Engine Won't Start

stsavios

stsavios

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stsavios
Hello all,

I'm back with the Cherokee 180, and it doesn't seem to want to start. It turns over just fine, but it doesn't seem to want to ignite.

The impulse coupling seems to be doing it's job just fine (according to 3 mechanics), and the Magnetos have about 150 hours since their last inspection.

I noticed after trying to crank it over, there was this blue "oily" substance on the nose wheel pant. Not sure what it is, but my guess is the blue dye from the gas, mixing with the oil. She says it's not oil, but I don't know.

She seems to think I'm over-priming it. But the entire time I've had my Cherokee, it is VERY cold-blooded. I hear it's hard to flood a cold engine, and in all the checklists I've read it recommends 6-7 shots of prime.

I might also add that it just started getting colder recently, and this might be contributing to it as well.

Any suggestions will be greatly appreciated.
 
dmccormack said:
6-7 shots???

That's alot!!
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That doesn't matter, it all went into his cowling because he wasn't cranking the engine while priming it.


thus the blue stuff in the cowl.
 
There didn't seem to be anything on the inside of the cowl, just a drop or two on the wheel pant (maybe I just overlooked the inside of the cowling, but I don't remember seeing anything).

Older Cherokees only get primed on 2 cylinders, so it's naturally always cold blooded.

It's always started in the last 200+ hours in the past year, I'm not sure why it's just started giving me issues.
 
stsavios said:
There didn't seem to be anything on the inside of the cowl, just a drop or two on the wheel pant (maybe I just overlooked the inside of the cowling, but I don't remember seeing anything).

Older Cherokees only get primed on 2 cylinders, so it's naturally always cold blooded.

It's always started in the last 200+ hours in the past year, I'm not sure why it's just started giving me issues.
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Do you know how to prime all cylinders on a Lycoming ?
 
Give it a shot of ether.
 
stsavios said:
I've done the whole "Mixture lean, throttle full" thing, but it doesn't seem to be working. other than that, I have no idea.
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Use the accelerator pump by pumping the throttle while cranking the engine.
 
It is hard to say what the problem is exactly. I have had a plane get difficult to start when the mag started to go out. The impulse coupling was still clicking at the time. As for the blue stain, I would think it is fuel from over priming, but hard to say. As suggested, you can try pumping the throttle while cranking, but that could lead to an induction fire if it back fires. I used to see it a lot with the flight school planes in the winter. Have you had your plugs and leads checked? The timing on the mag could be off as well.
 
The mags were inspected, he says. Did that include a check on the E-gap? If it's off the spark will be weak. And if the condenser is shot it can also weaken the spark. The impulse can click all it likes and the spark can still be weak if the rest of the mag isn't right. Once the engine does start the RPM of the mag can be high enough to make spark.

The blue oily stuff is the remains of evaporated fuel, probably fuel that ran down into the airbox after priming, or perhaps from a seeping carb.

Dan
 
CMTowner said:
As suggested, you can try pumping the throttle while cranking, but that could lead to an induction fire if it back fires. .
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how can it cause a fire when the fuel is being sucked up the induction system and into the cylinder?

pumping the throttle when you are not cranking will simply cause the fuel to fall into the air box below the carb.

you must be cranking the engine to get fuel into the cylinder, so why prime it in any manor when not cranking?
 
Leaky primer (O ring) or mal-adjusted carb. Somebody changed something so all your past experience with this aircraft is not worth anything given the current status of the aircraft.

BTW: who is "she"?
 
Checked the logbooks, and it did include a check on the E-Gap, and the Condenser checked out great, as well.

I am having it troubleshooted again tomorrow. Last mag inspections were done about 9 months ago, and have between 100-150 hours on them.

"She" is my mechanic. Probably the only female mechanic in Northern AZ.
 
I would first let someone else try to start it. (if they fail, you know its not operator technique; if they succeed, you were watching and learn their trick) Someone, like that mechanic who is going to be tshooting it. Good luck.
Air/Gas/Compression/Spark/Timing(of everything not just spark)
 
stsavios said:
Checked the logbooks, and it did include a check on the E-Gap, and the Condenser checked out great, as well.

I am having it troubleshooted again tomorrow. Last mag inspections were done about 9 months ago, and have between 100-150 hours on them.

"She" is my mechanic. Probably the only female mechanic in Northern AZ.
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A quick check of mag timing to engine will reveal if the points have slipped or the cam worn. Either one will change both mag timing and E-gap.

Dan
 
Ditto the "watch the mechanic start it". I learned a lot watching our mechanic start our engine.

My technique worked for years but he had it running in one blade. Mine would take two-three depending on conditions.

