Engine starting conundrum

This one has me stumped, so any advice from those with more knowledge on electrical issues than me would be most appreciated.

The boat has twin FL120's. She is on shore power 24/7 & the batteries (2) are fully charged and operated in parallel for starting. Cranking capacity is good.

Yesterday, the Starboard engine fired up as usual, however the Port engine would only crank very slowly, then give up altogether after a few seconds. The Victron charger/inverter would go into shut down mode, lights dim etc. Obviously a lot of power was been drawn down. A general check showed wiring , connections etc to be OK, a gentle tap of the hammer also had no effect.

Am I right in thinking that the issue is likely to be either the starter or the solenoid? However would a fault in either of the starter or solenoid cause the system to shut down.

Any advice much appreciated.

Not to be an alarmist but I had this happen on one boat and it ended up I had water filling up one cylinder. Hoping it's just a minor electrical issue or starter for you.

I ain't no mekanyik, but I'd think it's your starter.

I know nothing of Lehman's, but I'd suggest thoroughly checking the wiring. eg remove the engine/starter earth, try and wiggle the terminals at the cable ends to check for a loose crimp, clean the earth studs and refit cable. Do the same for the starter positive.

Its worth doing the obvious things quite carefully before getting someone who has the meter running to troubleshoot.

If the starter can be 'easily' (!!) removed then swap the starters on the engines. That will test for a stuffed starter.

Battery side of the cables too...remove, clean, preserve, replace.

Are you absolutely sure the start battery for that engine is good?

Andy,

If the posts above don’t work, then...

I have had a similar thing before. One or more of the batteries died, was my problem. Batteries will hold a ‘surface charge’ it seems, which can trick your charger, but as soon as you put a heavy load on they reveal their true selves.

There is something about batteries in sequence or in parallel, I seem to remember. A dead battery in one style will drag the whole lot down...

Just my thoughts, FWIW.

Hamish.

IGs parallel the 2 8Ds when starting. If one was dead and cannibalizing the other I think it would affect both, not one.
Wiring/connections could be the issue, if not the starter itself. I recently found a non functioning windlass was due to a slightly loosened bolt connecting 2 cables feeding it. Nip up the bolt hard and it worked again.

I would be very concerned that the starter drew a lot of amps - apparently much more than usual. There's really only 2 possibilities, either the engine was very hard for the starter to turn over, or the starter has developed an internal short. If you don't have a spare starter you could swap starters between engines. Also, you could try rotating the engine with a wrench and see if it is as easy to turn over as the other one. These things will help narrow down the cause. You could also double check the wiring.

Ken

A quick check with a heat reading gun may pinpoint the problem.

Andy G said:

The boat has twin FL120's. She is on shore power 24/7 & the batteries (2) are fully charged and operated in parallel for starting. Cranking capacity is good.

Yesterday, the Starboard engine fired up as usual, however the Port engine would only crank very slowly, then give up altogether after a few seconds. The Victron charger/inverter would go into shut down mode, lights dim etc. Obviously a lot of power was been drawn down. A general check showed wiring , connections etc to be OK, a gentle tap of the hammer also had no effect.

Click to expand...

What is resting voltage of the batteries, especially the port start battery... before you try to start the engine? How old are the batteries, especially the port start battery?

-Chris

Check the battery ground and the grounds all the way to your engine.
Just a guess.
Might be time to get an engine tech out there.

I'm with LaBomba & kchase....

Bar the engine over. Compare it to the other one. If it's not turning over by hand (wrench/bar), make sure it's not hydro locked. Check the oil, make sure it's not milky. Not to be alarmist, either, but eliminating this potential should be high up on the troubleshooting list. If it IS hydrolocked, adding more power to the starter can only increase the potential for significant damage. Your engine is giving you a warning. Find out what the problem is BEFORE going further.



If it IS hydrolocked, pulling injectors will allow the cylinders to eject the water and move ahead with corrective or DX measures. All that said, it could just as easily be an electrical problem, but you need to be sure!

We had lunch at RMYC where Andy`s Sarawana is berthed. And she was, without any crew. Unfortunately, it seems no quick solution presented itself.

"Unfortunately, it seems no quick solution presented itself."

"the batteries (2) are fully charged and operated in parallel for starting."

As one batt may be fine and the other not fine , perhaps attempting starting only on the one good batt might give a clue?

Your description definitely points to the port engine starter pulling lots of amps. With that much current flowing, I wouldn't be fooling with cables and connections. They are obviously tight enough to put a serious load on your pair of parallel batteries.

