Hit Rocks with my Mercruiser 3.0

[H20Rat]

Sounds like bad connections/cables. Doublecheck everything, you shouldn't be able to move the cables connected to the battery by hand. If you can, they are too loose.

 

[tmonteiro]

Just an update on this... I tried to bypass the slave solenoid and the starter solenoid and the engine still didn't start. I get sparks from both solenoids, they are both under 5.8V approx. Same thing, I get one click but the engine doesn't turn no matter what (I can turn it with my hands - very hard but I can)

 

[alldodge]

both under 5.8V approx.

The battery should never drop that low, so its either bad cables, bad battery or both. Also being that low there is not enough power to move the starter

 

[tmonteiro]

but this was the voltage on the starter solenoid. shouldn't it be less than 12v? I had a feeling I read that somewhere. It's weird because before my accident it was working, and after the hit it all went down the hill, that's why I'm not so sure if it's cables/connections.

If any of the solenoid or the starter are not working, should I listen at least one click (as I have now) or should i hear nothing?

 

[alldodge]

shouldn't it be less than 12v?

No, it should always be close to battery voltage, only something like a coil would be less, and only if it went thru a resistance wire

 

[tmonteiro]

An update on this case, I was traveling for work almost for a month and couldn't work on it. The issue was the starter, just replaced it with a new one and now it starts even easier than before. However, since now I have a new propeller and not the original one that comes with the boat, I wonder if that could make me lose a bit of power. I noticed that the boat now somewhere between 5-10 mph slower but feels more stable. My new propeller is a solas amita 14 - 1/2, 19 pitch 3 blades. I noticed some dirty water in the bilge, and it doesn't seem to be from the lake because of how dirty and smelly it is, maybe some loose hose?

 

[TurtleTamer]

What was the pitch of the old prop? If it was a 17p and you went to 19, you could see higher mph but take a lot longer to get there and have lower revs. If you went from a 21p to a 19, you'd have less speed but see more revs, all other things proper.

 

[Rick Stephens]

At some point you will need to list what your actual numbers are. At Wide Open Throttle (WOT), what GPS speed and what engine RPM is. That's the only way for anyone to actually tell you whether you are in the ballpark or possibly damaging something through lugging or over-revving.

 

[tmonteiro]

Just tested the speed using GPS and my max WOT speed was 33 mph at 4000-4100 rpm driving a distance of about 5-6 miles

 

[thumpar]

Your WOT is too low. It should be mid 4k somewhere (check your engine cover for actual.).

 

[Rick Stephens]

If your engine is running correctly then you probably need a 17 pitch prop instead of the 19.

 

[tmonteiro]

I believe it's running correctly since I've used it over 5 times and no problems happened, apart from the low speed. I don't remember the size of the one I replaced before.

should I go for a 14 - 4/5 or 15 - 1/2?

 

[andrewterri]

14.5x17 would be a better prop in terms of rpm. if you do a lot of cruising or towing you might think of a 4 blade prop. they really make a difference. there are many good write ups on here about propping you boat but just remember pitch and rpm have an inverse relationship. if pitch goes down rpm goes up, if pitch goes up rpm goes down. its about 200rpm per inch of pitch. so dropping to a 17p would add about 300-400rpm. that would get you a lot closer to the recommended rpm for your engine. from memory I believe, its 4200-4800 but it will be on your engine.

 

[TurtleTamer]

I don't think your engine is running correctly. While I'm no expert, similar boats to yours in size and weight easily break 40mph with the 3.0. I'm in a very heavy 20' cuddy with the same engine and break 35 with many different props. This summer after working out one or two last bugs I hope to break 40 though I'm well aware that may not happen. You're running similar props to me in a much lighter, smaller boat built more for speed.

If I were you I'd do a tuneup and compression test before propping the boat. Only after the boat is fully mechanically sound will propping be effective. The 3.0 tends to warp the head easily if heated up and it doesn't take much to leak just a little compression between cylinders 2 and 3. Ask me how I know, ha.

That being said the 3.0 is a trooper, a reliable little thing, so it's totally feasible you could have bought the boat with a slight mechanical issue and it "worked fine" the five times you went and used it.

 

[tmonteiro]

I don't think your engine is running correctly. While I'm no expert, similar boats to yours in size and weight easily break 40mph with the 3.0. I'm in a very heavy 20' cuddy with the same engine and break 35 with many different props. This summer after working out one or two last bugs I hope to break 40 though I'm well aware that may not happen. You're running similar props to me in a much lighter, smaller boat built more for speed.

If I were you I'd do a tuneup and compression test before propping the boat. Only after the boat is fully mechanically sound will propping be effective. The 3.0 tends to warp the head easily if heated up and it doesn't take much to leak just a little compression between cylinders 2 and 3. Ask me how I know, ha.

That being said the 3.0 is a trooper, a reliable little thing, so it's totally feasible you could have bought the boat with a slight mechanical issue and it "worked fine" the five times you went and used it.

How to check the cylinder? Now with you saying that it all makes sense. The issue happened not after I bought it, but after I had a considerable big accident hit some rocks, before that the boat was nice and smooth and much faster - that's how I realize that it's slow now.

 

[nola mike]

Everybody is still guessing. Did I miss what your old prop was, and what WOT rpms and speed were?