I realized right there that he starts more airplane's in a week than I do in a year and wasted time is wasted money for him. All clicked in an instant.

That was enough for me to change my ways. And another one of those little joys of ownership. I never even saw any of the mechanics at the bigger clubs. Airplanes were taxied away in the evening to some mystery hangar and mystery person and back on the line the next day or taken off the schedule if it was something harder or that required parts that had to ship.

Letting your mechanic start your bird with your butt in the right seat is a good learning experience.
 
If you have a start switch with the Mag positions on it (some Cherokees have a separate starter switch and mag key) you might have the switch checked, when they go bad they can ground out a mag or 2.
 
stsavios said:
Checked the logbooks, and it did include a check on the E-Gap, and the Condenser checked out great, as well.

I am having it troubleshooted again tomorrow. Last mag inspections were done about 9 months ago, and have between 100-150 hours on them.

"She" is my mechanic. Probably the only female mechanic in Northern AZ.
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Your mech. swapped the "P" leads when they had the mags out, now you are grounding out the wrong mag on the start position.

You only have 1 impulse coupling, now that mag is being grounded out when the key is in the start position.

Lycomings will start on the un-coupled mag when the prop spins fast enough, and the mixture is right.

easy to start, then it gets a mag inspection, then its hard to start, yeah the "P" leads are swapped.
 
Tom-D said:
Your mech. swapped the "P" leads when they had the mags out, now you are grounding out the wrong mag on the start position.

You only have 1 impulse coupling, now that mag is being grounded out when the key is in the start position.

Lycomings will start on the un-coupled mag when the prop spins fast enough, and the mixture is right.

easy to start, then it gets a mag inspection, then its hard to start, yeah the "P" leads are swapped.
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Now that I think about it, I did get my Impulse coupling re-assembled 20-25 hours ago. But I didn't have any trouble starting it in the past 20-25 hours.
 
6-7 shots of primer is way way too much. That's just going to end up on the ground. If you have blue on your wheel pant you either have a fuel leak or you're over priming. Sounds like over priming.

If it's real cold - two shots of the primer and 2 pumps of the throttle then crank. If it doesn't light immediately give the throttle a pump or two while it's starting and you'll be set.
 
jesse said:
6-7 shots of primer is way way too much. That's just going to end up on the ground. If you have blue on your wheel pant you either have a fuel leak or you're over priming. Sounds like over priming.

If it's real cold - two shots of the primer and 2 pumps of the throttle then crank. If it doesn't light immediately give the throttle a pump or two while it's starting and you'll be set.
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Depends on the Cherokee, took care of one that had an itty bitty primer and 6 shots was about right.

As far as pumping the throttle, I can't recomend it if the engine isn't cranking. I have seen fires caused by that as the fuel just pools in the airbox.
 
Skylane81E said:
As far as pumping the throttle, I can't recomend it if the engine isn't cranking. I have seen fires caused by that as the fuel just pools in the airbox.
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That's what I've been hearing all this time, and have been avoiding doing it like the plague
 
Only been at this mechanic thing for about 7 years now, and I've seen it three times.

Now if you're cranking you should have sufficent airflow into the cylinders to sweep the fuel in.

Side draft carbs might not be as likely to light up but in a standard updraft carb without something to suck the fuel uphill it will just fall back out of the intake manifold.
 
stsavios said:
That's what I've been hearing all this time, and have been avoiding doing it like the plague
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When you prime with out the engine cranking, where do you think the fuel goes?
 
FWIW, liquid fuel won't combust in the cylinders, it requires fuel vapor combined with oxygen in the proper ratio to light off in the cylinder when the plug sparks. Dumping raw fuel into the cylinders doesn't promote starting and it can strip what's left of the oil coating the cylinder walls It is true that a small puddle of fuel in the intake runners and/or carb throat will provide some fuel vapor and to some extent the bigger the pool the more vapor released. The fuel temperature (i.e. the temp of the intake piping) has a huge effect on how rapidly fuel evaporates and should be considered when choosing the amount of time between priming and starting (warm engine: little prime and crank immediately, cold engine: more prime and wait a minute for vapor to form). If the priming system atomizes the fuel (e.g. priming via fuel injectors) then cranking while priming works well but for the systems that just dump liquid into the carb throat or intake runners priming creates very little vapor immediately with a cold engine.
 
