Cessna 152 starting problems

Fly_Unity

Fly_Unity

Well-Known Member
Our flight school has a Cessna 152 with a Sparrow hawk STC. Recently in the past month it has been starting hard. Its close to TBO.

Mechanic checked it all out and said mags, compression's, everything looked good.

But its still starting hard. I had students and instructors run the battery dead three times just this week just trying to start it. For some reason the mechanic can start it fine (the three times he tried), I can usually start it ok after playing with it. It takes an art to start it. Put any renter, student or instructor in it, and it wont start. Mechanic states that we need to properly train our students how to start and prime properly.

It shouldnt be an art to start it. Every other 152 in our fleet never had a problem.

When trying to start it, it keeps trying to catch and gets a couple of strokes, then nothing. So prime it 2 strokes, start it again, get a couple more strokes, almost catches, then nothing. It does not matter if it you dont prime it, or if you prime it so much that fuel is dripping out the the cowling. It does the same thing. Almost catches, then it just turns the engine.

Any ideas?
 
If the mechanic can start it I'd have him write down a procedure that works for him give it to everyone who takes the plane up.

I recently had a similar problem with my Cherokee 180. It turned out to be the impulse coupling on the mag. I don't really know what the does, exactly, but the way I understand it is that it's ONLY for starting and the mags could otherwise be fine and the engine runs okay. But if the mechanic can start it I don't believe that would be the problem.
 
Haha, I was just going to post about impulse coupling as a possibility...

What the impulse coupling does is it's basically a spring loaded mechanism on one of your mags, because during the start engine RPM is pretty low, so magneto electrical output is also low resulting in a very weak (or no) spark. The spring loaded mechanism loads up the mag and essentially "flings" it through rotation to generate extra umph for a good starting spark. The snap/click you hear when you rotate a prop through a rotation is the impulse coupling firing.
 
Pull the impulse coupled mag (probably the left one) off and do a 500 hour inspection on it. Can almost guarantee that will fix your problem.
 
Roger Roger said:
Pull the impulse coupled mag (probably the left one) off and do a 500 hour inspection on it. Can almost guarantee that will fix your problem.
Click to expand...

Seconded.

I will say too that 152's have a special part number for the starter, if it's got the wrong starter on it it will be hard to start. The same starter for a 172 will fit but it's the wrong one. Was the starter changed recently?
 
You mean you don't keep cranking it until either the engine starts or the starter catches fire? One way or another you get combustion.... But seriously, I saw a renter burned the starter up, didn't notice the baffling smoking etc... He was perplexed when I said get out of the plane as I reached for the fire bottle.

I second the impulse coupling.
 
I also find that four shots of prime instead of the normal Cessna three works well for the one filthy too. But it doesn't sound like prime is your problem.
 
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