Engine rough then stalled, rough idle, weird noise from engine

[JackBronson]

Just bought a very nice 2008 Chaparral 190 SSI with a Mercruiser 4.3 (serial number 1A313653). 155 hours on the engine.
Out boating today, maiden sea voyage after running around the local lake last weekend for about an hour. It ran fine at the lake.
Motoring up river and experience a loss of power at about 1200 RPM (no wake zone, so I had it just in gear doing about 5mph) where the RPM dropped below 1000 so I gave it more throttle and it coughed and was unhappy so I grabbed an open mooring and shut it down. Hung out for a while, continued to the ramp, and it stalled as I was nearing the dock and of course stalled as I was nearing the trailer (with an outgoing river tide against my starboard along with a 15 mph wind - god I love trailering :facepalm.

anyway, bring it home, hook it up to the muffs, and start troubleshooting.
First off, its idling at the Merc spec 650 but its a rough idle. Like I put a lopey cam in it or something - maybe the 4.3 TKS is like this - I'm coming from a Merc 5 liter and this boat is new to me.
Then I notice this strange noise coming from the engine.

This is the noise coming from the motor:
https://www.youtube.com/watch?v=llmkNkG2FLo

This is the RPM moving about 150 - 200 RPM when I have it in the 'just in gear" throttle position (but I don't have it in gear - its in bypass mode) and I'm not touching the controls. Notice how the RPMs change.
https://www.youtube.com/watch?v=afPJECWIfgA

anyone have any ideas?

also I am creating a second thread because we put in at the ramp, motored no wake speed until the mouth of the harbor (about a 25 minute ride), and as when I powered up outside the no wake zone the boat behaved like I had a spun prop hub. went up to 3000 RPM but didn't go anywhere. i could motor around at 1500 RPM and make headway speed but at WOT the boat didn't get up and go. and I noticed there was a discernible vibration at 1500 RPM and when I powered up. now during THIS entire time of dealing with this issue the motor ran fine, didn't stall or anything. so we turned around and drove the 30 minutes back to the ramp fine until when the boat did the rough running / stall at the ramp thing, so I think these are unrelated.
If someone things they ARE related please fire away.

Thanks, Sorry for the long post

 

[tlewis1]

I think you may have a couple different issues going on. It's hard to tell if that noise is coming from the back of the engine in that video. If so I would pull that drive unit and inspect u joints/gimball brg /etc. You can even run it up with the drive unit off (water hooked up) and see if your noise went away. I'd get that noise issue looked after first as it doesn't sound good and then start focusing on the running issue. They may even be related.

 

[JackBronson]

It is from back of engine. It's not the pulleys or belt on the front for sure. And it's not from the stern drive itself. Definitely back of the engine area.

 

[Bt Doctur]

You wont know untill you remove the drive and run the motor but it sounds like a very loose U joint or the shaft moving around.
Might even be the coupler coming apart

 

[AShipShow]

Personally, in the first video it sounds like goats are eating your coupler... lol

But seriously, I agree, it almost sounds like U-joints or gimbal bearing noises... I would pop off the drive and at least isolate that as an option.. its a 10 minute job

 

[JackBronson]

jross - when I discovered this noise my first thought was "damn, sounds like a mouse suffering a painful death back there..."

OK, so let's say its one of the reasons tossed about - would this condition cause my first problem from yesterday, which was what appeared to be major prop slippage? I rev'd it up to 3000 rpms and the boat didn't go. Got a lot of bubbles and the appearance of action from the prop (hard to tell as we were in the ocean with wave action). I could move forward at speeds below 2000 rpm and make headway, but rev it up and it was like the prop had no traction.
I thought I must have spun the hub, but haven't hit anything, and I have the Flo-Torq hub which I don't see how that could be "spun" since its a square peg in a square hole. Inspection of the hub that last night revealed no damage.

 

[AShipShow]

That could be very well be a bad coupler that gives you a little bit grip at low rpm but once you straighten that right arm, it starts spinning on the input shaft... Still more reason to pull the drive.

 

[Bt Doctur]

sounding more like the coupler with every post

 

[JackBronson]

(gulp) let's say I pull the drive and run the engine and still get the same sound. what are the steps I should take to confirm that it is the coupler?

and if it is the coupler, if anyone is interested in a 2008 Chaparral 190 SSI, excellent condition, with 155 hours and bad coupler, make me an offer...:livid:

 

[Rick Stephens]

Pulling the drive, if it's the coupler, will make the noise go away.

I have pulled my 4.3l out for a leaky Y pipe o-ring, and reinstalled it in under 2 hours. It is not a huge deal. Hard (read possibly time consuming) part of replacing a coupler is making sure the motor is aligned perfectly so you don't fry another one.

The high pitched sound, to me, sounds like a gimbal bearing spinning and stopping.

