Yanmar 4BY2 180 HP won’t start

G

GaylesFaerie

Well-known member
Joined
Jul 20, 2020
Messages
579
Fluid Motion Model
C-28
Hull Identification Number
FMLT2701D112
Vessel Name
Gayles Faerie
Hi All, I hope I can get some insight on this one after disappointing Gayle this evening. The boat is a well maintained 2012 R27. I haven’t had a hint of engine starting problems after purchasing the boat last summer and so far this season running the boat 2-3 times a week.

I always leave the boat on Shore Power with just the Fridge ON on the DC side and the Battery Charger ON on the AC side. Upon boarding the boat the Victron battery monitor reads: 100% SOC and 14.35 Volts. I just topped off the batteries 3 weeks ago and saw no plates being exposed. The Hydrovolt Hygrometer readings in April for all cells in the four batteries were all over 1.25. The batteries were installed new in April of 2018.

The big red engine service switch is ON. Engine cooling seacock is OPEN. Turned the key, got the start alarm as usual, then it sounds like the starter engages for a quarter of a turn with a slight groan and then nothing. The DC analog meter at the helm (the 3 position switch is set to the 1 position) starts at 13.3 volts and drops down to 9 volts when attempting to start.

The engine (and house) battery post connections were all removed, cleaned, and refastened in good condition when topping off the battery. See pictures below. The engine fuse was cleaned this spring and shows no corrosion (see pictures, the brown color around the ring connectors is conductive grease to prevent corrosion). I haven’t checked the connections under the red service switch yet but that area in general is very clean.

In the engine compartment on port is a power post that looks suspicious. One side looks to have a pristine connector ring while the other side shows corrosion on the ring and on the braided wire that is exposed by the wire jacket not reaching and sealing with the ring connector. Could this be the problem? I think this is part of the starter circuit but am not sure - the end of the wire that is corroded disappears forward under the engine.

I don’t know if I’ve checked all the connection nodes in the starting circuit so I could use some schooling there if anyone knows where else to look. I suppose the starter connection needs a good look but don’t know where it is.

Battery post: https://photos.app.goo.gl/gUFrAPkSTrnHiwjC6

Engine fuse: https://photos.app.goo.gl/Mwtpm9vCaukcuqz6A

Power post: https://photos.app.goo.gl/qKfFVG17WSFS9DaQ7

P.S. I had just run the boat the day before and like usual, nothing unusual.

Thanks, GF
 
First thought is a weak start battery. There should be a large red switch with the others marked combination. That switch combines all batteries to the the start battery. Turn it on and see if it will crank over.
Any suspect wire/ terminal should be clean. On the rear of the engine there should be a yellow ground wire. Remove the wire and make sure the terminal and where it grounds to the engine is clean metal, no engine paint.
The engine starter is behind the intake manifold on the port side of the engine, you probably can’t see it.
 
Go with Brian's recommendation and make sure everything is clean, grounds as well. The engine does not like poor grounds. Also make sure ground and positive for ECU connected to engine battery are good. It could very well be the starter though. You should find out what the amp draw should be and see what the draw is when trying to crank. I will also assume you were not towed recently? A hydrolock will prevent the engine from cranking.
 
Thanks for the quick replies. Yea I forgot to mention that I did turn the Parallel service switch ON too and got the identical result. After posting this topic a dock mate well knowledged (and equipped) put a load voltage meter on the start battery, both sides of the engine fuse, and both sides of the power post and said he was seeing good readings. He did notice an electrical smell though after I opened the engine hatch. He theorized its possible something is “binding” the starter and causing over amperage. He suggested killing all electrical on the boat before going home which I did (unplugged Shore power, all four service switches OFF) just to be safe and not be in the news the next day. I left the 24 hour services ON. I’ll go down today and check that the remaining connections are clean.

<sinking feeling in belly coming on> If the Starter is shot, any thoughts on how difficult / expensive it is to replace? Not something I personally consider DIY. GF
 
Do you have the service manual? If not PM me your email and I will send it to you. I never had to get to the starter. Seems more labor intensive as parts have to be removed to get to it. Remember it’s a BMW part which should be cheaper than buying Yanmar. If it is determined to be the starter I would first take it to auto electrical shop to see if it can be rebuilt.
 
Hi Brian, I finally fished out the manual at home and it shows removing the starter requires removal of the intake manifold and fuel related parts as well. Good advice on replacing it from BMW as well. The saga continues. Thanks, GF
 
Removing the intake manifold in general is not a big deal. I have not had to change the starter so I cannot offer tips or part numbers. However I have removed the exhaust manifold and that is pretty easy.
 
Intake manifold, not exhaust. Parts of the fuel system also need to be disassembled as well. Not a job for this newbie. GF
 
We haven’t thought of the neural safety switch. Definitely check it out, it’s easy to bypass it with a jumper wire. See this older post. viewtopic.php?f=5&t=7329&p=52080&hilit=+Neutral#p52080

Also move the shift lever back and forth to make sure the switch is in the neutral position.
 
I've never had this (knock on wood) experience. So I'm just jumping in with no authority.

If the battery volts, particularly with parallel on, drop to 9, I'd say that the connections must be pretty good... drawing a lot of amps.

Unless the battery, or batteries, have suddenly gotten old.

Contrary logic is welcome.
 
