Starter or battery

Light air

Light air

.
Dec 29, 2021
89
Catalina, Tanzer C 22, 16 10910 Starr SC
I've narrowed down my starting problem on my Mercury 7.5 1982. I believe it is either the battery or the starter. What is happening is that the starter clicks on and the Bendix spins but does not raise high enough to engage the flywheel. The battery was my neighbor's that he bought new a few years ago but never used. I charged it up and put it on the boat. Started the motor a few times with no issues until the last time I tried it. The gear on the starter does not look worn at all. Starter or Battery?
 
Ward H

Ward H

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Nov 7, 2011
3,651
Catalina 30 Mk II Barnegat, NJ
I'd try a different, known to be good and newer, battery first. Despite never being used if the battery self discharged and sat discharged for those years, it could be bad. Maybe put a volt meter on it while trying to start the motor. If the voltage drops real low, the battery is bad.
You don't say what size battery it is. I don't think a fully charged Grp 27 shouldn't see much drop voltage.
 
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rgranger

rgranger

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Jan 19, 2010
12,370
Hobie 16 & Rhodes 22 Skeeter Charleston
As a test you could disconnect the old battery and run a jumper from your car to the OB leads. I wouldn’t recommend starting it up out of water but you could crank long enough to see if the fly wheel engages. Then cut it off.
 
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Joe

Joe

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Jun 1, 2004
8,005
Catalina 27 Mission Bay, San Diego
Pray it's the battery, starters are pricey. Batteries can go bad just sitting in the garage. If it's a 30 mo. battery, and it's been 36 mo and no charge maintenance.... it's likely done for.
 
Light air

Light air

.
Dec 29, 2021
89
Catalina, Tanzer C 22, 16 10910 Starr SC
The problem with trying to jump the starter is that it is on the boat and in the water. I tried to remove the starter but can't get the angle to pull it from the motor. I will have to take the cage on top of the motor off or drop the lower cowl to get it out. I am thinking that buying a new battery first is the way to go. If that doesn't work, then I may just pull the motor off the boat (hopefully without dropping it in the water).

I remember seeing a video about testing the starter and it did mention that even though the Bendix is turning, a weak battery could prevent it from extending it high enough to engage the flywheel. I can't find that video again but I'm hoping that is the problem.

I looked up the part number for the starter (50 78011) and it is no longer made or available anywhere. DB Electronics does not have a rebuilt starter for it either. If it turns out to be the starter, I will have to pull the old one and find a place to have that one rebuilt. Fingers crossed that it is the battery.
 

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jeepbluetj

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Jan 18, 2016
782
Catalina 387 Dana Point
Sounds like low voltage at the starter to me. That could be a bad battery, bad connections to the battery or starter, insufficient cable size, etc.

Try with a different battery or a jumpstart pack. a 7.5 O/B should be pretty easy to start. A 7.5 should also be pretty easy to remove from the boat and run in a tank or with 'earmuffs' for easier service/diagnosis.
 
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sailcapt340

sailcapt340

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Sep 26, 2008
554
Hunter 340 0 Wickford, RI
rgranger has a good idea in his reply to you. I've used a car battery charger that has a vehicle start setting procedure built into it to test an outboard for what you are describing. You can't run it for a long period of time, but, It will help eliminate the question of battery or starter for you.
My old, bench testing battery eliminator is great for this situation, but not readily available to you. I can physically dial in a voltage amount I need, be it 6 or 12 volts.
But you can get a very simple battery charger that has a start vehicle mode and rule out one or both items.
 
Light air

Light air

.
Dec 29, 2021
89
Catalina, Tanzer C 22, 16 10910 Starr SC
The motor is on the boat and in the water and I don't have a jump pack that works anymore. Great idea though. I found a local shop that can rebuild my starter if necessary. When I told him what it was doing he said that 90% of the time it turns out to be the battery. I'm going to bring the new battery out to the boat on Sunday and we'll see what happens. If it turns out to be the starter, I'll pull it then and get it rebuilt.
 
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B

Benny17441

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May 24, 2004
7,131
CC 30 South Florida
Impossible to tell with certainty, but I would put my money on the battery being bad. A battery sitting on the shelf for years will self discharge and sulfate the plates to the point where storage capacity is practically nil. It will charge but any load applied to it will quickly sap the capacity. Take the battery to an auto parts store and they will conduct for free a load test on it. .....I see you are having the starter rebuilt, I would have checked it first with a known good battery. When you get it back try it out with the old battery,. Good luck.
 
Light air

Light air

.
Dec 29, 2021
89
Catalina, Tanzer C 22, 16 10910 Starr SC
Benny, the battery I used on Sunday was brand new. I put my money on it being the battery also, but it is the starter. I took the starter to a repair shop this morning and should have it back tomorrow or Wednesday.
 
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