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#280340 - 02/08/16 10:21 PM Won't Start
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Went flying today. Weather was clear and 60deg. I couldn't wait to do some flying. But the plane was unusually hard to start. I mean, I have had issues starting it before, but never this bad. No amount of prime would get it to even catch. Finally after several attempts, and a rather flooded induction box, she reluctantly came to life and I was on my way. But that's highly unusual for a rather mild day to start with so much prime. I was weary of going anywhere and stayed close to my home field.

I decided to fuel up at my home airport and after a few minutes fueling it up, I turned they key and it kept cranking but no fire. Sometimes it sputtered and turned the prop a few turns but it would quickly die. And this was in a HOT carbureted engine. Normally not an issue, right? I gave up and talked with my home FBO. They pulled the primer and checked the seals. It was stiff but working. I tried starting it with their IA and we could not get her to run. It seemed no matter what I did, I could not achieve the proper fuel air ratio to get it started. The engine back fired a few times, evident by a loud pop while cranking. I asked we stop trying and we towed the plane to the hangar.

The shop said they did some troubleshooting and found the induction hoses were cracked and rotted. I can buy that given the hoses weren't replaced in forever. But I have a difficulty thinking this is the sole reason for my problems. So I also asked them to disassemble and check the left mag. I've had problems with a loose impulse coupling and corroded points causing hard starting problems.

I must add that once started, the engined seemed to run normally. I flew for about an hour with no issues. Run up checks were ok.

Any other ideas out or things I should check for?

I'm just happy I followed better intuition and stayed local. I'd sure hate to be stuck across the state with no way home. Blessings in disguise...


Edited by mobius4niner (02/08/16 10:25 PM)

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#280343 - 02/08/16 10:41 PM Re: Won't Start [Re: mobius4niner]
Flyboy712 Offline
Bronze Pilot

Registered: 08/27/14
Posts: 623
Loc: Washington
Intermittent short in the ignition switch in the start position?

Sounds like you are on the right track. The intake tubes could very well be the cause too. One thing at a time. Let us know what you find out?

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#280396 - 02/09/16 06:13 AM Re: Won't Start [Re: Flyboy712]
November X-ray Offline
Club Sponsor
Gold Pilot

Registered: 08/15/10
Posts: 2303
Loc: Brookshire, Texas, USA
So the ignition switch short would be to ground? If this is the case, could you not remove the P lead from the mag(s) and see if it made a difference? Just be aware that you will have a hot mag and can only kill the engine with mixture control.

I'm curious as to what you find out because mine acted the same way recently!
_________________________
N. X.




www.cessna172club.com

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#280415 - 02/09/16 09:09 AM Re: Won't Start [Re: November X-ray]
magman Offline
Gold Pilot

Registered: 10/10/12
Posts: 1378
Loc: buffalo NY
Type Engine & Mags?

Last time Mags were on the bench?

Hot starting issues are often related with bad Coils.

Another question could be ; "How many cylinders do you THINK

you're Priming?"

Sometimes the Primer Fittings coke up which can give you

No Prime in some & Over Prime in others.

What is a "Loose Impulse Coupling?"

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#280429 - 02/09/16 10:37 AM Re: Won't Start [Re: magman]
vettdvr Offline
Club Sponsor
Diamond Pilot

Registered: 06/24/10
Posts: 7724
Loc: Slidell La
1) disconnect the P lead that completes the ground on the mag. One or both depending on how many are set up on your plane to start. Mine has both mags fire on start up.
2) Start the engine. Does is start normal and run normal.
3) Kill the engine with mixture
4) connect P leads does it still start normally?
5) If is starts normal with P leads disconnected you have a ignition switch NOT grounding the circuit, or an open in the P lead to switch.
_________________________
Vettdvr

Single/Multi/instrument/type/commercial But then I am still learning.

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#280450 - 02/09/16 01:45 PM Re: Won't Start [Re: vettdvr]
Skyblazer Offline
Pilot in Command

Registered: 02/01/15
Posts: 327
Loc: Texas
Not a certified mechanic, but when I've had engines backfire on me and start hard it's usually been a timing/electrical or carburetor issue. I never had the carb off my airplane as I have't owned it very long. I hear they're simple and rarely fail. Just thinking since the hoses were really old maybe the carburetor needs some attention? Guess if the P-leads and mag check out ok it might lead you to the carb. Interested in what you find out. Good luck!

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#280457 - 02/09/16 04:11 PM Re: Won't Start [Re: Skyblazer]
Joeman434 Offline
Diamond Pilot

Registered: 02/19/14
Posts: 6752
Loc: Ocala, Florida
Do you have a Slick Start or a spark booster??
_________________________
Do it right the first time.

