HELP! Our boat won't go!!!

[maxum-mama]

Hi there! We're in desperate need of some advice! We just bought a 1991 Maxum 2100 LDR with a 120 Force. We took it out a couple times and it went about 30-32mph. A couple weeks ago my husband (OK fine it was ME!) hit a sand bar. It chugged through it for a coupole seconds before we could figure out what happened. Anyway, we got it out of the water and all "looked" fine (i.e., we still had a prop - a very shiny, smooth one anyway). We took it out a week ago, and could only get 2000rpm at full throttle. It was like it was barely above idle, just coasting. We took it into the shop and they said something on the carb was loose and they fixed it. We took it out today and same thing... when in neutral, it revs up just fine, but once it's in gear, it just won't go. We pulled it out and when it's hooked up out of the water, it seems to go just fine too (we revved it up in gear once, it got up to about 3500 rpm so we thought it was fine), but put it back in the lake and ...no power. HELP!! I'm getting really discouraged that we bought this boat! PLEASE tell me it's something simple... like I said, it ran fine before SOMEONE hit that sand bar!

 

[roscoe]

Re: HELP! Our boat won't go!!!

Check compression and check for spark on all cylinders.

 

[maxum-mama]

Re: HELP! Our boat won't go!!!

I think we figured it out... when we hit the sand bar, it stripped some sort of retaining nut in the propeller. Some sort of safety feature that strips out rather than ruining the whole lower unit. We're going to test it out tomorrow night after work, hopefully it will work right!

 

[Frank Acampora]

Re: HELP! Our boat won't go!!!

The prop has a rubber insert in the hub. Once you spin it it can not be repaired but must be replaced. (actually, you can repair them if you know what you are doing and have the tools, but for the average boater, replacement is the only option.) Send it to a prop shop either direct or through a marina and they will do it for someplace around 35-50 bucks. Keep a close eye on the water delivery or bite the bullet and drop the lower unit and replace the water pump impeller. When you stick it that far into the sand, it can suck sand into the pump and wear the impeller. Thus low water flow and overheated engine--major bucks. replacing the impeller is cheap insurance and preventive maintenance. It's easy, you and hubby (four hands are better than two) can do it together with regular hand tools--unless, of course, he is the type that screams a lot.

P.S. Most MALE boaters know that boats are meant to run in water, not sand. LOL. Don't get angry, just having a little fun. Everybody runs into a sandbar or rocks at least once in their boating life. It's a rite of passage--like leaving out the drain plug when launching. DOH!

 

[EricR]

Re: HELP! Our boat won't go!!!

"If you ain't run aground, you ain't been around"

Others have given good advice- sounds like a spun prop hub, and I'd get a spare prop while I was at it. Might save a weekend next time.

 

[roscoe]

Re: HELP! Our boat won't go!!!

Doesn't sound like a spun prop to me.

Usually with a spun prop, the engine will rev way up, but you barely move.

You stated you can only reach 2000 rpm?

 

[Frank Acampora]

Re: HELP! Our boat won't go!!!

I'm reaching here, but check to see if the prop is rubbing on the gearcase. This could happen if you broke the thrust washer behind the prop, or if you did spin the hub and wore the rubber insert to a shorter length. Don't know if it would slow you down that far, though.

 

[maxum-mama]

Re: HELP! Our boat won't go!!!

well, we took the boat out tonight with the other prop, and still only got 2500 rpm... so guess it wasn't a spun prop. We popped the back while we were going full throttle and moved the throttle by hand but still only got it up to maybe 2800. Any other ideas? I wondered if there could be sand in the intake and somehow blocking... but would that make the rpm's not increase? You'd think I'd know more about boats, growing up with one... but I was always having the fun with them, it was my dad bent over the back of the boat all summer!
Any advice is helpful, as we're going on vacation in a few weeks... and we need the boat!! Thanks!!

 

[roscoe]

Re: HELP! Our boat won't go!!!

Yes, check the compression and spark on all cylinders.

 

[QuadManiac]

Re: HELP! Our boat won't go!!!

Is it possible to create major internal engine damage from hitting a sand bar: rings, piston, rod, bearings, etc.?

 

[maxum-mama]

Re: HELP! Our boat won't go!!!

I can't imagine it could... I know of people who've hit sand bars, logs, etc. and it hasn't screwed up EVERYthing... of course I guess I don't even know if that IS what caused it... just know that it ran fine before, and doesn't now...

We will test compression & spark tomorrow afternoon... hopefully it'll give us some answers... someone else told us there's another bushing up inside that could be stripped out but it's a B to get to. Guess we'll see.

 

[QuadManiac]

Re: HELP! Our boat won't go!!!

