73 Evinrude 115 - Help on deciphering voltage drop test results

[BOAH]

I have a problem when trying to start the engine cold and I need to crank it a little more. With a new and fully charged battery, the battery seems to get drawn down quickly so that after just a few starting attempts, it won't have the strength to turn the motor over. So following the voltage drop tests in my manual, here is what I'm finding:

Test #1
Connect red voltmeter to positive battery terminal and black voltmeter to solenoid positive terminal - Crank engine - Reading should be less than 0.3 volts - Mine reads 2.6

Test #2
Connect red voltmeter to positive battery terminal connection on solenoid and black voltmeter to positive terminal on solenoid leading to starter - Crank engine - Reading should be less than 0.2 volts - Mine jumps around so much I can't get a single number????

Test #3
Connect red voltmeter to positive terminal on solenoid leading to starter and black voltmeter to positive terminal on starter - Crank engine - Reading should be less than 0.2 volts - Mine jumps around so much I can't get a single number????

Test #4
Connect red voltmeter to common engine ground terminal and black voltmeter to negative battery terminal - Crank engine - Reading should be less than 0.3 volts - Mine reads 3.0 volts

My negative ground cable is a 4 ga.

Where do I begin with these kinds of results? Thanks for your help!

 

[McGR]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Sounds like you are dropping a lot of voltage in #1 & #4 and the other tests are fairly inconclusive. I would thoroughly clean the battery terminals and the solenoid power terminals and the starter positive terminal then tighten everything down good, and test again.

 

[daselbee]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

More than likely the batt is not being drawn down, but that the batt cable fault is heating up due to internal resistance. I bet you will be able to feel the heated cable. That is where your problem may lie. Feel around after trying to start...

 

[BOAH]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

After trying to start, one thing that is extremely hot is the pinion assembly on the starter.

 

[daselbee]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Pinion doesn't carry any current. Maybe the armature is shorted, heats up, and heat transfers to pinion. Pinion should not get hot.

 

[Daviet]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Does the starter itself get hot? Have you got any way to check the amp draw on the starter to see what it is drawing when warm?

 

[tx1961whaler]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

It's drawing 10 times more current than it's supposed to, according the the voltage drops. Something is shorted inside that baby.

 

[BOAH]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

If I need to replace the starter, is it worth it to get a kit and rebuild it myself? If there's a problem with the armature, a kit isn't going to do me any good, right?

 

[emdsapmgr]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

You might have a bad starter solenoid. Check to make sure the starter solenoid is not sticking closed, tranferring current to the starter-heating it up from constant current flow.

 

[BOAH]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Here's the latest. I installed a new starter and a new solenoid and it cranks good and doesn't seem to drain the battery right away like the previous one did so I'm happy with that. Just for the heck of it (I should have just called it good at this point but I didn't) I decided to run my four tests again and long story short my results are better but all four tests came back with higher voltages than what the manual says they should be. Here's what they came back at:

Test #1
Connect red voltmeter to positive battery terminal and black voltmeter to solenoid positive terminal - Crank engine - Reading should be less than 0.3 volts - Mine reads 0.8

Test #2
Connect red voltmeter to positive battery terminal connection on solenoid and black voltmeter to positive terminal on solenoid leading to starter - Crank engine - Reading should be less than 0.2 volts - Mine reads 0.5

Test #3
Connect red voltmeter to positive terminal on solenoid leading to starter and black voltmeter to positive terminal on starter - Crank engine - Reading should be less than 0.2 volts - Mine reads 1.1

Test #4
Connect red voltmeter to common engine ground terminal and black voltmeter to negative battery terminal - Crank engine - Reading should be less than 0.3 volts - Mine reads 0.5

They're close but the results of #3 seems really high and it's a brand new starter? My concern is that since they're not in the expected range, it's just a matter of time before I fry this new starter as well.

I went back and checked / cleaned my ground connections again and made sure I had good connections at the battery. One thing that I saw in another thread that might be relevant is that the batteries are located in the center console and the cables are run under the floor to the motor. The wires are 4 ga. and approx. 10 feet. long. Should I maybe replace them? I put my ohmmeter on each one and setting the ohms on the setting that says 20, I got a reading of 0.9 on each one. Maybe I have a crappy meter but when I use that setting on 20 and touch the two probes directly together, the lowest reading I get is 0.5 So my thought is if my reading on a 10 ft cable is 0.9 hopefully that's pretty good.

I appreciate your help!

 

[inthedirtagain]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

I don't think they used digital VOM back then, so you may be working with equipment that is more accurate than what they had available at the time. Looking at your numbers, I wouldn't be concerned with too much, other than the age of your cables. If the ends are starting to tarnish (green), you may be due for a replacement set. As the cables corrode, they are going to draw more current and be less efficient. $50 in cable could me years of no/less frustration.

When it comes to working on my older outboard, I have this philosophy: If the parts are available and cheap, replace it now! Who knows when the part will actually break, how long the parts will remain available, and what it will cost in the future. Besides, if the parts are under $50, then I just do. Anything more than that, and I'll have to justify the costs versus my monthly budget.

 

[Fed]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Test #3
Connect red voltmeter to positive terminal on solenoid leading to starter and black voltmeter to positive terminal on starter - Crank engine - Reading should be less than 0.2 volts - Mine reads 1.1

I'd remeasure that one, make sure you are getting a good connection with your meter probes and be aware of the difference in measuring the stud Vs the lug etc on all the tests.

 

[tx1961whaler]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Test #3
Connect red voltmeter to positive terminal on solenoid leading to starter and black voltmeter to positive terminal on starter - Crank engine - Reading should be less than 0.2 volts - Mine reads 1.1

Clean up the ends of the cable that runs from the solenoid to the starter and try again. If it doesn't improve, then replace that cable. That's too much drop for that short of a cable.

 

[BOAH]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Here's the latest. I replaced the positive and the negative cables with 4 ga 11 ft new cables. Here are the readings that I just got a few minutes ago:

Test #1
Connect red voltmeter to positive battery terminal and black voltmeter to solenoid positive terminal - Crank engine - Reading should be less than 0.3 volts - Mine reads 0.8

Test #2
Connect red voltmeter to positive battery terminal connection on solenoid and black voltmeter to positive terminal on solenoid leading to starter - Crank engine - Reading should be less than 0.2 volts - Mine reads 0.15

Test #3
Connect red voltmeter to positive terminal on solenoid leading to starter and black voltmeter to positive terminal on starter - Crank engine - Reading should be less than 0.2 volts - Mine reads 0.3

Test #4
Connect red voltmeter to common engine ground terminal and black voltmeter to negative battery terminal - Crank engine - Reading should be less than 0.3 volts - Mine reads 0.48

So I'm a lot closer now. Is that close enough or should I continue to work on it?

 

[Fed]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Test #1 and #4 should be identical, how many wires are connected to each battery terminal?

Is that close enough or should I continue to work on it?

At the very least you should find out why tests #1 and #4 are different.
You should also check if 4 Gauge is the right size for your motor.
Good luck with that I've never been able to find out what the standard sizes are for OMC motors.

 

[clanton]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Wire size for late model crossflow V4, from OMC manual.

1-10 feet 4 ga.
11-15 feet 3 ga.
16-20 feet 1 ga.

 

[F_R]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Are you using 100% copper cables?? Other materials will give higher readings.

 

[Fed]

Re: 73 Evinrude 115 - Help on deciphering voltage drop test results

Thanks Clanton, my manual (1988) lists those sizes as battery cable extensions rather than the original sizes.
They are in the total extended length column, am I interpreting in wrongly?