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#280479 - 02/09/16 06:39 PM Re: Won't Start [Re: Joeman434]
November X-ray Offline
Club Sponsor
Gold Pilot

Registered: 08/15/10
Posts: 2303
Loc: Brookshire, Texas, USA
I should have added a Slick Start long ago, but with all the new technology, always hoped someone would have come out with a new style ignition system by now that would far surpass the old magneto that was affordable and approved! Of course while hoping, might as well consider a new fuel delivery system that made twice the power with half the fuel burn. Heck, might as well expect to win the next billion dollar powerball lottery too!
_________________________
N. X.




www.cessna172club.com

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#280505 - 02/09/16 09:37 PM Re: Won't Start [Re: November X-ray]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Shop said they found minor leaks on the induction system. They lubed the primer and said they were able to start the engine ok. The mag was timed properly but they didn't disassemble it. I gave them the ok to replace the rubber hoses and gaskets on the induction tubes. I think this will resolve another problem I have with rough idle and throttling down from cruise. But I don't think the induction leaks are severe enough to cause hard starting problems.

The engine is an O-320-E2D. My hard starting issues have been ongoing for several years so this is nothing new to me. Those familiar with my rants have probably read all my posts about it. Ha ha! But all the problems seemed to begin after the left mag 500hr inspection was accomplished in 2012, so I suspect mag issues. I never had starting issues prior to the inspection. I've asked the shop to examine the mag during the past years. They would find the points were worn or corroded, clean the mag and return to service. The plane would start fine for a few months and I'm back to the same problems. If they find any evidence of mag issues this time, I plan to replace the mag with new.

The left mag is 16 years old and has 600+ hours on it.

The shop is backlogged and will take awhile to get to my plane's problems. But I will definitely keep everyone posted on the outcome. I just hope this will help others who experience similar issues- and hopefully not waste so much $$ troubleshooting the cause.



Edited by mobius4niner (02/09/16 09:53 PM)

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#280506 - 02/09/16 09:43 PM Re: Won't Start [Re: magman]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Originally Posted By: magman
Type Engine & Mags?

Last time Mags were on the bench?

Hot starting issues are often related with bad Coils.

Another question could be ; "How many cylinders do you THINK

you're Priming?"

Sometimes the Primer Fittings coke up which can give you

No Prime in some & Over Prime in others.

What is a "Loose Impulse Coupling?"


Right mag 500hr inspection in 2011.
Left mag 500hr inspection in 2012.

I installed a modified 3-point primer system myself in 2013 to assist with the starting issues. It definitely helps reduce the single cylinder flooding problems. The shop checked the nozzles and primer flow. It was sat.

After the left mag 500hr inspection, I had problems with the impulse coupling not engaging when it was supposed to. I haven't disassembled the magneto myself, so I don't know what it looks like internally. I only understand the impulse coupling is a spring that builds up a large spark for starting purposes. Based on my review of part numbers, it appears only the left mag has the impulse coupling. I can hear it click when I rotate the prop by hand. Perhaps "loose" isn't the appropriate term.



Edited by mobius4niner (02/09/16 09:46 PM)

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#280507 - 02/09/16 09:48 PM Re: Won't Start [Re: Joeman434]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Originally Posted By: Joeman434
Do you have a Slick Start or a spark booster??


No, I do not. I do know the device exists though.

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#280508 - 02/09/16 10:02 PM Re: Won't Start [Re: mobius4niner]
combahee Offline
Pilot in Command

Registered: 07/29/12
Posts: 428
Loc: Lowcountry, SC
If the points are continually pitting replace the condenser.
_________________________
1959 172 straight tail

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#280510 - 02/09/16 11:02 PM Re: Won't Start [Re: combahee]
Flyboy712 Offline
Bronze Pilot

Registered: 08/27/14
Posts: 623
Loc: Washington
The induction leaks can definitely cause hard starting. A good tell tale sign that they are bad or you have some type of an induction leak are rough idle like you described.

I'll also second what combahee said about the condensers. Being 16years old I'd get both mags overhauled. The coils can degrade with time and could be some corrosion. Has the plane been in the Seattle area for a while?

Oh and there's a shop over there that does nothing but magnetos I'll look and see if I can find the name.

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#280519 - 02/10/16 12:28 AM Re: Won't Start [Re: Flyboy712]
magman Offline
Gold Pilot

Registered: 10/10/12
Posts: 1378
Loc: buffalo NY
If the Impulse does not engage it's likely you have

a magnetized Impulse Coupling.

After all; it IS a chunk of steel at the end of a magnet.

