Hard starting 0-235

dell30rb

dell30rb

Final Approach
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The 152 I fly has some difficulty starting. THe engine has about 1000 hrs, good compressions. Just out of annual.

When starting, it will occasionally "pop" when cranking over and then will catch and stumble along on its own for a bit. Repeat this once or twice when it's cranky and it will finally fire up. Once running, it runs very well.

Any ideas? I have flown 5 different 152's and this is one of the more difficult ones to start. The owner asked the mechanic to address this problem at annual, guess it did not get solved.
 
Guessing this is an issue with valve timing, ignition timing or mixture. Just wondering if anyone has had a similar experience with this motor and the solution. It's one of the smoothest running 152's but the most difficult to start
 
dell30rb said:
The 152 I fly has some difficulty starting. THe engine has about 1000 hrs, good compressions. Just out of annual.

When starting, it will occasionally "pop" when cranking over and then will catch and stumble along on its own for a bit. Repeat this once or twice when it's cranky and it will finally fire up. Once running, it runs very well.

Any ideas? I have flown 5 different 152's and this is one of the more difficult ones to start. The owner asked the mechanic to address this problem at annual, guess it did not get solved.
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How are you priming it?
 
Today, about 55 degrees. Gave 2 full shots of prime. Cranked and after going through about 3 revolutions it gave a loud pop, then stumbled along for about 8 seconds and died. Feathering the throttle during this time. I have tried continuing to prime on colder days while it's stumbling to keep it running.

For fear of flooding it if it does not start after the first cycle I'll try again a 2nd time with no prime. If it fails to start, I'll prime 2-3 more strokes and try to start again
 
Give it an extra squirt or two of prime before you turn the key. BTW, does it only have one primer nozzle or 4? Engines need fuel ad spark, lots of fuel to start. Planes don't have chokes and are difficult as hell to flood, minimum 4 shots of prime to start is what I always give cold engines. When the temps drop below 60 I'll add a pump for ever 10 under. Temps below 40 I'll also crank (mags cold) a few turns while priming. Lot's of fuel....
 
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Once had a Tomahawk that had similar symptoms. Cleaning the plugs helped a bit for a while but the ultimate fix was a new set of spark plugs.

Brian
CFIIG/ASEL
 
What altitude are you at on the ground?

I watched my mechanic start our C-182 one time and he did something no CFI ever mentioned or demonstrated up here at approximately 6000' MSL...

He leaned for start.

Brilliant!

No prime, engine turned one blade and popped to life.

Ever since, it's been two shots of prime if cold, none if warm, and the mixture comes back an inch or a little more for start. Throttle just cracked open.

It's rare to see two blades pass ever. Fires right up and I don't have to quickly pull the mixture out to keep it from chugging.

Prior to seeing that done that day it'd still start fine but it'd take three or four blades. It was just too rich up here.
 
Thanks. It did have the plugs cleaned at annual and the mag checks just fine. I'm going to try leaning a bit, though I'm only at 250msl.

Flying a bit more today and I'll keep an eye on it!
 
The O-235-K2C in our Citabria 7ECA was notoriously hard to start, too. The O-235 has that reputation. The -K2C had two impulse mags, but it seemed to help little. We experienced the same behavior through three engines over eight years, indicating that there was no faulty carb or mag or anything else; they were all new at each engine change. The primer fed three of the four intakes.

The best way to get results was to set the throttle at about 1/8" open, no more. Three shots of prime (it was a short-stroke primer), and use lots of force doing that to get good atomization, and immediately crank the engine. This engine does not want a lot of air for starting, and fumbling with the checklist after priming to see what comes next just lets the atomized fuel collect on the intake walls and down the runners. Wimpy priming push just dribbles the fuel and doesn't help matters.

If the engine has lots of time on it, or if the primer nozzles weren't properly cleaned or replaced when the engine was installed, those nozzles might be full of coked fuel. If the primer knob moves in really slowly even when pushed hard, the nozzles are likely clogged. The money to replace them is well worth it, since even one or two lost flights because the thing won't start will cost the operator money. There are a lot of little things like that on airplanes, and uninformed owners often lose time and money and aircraft life trying to save on them.

