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garrys

Active Member
I haven't found this on the forum yet. I have a 7-A with an IO-360 with a starting problem. When I engage the starter (when cold) I get 1/8th of a blade turn then nothing, sort of like a dead battery. I try again and get about 3/4 of a blade before everything stops turning. I try a third time and the engine readily turns over normally. The battery is fully charged and I've checked all connections. Someone suggested I had a bad ground from engine to airframe, but everything looks good. Another suggested I might have a bad master relay or bad solenoid. Before throwing a lot of money at replacing parts I'd rather determine the root cause of the problem at the beginning. Has anyone else ever experienced this and if so, what did you do to correct it?
 
garrys said:
I haven't found this on the forum yet. I have a 7-A with an IO-360 with a starting problem. When I engage the starter (when cold) I get 1/8th of a blade turn then nothing, sort of like a dead battery. I try again and get about 3/4 of a blade before everything stops turning. I try a third time and the engine readily turns over normally. The battery is fully charged and I've checked all connections. Someone suggested I had a bad ground from engine to airframe, but everything looks good. Another suggested I might have a bad master relay or bad solenoid. Before throwing a lot of money at replacing parts I'd rather determine the root cause of the problem at the beginning. Has anyone else ever experienced this and if so, what did you do to correct it?
Click to expand...

I had the same issue you describe with my IO-360. I have a Skytec starter. I found a bad ground from the firewall to the engine to be the problem. I removed the ground strap from the engine and discovered the bolt to be slightly loose. There was some corrosion or dirt on the surfaces. I used a fine wire brush to clean up the ring terminal, bolt, washers and engine surface. Put it all back together and it spins the prop first try now and significantly faster than before.

Now I have to figure out where the ground issue is on my oil temp sensor. While running stobes and nav lights my oil temp indicates about 14 degrees higher than with the strobes and nav lights off. With the strobes on and nav off its about 7 degrees higher.

Check this out: http://www.skytecair.com/images/PDF/Troubleshooting Diagram_5.0.pdf
 
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Fat wires

I had a similar problem and eventually discovered bad crimps in the fat wire from the battery + terminal. It should take more than 500 lbs to pull that crimp apart.

Edit: I should add that these fat wires were factory crimped from the wiring harness kit.
 
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The starter is not getting the power it needs, so yeah, connections, I too have had that problem, and found some corrosion on the ground connector.

You can take a voltmeter and place along the starter electrical circuit at different points to eventually narrow down where the problem is. If you see normal voltage at one point, and massive voltage drop at the next, your problem is somewhere between those two points.

There was a nice tutorial/graphic online showing the debugging process, I can try to see if I can find it ...

Ah, here it is: http://www.skytecair.com/Troubleshooting.htm
 
garrys said:
I haven't found this on the forum yet. I have a 7-A with an IO-360 with a starting problem. When I engage the starter (when cold) I get 1/8th of a blade turn then nothing, sort of like a dead battery. I try again and get about 3/4 of a blade before everything stops turning. I try a third time and the engine readily turns over normally. The battery is fully charged and I've checked all connections. Someone suggested I had a bad ground from engine to airframe, but everything looks good. Another suggested I might have a bad master relay or bad solenoid. Before throwing a lot of money at replacing parts I'd rather determine the root cause of the problem at the beginning. Has anyone else ever experienced this and if so, what did you do to correct it?
Click to expand...

How old is the starter? While a bad connection can cause these symptoms, when the starter performs differently in different initial positions (rotation), you should also be checking the brushes and armature in the starter, especially if your not finding other sources that are reducing the flow of amps to the starter (a starter contactor/relay is also another source, as they are wearable devices.

Larry
 
Start with a known good battery, fully charged doesn't mean squat, you need to load test it. Start there.
Then similar to what JF said but different, place the voltmeter leads one on the negative post, the other on the engine case. While cranking, you should see not much more than about 1 volt. If more begin working back toward the battery one connection/terminal at a time until you find the culprit. Do the same on the positive side from battery post to starter terminal.
Other than the battery, very common to find the starter relay contacts fried, and again it will show up using the described test.
Good luck
Tim Andres
 
I had some minor electrical anomalies- voltage was 13.7, oil temp indication was unstable, and alternator would go to discharge occasionally. I checked all my Van's supplied cables and found slight looseness in the engine to airframe ground. I cleaned and soldered the cable ends and have had no further problems. Battery voltage is now 14.3, as recommended by Plane Power, and oil temp indication is absolutely steady. Although I don't favor soldering small wire terminals, I believe it advantageous to solder the large ends, as it is difficult to crimp them properly.
Good luck!
 
Thank you everyone for your very helpful responses to my starting problem. Y'all have given me some great tips and I'm' off to the airport to start the debugging process!
 
Ground the engine at the grounding post on the starter. Use the same gauge wire for this ground as you do the +12vdc to the starter.

Carl
 
One more; if you suspect your start contactor, remove the battery and starter cables, connect a ohmmeter across the big terminals, and apply coil power repeatedly. You should see the same low resistance every time. If the resistance is highly variable, engagement to engagement, remove the contactor for a flotation test.

I too have seen a few bad crimps on heavy gauge Vans cables. It's probably worth re-crimping or soldering them before they are ever installed. On the ground side, a B&C braided ground strap is MUCH better.
 
A braided ground strap from NAPA autoparts will work just fine. Best to have two high capacity ground sources from the battery/firewall to the engine case.
 
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