If that's the case; when it does fail to engage you will have

a weak, advanced spark.


This can; of course, still break the Starter off the Case!

A weak Capacitor ( Condenser) will also give a weak spark.

Easy to demagnetize the Impulse Coupling.

An Auto Electric Shop can put the Impulse (removed from Mag)

in a "Growler"

or

Spin the Coupling by hand on the end of a Rotating Magnet and

let it fall off the end.

If the Starting Issues began with the 500 Hr then it's likely

the E-Gap was not properly adjusted.

Looks like it's time for the Left Mag to come off.






Edited by magman (02/10/16 12:31 AM)

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#280547 - 02/10/16 08:08 AM Re: Won't Start [Re: magman]
vettdvr Offline
Club Sponsor
Diamond Pilot

Registered: 06/24/10
Posts: 7724
Loc: Slidell La
FWIW I fly IFR / IMC at times and my mags come off at 400 hrs.
_________________________
Vettdvr

Single/Multi/instrument/type/commercial But then I am still learning.

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#280728 - 02/11/16 10:22 PM Re: Won't Start [Re: vettdvr]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Update: They took apart the left mag as I requested. There was really nothing out of the ordinary. My dad is an A&P and at his request I asked they check the E-gap, which turned out ok. There was one broken ignition lead at the distributor cap which they repaired. Since there were no obvious problems with the mag, I opted not to replace it just yet. They retimed both mags to the engine. They adjusted the carb idle mixture screw and fixed the stiff primer by lubing the o-rings. They said the plane started on two blades and they returned it to my hangar. I haven't had a chance to start it yet because the weather is so bad here. I don't like starting the engine if I ain't gonna fly it. I hope to get some VFR weather Monday and do a test flight. They're saying its a 70% chance of rain which, for Washington standards- isn't bad.

Thanks for all the help everyone. I hope this resolves my problems. I will follow up with a post test flight report.


Edited by mobius4niner (02/11/16 10:24 PM)

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#280731 - 02/11/16 10:43 PM Re: Won't Start [Re: mobius4niner]
N5479R Offline
Gold Pilot

Registered: 04/13/14
Posts: 2223
Loc: Florida
I don't see any mention of your spark plugs. How many hours are on your plugs? Have they been cleaned, gapped and tested? Bad plugs can cause hard starting and other problems as well.

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#280762 - 02/12/16 08:35 AM Re: Won't Start [Re: N5479R]
vettdvr Offline
Club Sponsor
Diamond Pilot

Registered: 06/24/10
Posts: 7724
Loc: Slidell La
broken ignition lead at the distributor cap??


This might be a issue especially if you only use one mag to start and this one was the start mag.
_________________________
Vettdvr

Single/Multi/instrument/type/commercial But then I am still learning.

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#280777 - 02/12/16 09:41 AM Re: Won't Start [Re: vettdvr]
Skyblazer Offline
Pilot in Command

Registered: 02/01/15
Posts: 327
Loc: Texas
I hope your problems are fixed! I'm going to chime in with some thoughts after reading the above post--N5479R is spot on. I've made the false assumption before that my plugs were good when I had no spark on my Harley. Replaced coil, cam sensor, and spent a bunch of time...finally took it to the mechanic who put a see through adaptor in line and saw there was spark going to the plug, but none coming out...never thought 2 would go bad at the same time, but they did. Replaced them and it fired right up. I plan to pull my plugs at the next oil change to inspect and ohm them as a preventative measure...and to see how my leaning is working.

Not saying I think plugs are definitely your issue here, but I do agree with the post above and have seen buddies spend literally thousands on vehicles and I've spent way too much when the fix was very simple. Carb adjustment seems to make sense to me. My "71 Muscle car acts the way you described your airplane acting when it's telling me it's time for some carb love...which involves rebuilding and it's harder and harder to find the kit. I've been told aviation carbs are simple to rebuild...I'm looking forward to seeing one apart someday.

Good luck on your test flight...hope the wx clears up nice for you.

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#280869 - 02/12/16 10:02 PM Re: Won't Start [Re: Skyblazer]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Good points about the plugs guys and sorry I did not mention them. I actually replaced the plugs with new REM40E three years ago when I was still experiencing hard starting problems. I did have my shop check and clean the plugs. There were no noted issues. I typically clean, gap and rotate the plugs during my oil changes. I feel I am pretty on top of my plug maintenance smile

As for the carb, I replaced it with a Marvell scheduler overhauled unit during my 2013 annual The old carb throttle bushing was essentially non existent.


