3.0 mercruiser. lost 20mph

[droptheline]

i got a 3.0 merc. i recently changed my outdrive with what was suppose to be the same thing as before. now my boat will only get to about 2,300 rpm and wont go any faster. reverse's to full rpm. any idea's on y i cant go more that 5 mph? thanks

 

[jerryjerry05]

Re: 3.0 mercruiser. lost 20mph

Evidently you have a different gear ratio in the new drive.
Check on the side for the ratio it should be stamped on the side of the top section.
Your old was a 1/98-1 Your new sounds like it came off a V-8
Post what you find.Jerry

 

[droptheline]

Re: 3.0 mercruiser. lost 20mph

i dont see a gear ratio anywhere. i did some sticker peeling and found a serial # 5115607 if i do have a gear ratio for a v-8 im basically screwed right? would the gear ration for the upper unit be diffrent 2? thanks for the help

 

[Don S]

Re: 3.0 mercruiser. lost 20mph

Here is where you can find the gear ratio (depending on year of your drive)

If you can't find it, you can check it by putting the drive in forward and turn the engine (By Hand) till all the slop is removed and the prop starts turning. Mark the prop blade and the engine crankshaft pulley and turn the engine in the normal rotation and count the number of revolutions you turn the crank to get the prop to make exactly 1 revolution.

Over 2 turns of the crank and you have the proper ratio in the drive
If you only get 1 and 1/2 turns, it's a V8 gear ratio.