Hard starting 0-235

Kiloalphadriver said:

Did you actually check to make sure the lag angle (a question in my first post on this thread) was correct?? Noooo...you can't do that!! lol

Nice post...thanks!!
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You referred that the lag angle could change in service ,,,, it can't.

You'd have to have the wrong mag installed at overhaul in 2000, to have the wrong lag angle, because it is built into the mag housing and the model/serial number would reflect that.
 
Kiloalphadriver said:
You sure took the long road to do it. :)

Whew!! I was beginning to wonder if they had stopped putting ignition systems on 152's!!

It's nice to see a shop approach a problem without the assumption it can ONLY be one thing.

slowly rotate the engine forward to TCD noting where the impulse coupling snaps. if at 5 degrees, your SB has been complied with.

Did you actually check to make sure the lag angle (a question in my first post on this thread) was correct?? Noooo...you can't do that!! lol

Nice post...thanks!!
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Ray:

There's nothing wrong with suggesting that the ignition on the stubborn 152 might be bad. 90% of engine troubles tend to be electrical, after all. BUT: The fact that it's an O-235, and the fact that the impulse can be heard to snap aggressively, and the fact that once it starts and settles down after the belching and stumbling it runs and pulls just fine, we can reasonably point the OP to the primer nozzles. They WILL need cleaning or replacing, after all, if they have more than 1000 hours or so since they were brand-new or last cleaned (based on my own experience) and cleaning them WILL improve the starting performance.

A weak spark would show up in the runup and at full throttle if the mags were checked there. It can also be checked at low idle (pull the carb heat to slow the idle further) and try the mags there. At such low RPM a weak mag or plug will be pretty much dead or will misfire easily.

I used to check primer nozzles by removing them, reconnecting the primer lines to them and bending the lines enough (remove the clamps) to point the nozzles away from the engine, and work the primer. No spray is bad. A straight, narrow stream is bad. A conical fan of very fine mist is good, and those primers have to be pretty much spotless inside to do it. They can be cleaned to get flow but are not always cleaned enough to get the fan mist. For the O-235, you really need that fan.

Dan
 
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I gave the shop the keys on Monday, told them it was hard to start and that I suspected the primer nozzles were clogged.

Just got off the phone with the mechanic. He said they cleaned the nozzles, replaced 3 spark plugs (not sure why this arbitrary number) and it is 100% easier to start. I'll probably aviate at some point this weekend so I'll let you all know how it goes. If I see the guys around this weekend i'll ask why 3 plugs.
 
dell30rb said:
I gave the shop the keys on Monday, told them it was hard to start and that I suspected the primer nozzles were clogged.

Just got off the phone with the mechanic. He said they cleaned the nozzles, replaced 3 spark plugs (not sure why this arbitrary number) and it is 100% easier to start. I'll probably aviate at some point this weekend so I'll let you all know how it goes. If I see the guys around this weekend i'll ask why 3 plugs.
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Because they aren't ripping you off, they are only replacing what is bad, be thankful you have them.
 
Definitely nice.

I have no clue how much aviation spark plugs cost, I am guessing too much.
 
dell30rb said:
Definitely nice.

I have no clue how much aviation spark plugs cost, I am guessing too much.
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Obviously these three plugs had something wrong that differentiated them from the others. I am curious what that is. Electrode wear? Lead fouling that could not be cleaned?

I run it on mostly 93 octane auto fuel and at about 65 percent power, as lean as it will run and stay smooth. A nice light tan color on the inside of the exhaust pipe.
 
dell30rb said:
Obviously these three plugs had something wrong that differentiated them from the others. I am curious what that is. Electrode wear? Lead fouling that could not be cleaned?
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Most likely the internal resistors had failed. That makes for a weak spark, or a spark that blows out at higher compression pressures. The plug tester catches it. Nobody is making a decent plug anymore since Champion bought Auburn and shut them down. Auburns were great plugs. Miss them.

Dan
 
Dan Thomas said:
Most likely the internal resistors had failed. That makes for a weak spark, or a spark that blows out at higher compression pressures. The plug tester catches it. Nobody is making a decent plug anymore since Champion bought Auburn and shut them down. Auburns were great plugs. Miss them.

Dan
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Me too, I had great luck with Auburns, not so good with Champions.
 
It was my Skipper on the Red Board that had the clogged primer injectors that Dave mentioned. It has 4 primer lines, and three of them were very clogged. I cleaned them and it now starts perfectly.

I researched the impulse coupling issue, and learned that the 5 degree impulse is only for some 24 volt engines (my plane is 12 volts). The 24 volt system caused the starter to spin too fast. There were two solutions:

- mags with 5 degree lag or
- a slower spinning starter

I suspect doing both would be a problem, as would doing neither. Worth checking!
 
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