Edited by mobius4niner (02/12/16 10:06 PM)

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#280995 - 02/13/16 08:34 PM Re: Won't Start [Re: mobius4niner]
Rockhead Offline
Safety Pilot

Registered: 09/21/14
Posts: 82
Loc: West Tennessee
Your initial cold starting could be your priming system. All 3 of my priming nozzles were plugged and had to be replaced. Also some planes only prime 1 cylinder. This easily increased to 3 cylinders.

Another thought is your starter turning the engine fast enough?

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#281158 - 02/15/16 01:14 PM Re: Won't Start [Re: Rockhead]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Well, today was 43 deg F, overcast at 800 and winds at 30mph- hardly VFR flying weather. But I drove to the airport with my wife and one year old and decided to test start the plane. It took a large amount of primer. I gave it three shots of prime and it needed another three more before the engine came to life. I did a full runup and there were no anomalies. I ran it for about 15min at 1700rpm until the oil temp was up.

I stopped the engine to fuel it up at the fuel depot. She still has a weird time starting when hot. I didn't prime it. The engine fired on what seemed only one cylinder. I had the starter disengaged and the engine would puff and puff by itself but wouldn't run until I pulled the throttle all the way back (essentially choking it). Maybe I have a bad starting habit or something. Of course, now with all the repairs- I have to readjust my habits to accommodate. I still have more local maintenance flights to do before I'd feel comfortable flying it somewhere smirk

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#281159 - 02/15/16 01:19 PM Re: Won't Start [Re: Rockhead]
mobius4niner Offline
Pilot in Command

Registered: 09/09/11
Posts: 454
Loc: Seattle, WA
Originally Posted By: Rockhead
Your initial cold starting could be your priming system. All 3 of my priming nozzles were plugged and had to be replaced. Also some planes only prime 1 cylinder. This easily increased to 3 cylinders.

Another thought is your starter turning the engine fast enough?


Hi Rockhead. I did install a 3-primer system on my engine. The old primer system only had one nozzle and it was easy to flood it. The 3-point primer is much better, as it distributes fuel to multiple cylinders. But since a single shot of prime is now divided into thirds- I notice it takes more prime to get it started.

My starter is relatively new (3 years old). It's a Hartzell E-Drive. I bought it because I heard the skytecs actually spin the engine a little too fast. The Hartzell is also guaranteed against kickback. It turns faster than the old Delco but slower than a skytec. Unlike the Delco, the starter pinion will disengage when the start switch is let go. I like the Hartzell starter. It's only 9lb and it's endured a lot of abuse in its 3 year life.

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#281160 - 02/15/16 02:02 PM Re: Won't Start [Re: mobius4niner]
bnt1983 Offline
Second in Command

Registered: 03/26/11
Posts: 199
Loc: USA
I have an O-320 E2D and let me tell you, good luck!

We have had it about 10 years now and no, it has NEVER been a great starting engine. I'm an A&P IA so I kinda take it personally.

Over the years we finally starting putting some money into it:

#1 New starter 5 or so years ago. Old one failed, has a skytech now.
#2 ALL new plugs and wires about 3 years ago.
#3 Reman carburetor and sealed the induction system up good new gaskets and rubbers. Checked the pipes in the sump. - It runs fantastic but didn't really change the starting behavior much.

#4 Removed the single impulse slick magneto system and installed two factory reman TCM (Bendix Mags with impulses on both) another new ignition harness and all new finewire plugs. Removed the grounding strap from the ignition switch making both mags hot when in the ignitions switch is in the "START" position. All new P-lead wiring.

This engine runs great I'm very happy about it. But does it start well? Not really. I work on a friend's higher compression O360A1F6D that has a ratty ignition harness, new plugs, older bendix dual mag, old carburetor and the things starts and runs amazing well and it always has. I wonder if its the higher compression?

Back to the O320E2D we have. It too primes only one cylinder. When hot I usually quickly pump the throttle about 1/2 way while the starter is engaged, this seems to help get fuel to all 4 cylinders.

Its a finaky lil bugger but it I have ALWAYS been able to get it started. Sometimes with grace and other times not so much. I've seen cold O320s in Pipers being cranked till the battery is dead during the winter months. The oil pan heater on mind is a life savor when its cold out (Nebraska)

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#281161 - 02/15/16 02:09 PM Re: Won't Start [Re: bnt1983]
vettdvr Offline
Club Sponsor
Diamond Pilot

Registered: 06/24/10
Posts: 7724
Loc: Slidell La
For comparison

My D2J higher compression
Skytech starter
2 new mags
both mags have Impulse coupling and fire to start

After sitting a month battery down

I hit the starter and prop slowly moved 1/4 turn, first cylinder fired engine started.
_________________________
Vettdvr

Single/Multi/instrument/type/commercial But then I am still learning.

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