 

[JackBronson]

Rick - so if it's the gimbal bearing, the sound would continue after pulling the drive?

as far as pulling the motor, the problem is that it appears the engine was installed before the top cap of the boat. I have hard fiberglass over the back half of the engine. I specifically sold my easy to service Starcraft last fall because it was 30 years old and I wanted something much newer that I wouldn't have to deal with any major on for a while. Second ride out in it and this happens.

Anyway I appreciate all the helpful suggestions.

 

[Rick Stephens]

When you pull the drive you also pull the drive shaft - comes out with the drive. So the coupler no longer has anything in it and the gimbal bearing no longer turns. You can access the gimbal bearing and turn it by hand. And you can look through the gimbal bearing at the coupler and see if it is melted or otherwise abused. Noises from outdrive, coupler and bearing would no longer be present. Pulling the outdrive is a 15 minute job. One you should get comfortable doing.

 

[JackBronson]

Thanks Rick, that's helpful.

I'm comfortable pulling an Alpha 1. Have done so 3 times and have done lower unit another 4. I just didn't expect to be doing that to this boat so soon.
Bonus: my buddy found a stern drive jack/cradle at his work in a back room. That will be arriving here tomorrow.

 

[2fishy4u]

That video literally sounded just like mine did a couple months ago. Mine turned out to be the Gimble bearing came apart and the noise was the shaft jumping around in there. (did some damage on the gimble housing) Also when it first happened, I could not go fast either. I gave throttle and it would just rev. And when I stopped to see what was going on. Thats when I heard the noise. But, simply pulling the drive will tell you everything you need to know.

 

[JackBronson]

OK, here's where I'm at: pulled the drive, and when pulling it I had gear oil leaking out from where it separated from the gimbal housing, so maybe this was overfilled or oil is getting past a seal. There is no water or oil in the bellows (which are new this season).
A ton of grease on the spline end of the shaft, probably more than should be there.
Can't see the coupler - not sure how anyone could.
as for the gimbal bearing, it has a little play in it when pulling and pushing (fore and aft) on it.
Could a loose gimbal bearing cause my loss of traction when I was getting on the throttle? I think it would explain the vibration I was having.

 

[Rick Stephens]

OK, here's where I'm at: pulled the drive, and when pulling it I had gear oil leaking out from where it separated from the gimbal housing, so maybe this was overfilled or oil is getting past a seal. There is no water or oil in the bellows (which are new this season).

Any oil is a leaky seal behind the u-joint yoke. If there is no water present, then the oil should be the right color and if gear oil, should smell like gear oil. If it is a greyish slurry, then it may be grease and water mixed together. Take a swipe with a finger and smell it to know for sure. Gear oil stinks. If gear oil is present, you will need to reseal the upper gear case.

A ton of grease on the spline end of the shaft, probably more than should be there.

Not really a problem other than messy. Too much grease is always better than too little.

Can't see the coupler - not sure how anyone could.

Shine a light through the gimbal bearing, you are looking at the splines in the coupler.

as for the gimbal bearing, it has a little play in it when pulling and pushing (fore and aft) on it.
Could a loose gimbal bearing cause my loss of traction when I was getting on the throttle? I think it would explain the vibration I was having.

GImbal bearings will usually just cause noise and vibrations.... until they fall apart, then they cause damage. Pull the bearing since it is obvious it needs replacing. You will have a much bigger viewpoint to the coupler with the gimbal bearing out of the way.


Rick

 

[AShipShow]

The gimbal bearing can't cause a loss of "traction". Its simply just a bearing that supports the input shaft to the drive. The input shaft should be mechanically coupled the whole way from the coupler to to prop. The only things that can cause a break in that coupling is the coupler, the gear sets inside the drive, and the prop hub.

 

[JackBronson]

I appreciate everyone's help. I have a question for clarification: should the be no for and aft movement of the inner ring of the bearing? Mine moves maybe 1/16th front to back. The "spin" movement of the bearing is nice and smooth.
How does a bearing on a 9 year old boat with 155 hours wear enough to need replacing?

Thanks.

 

[2fishy4u]

It should be rock solid, only the bearings should spin freely. The gimble part should have no play at all. From what I have read you should change the bearing every 2 or so years depending on usage and such. Any water intrusion will kill them fast. Yours sounds like its just old and used. Its a simple replacement, takes me under 10 minutes now to pull and replace. And go mercury, then sierra, and avoid SEI if possible for replacement. SEI gives about half the life.

 

[redneck joe]

Listen to these folks they haven't steered me wrong yet. replace the gimble. The coupler will be an engine pull.

my coupler went bad while on plane and apparently in the process killed my gimble. My noise was much worse but again I was at speed.

The coupler failure was caused by bad alignment. The bad alignment was caused by the mounting bolts not being tight from why my @*&$@*&$ previous mechanic didn't tighten them down when they put my motor back in (new transom) so every time I gave it juice the motor tilted and became out of align.

with as low hours as you have there may be other factors causing failures.