Check/Fix/Replace Starter Motor 1996 50hp

[janul15]

I was just about to wire up and attach my PTT unit as discussed, Johnson BJ50 BELEDS,when I decided to start my engine. No start. No crank, solenoid clicks. Someone noticed that the 9 spline cog on the starter motor was in the upper (engaged) position when I tried to start it. He thought it should have dropped. ( is that bit, with the spring, the Bendix?). Anyway, put a +ve feed directly from the battery onto the +ve terminal, and the response was very poor. Sometimes nothing, sometimes slow rotation, sometimes a bit more rapid and the Bendix moves up to engage, but won't turn the flywheel. Are there any more tests I should do before I take off the starter motor? If I take it off, should I try and fix it, or replace it?

 

[racerone]

Very important to answer questions here in order to help YOU.--What is the history on this motor, or new to you motor?----Verified that is not bearings in engine locked up ?----Verified that it is not the lower unit binding ?----Load test the battery.-----Inspect battery cables.----Compression , actual values ?-----Take starter apart and take ohm reading from commutator to the lower stub shaft.----Report that value.

 

[janul15]

This is what I can give you. Engine is not new to me. Was running last summer on muffs. Found a serious hole in the boat's hull, so fixed that over the winter. Flywheel turns by hand. Compression has been good when previously checked, 150psi on each cylinder. Big voltage drop noted when +ve and -ve cables applied to starter motor (from my car's battery while engine running) .
I'm seeing 14v drop to 6 or 7v. I've removed the starter motor, but not opened it up yet.

 

[Chris1956]

First source a new starter and some brushes, then try to repair it. ARCO, Sierra and others make replacement starters. Try ebasicpower, crowleymarine, iBoats and Marineengine.com and see what they have.

You will need an ohmmeter to check the starter. There can be no continuity between the commutator and the and the frame of the starter. If that checks, inspect the brushes for cracks and breaks. Brushes are usually available for replacement.

 

[racerone]

I have the brushes on hand.----Picked up from local starter shop.-$6.00 a set.----Compared to $30 from other places.----These starter are so easy to check out !!

 

[saltchuckmatt]

Agreed, starter is pretty easy to test and cleanup. Installing the brushes is the hardest part but doable.

While spinning and under load, that starter should read 10.5 volts or so.

I assume you have bench tested the starter on the outboard....(By passed some electrical components) ?

 

[racerone]

In my opinion , there is nothing hard about installing the brushes.

 

[Mc Tool]

In my opinion , there is nothing hard about installing the brushes.

Yep , easy job , and cleaning out all the coppery dust from worn brushes can also help with internal leakage.

 

[Crosbyman]

one option is take it to a repair shop but here is a typical fix up

.

 

[saltchuckmatt]

I was just looking through the eyes of an inexperienced or super busy op....compared to many starters it's not AS easy. Simple tool is easy to make.

 

[racerone]

Cardboard is a bit of a joke for the tool.----I have used 2 kitchen knives to hold brushes in place while lowering the starter assembly.----And there is a proper tool for the job as well , if you do a lot of these.

 

[Chris1956]

I have used carboard and masking tape to install the brushes on a 4 brush Mercury starter. I also bent and trimmed some flashing into a U shape, for the same purpose.

 

[janul15]

Cleaned up the inside of the starter motor. Put it back together using some thin strips of plastic to hold the brushes in place. Now for the important details. On the boat, I have 2 batteries. I hooked up the engine to the most conveniently placed battery. It's charged, but maybe not man enough to start a 50hp. The specifications I can see tell me it's 60Ah, 480CCA. I said I tried to power the starter using starter jump leads from a running car battery directly to the starter motor. The voltage dropped from 14v to 6 or 7 v. I think the jump leads I used are shot. Next steps, 1)find, clean and charge my more powerful battery (610 A, 660 SAE) and hook that up securely to the engine.
2) buy new jump leads. Try again, at the boat.

 

[racerone]

What was the ohm reading on the starter armature?------Should read infinity.

 

[Chris1956]

Gee, I would think almost any good 12VDC marine battery would crank a 50HP motor.

If you put the voltmeter on the battery binding posts, crank the motor and while cranking the battery (at the battery posts) reads 6 or 7 VDC, you either have a really bad battery or the starter is partially shorted pulling way more current than expected. A clamp-on ammeter could tell how much amperage the starter is pulling. I would expect it to be 200A or less.