Motor pulls transom under water

[ellasdad04]

15 ft fiberglass tri hull 1986 Mariner 40HP 2 Cylinder w/ Yamaha<br /><br />i have hit a few rocks but recently while driving the tilt let go and the motor dropped while doing 30 mph. Just the prop looks as though were damaged, changed it and went out as planned, when i start to get moving 30-40 % power the transom seemed to be being pushed in to under the water and wasnt picking up speed. there also is a large hump of water behind the boat. i adjusted tilt tight to boat (normallly 4 slots out),<br />ran better but motor sounded LOUD and began vibrating and of course wouldnt plane properly. shut off and trolled back. used a hangar jig to check prop shaft. small warp dont have shims but i used to work CNC shop i would say .020+.. with prop on you cant see any difference when spun? could you tell what i need to do parts anything will help. I also have recently noticed a small amount of oil from #2 spark plug cylinder stained on engine. more than normal oil in cylinder too. # 1 has dry burnt oil on plug thats it.<br />I was given the boat by my father in law who passed recently and he had kept boat good but also didnt use much. it was missing most of skeg when i recieved it also. Always starts before most the new boats on the launch. idles a little high but dosent die. Always grinded when getting in to reverse though.<br /> the boat does 28.6MPH ... the motor " dropped" on the pave ment while going over railroad tracks and the prop smashed pretty hard. missing 40% of one of the prop fins. Luckily the lower unit is a shy short of touching the ground while being towed. sorry about the missed info

 

[studlymandingo]

Re: Motor pulls transom under water

The damaged prop is causing your problem. If the prop that was on a 40HP was pushing a tri-hull 15' glass boat at 30MPH, then I would go back with the same pitch prop that was damaged. You can take the prop that is on there to a shop and have it repaired if it is only slightly out.

 

[Arty_G]

Re: Motor pulls transom under water

What is you RPM at idle? "idles a little high" is most likely why it is grinding going into reverse. Adjust idle screw, and see if that helps cut down on the grinding.

 

[sleepinin]

Re: Motor pulls transom under water

If someone can answer that my hat is off to you.

 

[ellasdad04]

Re: Motor pulls transom under water

thanks studly and everyone else for helping, even though the shaft is bent a tiny bit you think a new prop would fix it? i'll try tomorrow. Just dont want to do any "expensive" damage to the motor . a little low on "Cha Ching" if you know what i mean. FRED

 

[ellasdad04]

Re: Motor pulls transom under water

 

[ellasdad04]

Re: Motor pulls transom under water

 

[studlymandingo]

Re: Motor pulls transom under water

If the shaft is bent, it will most likely cause vibration that will ultimately lead to more damage. You will probably first wear out the lower unit seals that will lead to water intrusion. The shaft and the prop both need to be repaired.<br /><br />As for the condition of the plugs, sounds like you need to do some carburetor adjustment. Also might benefit from a good decarb. Do a search on decarb (use the red "SEARCH" at the top of this page.

 

[ellasdad04]

Re: Motor pulls transom under water

would i replace the shaft or is there a way fixing it?

 

[studlymandingo]

Re: Motor pulls transom under water

There are probably machine shops that could fix it, but for the money I would suggest looking around a few marine salvage yards or shops to see if you can find a used shaft. I rebuilt an entire lower unit on a 'rude last year for less than 100.00.

 

[ellasdad04]

Re: Motor pulls transom under water

I have checked around and so far i can not find a used shaft a between WI and MN. A new one is 300. does anyone no of places that have salvaged parts?? Thanks for any replies