The "pop" on cranking is often a backfire through the carb, caused by too much liquid fuel flooding the cylinders.

Dan
 
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I always use three full shots of primer on 152's, FWIW, and get good results.
 
Dan Thomas said:
The best way to get results was to set the throttle at about 1/8" open, no more. Three shots of prime (it was a short-stroke primer), and use lots of force doing that to get good atomization, and immediately crank the engine. This engine does not want a lot of air for starting, and fumbling with the checklist after priming to see what comes next just lets the atomized fuel collect on the intake walls and down the runners.
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In really cold conditions if it's really giving me hell and has given me a few pops to get just a touch of heat into the cylinders (every bit helps) I'll prime again and even crank the engine while I prime to load some fuel into the cylinders and then just let it sit a couple minutes to evaporate some to build an explosive vapor mix in the cylinders and induction to get me a couple more pops of heat and I repeat the process until finally enough heat gets soaked into the engine to start. Operating in cold weather without a heater is a PITA.
 
0-235s are notorious for hard starting because they do not get enough fuel during prime.

try this give it 3 strokes of the primer, then pull the primer out, wait until it fills and hit the starter and when it fires push the primer in slowly. this will keep it running until the engine gets enough air thru the carb to keep it running.

you can also try stroking the throttle while cranking see if getting fuel to all 4 cylinders will help.
 
Tom-D said:
0-235s are notorious for hard starting because they do not get enough fuel during prime.

try this give it 3 strokes of the primer, then pull the primer out, wait until it fills and hit the starter and when it fires push the primer in slowly. this will keep it running until the engine gets enough air thru the carb to keep it running.

you can also try stroking the throttle while cranking see if getting fuel to all 4 cylinders will help.
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I don't recall accelerator pumps on 152s...
 
Henning said:
I don't recall accelerator pumps on 152s...
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Same with the 7ECA. I think many O-235s had the MA-3A carb which has no accelerator pump. According to the TCDS, they all used either the MA-3A or the MA-3PA. I don't know if the PA has the pump. I know the -SPA does. The P might mean Pump.

Dan
 
It's really simple guys. If stroking the throttle doesn't help, quit doing it.
 
Dan Thomas said:
Same with the 7ECA. I think many O-235s had the MA-3A carb which has no accelerator pump. According to the TCDS, they all used either the MA-3A or the MA-3PA. I don't know if the PA has the pump. I know the -SPA does. The P might mean Pump.

Dan
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Check the authorized replacement part numbers. I believe you'll find it says MA3-PA
http://www.kellyaerospace.com/fuel_charts/Carburetors/Facet_Marvel_Schebler_Carb.pdf

Cessna 152s produced between 1977 and 1982 were equipped with Lycoming O-235-L2C engines producing 110 hp (82 kW) at 2550 rpm. This engine still suffered some lead-fouling problems in service and was succeeded in 1983 by the 108 hp (81 kW) O-235-N2C which featured a different piston design and a redesigned combustion chamber to reduce this problem. The N2C engine was used until 152 production ended in 1985.

check the first chart, you'll find the 0-235 N2C takes a 10-5267. then see this chart

http://www.kellyaerospace.com/fuel_charts/Carburetors/MA-3AMA-3PAMA-3SPAMA-4SP.pdf

and you'll see it has the pump parts listed.
 
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Have the mech do a quick check to make sure the left mag P lead is REALLY on the left mag.
I can't tell you how many "starting problems" on Lycomings can be traced to someone getting their wires crossed (literally) during mag/engine maintaince.

On my Grumman AA1B with the 235-C2C I would (if it was below 40*F) put in two strokes and spin the starter, putting in the third shot while the prop was going round...as per Tom D.

Chris
 
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I think the airplane does have an accelerator pump. A good shove or two of the throttle produces some results. This leads me to think it is a prime issue.

Its still hard to start. It does like to do the pop - backfire through the carb thing, and occasionally will kick back 1-2 blades.

Does anyone have info on cleaning the primer nozzles. I think this is a good place to start. IE a pic or something with a short description. I can probably pull the cowl and figure it out myself, the airplane is located 30 minutes from me and its not exactly convenient. I'd like to have an idea of what i'm getting into and what tools i'll need.

