Starter or Battery Problem?.. Help Needed Again

[bobk]

Engines are 6V92's 425 HP on a 1981 48MY. About a month ago I started noticing a larger voltage drop when starting the starboard engine, and sometimes a real slow cranking. I assumed the 8D's were loosing it again, but they are not yet three years old. Furthermore two 8D's are wired in paralled on this engine to serve it and the 12.5 Westerbeke. Battery water levels are OK and specific gravity on each cell was normal and uniform.

I had a mechanic do a load test and he found the batteries were fine. He also tested from the battery to the starter and it still looked good, but found when starting, voltage dropped to 5-8 volts at the battery. Paralleling the other 8D in did not help. After three or four test starts, the starter didn't turn over the engine. My mech felt the various connections and didn't find any that were warm.

The mech pulled the starter and I took it to P&H Automotive who checked it and found it was fine. They did a PM job on it for $135. The technician found no evidence (discoloration) of having pulled a heavy amp load. Any thoughts on where else to look before the starter is installed?

Bobk
Chateau de Mer

 

[Boatsb]

Ground. That is where I see a lot of people miss the boat ( pun intended ) when it comes to troubleshooting.

 

[Seabrooke]

Ground. That is where I see a lot of people miss the boat ( pun intended ) when it comes to troubleshooting.

G'day Bob,

I agree with Scott.

Poor ground (or earth - depnding on the terminology that you are used to) is most likely to be the cause of the big drain and poor cranking.

Recently I could not get my engine to turn over fast enough to start for love nor money. The battery was absolutely fully charged and the engine was fine.

When I eventually checked - and sorted - the earth connection (check any and all) it turned over like a beauty and fired instantly.

Most problems that seem mysterious have simple solutions.

Hope this helps.

 

[Canuck Dennis]

I had same issue with generator....click..click...fixed the ground and whir whirrrrrrrrrrr...

 

[Boatsb]

The other issue could have been a hung brush but if it was gone over that would have been fixed already.

 

[MikeP]

Basically after his battery test, the voltage drop test proved it was a wiring issue. There was no reason to pull the starter. Connections/wiring that aren't passing current won't get warm because there is insufficient current to make them warm. A cable could be bad somewhere internally anywhere along it's run. But I agree that the grounds are the first thing to check.

 

[daniel r morrison]

I would try cleaning the battery posts. what bothers me is why the voltage at the battery dropped so low. without a ground there would be no current flow and no load on the battery. high resistance in the circuit could be enough to block voltage and result in the same no load cituiation on the battery. a battery with no load should read 12.6+- volts. Did the mechanic test voltage on the actual battery posts or on the wire terminals connected to the posts. I had a similar problem where 6" of wire at the starter connection had corroded internally, ( actually turned an orange color). When I tried to crank the engine the voltage at the starter terminal went to 0 but remained high at the battery. under no load the voltage at the starter terminal was the same as the battery.

 

[Kim Beatley]

Interesting, something must be in the water!!! I just had (and still have) the same problem..... Good battery test, but no crank on the other end. Thanks for the tips. Will start working connections and grounds on Saturday.

 

[krush]

Define PM job on the starter. ASSUMING everything else is correct (wiring, etc), it is possible that the starter is toast but looks fine on the bench because they just run it without a load.

I just replaced an outboard starter that sounded fine on the bench but it wouldn't crank over the motor and drew tons of current and got the wires hot, etc. First I thought it was batter connections, then battery. It was the starter....

 

[MikeP]

The purpose of a voltage drop test is to check the wiring/connections. If the voltage drop was as described, then the wiring/connections are faulty or the wire gauge size is too small for the application. Of course, that doesn't mean the starter can't also be a problem - which could have been caused by the low voltage. But the V drop test is the first thing to do and the wiring the first thing to correct.

 

[bobk]

Define PM job on the starter. ASSUMING everything else is correct (wiring, etc), it is possible that the starter is toast but looks fine on the bench because they just run it without a load.

