edited to clarify it wasn’t one day annual, it was two.

 

[455 Bravo Uniform]

Thoughts:
-Prior problem, recently fixed.
-Low comp just now, fixed. “Likely carbon or debris”.
-#4 CHT different from before.
-“It didn’t feel right”

Something is not right. Maybe minor, maybe not. Figure it out.

Why you discounting your own judgement???

<edit> Wait, you flew it to your annual and back in one day? What the heck kind of annual was that? That’s another data point to the 4 I listed above. Time to worry.

 

[Daleandee]

The OP clarified that his annual was done in two days not one. But to answer your question of what kind of annual is done in a single day ... you need one of these;

 

[Magman]

Which version? ( 12 days of Christmas?)

Inspection and paper chase on aircraft that IA has done several times?

Inspection and paper chase on aircraft that IA has NOT done before?

Inspection, service and paper chase on aircraft IA has NOT done before?

Opening, Inspection , service, paper chase and closing on aircraft IA has not done
before?

Opening, Inspection, service , paper chase, repairs and closing on aircraft on
aircraft IA has NOT done before?

 

[Greg Bockelman]

Unless a few things needed to be fixed, why would an annual on a 150 need to take more than a day?

 

[Dan Thomas]

Unless a few things needed to be fixed, why would an annual on a 150 need to take more than a day?

It can be done in a day, but if you're going to get a look at the internal structure and systems like you're supposed to, it takes a couple of people one day. Taking out the seats and the plastic interior takes time, and it takes longer to put it back than to take it out.

Internal structure and systems in a 150?? Seldom get checked, based on what I used to find. Cracks in the bulkhead at the aft end of the baggage compartment. Frayed control cables, seized pulleys. Controls out of rig. Wiring and plumbing behind the instrument panel in awful shape, stuff being chafed by moving controls. Heat-damaged crimp connectors on switches and breakers. Unaddressed ADs on altimeters and ignition switches and other stuff. Rust-pitted gear legs ready to fail and wreck the airplane. Any time I encountered an airplane for the first time it got a thorough inspection. Subsequent inspections, as long as all the defects found in the first one were fixed, were quicker and easier.

Yes, tapping the rocker to see if the leak smartens up, is normal. Just pulling the top sparkplug out can dislodge carbon that falls on a valve.

 

[unsafervguy]

what it means is that #4 is talking to you. does it mean that there is a big problem with it? maybe, maybe not. what it means to me is fly it a bit with a close watch on how you fly it. O-200's really hate 100LL, pay attention to how you lean it, keep an eye on temps, and re-check the compression after a few hours. if its fine, it could have been carbon or crud. if it needs to be spiked again i would say that there is something going on in it and a closer look is needed.

 

[Matthew Rogers]

what it means is that #4 is talking to you. does it mean that there is a big problem with it? maybe, maybe not. what it means to me is fly it a bit with a close watch on how you fly it. O-200's really hate 100LL, pay attention to how you lean it, keep an eye on temps, and re-check the compression after a few hours. if its fine, it could have been carbon or crud. if it needs to be spiked again i would say that there is something going on in it and a closer look is needed.

Get the Mogas STC and fly with Mogas for a while. Solves the problem of lead and whether you are leaning correctly (unless the problem is carbon). We use 90+% mogas and have never seen a single bit of lead build up, despite student pilots using the plane and lots of 100% full rich flights.