I found a 150 service manual online for free download but have not seen anything for a 152. I did read through it as the aircraft are similar, but obviously they have different motors. This is a 1981 model "T" 152.

Also, is this an owner maintenance thing or will it require an a&p signoff?

PS thanks everyone for the replies.
 
dell30rb said:
Does anyone have info on cleaning the primer nozzles. I think this is a good place to start. IE a pic or something with a short description. I can probably pull the cowl and figure it out myself, the airplane is located 30 minutes from me and its not exactly convenient. I'd like to have an idea of what i'm getting into and what tools i'll need.


Also, is this an owner maintenance thing or will it require an a&p signoff?
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Very hard to clean those nozzles. I soaked several of them for months in a jar of MEK. No dice. I soaked another bunch in a container of carbon stripper (Gunk) and even made a device to try to force the Gunk through them under pressure. Nothing. The passages inside these things are really tiny. The fuel is spun inside them and then forced through the tiny outlet where it atomizes in a cone-shaped pattern caused by the centrifugal force. IIRC, I paid around $14 apiece for new ones; cheaper than spending hours trying to clear them. Poking tiny wires into them would likely just mess them up and they wouldn't work properly anymore. The strippers just don't have enough access to the crud inside.

They'd be an A&P signoff, I'm guessing. They would be here in Canada.

Dan
 
Tom-D said:
It's really simple guys. If stroking the throttle doesn't help, quit doing it.
Click to expand...

Problem is that stroking throttle ( with an accelerator pump) without the engine cranking is probably the leading cause of planes burning up.
 
I do want to get the priming system fixed. If the nozzles are only $14 i'll go ahead and replace them. Problem is I don't have an exploded diagram of the system or the part numbers.

Is my only option here to buy the service manual?
 
Thanks for the help.


I see the discharge nipple is the part that is likely clogged. When disassembling the hose and elbow to remove the discharge nipple from the cylinder, are there any other parts that need to be replaced at this time?

I have a friend who is an a&p that is willing to help and provide the necessary sign off. However he has not worked on a motor like this before. His experience is mostly with turbines. I'm sure we will see what the issues are when digging into the system but I'd like to have any parts that will for sure need to be replaced already on hand so the job can hopefully be done in an afternoon and I won't have to spend days waiting on ordered parts. This is probably a pipe dream.

At$12each I'm fine with just replacing the nozzles. I'm guessing they are much like carb jets. Cheap and better off just replacing than trying to clean.
 
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My mechanic soaked them in Hoppes gun cleaner. I wouldn't replace them if they can be cleaned.

dell30rb said:
Thanks for the help.


I see the discharge nipple is the part that is likely clogged. When disassembling the hose and elbow to remove the discharge nipple from the cylinder, are there any other parts that need to be replaced at this time?

I have a friend who is an a&p that is willing to help and provide the necessary sign off. However he has not worked on a motor like this before. His experience is mostly with turbines. I'm sure we will see what the issues are when digging into the system but I'd like to have any parts that will for sure need to be replaced already on hand so the job can hopefully be done in an afternoon and I won't have to spend days waiting on ordered parts. This is probably a pipe dream.

At$12each I'm fine with just replacing the nozzles. I'm guessing they are much like carb jets. Cheap and better off just replacing than trying to clean.
Click to expand...
 
Henning said:
If you have access to an ultrasound cleaner tray thing as well, they're useful.
Click to expand...

Matter of fact I have a nice, new branson cleaner at work. Some nice forum member offered to scan and e-mail me part of the service manual and parts list. Hoping to get the nozzles pulled tonight.
 
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A friend of mine showed me what she does with her 152 when it's cold and I have tried it with mine and it worked....
Prime it 3 times, pull the prop thru several times... Engaged starter and pump throttle twice... Now that seems odd but it worked.

Also, I keep REM 38 BY plugs in my O-235L2C as they are less prone to foul.
 
I've never understood "pulling the prop through" on a typical engine (not talking about radials here, and hydrolocking them...)... isn't that exactly what the starter does?

The whole "pulling oil up into the engine" thing doesn't fly with me... since you're also just scraping off whatever oil was left on cylinder walls, etc. Just like at really low RPM idle where you're not flinging enough oil around inside the engine for parts that aren't directly handled by an oil galley under pressure, etc.