I checked the ground on the transmission and it looks good. The wiring coming into the ECU (all 3 bundles) looks fine and I even checked the two sets of blade fuses in the ECU - all good.

I'll look at the Neutral Safety Switch next. Some folks I've talked to think that the starter and flywheel are somehow locked? That seems odd but easy enough to check - I can throw a socket on the flywheel nut and use a breaker bar to move the flywheel like I did when changing the belts, or is that just silly dock talk?

In the meantime its impossible to find any technician to look at this. Everyone is booked weeks out. Maybe that's normal and maybe all the new Covid boaters are taking up their time too. (sigh) GF
 
i doubt it is the neutral safety switch. That either works or it does not. The fact that the engine starts to crank and your voltage is dropping is because of a large draw. If all connections are good then it is either a bad battery, starter of a hydrolock. I'd put my money for now on a bad starter. And I did edit my post from exhaust manual to intake, my mistake!
 
Neutral safety switch is between the Strat switch and the neutral safety switch. If it was out of adjustment or failed there would be no voltage drop or no adept to start at all. The fact that the starter does engage and pull battery amperage down would indicate neutral safety is operational.

The indications of a high amp draw with starter engaged can be eliminated in a process of elimination. Check all wiring connections, Tight and clean, Check all cables for evidence of corrosion at the ends. A cable can look ok exterior casing but many times it is corroded in the casing. ( it would be unusual for this to happen over night as your issue did) I would still inspect the cables. If all grounds and positive cable connections are checked and prove to be in good working condition. I would check the starter solenoid. By the description of removal of the starter this may be difficult to check.

The starter solenoid does two things (1) makes the connection between the battery and the starter motor (2) engages the starter Bendix. From your description the starter Bendix is engaging
GaylesFaerie":2g2u64tj said:
then it sounds like the starter engages for a quarter of a turn with a slight groan and then nothing.
Click to expand...
The failure to continue to turn the engine over is possibly . Not enough amperage because of poor battery condition ( I believe you ruled that out).* Poor connections high resistance ( You have inspected all cables and connections) High resistance, poor connection at the solenoid plunger disk . Battery connection at the solenoid can be good but is the solenoid plunger has internal corrosion or poor conductive surface the voltage drop across it will not provide enough amperage to the starter motor. This will create a great deal of heat at this this location. (Possibly your issue) Unfortunately it requires removing the starter to replace in most cases. Many times when a starter is deemed bad it is just the starter solenoid that has failed.

The another issue that was brought up once in this thread is a possible engine Lock. While this seems to be a stretch I have seen this happen many times in a boat with a low engine mount. The engines in the Rangers and Cutwaters are mounted low and the possibility of water intrusion from the exhaust is a possibility.

The bendix gear to fly wheel gear getting stuck is a stretch but has long as you are turning the engine over by hand you will be checking both Hydrolock and the gear being stuck.

My opinion from a thousand miles away is a starter motor. With proper troubleshooting you will find the answer. Best not to throw in the towel. Troubleshoot and repair is the best way to repair things.
 
Thanks KnotFlying and BB. Really good information and schooling on the neutral safety switch. I'm confident the batteries are not the issue or wiring up to the power post on the port hull next to the engine. Its that last stretch of wire that still seems suspect or as you both have pointed out, the starter itself. In the power post picture the left side leads forward to what I presume is the starter. However, I can't get a look at it except the ring connector on the power post which does show corrosion and a peeled back jacket but is it enough to prevent the engine from starting? Also, I'm curious how corrosion failures progress. Would the failure go slow with perhaps the engine taking longer and longer to start versus what I experienced which was always instant start and then 1 day nothing? In the meantime, I'll hand crank the engine just to feel like I'm eliminating something from the deck. Thanks, GF
 
The corrosion progresses over time. As it progresses the resistance will build. Eventually you reach a point where there is not enough power to run the item being powered. In the interim the wires and of connections were heating up without notice. It could be a combination of contact points and then caput.
 
Finally got a mechanic on board. The starter was shot. After he pulled it out it was still hot from just a handful of attempts to start it and had that burnt electric smell. Waiting for it to be replaced. Its a bit distressing to have it go with less than 500 hours on the motor but that "last mile" connection did look pretty sketchy. Thanks all. GF
 
At least half of the frustration is not knowing what is causing the starting problem. From your description, it does sound like a bad starter. Hopefully you will be back in business soon.
Just a thought, you may want to double check the function of both bilge pumps. Excess salt water in the bilge sloshing around might have been a factor in the starter’s failure.
 
GaylesFaerie":1yajgogq said:
Finally got a mechanic on board. The starter was shot. After he pulled it out it was still hot from just a handful of attempts to start it and had that burnt electric smell. Waiting for it to be replaced. Its a bit distressing to have it go with less than 500 hours on the motor but that "last mile" connection did look pretty sketchy. Thanks all. GF
Click to expand...
How difficult was the removal?
 
I'd say it took the mechanic no more than an hour to remove the starter. Not sure I remember all the steps but cover off, wire harness(es) off, intake manifold off, starter bolts out, and finally a coolant hose off that blocked starter from coming out. This guy has been around the block and attacked it without hesitation but being careful at the same time, stuffing any openings with paper to make sure no bolts or nuts fell back into the engine and narrating the whole event as if to double check his procedure along the way. GF
 
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