Troubleshooting Strange Starter Symptoms

[William Miller]

Need Thoughts and Ideas
06 290 Amberjack.
2x 350 mag mpi Bravo III

I refurbished both engines and reinstalled them last summer. They both run great.
Both original starters were replaced because they were pretty ugly and because they are so easy while the engines were out.
Both worked perfectly on the bench.

Starboard engine srarter has an intermittent problem thats slowly getting worse.

It sounds as if the starter motor spins without the bendix pushing the gear to engage the ring gear on the flywheel.

After a few tries it would work... never been stranded. Usually this happened when the boat sat for several days

Some time i could help it work by using the emergency start switch on the dash which combines all four batteries.

The starboard 2 batteries were new. They read 12.6 v and 13.6 aprox. With the engine running.
After half of this season with frustration and limited time I decided to replace them.
Did normal maintence on the port bank. Cleaned all the terminals and some of the connectiona that i could reach on the bus bars and Emergency switch Solinoid.
By the way I live over an hour and a half from the boat an my battery tester was home.

So of course no joy except I ruled some things out. But am now thinking its a resistance/ voltage drop problem , bad ground or bendix is just getting stuck.

So if I get the port side running its pushing 14.6 or so then hit the emergency switch it raises the voltage on the starboard side to the same. IT will then start.

So I will head down Friday for the weekend.
I have a second new starter on its way along with a new 90 amp fuse that goes at the starter.

To get to the starter i have to remove all 4 batteries. Slide down on top of the trays on the starbord side of the starbord engine and hope to get my hands and tools between the stringer to get those lower bolts out.

Ill check the ground on that side, the fuse and positive terminal. Plus check out the wire that energizes the bendix.

Ill probably bench test the new new starter and just i stall it just because.

So what am I missing?
Thanks for your thoughts and prayers!
This will not be fun.
Unfortunately my son is out of the country.....

 

[Skybolt]

...
So what am I missing?
Thanks for your thoughts and prayers!
This will not be fun.
Unfortunately my son is out of the country.....

Lithium grease on the starter bendix and cleaning the wire ends and putting dielectric grease on terminals.

However, using the parallel switch fixes things and starts the engine has me thinking the batteries or their connections are not what they should be, so I would use that battery tester first and see whats going on. I have seen rebuilds go bad quickly as most of the time the armatures are not replaced and you could have one needing more current to get going. Tough problem to diagnose, good luck! Post your findings when you get it fixed.

 

[Woody]

Lithium grease on the starter bendix and cleaning the wire ends and putting dielectric grease on terminals.

However, using the parallel switch fixes things and starts the engine has me thinking the batteries or their connections are not what they should be, so I would use that battery tester first and see whats going on. I have seen rebuilds go bad quickly as most of the time the armatures are not replaced and you could have one needing more current to get going. Tough problem to diagnose, good luck! Post your findings when you get it fixed.

+1

 

[markrsimon]

The starboard 2 batteries were new. They read 12.6 v and 13.6 aprox. With the engines running.

Not sure if I am reading/interpreting this correctly. You have 2 batteries for the stbd side, in parallel, and with the engines running you have different voltages on each?

The voltage at each battery in a fully wired bank should be close to the same. Are you testing at the battery terminals (posts) or the cables that attach to the batteries?

Does the boat red go to one battery and the boat black to the other battery by chance?

Disconnect each battery test. Clean all connections. Suggest boat red/black goto the same battery, using the posts (not the threaded terminals with wing nuts).

 

[Nater Potater]

Same thought as @markrsimon, and to elaborate a bit on the voltage; when running at, say, around 1500 rpm and above, assuming you have fully charged batteries, you should see around 14.2 to 14.5 volts at the battery. Current, modern day systems run even higher. And, assuming the batteries are in parallel, you should see the identical voltage on both batteries. Anything different, and you've got a bad connection somewhere in the cables. This could definitely cause your starter Bendix to act hesitantly. Your statement of "So if I get the port side running its pushing 14.6 or so then hit the emergency switch it raises the voltage on the starboard side to the same. It will then start" pretty much confirms that.

 

[techmitch]

Battery, main engine ground and starter connections X10. Then an inductive amp probe on the main positive cable at the starter would tell you if it's pulling enough current.