If the starter can't turn the thing over, the battery's weak, the starter's undersized for the temperature, the oil's too heavy for the temperature range, or something else is wrong.

"Pulling the prop through" always seemed like a good way to learn the hard way that a P-lead wasn't really grounded, and to become another hand-propping statistic, because lots of people have their guard much further down doing a "pull it through" than if they were truly "hand propping" and trying to start the engine... but you're doing the same thing.

If you have to turn the prop... as long as you're turning an engine that doesn't have an odd magneto or something amiss in an accessory... turning it backwards, so the magneto can't fire at all, seems smarter than forwards, too. You just have to know your accessories and the engine don't have any problems with that. Most don't.
 
Yeah, Nate I agree. I was surprised when she did it, but she's been around a long time and could be that is what she learned "back in the day".
 
Jeanie said:
A friend of mine showed me what she does with her 152 when it's cold and I have tried it with mine and it worked....
Prime it 3 times, pull the prop thru several times... Engaged starter and pump throttle twice... Now that seems odd but it worked.

Also, I keep REM 38 BY plugs in my O-235L2C as they are less prone to foul.
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The reason, I'm told, this was taught was for when hand propping was the norm. You primed with the mags off and then pulled the prop through several times to distribute the prime. All the cylinders would at that point be primed to start so you'd only need to swing the prop once for the engine to start once the switch was on. It makes sense.
 
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denverpilot said:
Just like at really low RPM idle where you're not flinging enough oil around inside the engine for parts that aren't directly handled by an oil galley under pressure, etc.
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How slow would that be? most engines idle at 500-600 RPM .
 
Tom-D said:
How slow would that be? most engines idle at 500-600 RPM .
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I've been told... and hell, you're the expert here... that the O-470 doesn't "fling" enough oil around internally for some components until 800 RPM or so. Not enough "splash" so to speak.

Seems high to me, but some people do sit with the thing idling and barely running and the mixture way back on the ground at 400 or so for long periods of time.

(This is from Tom at CPA during the C-182 "Legacy" course last year... He sternly recommended the class not idle O-470's that low.)
 
denverpilot said:
I've been told... and hell, you're the expert here... that the O-470 doesn't "fling" enough oil around internally for some components until 800 RPM or so. Not enough "splash" so to speak.

Seems high to me, but some people do sit with the thing idling and barely running and the mixture way back on the ground at 400 or so for long periods of time.

(This is from Tom at CPA during the C-182 "Legacy" course last year... He sternly recommended the class not idle O-470's that low.)
Click to expand...

So, what do you do? ride the brakes when taxiing ?

the 0-470 is basically the 0-520's lower end do they have any problems that way?

To me, to have the lubrication problems you describe, you would have low oil pressure problems too.

I would like to see some documentation or references on the problem. before I'd take 1 persons opinion to heart.

Geared engines such as a GO-300- is a different matter always keep the gear box under a load to stop chattering of the gears.
 
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Askin' questions I can't answer, there Tom. ;)

Oil pressure was also mentioned as a reason as I recall. There was a whole mini-discussion of oil pressure settings in the classroom but it was mainly focused on some folks who didn't realize it could be changed who had low oil pressure readings at idle. Ours is good so I wasn't paying a lot of attention at the time.

Personally I just idle ours a little faster than the loping barely-firing sound you hear from some folks just barely letting the thing run.

That usually ends up being up around 650 when leaned enough it'll try to die if you advance the throttle on ours.

See a lot of people up here not leaning and blubbing along on the taxiways sounding like they're way too rich. J

A side effect of the altitude and the standard checklist "mixture full rich" for start. I don't start ours full rich. It doesn't like that. Starts way easier pulled back an inch or so.
 
denverpilot said:
Personally I just idle ours a little faster than the loping barely-firing sound you hear from some folks just barely letting the thing run.

That usually ends up being up around 650 when leaned enough it'll try to die if you advance the throttle on ours.

See a lot of people up here not leaning and blubbing along on the taxiways sounding like they're way too rich
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There is an idle mixture screw, play with it, you can lean the idle circuit to stop the loping at idle.

you want a 10-50 RPM rise as the engine dies after the mixture is pulled.
 
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