Piper Cherokee whine from engine during start

[jmarine225]

I've had an issue recently with my Cherokee during startup. Occassionally, when I attempt to start the engine, a loud "Vroom" and whine is heard, but the prop doesn't spin. I'll wait a minute or so, try it again and the prop will spin and startup. The engine then runs normally without any issues. Specifically yesterday, the engine was shut down and I attempted to restart. Nothing at all but those noises and whines from the engine compartment.

 

[RyanB]

Is the starter bendix not engaging?

 

[jmarine225]

Is the starter bendix not engaging?

As I'm a new owner, I'm not sure what happens if the starter doesn't engage or is a bad starter. That is the only thing which came to mind though. Sometimes it engages and sometimes it doesnt and just make the whining noise.

 

[RyanB]

As I'm a new owner, I'm not sure what happens if the starter doesn't engage or is a bad starter. That is the only thing which came to mind though. Sometimes it engages and sometimes it doesnt and just make the whining noise.

If the bendix is not engaging with the flywheel, it will result in the ‘whine’ noise you’re describing. It could be dirty or just going bad and will need to be replaced all together at some point.

 

[jmarine225]

If the bendix is not engaging with the flywheel, it will result in the ‘whine’ noise you’re describing. It could be dirty or just going bad and will need to be replaced all together at some point.

Yeah the whine noise is awful to hear. Anyway I can troubleshoot that to see if that's the problem? I have two new magnetos, battery is good with the plane off so I'm down to the starter. Curious why it sometimes engages, and sometimes it doesn't.

 

[RyanB]

Curious why it sometimes engages, and sometimes it doesn't.

The bendix collects dirt, moisture, etc by moving back and forth. Eventually it becomes goobed up enough that the bendix will not engage. Happening intermittently is not uncommon. I had it happen once while the Archer was on tie down after a rain storm. Presumably some moisture/water was around the bendix and it would not allow it to engage on the first try.

If it continues enough, I’d have it lubricated, but ultimately it will have to be replaced at some point.

 

[Morgan3820]

The bendix gear, when engages, thrusts out to meet the flywheel. If it is sticky or not lubed, the bendix gear will not engage. Do you not have an A&P on the field to consult?
As an aside there are a couple of books and a multitude of online resources about aviation maintenance available

 

[jmarine225]

Thanks for the replies. I can have my mechanic look at it, but wanted to check if there is something I can t try lubing or whatever first to see if that helps. I'm not even sure where to locate the start within the engine compartment. lol

 

[RyanB]

I'm not even sure where to locate the start within the engine compartment. lol

You need to let your mechanic do it.

 

[Magman]

Presuming it’s Old School Starter there is a recommendation that you clean with

Mineral Spirits and lube with Silicone every50 hrs.

If exposed to elements it may be needed more often based on calendar time.

The procedure allows the small “Bendix Gear” to slide forward and engage the

Ring Gear.

Failure to slide and engage will render the Starter inoperative.

The rest of the story:

This is also to enable disengagement after a start.

Visualize the big Ring Gear rotating at a fairly low speed, 1500 RPM?

Now consider the still engaged Bendix and speed it is going!

Since the Starter is now a Generator your Charging System goes crazy.

Often not for too long though as the Bendix disintegrates.


While serious; the good thing about this it only requires cleaning and lubing.

This is a task Owners are allowed to do as Preventative Maintenance.

While easy; won’t hurt to have your Tech walk you through.

Hope this helps!

 

[jmarine225]

Presuming it’s Old School Starter there is a recommendation that you clean with

Mineral Spirits and lube with Silicone every50 hrs.

If exposed to elements it may be needed more often based on calendar time.

The procedure allows the small “Bendix Gear” to slide forward and engage the

Ring Gear.

Failure to slide and engage will render the Starter inoperative.

The rest of the story:

This is also to enable disengagement after a start.

Visualize the big Ring Gear rotating at a fairly low speed, 1500 RPM?

Now consider the still engaged Bendix and speed it is going!

Since the Starter is now a Generator your Charging System goes crazy.

Often not for too long though as the Bendix disintegrates.


While serious; the good thing about this it only requires cleaning and lubing.

This is a task Owners are allowed to do as Preventative Maintenance.

While easy; won’t hurt to have your Tech walk you through.

Hope this helps!

Any idea how to find this within the engine compartment of the cherokee and can it be done without taking the cowlings off, just opening both sides? Then the procedure from there? If not, guess I'll call the A&P.

 

[RyanB]

Any idea how to find this within the engine compartment of the cherokee and can it be done without taking the cowlings off, just opening both sides? Then the procedure from there? If not, guess I'll call the A&P.

The starter is right under the flywheel on the right hand side, but like I say, this not something you need to be doing, because you’re likely to make matters worse by not knowing what needs to be done. Consult your mechanic.