I agree with the plan to put a big wrench on the port engine and see if you can turn it over by hand. It should move (slowly and with some wheezing noises) with just arm power. This is a super easy test because you don't need to disassemble anything.

If the engine feels okay (if you aren't sure what okay is, pull the other one through and see if it's similar), then I would remove the starter and take it to a starter/alternator shop. They should be able to test it for free.

Here's to hoping that it's a starter problem and not an engine problem

Engine Won't Start

The attached article might be helpful.

Steve Zimmerman

I have had this issue before. Do not rely on your visual inspection of the batteries and connections to rule those out as the problem. I started my right engine and it fired right up. The left engine did exactly as yours did. I went poking around looking at connections and batteries. It looked PERFECTLY fine. I went next door to my buddy for help. He came aboard and disconnected some battery cables and cleaned them up and boom....everything fired right up. My point being is that just because they look okay does not mean they are. I consider myself fairly sharp. At least sharp enough to diagnose a problem like this. I felt like an idiot as I was about to go down all the rabbit holes you are considering....and all it took was to clean up the battery connections. You may want to go down there and just disconnect all of your battery connections and clean them up. It surely can't hurt anything.

PS....my boat is wired with one big battery bank so they are always "paralleled".

SteveZ said:

The attached article might be helpful.

Steve Zimmerman

Click to expand...

Thanks, Steve!!

Sometimes you can learn a lot by pulling the dipstick and looking at the oil.

Simple Check

What happens if you start the port engine first? Does it behave differently?
That should tell you something.

Our 4-236 Perkins had similar issues. The problem turned out to be the starter solenoid. The contacts had arced over time to the point that they no longer made sufficient contact to run the starter motor under a load.

The comment to swap starter motors makes a lot of sense!

Andy, any progress?

Andy G said:

This one has me stumped, so any advice from those with more knowledge on electrical issues than me would be most appreciated.

The boat has twin FL120's. She is on shore power 24/7 & the batteries (2) are fully charged and operated in parallel for starting. Cranking capacity is good.

Yesterday, the Starboard engine fired up as usual, however the Port engine would only crank very slowly, then give up altogether after a few seconds. The Victron charger/inverter would go into shut down mode, lights dim etc. Obviously a lot of power was been drawn down. A general check showed wiring , connections etc to be OK, a gentle tap of the hammer also had no effect.

Am I right in thinking that the issue is likely to be either the starter or the solenoid? However would a fault in either of the starter or solenoid cause the system to shut down.

Any advice much appreciated.

Click to expand...

If you've already figured out the problem, please post the solution for everyone's benefit. Otherwise....

Over my 50+ years of mechanicing (both professionally and privately), I've learned that Diagnostic Rule #1 is always look for the simplest explanation first! For example, you can spend hours chasing an electrical gremlin only to discover that the problem was a blown fuse. If I encountered this problem, my diagnostic process would be as follows:

The biggest clue here is that the engine does actually crank some but slows down. This means it's not the solenoid- they either work or they dont. Second, starters have a similar trait - a bad starter will usually either not crank or crank hard, but at consistent speed. If the latter occurs, crank it a bit then carefully touch the starter body. If its bad it will be hot.

So, assuming the starter and soley are good, the next suspect is current:
1. We can eliminate a fuse or relay because the starter responds.
2. The batteries are probably good because the other engine cranked properly. To find a weak battery, crank the problem engine then test the voltage immediately or monitor voltage while someone else cranks the engine.
3. This brings us to my primary suspect - the cable connections. To test this, crank the engine again then immediately use a temp gun or carefully touch the cable ends at both the battery and the starter. If one is hot, you've got a bad connection. You can also compare the voltage tested across the battery posts, then across the cable terminals.
4. If you want to skip #3, just remove and clean the cables at both ends (my recommendation). It really doesnt matter which end was the culprit because cable connections regularly degrade and should be cleaned periodically anyway.
5. It these tests dont solve the problem, then you should suspect the starter and, as someone else mentioned, try swapping it with the other engine.

Someone mentioned the possibility of water in the cylinder. This is the least probable cause and you would probably have noticed a miss in the engine. However, if you do try hand-cranking the engine, it will come to a stop if a significant quantity of water is present in a cylinder because water will not compress like the fuel-air mixture does. This condition is called hydrolock and the source of water is most likely a blown head gasket. DO NOT try to turn the engine further as doing so can force water past (and even damage) your piston rings. Remove the injectors and crank the engine to determine which cylinder has water.

Good luck

Turn engine by hand. Remove starter and bench test. Load test batteries. Swap starters. Divide and conquer.


Hydrolock can bend rod. No, no.

Any resolution yet?