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  #11  
Old 06-25-2018, 02:58 PM
Bicyclops Bicyclops is offline
 
Join Date: Oct 2012
Location: LA, California
Posts: 323
Default Single point ground

Quote:
Originally Posted by Dale D View Post
Larry & Others,
I have two ground cables. One approx. 8" mesh ground strap originates from the battery's negative post and terminates to the firewall. The 2nd approx. 18" #2 ground cable originates from the engine block to a 2nd location on the firewall.
I have measured "0" ohms resistance between: battery negative post & ground cable #1 end, battery post & ground cable #2 at firewall, and battery post and starter housing.
However, I can try running a substantial cable directly from the starter case to the negative battery post.

Maniago,
I'm not sure how I would disable the ignition, short of removing all plug boots, as the ignition is part of the key-switch.

KAdriver
You raise an interesting possibility with the key-switch that I haven't yet explored. I have never really paid attention to where my key position is when the prop stops. This will be an easy one to check this evening.

Dale
Grounding to 2 different points on the firewall isn't ideal. The firewall is stainless and not the best conductor ever. Move the ground strap from the engine case to land on the same bolt as the battery ground wire. A flexible braided ground strap would be a better bet than a fat wire from engine case to the bolt where battery negative lives.

Ed Holyoke
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  #12  
Old 06-25-2018, 03:00 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,652
Default

If I read the OP correctly, there is now a new NL starter on the ship - which should spin a std compression 320 fast enough to taxi around with. If the heavily geared NL is struggling to get over the hump, but have 10+ volts at the starter post then you must have a really bad ground. Might try a single jumper from the neg battery post to the starter case (leaving the originals in place) and see if it improves performance.
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1940 Taylorcraft BL-65
1984 L39C
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  #13  
Old 06-25-2018, 03:20 PM
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KAdriver KAdriver is offline
 
Join Date: Dec 2017
Location: Louisiana
Posts: 32
Default

Quote:
Originally Posted by Dale D View Post
Larry & Others,
I have two ground cables. One approx. 8" mesh ground strap originates from the battery's negative post and terminates to the firewall. The 2nd approx. 18" #2 ground cable originates from the engine block to a 2nd location on the firewall.
I have measured "0" ohms resistance between: battery negative post & ground cable #1 end, battery post & ground cable #2 at firewall, and battery post and starter housing.
However, I can try running a substantial cable directly from the starter case to the negative battery post.

Maniago,
I'm not sure how I would disable the ignition, short of removing all plug boots, as the ignition is part of the key-switch.

KAdriver
You raise an interesting possibility with the key-switch that I haven't yet explored. I have never really paid attention to where my key position is when the prop stops. This will be an easy one to check this evening.



Dale
To clarify Dale my issue was if I turned the key all the way to the right till the the key no longer moved I had an issue. The prop would start to move as the key was turned then it would cut out as the key moved past the good part of the switch. Gave the impression of a weak starter or battery. Just turn the key till the starter Engaged and no further. Problem solved.
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  #14  
Old 06-25-2018, 04:24 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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KADriver,

That problem should manifest noticeably different symptoms, if you know what you're seeing and hearing. If the start contacts of the ignition switch are flaky and dropping out, you should also hear the start contactor drop out along with the switch contacts, and the sounds from the engine/starter will be different. You'd also see battery voltage return to near no-load levels.

To the OP,

Fat welding cable is very flexible, readily available locally, and serves well in many homebuilts as battery/starter/ground cable.

The only thing that should be in the ground path from starter/engine case to the battery negative should be a brass or copper feedthrough bolt on the firewall, if the battery is aft of the firewall.

There have been cases where starters (and alternators) have had poor grounds due to heavy paint or powdercoat on the appliance, the attachment bits, or the motor itself.

When doing your measurements, be sure the meter negative is directly on the battery post (not the clamp or bolt). Work your way along the ground path, on both sides of all joints, with the meter positive lead. You should never see more than a half volt or so (in the extreme) between any point from starter case and the battery negative post, while the starter is under load.
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  #15  
Old 06-25-2018, 07:50 PM
Loren Loren is offline
 
Join Date: Jun 2006
Posts: 36
Default ETX900

Probably not the same problem. I had a PC680 that was just struggling to turn my angle valve engine over so I swapped it out for a ETX900. Now I save fuel by taxiing to the runway with the mags off. 😜
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  #16  
Old 06-25-2018, 08:11 PM
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Dale D Dale D is offline
 
Join Date: Aug 2017
Location: Zeeland, MI
Posts: 25
Default Key Switch Technique - May Be the Solution!

Quote:
Originally Posted by KAdriver View Post
To clarify Dale my issue was if I turned the key all the way to the right till the the key no longer moved I had an issue. The prop would start to move as the key was turned then it would cut out as the key moved past the good part of the switch. Gave the impression of a weak starter or battery. Just turn the key till the starter Engaged and no further. Problem solved.
KAdriver: I just returned from flying after two successful starts on the 1st attempt by duplicating your key switch technique! This hasn?t happened for a long time.

After the 1st successful start, I intentionally shut the engine down to try a 2nd time. The same key technique gave me the same success.

I know one sunny day doesn?t make a Summer, but I am encouraged.
I will keep everyone posted.
Dale
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  #17  
Old 06-25-2018, 09:22 PM
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Sam Buchanan Sam Buchanan is offline
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Location: North Alabama
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Toss that flakey switch and install a couple of toggles and a pushbutton.
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  #18  
Old 06-25-2018, 10:47 PM
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KAdriver KAdriver is offline
 
Join Date: Dec 2017
Location: Louisiana
Posts: 32
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Quote:
Originally Posted by Dale D View Post
KAdriver: I just returned from flying after two successful starts on the 1st attempt by duplicating your key switch technique! This hasn’t happened for a long time.

After the 1st successful start, I intentionally shut the engine down to try a 2nd time. The same key technique gave me the same success.

I know one sunny day doesn’t make a Summer, but I am encouraged.
I will keep everyone posted.
Dale
Glad I could help! Now you have a bunch of spare parts!
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RV6
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  #19  
Old 06-26-2018, 06:00 AM
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maniago maniago is offline
 
Join Date: Aug 2014
Location: Bowie MD
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Quote:
Originally Posted by Sam Buchanan View Post
Toss that flakey switch and install a couple of toggles and a pushbutton.
What Sam said. I use toggles for everything - each ign, and an "arm" toggle ganged to a momentary toggle for the starter solenoid.....

Key switches look cool, do multi functions, give the appearance of security, but have an insidious history of exactly what youve encountered.
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  #20  
Old 06-26-2018, 07:04 AM
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Toobuilder Toobuilder is offline
 
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Great it appears to work now, but can anyone explain why? If the primary symptom is the inability to crank over the first compression stroke, then how does an intermittent contact on the key switch do that? The key activates the starter solenoid, and the starter solenoid sends the big power to the starter. the starter solenoid is either on or off. Bad contacts in the key switch will not alter the amount of power running through the main plunger contact in the starter solenoid. The only way I can see this happening is if the solenoid makes/breaks contact because of the poor signal from the key. But this would manifest as a buzz or chatter of the solenoid, which would be obvious to the pilot.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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