 

[WannFly]

Not sure which version of Cherokee you have, in my archer, I can see the bendix without opening up the cowling. If you have those fancy cowling with two small holes in the front, that won’t work. More importantly, you need to have someone engage the starter while taking a look at the mechanism to figure out if the bendix is engaging or not. And if it engages that particular time, do stay away from that big fan.

Happened to me, got it lubed and bumped by a screw driver to get it going and all. Had to change it, went to the lightweight starter and it’s a breeze.

You mentioned it’s a new to you plane, not sure if you are new to aviation or not, if you are, get your AP involved.

 

[RonP]

Mag man,

not clear on how a spinning starter can make the charging system go crazy. If the starter solenoid is deactivated breaking the Electrical path from the starter to the battery how does a spinning starter put current into the electrical system?

 

[GRG55]

The starter is right under the flywheel on the right hand side, but like I say, this not something you need to be doing, because you’re likely to make matters worse by not knowing what needs to be done. Consult your mechanic.

Aren't the Lycoming starter mounting pads on the left side of the engine?

 

[RyanB]

Aren't the Lycoming starter mounting pads on the left side of the engine?

Well, if looking at it from the front of the prop, it’s on the bottom right side, but ya.

 

[Dan Thomas]

The bendix collects dirt, moisture, etc by moving back and forth. Eventually it becomes goobed up enough that the bendix will not engage. Happening intermittently is not uncommon. I had it happen once while the Archer was on tie down after a rain storm. Presumably some moisture/water was around the bendix and it would not allow it to engage on the first try.

If it continues enough, I’d have it lubricated, but ultimately it will have to be replaced at some point.

The cause of this issue is the mechanic or owner that squirts oil of any sort into the bendix. Oil attracts dust and forms a sticky, tough sludge that makes the bendix reluctant to move forward on its spiral splines. Adding moisture makes the sludging even worse.

Service manuals are full of advice that is far too often ignored. The manuals will tell us to use a dry silicone lube on that bendix. It also talks about cleaning and drying it, but once a person has had one of those things apart, he (she) realizes that cleaning it without taking it apart is pretty hopeless. The best thing is to make sure your mechanic is using the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator, except as noted in §43.16. He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.

That's right out of FAR 43.13.

 

[Dan Thomas]

Mag man,

not clear on how a spinning starter can make the charging system go crazy. If the starter solenoid is deactivated breaking the Electrical path from the starter to the battery how does a spinning starter put current into the electrical system?

It can't. As you say, the contactor is open and isolates the starter. The bendix also has a ratchet in it that prevents the engine driving the starter even if the bendix doesn't retract.

 

[GRG55]

Well, if looking at it from the front of the prop, it’s on the bottom right side, but ya.

I thought that might be what you meant. But, are we going to tell him to open the RH side of the cowling to get a better look?

 

[JOhnH]

What @Ryanb said.

Even if it is just a matter of cleaning and lubing, get your mechanic to do it and show you how. Then you can decide if you want to do it yourself next time. But in my experience, next time will be in east bumfum with no mechanic around, and it won't start at all. I'd listen to my mechanic's suggestion, but I'd hope he would just replace the dang thing.

 

[Omalley1537]

I would highly suggest an owner-assisted (or at least observed) annual for you at the next annual. Even if you never plan to touch a wrench, knowing the basic systems on your aircraft will pay great dividends down the road when you have something wrong with the airplane.

 

[Magman]

I think I miss spoke.

I have seen the Bendix Gear disintegrate from failing to disengage.

The Electric Crazies were caused by a Contactor with welded contacts.

I've seen a few Aircraft with a Warning Light added to warn of the condition.

I mixed the 2.

 

[3393RP]

Any idea how to find this within the engine compartment of the cherokee and can it be done without taking the cowlings off, just opening both sides? Then the procedure from there? If not, guess I'll call the A&P.

If you are this unfamiliar with the big thing under the cowling, it's probably a good idea to let your mechanic look at it. This should be done sooner rather than later, because what you're describing can cause large amounts of money to fly out of your bank account if not addressed.

 

[Dan Thomas]

I have seen the Bendix Gear disintegrate from failing to disengage.

Then you haven't dealt with the usual Lycoming setup, which has a ratchet in the bendix. One can see it in operation if one briefly engages the starter with the key, then shuts everything off, disconnects all the sparkplug leads, and goes to the prop and turns it forward a little. The bendix is locked in the engaged position and that ratchet will click as you move the prop forward, the starter will not turn. The starter will turn backwards as the prop is turned backward. Better yet, get your mechanic to show you.

The stuff in airplanes is often subtly different from that found in cars. Auto mechanics sometimes think they have it all figured out.