Strange Starter Behavior

Greetings all. Haven't seen this one before, and I think I've seen a few starter problems in my time. Before I swap out a 70lb starter I thot id see if anyone had other ideas.

Was headed out on an end-of-summer trip with some friends. Started port engine no worries. Tried to start stbd side. Click. .

The engines share the same battery bank. These batteries are 1 year old and test great. The port starts multiple times w/no issues. Stbd won't turn over more than 1/4 turn.

I carry two new spare starters. I take a new solenoid off a new starter and replace the stbd engine solenoid. No change. I'm about to begin the painful process of swapping starters, when, on a whim, I parallel the house bank with the starting battery bank. Bam, the stbd engine starts up immediately.

I head out, go for about 2 hrs, shut down, RON. The next morning, port starts fine, stbd only turns about 1/4 turn. I parallel the house and start banks and she starts right up.

We spent the weekend out, and when I tried starting while the engine was hot the stbd engine would start when using only the starting bank. But when cold, the stbd engine would only start with paralleled house and start banks.

Thoughts? I'm guessing the starter, but I can't think of what would cause these symptoms outside a solenoid.

Thinking out loud ,It could be the Bendex.


The starter Bendex gives a slight spin to the starter gear that engages the fly wheel, so it has the best chance of slipping in should the gears be inline.


You should be able to use a Volt meter to observe weather the volts drop when hitting the start button.

I had a motor leak raw water into a cylinder that hydro locked it cold, but it operated normally on hot restarts.
But, i would also start with a voltmeter on the starter post.

Take a "YouTube University" class on how to do a proper starter volyage drop test and check out your system. Include both the positive and negative cables to the starter.
That will tell you if you need new cables or connectors.

1. Remove the current 'start battery' and jump it off the other 'start battery'. (second battery posts to starter post)

I suggest, corroded or loose connections to starter and or at the battery point.
Remove cables to starter, "brighten" both the cable connections and connection point on the starter.
Do the same at the battery end too.
If that doesn't correct the problem, could be voltage drop while trying to start the engine. Could be suggesting 'less than stellar' health.

+1 for the battery connections. It fits the symptoms.

I don't think Hat uses one bank for starting both engines. Might want to look a bit closer at your batt system. Every Hat I've been on had a separate bank for each engine.

Your symptoms are in line with a bad batt or bad connection on the stbd bank.

My bad. Knew there was something I forgot to include.

During the solenoid R/R I also cleaned up and tightened the nuts, washers, cables and studs. That was my first inclination as well since one engine started easily and the other didn't.

Good thought on the bank issue, but the engines both start off the same bank. It's a single bank of 4 x 8vdc batteries in series. The batteries should be in good shape. They're 1 yr old, and I checked them with a Fluke multimeter and a hydrometer, and the other engine spins great off of them. But I admit, I didn't do it under load. I'll give that a shot first.

Check the ground cable from the start bank to the non-performing engine. Perhaps when paralleling to the house bank you are using a different ground path.

diver dave said:

I had a motor leak raw water into a cylinder that hydro locked it cold, but it operated normally on hot restarts.
But, i would also start with a voltmeter on the starter post.

Click to expand...

Mine was coolant (bad head gasket 3208TA). One day it went click for the last time and two bent rods. An engine rebuild later everything was fine

I have single battery starting both engines. One engine started/cranked easily, the other which had much longer runs was very slow cranking. Installed new starter motor no change. All connections cleaned and retorqued no change. Replaced the battery disconnect switch with a blue sea unit rated for 2800 amps for a few seconds much faster cranking. The old switch had .375 brass posts 750 amp rating, the blue sea .500 copper posts reduced the voltage drop. Look $&

It could also be a bad crimp connection, you checked the nuts and washers but how does the crimp look? Our last boat had some pretty shaky crimp connections on the start batteries but it still worked. I was able to cut off a couple of inches on the cables and got to good cable. Then put new connectors on the ends. Got quite a bit better voltage.

Hmmm, one battery bank for 2 engines?
That narrows it down to screwed up cable to the offending starter or as pointed out, a problem with the starter switch. I would have never considered the starter switch. SHRUG

That's why Im thankful for the forum. Multiple good ideas for things I haven't checked (start switch, battery switch, crimps, cable issues).

I have some work ahead. I'll dig into those this week and let y'all know what I find.

Thanks!

My Starboard engine is attached directly to the positive terminal on the start battery. My Port engine positive terminal is attached to the starboard starter.
The Port engine stars right up, 1/2 a turn gets it running. Always has. The Starboard engine has started behaving as described by Neil, above.
I will now try the battery combining solenoid and see if that helps.

Why not just run both of them to the battery directly. By having it go from one engine and then to the other you are adding potential voltage drops. Even though the second engine starts fine now, it may not always.

Island Cessna said:

Check the ground cable from the start bank to the non-performing engine. Perhaps when paralleling to the house bank you are using a different ground path.

Click to expand...

This is an often overlooked issue, but from what I understand the engine start with a loose ground cable is completely dead, as in not even a click?

"Helper Solenoid"

IF your boat's starter / electrical system has a "helper" solenoid, add that to the list of things to replace. A bad "helper" solenoid got me similar symptoms on my last boat. It was not even in the vicinity of the starter. It is an inexpensive part that should be changed out with every replacement starter.

Good luck. Let us know.

Found the problem.

First, thanks to everyone for making me look harder. I didn't think a cable could "go bad". But it did.

The positive cable from the battery switch had at some time in the past (before I owned it) arced. It was enough to melt about 1/4 of the metal around the "neck" of the terminal lug at the solenoid.

The arced area faces toward the oil pan so it's invisible. Over time the lug loosed on the cable. I bought some new lugs and will replace the damaged one this week.

Gotta love the TF! Saved me replacing a starter.

Glad you got it fixed. There are a lot of bad cable connections out there. As I said in a post our last boat had a couple of bad crimp connections on the battery cables. They looked good but had a large drop over them due to being loose and corrosion.