Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

jran · Jul 7, 2012

I have a 1989 sea ray 17 ft 3.0(130 hp) mercruiser with a alpha stern drive.19 p prop.Engine was just rebuilt and is running great. Problem is that at 4000 rpm's it will only go about 25 mph with me and one other aboard. Feels like I am dragging a grand piano behind me.......4000 rpm's and only 25 mph ?????Help.....

oldjeep · Jul 7, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

Maybe the prop is slipping? Put the spare on and try it out. 19p on a 17ft 3.0L should go over 40mph

fishrdan · Jul 7, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

With a 19P prop and 10% slip at 4000RPM, the boat should be going around 32MPH. Was the speed measured with GPS or off the speedo? Is 4000RPM the maximum the engine will turn, or will it go higher at WOT? What is the condition of the prop and have you verified it's a 19P?

Don S · Jul 7, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

What is your WOT rpm (wide open throttle) that is the number than means something.
Is this boat new to you? Have you tried raising the trim (Don't look at a trim gauge, that's a waste of time). Do you have the proper gear ratio?

jran · Jul 7, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

I have had boat at 4300 rpm's and still about 25 to 27 mph....I have a brand new aluminum 19p prop .......I will sound real stupid but how do I check for prop slip??? And speed was measured off of speedo..........but almost every boat litterally passes me like I am just putzing along........very disapointed.....Again...the engine has no misses and I can get the rpm's ..just cant get any speed above 25 to 27 mph...

Don S · Jul 7, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

Moved this to the prop forum where you can discuss slip and props, but I will ask one more time. Have you used tried using the trim?

jran · Jul 7, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

Yes I have tried moving trim in and out tryin to find that so called sweet spot.......just aint workin........but thanks....

Tagerman · Jul 8, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

I had a 1985 17' 4winns with the merc 140 (3.0) with a 19p prop and with proper slip and everything I never broke 30 with more than me on the boat. That boat did have a deep hull but the 3.0 is not a hot rod motor that speed doesn't sound too off to me.

steelespike · Jul 9, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

Don S said:
Moved this to the prop forum where you can discuss slip and props, but I will ask one more time. Have you used tried using the trim?

Moderators this is already on props; maybe we can combine them.

jran · Jul 9, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

I would like to thank all who gave ideas and helpful suggestions.........Almost all of you had suggested prop...prop...prop...ideas....so I took prop off my boat and drew those slip lines across hub and prop area....then before I put everything back together...I GREASED...LOL..the hub and thrust washer on both sides and spline and low and behold as they say in England.....Release the hounds.......I went straight to the water and that damn boat jumped right up on plane and at 4500 rpm's I was at between 33 and 35 miles per hour......where as before it was 25 mph.........I know that to most of you 35 mph is not that fast but for me ....I am a PUTZER....lol...and the biggest difference i noticed was the boat splash.........before the boat splash was coming out by me while I was driving. Now the boat splash was by the back seat and beyond....Again .....Thank you all for your help and Ideas......jeff

Maclin · Jul 9, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

You put the same prop back on and now all is well? I am asking because greasing the splines would not have helped fix any of your problems, the prop spline greasing is done to make sure you can get the prop off the next time.

steelespike · Jul 9, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

I'm wondering if you were missing a cylinder and it decided to kick in or perhaps the trim wasn't working right and raising and lowering the leg "fixed" it.All's well that ends well.
Boat safely; over the holiday here in central NY We had 4 boating fatalities and 3 others had to be rescued.

jran · Jul 9, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

What I am thinking is that the thrust hub had no grease on it and possibly I over tightened the nut that holds prop on spline and therefore causing friction between the thrust hub and the back of lower drive........if that makes sense..........

Maclin · Jul 9, 2012

Re: Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

Me thinks it is best you be clear on what exactly happened, not just here but for yourself. Can you post some pics of the prop and drive?

Does the hub touch the drive casing now? If so stop running it and figure out what is missing in your prop mounting sequence. The hub should never touch any part of the drive. There can be an anode mounted inside the housing right there, be sure if it is there it is not broken and hanging out in the way.

If it was rubbing before then your drive casing will have some serious damage not to mention the prop or prop hub. Plus, tightening the hub against the casing would tend to pull the shaft out and stress those bearings.

Sea Ray 17ft 3.0 mercruiser alpha stern good engine "NO SPEED"

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