The interesting thing here is that if anything were stripped, etc, the engine would not be seeing the load of the prop, and would reach high RPM easily. Example would be spun prop hub or stripped spline in the drive train. If this were the case, the engine's power is not being delivered to the prop, and cuz the prop is not loading the engine... it would be able to scream!

THis does not seem to be your case. You are having difficulty reaching high RPM which implies additional friction somewhere in the system loading down the engine, or something in the engine that is damaged or messed up enough that adequate power is no longer being generated.

It's a poser! Assuming compression test shows good values, I'd start looking for things that could have been shaken loose by the impact and vibration caused by chuggin through the sand bar... carb linkages, ignition wires, spark advance mechanism, etc. It's possible this is a simple consequence of your 'accident'.

Good Luck!

 

[scoopyex]

Re: HELP! Our boat won't go!!!

Our Maxum 2100 MN was doing the same exact thing last summer. replace all of your fuel lines. I pulled the fuel lines from the engine back to the tank on ours and replaced them with new, and took out the filter in the pump and installed an inline filter with a bulb primer.

When you remove the fuel lines, you might take a look down inside of them and see a nice thick coating of a waxxy substance.. sorta akin to having clogged arteries it'll limit or totally cut off the fuel supply to your engine.

 

[scoopyex]

Re: HELP! Our boat won't go!!!

Is it possible to create major internal engine damage from hitting a sand bar: rings, piston, rod, bearings, etc.?

Worste case would probably be a sheared off prop, and bottom material messing up your cooling system impellor.

 

[QuadManiac]

Re: HELP! Our boat won't go!!!

Doubt it. The impeller can't cause enough load to keep the engine from revving fully,it will just grenade, and then the engine will freewheel. The prop's already been replaced.

 

[QuadManiac]

Re: HELP! Our boat won't go!!!

Our Maxum 2100 MN was doing the same exact thing last summer. replace all of your fuel lines. I pulled the fuel lines from the engine back to the tank on ours and replaced them with new, and took out the filter in the pump and installed an inline filter with a bulb primer.

When you remove the fuel lines, you might take a look down inside of them and see a nice thick coating of a waxxy substance.. sorta akin to having clogged arteries it'll limit or totally cut off the fuel supply to your engine.

Would be a huge coincidence. What would cause this failure mode immediately upon hitting a sand bar? Don't see it, except for coincidence.

 

[maxum-mama]

Re: HELP! Our boat won't go!!!

I sure hope this is a simple fix! Without knowing a lot about boat motors (OK next to nothing-for me anyway), we've racked our brains trying to figure out what it could be. Everything we think of we come back with, "no, that wouldn't make our RPM's drop"... Hopefully we'll figure it out this weekend. Thanks for all your help, I'll keep you posted!

 

[MikDee]

Re: HELP! Our boat won't go!!!

I'm reaching here, but check to see if the prop is rubbing on the gearcase. This could happen if you broke the thrust washer behind the prop, or if you did spin the hub and wore the rubber insert to a shorter length. Don't know if it would slow you down that far, though.

This is my thoughts also, irregardless of which prop you use, can you take it off, and any prop washer with it, look at it good, and check to see if there's any wear, or rubbing marks, on the front or sides of it? I know the Force motors use a large round flat zinc donut (for preventing electrolysis, I believe bolted in place over the shaft, ahead of the prop) If you see it, it should be dull looking, and not show any signs of rubbing or wear. If your prop is pushing into this, it will act like a disc brake on a car, and bind the prop.

 

[QuadManiac]

Re: HELP! Our boat won't go!!!

Turn the prop by hand, in neutral. If you CAN turn it, i don't see how there would be enough friction in this area to load down the engine to 2000+ RPM, does anybody else? Turn the engine over by hand (in forward gear) using the flywheel (ignition off, of course). If you CAN i don't see this being a friction issue at all, anywhere in the engine or drivetrain... again, anybody else think so?

To load the engine down enough (through friction) to keep it from revving above 2800 RPM something would have to be absorbing and dissipating some significant fraction of 125 HP. If we assume, say, 30 HP, and i think thats too little, that would be around 23 kiloWatts of energy that HAS to go somewhere. Why isn't something melting???

I do not believe it's a friction issue. (But that's just from an engineer's theoretical viewpoint)

 

[Frank Acampora]

Re: HELP! Our boat won't go!!!

I have two gearcases with about 1/2 inch worn off the prop end due to a broken thrust washer. When the engine is in the driveway, there is no forward thrust on the prop and it spins freely. When thrust is put on it in the water, it contacts the case and rubs. Remember: you are dragging the lower unit through a couple of million gallons of the best coolant in the world, with good surface contact and laminar flow (hopefully) and aluminum has a high heat transfer coefficient. It's easy to dissipate a lot of horsepower as heat.

Now, I'm not saying that this is actually happening, but it is worth looking at.