Mercruiser stern drive - does this sound normal?

JackBronson

Petty Officer 2nd Class
Joined
Jun 4, 2012
Messages
170
Hello,

First time boat owner. Been around the block with cars a lot, decided to try some boating. Acquired a 1987 Starcraft 191S, Mercruiser MCM 230, 230HP 5 liter, engine serial number B530375, drive unit serial number 0B539283, Alpha 1.

First drive on the water the engine started hesitating above 3000 rpm. I could do 30-35 mph fine but when I tried to throttle beyond that it would stutter or act like it was going to stall, recover, stall, etc. So my first question is what to look at for that issue? I looked under the cap, rotor and cap both good. Nothing obvious under the hood. Had fuel in it.

Ran it at home and the motor runs fine above 3000 rpm. Took it up around 3800 rpm without a problem with the drive disengaged.

The next issue is when I engaged the drive. It seemed OK but as I increased the RPM it didn't sound like I thought it should, but being an outdrive newbie I captured a couple of videos and hope someone can give a list and tell me if this sounds normal. On the video taken with more light at about 7 seconds I can hear what sounds like a grinding noise as the motor accelerates, again a little when accelerated more, and then right at the end as the drive is powered down. the second video I took from on the boat hoping to get some better sound (but worse video).

http://www.youtube.com/watch?v=K6WL76iDyas
http://www.youtube.com/watch?v=z8FgakMsH2U

maybe the sound is normal and its just the prop making the noise.

any feedback anyone can give me would be much appreciated. thanks in advance.
 

ktbarrentine

Lieutenant
Joined
Dec 12, 2011
Messages
1,296
Re: Mercruiser stern drive - does this sound normal?

OUch, Ouch, Ouch!!! Please tell me you aren't running that drive in the full up trailered position!!!! Sure looks like it. DEFINITE NO-NO! You'l trash you're u-joints if you haven't already, and that is more than likely the source of your abnormal noise!!! Plus, I rarely engage my prop while on muffs, and best not above idle for very long at all, just to test the shift. While that might not be too bad on the drive, it's just a safety situation I dont place myself in.

Couldn't help myself but had to watch again.... When you started revving up, your muffs looked like they should, leakage out of the muffs decreased.... more flow to the engine.... Then, at the very end, at the highest RPM, leakage around the muffs came back.... I hope you didn't trash your impeller.... If you run too fast on muffs, you have a chance of sucking the hose to the point of collapse, and the lack of water flow will trash the impeller....

Oh, and to your basic initial problem of dogging out at higher RPM on the water.... I would check the fuel water separater and the fuel filter at the carb... but that is just a start.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,092
Re: Mercruiser stern drive - does this sound normal?

Replace water pump, Hi rpm`s most likely damaged it
Replace U joints from running the motor at hi rpm , fully trimmed up.
You NEVER run the motor above "X" max rpm on a hose trimmed up in trailer position
"X"= max rpm reached when "splash" is no longer visable at the muffs and is dependent on your water pressure suppy
 

Grub54891

Vice Admiral
Joined
Jun 17, 2012
Messages
5,908
Re: Mercruiser stern drive - does this sound normal?

Well,First check the drive lube,make shure it's full!,Best to drain it,refill.See if the oil look's milky or really black/check for metal shavings in the oil.If milky it needs re-sealing.If shavins are in iy it should be checked by a qualified sterndrive repair place.
Do not run it with the drive trimmed up like that,the noise could be the u-joint's going bad.With the drive up like that it will destroy them faster.Can't say about your lack of power,but if the drive is going bad it could hold the motor back on power.
My 2cent's Grub
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Mercruiser stern drive - does this sound normal?

I cringed as I watched the first video... I couldn't bring myself to watch the second...

Pull the drive and replace the unis and the entire water pump assembly (base, housing, impeller, plate and all gaskets)... For the reasons already mentioned...

Then pull the carbie and strip and clean it (and set all the adjustments).... That's where the 'over 3000 rpm' problem is... That's just when the secondaries start opening... They don't open when the engine's not loaded.

Chris...
 

JackBronson

Petty Officer 2nd Class
Joined
Jun 4, 2012
Messages
170
Re: Mercruiser stern drive - does this sound normal?

OK everybody, thanks for the information. I'll get to work.
 
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