Hit Rocks with my Mercruiser 3.0

[tmonteiro]

Hello,

First time on iBoats, so let me know if the subject doesn't fit this category and or if this already exists (I searched older topics and couldn't get something similar to mine tough).

I have a 1989 Larson All American 170 with a 3.0 Mercruiser engine and this weekend I was in the lake (Ray Hubbard - Dallas TX) and was relaxing and fishing with the boat turned off when my girlfriend told me we were too close to the shore. When I realized the distance I tried to start the boat to get far from the rocks, however I didn't count that I was already on the rocks and as the engine started the propeller hit the rocks, the steering wheel turned abruptly and engine went off. I needed to jump in the water (it was shallow) to drag the boat against the current and waves to stop if from hitting the rocks. After some heart attack minutes I was able to drag the boat to a place without rocks, started it and went away. The three blades of the prop got damaged but the boat was running until it started to slow down and turns off. I wait a bit, started it again (I needed to reach the marina at least) and drove a couple minutes more at a very slow speed even with full throttle and then it died again. After that I saw that the battery was low and the boat didn't start again, and it makes sense because of all the time I tried to start the boat, probably the alternator wasn't being able to hold it all and charge the battery - however battery is not the issue.

What else, apart from the prop (which I have already bought a new one) should I be concerned? Was the boat not keeping it up and dying because of the prop that was messed up and couldn't keep the power up? What else should I check after replacing the prop to make sure I didn't damage anything, such as steering wheel calibration?

 

[Scott Danforth]

your engine shutting off is most likely not related to your prop, however was your engine temp really warm?

as for your run-in with the lake bottom, also check your hull for nicks/dings/scrapes

 

[tmonteiro]

Thanks for the reply Scott. I do recall to feel the engine a bit overheated, now that you mentioned it I remember to feel it.

 

[alldodge]

With your battery being low, it could be there was not enough juice to keep it running. Charge it up and get it running, then see if there are any issues showing up and let us know

 

[thumpar]

You say you were at full throttle but going slow. Did the engine RPM go up and you still went slow? If the engine RPM actually went up but you were going slow it may be a spun coupler so the drive was turning very slowly and that could have caused an overheat since the drive rotation is what makes the impeller turn.

 

[RaceCarRich]

Wouldn’t it be likely a spun prop hub given the prop strike and the slow speed at WOT (assuming engine reaching high rpms)?

 

[tmonteiro]

the rpm was going up only to the max speed the boat was reaching, however if I start the boat with the throttle at full (of course, not shifting the gear) the rpm goes up and down as I control it with the throttle, but if I engage the gear to move the boat it will not go up

 

[Scott Danforth]

Spun prop can be determined by using a sharpie. Spun coupler will leave rubber bits in the bilge

 

[RaceCarRich]

Sounds like the motor wasn’t revving in gear like something was loading it down. Gotta thing something is bent or otherwise unhappy in the outdrive.

 

[tmonteiro]

I will be able to test it only next Saturday, as I am still waiting for the new prop to arrive. I will replace it and go for a ride to check how that will be.

I will get back here for the feedback

 

[Rick Stephens]

I would advise you not just slap a prop on it and go boating. Instead, take your time and inspect everything. First thing, is the prop shaft bent? With the prop off, spin it and look closely. Next, install the new prop and run it on muffs in the driveway. In and out of gear, run for a while, does it overheat? You probably won't be able to tell in the driveway if the coupler is damaged, but like Scott mentioned, check the bilge for any small piece of rubber. Might even feel around where the drive shaft sticks into the flywheel area to see if you can feel any of the rubber coupler coming apart.

Personally, after whacking a prop, I'd pull the outdrive and inspect everything before dunking back into water. That's me though. It only takes about 15 minutes to have a drive off.

Rick

 

[dlogvine]

How badly was the prop damaged? If you broke the blades on a plastic prop it is possible that the remaining parts of the blades were not creating any water flow to push the boat even on high rpms. Either way, I'd take the outdrive off and inspect it for the possible damage before taking the boat to the lake. Or at least run the engine on muffs to see if it runs without overheating and noises.

 

[tmonteiro]

the three blades got broken a small piece - ugly enough to not even try to think about repair. I will do all these tests on saturday

 

[TurtleTamer]

A badly bent prop could cause too much rotational drag for sure, and then the extra work combined with lower rpm would then cause it to heat up. I whacked a stump out of the water, in my driveway on muffs. LONG story, and I bent the prop shaft too, so I'd second what was mentioned above. The difference is, it was much easier to see that it was bent with the prop still installed. It was probably just easier to give it a good spin though.

I keep a spare prop onboard just in case something happens on the water. You can usually find a cheap one on ebay or craigslist. It doesn't have to be the exact right pitch or totally free of dings, but having its own hub is important.

 

[tmonteiro]

Update on the situation... I replaced the prop this weekend, there was some water in the engine compartment, which I drained out, also checked all cables from the engine outside the boat and they are all connected and firm, however the boat doesn't want to start and I believe the starter is now messed up, maybe the hit on the rocks while the prop was on damaged something or even some water that got into the engine compartment. It happens that when I try to start the engine, I only hear one click and that's it, the engine doesn't turn, or try to turn, so I believe that initial push is missing, which can be the starter. Just not sure if it's completely messed up or some electrical part inside of it got damaged

 

[alldodge]

Might be might not, just not enough info for me to make a guess.

Is the battery fully charged and can read 12.8V?
.There is a slave solenoid on top the motor. Jumper across the two top terminals to see if the starter turns the motor over. Looks like this

 

[TurtleTamer]

Might be might not, just not enough info for me to make a guess.

Is the battery fully charged and can read 12.8V?
.There is a slave solenoid on top the motor. Jumper across the two top terminals to see if the starter turns the motor over. Looks like this

Wouldn't that short the circuit? Or were you talking about the larger terminals? I have my solenoid mounted to where the top terminals are the coil connections, but I am not sure the orientation is correct.

 

[alldodge]

Wouldn't that short the circuit? Or were you talking about the larger terminals? I have my solenoid mounted to where the top terminals are the coil connections, but I am not sure the orientation is correct.

The two top (larger of the two sets of terminals) terminals will not short circuit. The two smaller terminals will cause a short

 

[tmonteiro]

I tried doing the trick with the solenoid but the results are the same as when I try to start it normal with the keys. It clicks but doesn't start, and it's a single click, it's not that it keeps clicking non stop like when it's a battery issue, some spark comes out (I think it's normal).

The battery is brand new, just got it last Saturday. However something interesting is happening, if I use an external way to measure the battery it shows 12-13V but in the dashboard of the boat it doesn't go higher than 10. The battery is not the problem because I tested 2 brand new and the issue was the same with the measure.

Could it be the solenoid that messed up and need replacement or the starter? Because the engine doesn't even turn (and doesn't try to) as if there was not enough mechanical power to turn it, but if the mechanical part is not working it can also be that the initial electrical push is not getting to the engine to trigger it.

 

[alldodge]

The helm meter is not always accurate. If your battery cables are clean and tight, then its probably the starter or there is something wrong with the motor or drive. Pull the drive and see if it will crank over, if it doesn't pull the plugs and see if you can rotate it by the belts.