engine revving but not moving much at times...slipping

[rdstillw]

Hello,
I am proud owner of a 1997 Sea Ray Dancer alpha drive and I had it out in the water about 6 times and I am encountering a problem. The problem has happen twice so far. It seems to happen when I'm over 3400 RPM. The motor seems to be straining but the boat is actually loosing speed. The engine also seems to be making more noise than usual. It kind of reminds me of a slipping transmission. The last time this has happen I slowed below 2.5K RPM and let it sit for a minute and the problem went away when I brought it back up to speed. Did I buy a lemon? I had it checked out buy a professional surveyor, so I tried to cover all my bases. Any advice would be much appreciated.
Regards
Very nervous Sea Ray owner.

 

[Lazy Daze]

Depending on the type of prop, could be (hopefully for you) a spun hub. Prop can be re-hubbed or get a newer style w/o hub. Newer styles are less likely to spin, but can still happen. Look at your prop.

The other possibility is a bad coupler. This would not be good for you as the engine needs to be pulled to R/R the coupler.

There's a few thread on here about hubs and coupler's - try a search if you want to do some more reading.

If there is any possibility the hub is bad - take care of that, first. See if it corrects your problem.

 

[rdstillw]

Wow...I really hope its not the coupler. Is there any lemon laws in NY that cover this. Bought the boat through True North Marine in Lindenhurst NY. Found a good article regarding this issue.

[FONT=Verdana, Arial, Helvetica]Increased RPM With Slower Forward Movement[/FONT]

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[FONT=Verdana, Arial, Helvetica]Many of the emails we receive are related to increased engine RPM and slower forward boat movement. The most cause of this on MerCruiser Pre-Alpha, Alpha One, Generation II and sometimes on Bravo outdrives are as follows :[/FONT]​

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[FONT=Verdana, Arial, Helvetica]1st - A spun hub inside of the propeller.[/FONT]​

[FONT=Verdana, Arial, Helvetica] Sometimes the hub will slip inside of the propeller at higher rpm's. The quickest way to check a bad hub is to try another propeller to see if it slips at the same rpm's or you can try putting a dab of paint on the hub and a dab on the prop and try it to see if the 2 marks still lineup after a trial run. If the hub has spun, you will have to take it to a prop shop for a hub replacement. This can cost between $50.00 to $75.00 and some prop shops will not guarantee the new hub to hold. [/FONT]​

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[FONT=Verdana, Arial, Helvetica]2nd - The incorrect propeller thrust washer.[/FONT]​

[FONT=Verdana, Arial, Helvetica] The propeller thrust washer must match the type of propeller being using. To thick of a washer on a Black Max Prop will not allow the propeller to go deep enough to seal the escaping exhaust gas. The gasses will come out around the propeller instead of going thru the prop causing cavitation. The engines revs up at a certain rpm and slips just like a spun prop hub. Make sure the propeller enters the lower gear housing by at lease a 1/4 of an inch after being torqued down to 50 foot pounds.[/FONT]​

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[FONT=Verdana, Arial, Helvetica]3rd - A worn outdrive housing rear inside diameter or outside prop diameter.[/FONT]​

[FONT=Verdana, Arial, Helvetica] If the prop is going a 1/4 of an inch into the lower housing and you still have the same problem, it could be the inside diameter of the lower outdrive housing or outside diameter of the propeller has worn due to getting an anchor rope or something wedged in between the 2 diameters. [/FONT]​

[FONT=Verdana, Arial, Helvetica]A new housing is 4.400 dia. and a new prop is 4.350 dia. which means there is suppose to be only .025 clearance on each side of the 2 diameters. If this clearance gets to be to great, again the exhaust gasses will come out around the propeller causing slippage. [/FONT]​

[FONT=Verdana, Arial, Helvetica]Try another propeller with a larger diameter to see if it slips at exactly the same rpm. [/FONT]​

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[FONT=Verdana, Arial, Helvetica]4th - A spun engine coupler.[/FONT]​

[FONT=Verdana, Arial, Helvetica] If the propeller appears to be ok and your still having the same problem, it could be the coupler at the back of the engine. Generally speaking, if the rubber hub inside of the engine coupler slips, you should be able to smell burning rubber at the rear of the boat. If the boat is in the water and you have someone with you, you can have them look behind the engine to see if the driveshaft coming out of the coupler going to the outdrive has the same rpm when the slippage occurs. If the engine rpm increase but they see the driveshaft rpm decrease, the coupler is bad. Sometimes the engine will even start to overheat because the water pump in the outdrive is not turning fast enough to cool the engine.[/FONT]​

[FONT=Verdana, Arial, Helvetica]To replace an engine coupler, the outdrive must be removed and the engine has to be lifted high enough to turn it around inside of the boat to replace the coupler.[/FONT]​

 

[Lazy Daze]

I highly doubt there is any lemon law covering this as this would be considered normal wear and tear.

Did you (or the surveyor) take the boat for a test ride?

Did you buy from a reputable dealer? They may be willing to help. Even if I sold that boat w/o a warranty, it would still be Peters Marine's name at stake and I would want to help.

 

[Kurt]

I agree with Dennis, I had the same issue years ago on my Crownline. I went first to the hub then looked inside the bildge and saw the dreaded destroyed coupler rubber bushing splattered on the bilge.