1996 Mercruiser 3.0LX dying consistently

[trevorw0990]

All,

This is my first post. Thanks for having me! This is kind of a long post, but I am looking for some help so I can use my boat memorial day weekend. Anyways, I wanted to get some guidance on troubleshooting a problem I am having with my 1996 Dynasty Elanti 180. It is running a Mercruiser 3.0LX, and I'm having some trouble with the it. Any ideas are much appreciated!

Last Saturday I was out on the lake all day, and the boat was running fine. We managed to make a 1.5 hour trip up to a more quite spot on the lake to throw the anchor out and relax. We made a couple runs back to a friends dock to pick them up, and drop them off. No problems. On the way back to our marina, I lost complete power in the engine while cruising at ~3K RPM. The first two times the boat recovered, and came back up to power. The third time it lost complete power, and the engine completely shut off. I started to panic as we were sitting in the middle of the lake. After moving the throttle back to the neutral position, I turned the key to the off position. I attempted to start the boat back up, and it would click once, and stop. At this point, I am thinking were in for quite a paddle back to the marina. After several more failed attempts to start the boat back up I tossed the anchor out, and called a tow service. $390 later we were back at the marina, and safe.

Yesterday, I went back to see if I could reproduce the problem. I was shocked to find that the boat started right up quickly. Turned over on the first stroke actually with a few pumps of the throttle. Once it was started I went to the engine bay to check for any abnormalities, and noticed a strange "hissing" sound coming from the outdrive (very noticeable even though trim had the drive sitting completely submersed). The engine was stroking just fine. I did add some drive oil to the reservoir, and checked connection to the battery. All was good. I let the engine idle and warm up to get the engine temp ~140*. I even revved the engine out of gear up to 3K RPM and let it run for a minute. Everything was good except that hissing sound out of the out drive.

I decided to have my dad follow me out in his boat, and go for a test run. Luckily this time it was in a controlled environment, with a tow back if I needed one. When I got outside the no-wake zone I slowly increased the throttle, and the boat came up to plane no problem. I did notice a whining noise out of the engine bay (high pitched), something that drew my attention quickly. Sounded like the engine was struggling under load. I ran the boat for another 2 minutes, and then boom! It dies again. Lost all power. Boat shuts off completely. No sputtering, not like it was starved of fuel, just an abrupt loss of engine. Again, I pulled the throttle back to neutral and shut the key off. I let it sit for a few seconds, and tried to start it back. No luck. The engine was turning over, but not even attempting to start.

I pulled the battery out when I got back to the marina, and had it tested this afternoon at an AutoZone. They said the cells, and battery condition is great, but the charge was only at 80%. I had him run the test twice to verify, and it came back with the same results. I have done some reading, and some things are pointing to the ignition system (coil, plugs, etc...). Also, some forums I have read make me believe it could be as simple as the alternator. I wanted to get some personal opinions on things to look for to keep my boat from having to be pulled out of the water, and taken to the shop. The local marina shop is backed up with people looking to get their boat ready for memorial day, so it is highly unlikely that they will be able to get to it by then. Any suggestions would be awesome!

 

[spannerman]

First check all of your battery connections plus and minus all the way to the engine and the main engine harness connector, the clicking indicates the starter relay is working but could be not delivering power to the solenoid on the starter itself. If these seem OK it could be the hall effect sensor in the distributor, these usually fail after the engine has got warm. If its an ignition fault the rev counter will drop to zero instantly as it loses its signal from the coil. If its fuel it will fade out and the rev counter will sink more slowly as the engine runs down, usually fuel starvation is accompanied by pops and bangs from the carb. You need to check the supply to the coil and distributor and see if the coil is switching on and off after its died, the grey wire should pulse with a test light or the rev counter should flicker when cranking. Unlikely to be the alternator but you can check the charging voltage which should be 13.8 to 14.2 when running, and if it wasn't charging so the battery runs down you would struggle to crank it after the engine died.

 

[BruceK]

Worth a quick check....I had a similar problem to yours with the starter motor not disengaging. There is a bolt that is prone to shearing (which I discovered when researching my issue) and causing the starter motor to misalign and bind. What brought this to mind was you mention of a hissing sound and the fact that in one of your attempts nothing happened but you heard the solenoid click in despite having good battery.

 

[trevorw0990]

Thanks for the quick responses. I am waiting for my dad to get back in town so we can take it for another test run.

@BruceK was the hissing noise you heard coming from the upper portion of the stern drive, or the engine bay? I am hearing the hissing sound just at the top of the water on the upper stern drive. When i took it out the last time and it shut off on me the engine was actually responding to me attempting to crank it. It was slowly turning over. Seemed to me like a weak battery. Which is what surprised me because the battery checked out just fine. The other noise was more like a "whining" noise from the engine when it was under load at ~3K RPM. I new right away that something wasn't right, and then it shutoff maybe 2 minutes after getting up on plane.

@spannerman i am not sure the sensor wouldnt have been tripped while it was running at idol in the marina slip. I let the temperature get all the way up to 140* and even had it revved up to 3K rpm out of gear for a bit. I'm concerned that it will be a lot of trial and error because it is not reproducible unless the engine is under load and the gear is engaged. Makes it a serious pain in the balls to work on because i have to leave the marina to get it up to speed, and get towed back every time we try something new.

 

[BruceK]

No, not from the leg but at the rear of the engine underneath. Was is a hissing or the grinding sound of a dry bearing? When last was the gimbal bearing greased / replaced/ checked during a bellows change? Was the engine whine the sound of a siezing bearing?

 

[[2068]]

I was thinking "something seized" as well.

You can test "in gear" at the dock with a sturdy set of mooring lines attached to multiple cleats. Maybe not 3000rpm, but something like 1500rpm in gear at the dock might be enough to reproduce the situation.

 

[spannerman]

Ignition faults only usually show up when the engine is under load, you seldom find a misfire ect just revving it in neutral.

 

[Vitesse]

In the event it's a seizure, do these motors have magnetic sump plugs?

I suppose oil pressure is okay?

 

[trevorw0990]

I wanted to update on my progress. Thanks everyone for the helpful replies! I replaced both the distributor cap and the spark plugs. My engine is running fantastic now. The old distributor cap was extremly corroded and the spark plugs looked like they were spray painted black.

As well, I figured out the hissing problem coming from the outdrive. Turns out after inspection that the upper unit had taken on some serious water. I pulled the boat out of the water so I could get the outdrive off. One thing leads to another... After removing the outdrive from the bellhousing the gears in the upper unit were chewed to $@#$ and started making some awful clanking noises. The upper unit is completely seized, and in need of some serious repair. It tipped me off that I had a seal issue somewhere because I noticed that i was dumping gear lube into the lake. If anyone is interested in a fixer upper let me know.

I mounted the new upper unit to the lower last night, and going to pressure test this evening to make sure I don't have any leaks. The job will be finalized with inspecting the gimbal bearing, u-joint bellow, exhaust bellow, and shift cable bellow to ensure that there is no water being introduced to this new drive. Luckily the new SEI upper is under 3 year warranty so I have some confidence. Hopefully will have her on the water by Sunday, and will update with the test run results.