 

[Espos4]

+1 on cleaning the connections. Also check for a voltage difference between the cable connector and the battery terminal itself. Any corrosion right at the connector will show a voltage drop between the connector and the battery terminal it’s attached to. Maybe .5 to 2 volts.

This is a common issue on older cars with remote or trunk mounted batteries. Corrosion at a bulk head connection prevents the battery from charging as well as it prevents maximin current flow to the starter.

Also, if they weren’t so difficult, I’d say swap starters side to side and see if the problem moved, but most of us would rather gouge our eyes out than replace a starter in the boat, never mind two of them.

 

[William Miller]

Thanks for all the ideas!

The new starter, scheduled to deliver by end of day maybe late.
Trying to leave by 2pm to beat the beach traffic over the bay Bridge.
I pulled my old starter off the shelf so I have that for parts.

So after reading all the comments and sleeping on it, I'm now thinking the big wires terminals and grounds are good because once the bendix and gear engages there is no problem at all cranking.

It could be the bendix itself is sticking.
I might need a shim to get the starter gears to mesh easier.

On the electrical side. I need to check the solinoid connection (start wire) could be loose or corroded. Check the start relay on top of the engine. (That's easy to get to and bypass.) This will be first to narrow down several possibilities.
It could be upstream or downstream from there!
The solinoid on the starter is a big relay but also pushes the gear out to mesh with the ring gear.

If I'm lucky my parts will show up in time , I'll beat the traffic and get a start by dark!
Thanks again. I'll post some progress or success as soon as I can!

 

[William Miller]

Battery, main engine ground and starter connections X10. Then an inductive amp probe on the main positive cable at the starter would tell you if it's pulling enough current.

Thanks

New batteries. Cleaned terminals and several other connections that I could reach.
Have to pull all the batteries out again to get to the ground.
Will bring my amp probe and battery load tester.

Going to check solinoid start circuit

 

[William Miller]

Same thought as @markrsimon, and to elaborate a bit on the voltage; when running at, say, around 1500 rpm and above, assuming you have fully charged batteries, you should see around 14.2 to 14.5 volts at the battery. Current, modern day systems run even higher. And, assuming the batteries are in parallel, you should see the identical voltage on both batteries. Anything different, and you've got a bad connection somewhere in the cables. This could definitely cause your starter Bendix to act hesitantly. Your statement of "So if I get the port side running its pushing 14.6 or so then hit the emergency switch it raises the voltage on the starboard side to the same. It will then start" pretty much confirms that.

This is with the port side running and charging at over 1500 ram. Smartcraft reads about 14.5 or .6. For that bank. Starboard side switch on not running reads about 12.6 +/-. Push and hold the emergency start switch combines both banks and the Starboard side voltage gauge rises to match the other bank . Hit Starboard start switch with now 14+ volts. That was enough to get it to kick in and start the Starboard side,

 

[Nater Potater]

This is with the port side running and charging at over 1500 ram. Smartcraft reads about 14.5 or .6. For that bank. Starboard side switch on not running reads about 12.6 +/-. Push and hold the emergency start switch combines both banks and the Starboard side voltage gauge rises to match the other bank . Hit Starboard start switch with now 14+ volts. That was enough to get it to kick in and start the Starboard side,

What does the voltage on the starboard side climb to once the engine starts? It almost sounds like that side's not charging the battery up to where it should be. Looking back at your original post, you mentioned it was up to 13.6 when running. As mentioned before, it needs to be about a volt higher. I'm thinking your starter problem is really a charging problem.

 

[William Miller]

Unfortunately Amazon failed to deliver.
FORTUNATELY......
Picked up a starter on the way to the boat.

New starter in. Found JOY on first crank!

Some water or coolant had dripped on the starter and corroded the shaft for the pinion.
Yup it was just sticking.
Found a few suspect clamps and and a tiney leak at the engine drain cock.

Will take a better look in the morning.

This was about the hardest things to get to short of pulling the engines.

Tired and sore. Ready for some Rum!
Thanks for all the support.
This is a great fourm.

 

[Espos4]

Good news!

 

[William Miller]

Good news!

Can say that again!