gismo said:
FWIW, liquid fuel won't combust in the cylinders, it requires fuel vapor combined with oxygen in the proper ratio to light off in the cylinder when the plug sparks. Dumping raw fuel into the cylinders doesn't promote starting and it can strip what's left of the oil coating the cylinder walls It is true that a small puddle of fuel in the intake runners and/or carb throat will provide some fuel vapor and to some extent the bigger the pool the more vapor released. The fuel temperature (i.e. the temp of the intake piping) has a huge effect on how rapidly fuel evaporates and should be considered when choosing the amount of time between priming and starting (warm engine: little prime and crank immediately, cold engine: more prime and wait a minute for vapor to form). If the priming system atomizes the fuel (e.g. priming via fuel injectors) then cranking while priming works well but for the systems that just dump liquid into the carb throat or intake runners priming creates very little vapor immediately with a cold engine.
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Couple things, there is no place for a puddle to form in a up draft system that we have in most all aircraft systems using a bottom mount carb.

fuel drawn into the cylinder when you prime while cranking will be heated on the compression stroke.
 
Well a top induction will do that, but I haven't seen it with a carb.
 
Haven't come across those yet, only top intake engines I've played with are of the new(er) TCM I variety (IO240, TSIO360, IO550 etc) all the standard O engines I play with have the less than ideal bottom intake bottom exhaust set up.
 
Turns out the oil slinger came loose, and was coming in contact with the Impulse coupling. Has anyone ever heard of something like this happening before?
 
stsavios said:
Turns out the oil slinger came loose, and was coming in contact with the Impulse coupling. Has anyone ever heard of something like this happening before?
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Explain "Slinger Ring" ?
 
Tom-D said:
Explain "Slinger Ring" ?
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The only slinger I know of is the integral flange behind the front crankshaft seal. Long ways from the mags, and it doesn't fall off anyway. I wonder if the mag inspection introduced some error and they're feeding the OP some line about it.

He did say "slinger," not "slinger ring." Maybe his engine has the small oil squirt nozzle that directs a jet of oil onto the accessory drive gearing, and it rotated or something.

Dan
 
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Dan Thomas said:
The only slinger I know of is the integral flange behind the front crankshaft seal. Long ways from the mags, and it doesn't fall off anyway. I wonder if the mag inspection introduced some error and they're feeding the OP some line about it.

He did say "slinger," not "slinger ring." Maybe his engine has the small oil squirt nozzle that directs a jet of oil onto the accessory drive gearing, and it rotated or something.

Dan
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I believe it is a nomenclature thing, there is no engine using slinger rings on a mag seal.

some one is blowing smoke, I haven't figured out who.
 
stsavios said:
Turns out the oil slinger came loose, and was coming in contact with the Impulse coupling. Has anyone ever heard of something like this happening before?
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I wonder if he means "Oil Deflector".....one version is PN 10-51678 (Bendix)
Seen them loose but not fail a mag.

is it this?
 

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Let'sgoflying! said:
I wonder if he means "Oil Deflector".....one version is PN 10-51678 (Bendix)
Seen them loose but not fail a mag.

is it this?
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That is a thought, but the oil is sealed by the garlic behind it, they can't have any effect on the start of the engine.

he has been trouble free for the resent past.
 
Tom-D said:
That is a thought, but the oil is sealed by the garlic behind it, they can't have any effect on the start of the engine.

he has been trouble free for the resent past.
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I thought he said the deflector broke loose and somehow jammed up the IC = no start.
 
Let'sgoflying! said:
I thought he said the deflector broke loose and somehow jammed up the IC = no start.
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It can't do that. the base for the impulse coupling is a heavy gauge steel, and larger than the oil deflector, which is a thin disk jambed between the impulse coupling and the large portion of the rotor shaft where the garlic is making the seal.
 
Let'sgoflying! said:
I wonder if he means "Oil Deflector".....one version is PN 10-51678 (Bendix)
Seen them loose but not fail a mag.

is it this?
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on the invoice, the P/N for the "slinger" is 10-51678.

It didn't fail the mag, just somehow caused the impulse coupling not to work. once running, it would run fine, just wouldn't start.
 
stsavios said:
on the invoice, the P/N for the "slinger" is 10-51678.

It didn't fail the mag, just somehow caused the impulse coupling not to work. once running, it would run fine, just wouldn't start.
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I find that hard to believe, with out a bunch of metal in the oil.
 
Tom-D said:
I find that hard to believe, with out a bunch of metal in the oil.
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Considering I just changed the oil, and there was no metal in the filter, I don't find it very hard to believe.

Also, it was one of the cheapest repairs I've seen in a while. And now it starts, no problem. So it sounds like that was the problem to me.

The (reputable)mechanic also said he had never seen anything like that before.

You really seem to think it was strictly "pilot error", and couldn't possibly be anything else?
 
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