I just replaced an outboard starter that sounded fine on the bench but it wouldn't crank over the motor and drew tons of current and got the wires hot, etc. First I thought it was batter connections, then battery. It was the starter....

The shop did do a no-load bench test. P&H is a big outfit, but said almost no one can afford to set up for a bench test for a specific starter.

They replaced brushes, drive (Bendix) and solenoid and maybe some other stuff. I talked to the tech and he said if the unit is toast and draws high amps, that the brush wiring would have discolored, but this wasn't.

Doesn't a good battery load test run with the connections between the battery negative and the starter positive eliminate the possibility of bad grounds? I guess we'll just have to go through these one at a time. What I don't understand is how a volt meter connected to the battery posts would show low voltage if there is a bad ground restricting electron flow?

Other ideas?

Bobk

 

[MikeP]

"Doesn't a good battery load test run with the connections between the battery negative and the starter positive eliminate the possibility of bad grounds? "


A battery load test and a voltage drop test are not the same thing. A proper voltage drop test requires several measurements. Here's a good, thorough description of how to perform a V drop test. This is what they should have done to perform the test/diagnose the particular issue.

Voltage drop testing is extremely useful and should be part of any mechanic's arsenal.

http://www.engine-light-help.com/voltage-drop.html

 

[bobk]

Mike, thanks for the reference. Makes good sense and I'll check into it.

My mech may have erred in testing the batteries while linked in parallel. I'll try to find out more detail.

Bobk

 

[piripucha]

Clean the cable ends at the starter, because they are difficult to reach, we usually don`t give them the proper care. It happened to me once. The engine din `t turn and after paralleling the batteries, bringing in a fresh one, it only cliked and dint turn.I even thought I had water in the cylinders.. Good luck!

 

[bigbill]

check the ground at the engine block also

 

[bobk]

And the good new is...... the simple rework on the strarter worked Five or six test starts and voltage at the bridge helm never dipped below 11 Volts. Engine fired up real fast.

Sure looks like the mechanic's tests and judgement were fine, probably brushes or something simple. Glad that's done. BTW, he had it out and re-installed with about 1.5 hours labor time.

Now working on the generator fuel leaks. Injection pump banjo's were really dripping, but down a hot surface so I never saw fuel, just what looked like an old residue streak. This one will be simple.

Bobk
Chateau de Mer

 

[krush]

Glad everything is good to go.

Your story confused me. It sounded like the mechanic pulled the starter off, took it to the shop, and then put it back on the boat and you still had the same problem.

Instead, you had the problem, mechanic pulled the starter, and you asked if anything else could be wrong WHILE the starter was at the shop.

A good mechanic would've checked the wiring and connections (which it sounds like yours did). Everybody is happy...time to boat.

 

[MikeP]

Concur with Krush.

 

[bobk]

Glad everything is good to go.

Your story confused me. It sounded like the mechanic pulled the starter off, took it to the shop, and then put it back on the boat and you still had the same problem.

Instead, you had the problem, mechanic pulled the starter, and you asked if anything else could be wrong WHILE the starter was at the shop.

A good mechanic would've checked the wiring and connections (which it sounds like yours did). Everybody is happy...time to boat.

Yeah. This guy is quite good. His test of the wiring connections was unconventional....load test both at battery and at starter...but thinking about it, he would not get a good load test at the starter if the ground or other connections were bad. He simply did all the connections in one step. Anyway, I'm happy.

Bobk

 

[bobk]

OK, Now I have a very similar issue with the port engine. Batteries almost new, new battery terminals, etc, did the PM job on the starter and it was OK for several months. Today I went to start it and the volt meter fell way off and it cranked slowly. When I hit the parallel switch it spun right to life and the voltage stayed normal. Another intermittent issue. I'll check the grounds again... the one to the block looks suspicious, but would paralleling the batteries have overcome this? ER temperature was about 70 degrees.

Bobk
1981 48MY
6V92TA 425 HP