Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

[HOMBRE DE MAR]

Hi, I am new here and I will like to request some help, I have a 1985 Renken with a 3.0 140 Mercruiser. The mechanic replace the second coupler already but it still doing the same. It will engage forward and reverse just fine, but when I accelerate it seams to desengage the gear and smell rubber like the coupler is bad. If slowed down again it will idle once more. The mechanic replaced two couplers and fixed the front support of the engine mounting. According to him that was in bad shape and provoqued that the engine was out of aligment. It suposed to be fix now but I still have the same issue. Please I need Help, I spent a lot of money without possitive results, Thanks.

 

[TowRoper]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

bet its a spun prop hub my friend to make sure just mark the prop and the hub and if the Marks don't keep aligned its a spun hub

 

[bigskiohio]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

spun prop smell like rubber? Learn how and do the work yourself.

 

[TowRoper]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

yeah fixing this one is easy

 

[Bt Doctur]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Were the rear motor mounts replaced, their the leading cause of coupler failure.

 

[HOMBRE DE MAR]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Thanks for all the answers. I just can't wait to start working on it. Tomorrow I will take the prop apart and I will let you know what I found. The mountings were check and replaced by the mechanic " I guess...." I am a DIY guy but I am new in boats. Any way I will give it a try... Thanks to everyone....

 

[HOMBRE DE MAR]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Hello here I am again, I put a new propeller but It didn't resolve the issue. It get worse, while I was trying the new prop. the issue increased to the point that now the propeller doesn't turn any more and now it sounds like something is blocked. When I try to give it more accelerator power it seams like the gear desengage and started making noises. If some one can figure what it is please let me know. I called the mechanic I he don't know what to tell me , thanks.

 

[Bt Doctur]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Have you checked the oil level in the outdrive, it should be up to the vent hole on the port side of the upper unit

 

[HOMBRE DE MAR]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Yes, I did it. It is clean ( no metal residues or water) and at the right level. When I replaced the propeller just behind the big metal ring ( called like that because I don't know the name of it) that goes behind the prop I saw like rubber residue and a spring exposed, like part of a seal that is dissapearing. I don't know if could be related but I don't thinkg that it will stop the boat from running.

 

[bigskiohio]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Trying to figure out what somebody else did is tough. coupler shot or outdrive shot or prop shot . check with engine off and put i gear and turn prop both ways should click one way and lock up the other against motor.

 

[myoldboat2]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

bigski> coupler shot or outdrive shot or prop shot

yup.

the smell of rubber makes me lean toward coupler or prop. but you said you replaced the prop, and now it's not turning.

you need to see if the coupler is spun. if it spun the rubber donut in the coupler, then it might grab at idle but not at speed.

a test i have done at idle is this--first, disconnect the battery and take it off the boat. really. then, you can work your hand down behind the engine and find where the sterndrive splined shaft enters the center of the coupler. with the engine not running and the lever in forward gear, have someone turn the prop in the direction it should be locked (not the click, click direction). if they can't turn the prop then the coupler may be grabbing and the engine resistance is stopping it. if they can turn the prop and you don't feel the shaft turn, the prop is spun or the outdrive is shot. if they can turn the prop and you feel the shaft turn but the coupler not turn, then the coupler is spun again.

most likely they will not be able to turn the prop. then do this: if you can see a little bit of the splined shaft that enters the coupler, clean it real good and mark a line on it in the direction of the shaft (from front to back). get your hands out of there, bring the battery back and hook it up, shift back to neutral, start the engine. have someone who knows what they are doing handle the throttle. shine a light on the shaft you marked. that shaft should always be turning when the engine's running. as your helper increases the throttle (stay in neutral), you may see the shaft stop turning or start/stop like the coupler is slipping. then the coupler is the problem.

if it's the coupler again, then Bt Doctur already said that the rear engine mounts are probably shot. Or your mechanic isn't aligning the drive to the engine correctly. In either case, I wouldn't use that mechanic any more. I'd get the manual and the alignment tool and do the work myself. Or find a good mechanic.

Hope you find it, good luck.

 

[meesh]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

It sounds like the coupler. You also mentioned behind the prop and the big metal ring I'm sure your refering to the thrust washer, you saw rubber and an exposed spring. That prop shaft seal should not look like that. Are you sure your drive is OK?

 

[myoldboat2]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

post photos.

 

[HOMBRE DE MAR]

Re: Merc 3.0 140-coupler replaced and only idle but it desengage when accelerate

Thanks to everyone that took the time to read my posts and give me ideas based on your experiences. The problem was the mechanic!!!!!!! He was trying to cheat me telling me that he changed the coupler when he didn't. It tool me a day standing behind him in his shop and guess what???? the boat was alive again.
Thanks once more.

I sold that boat and bought a 93 Sea Ray, no complaints just enjoyment!!!!!!!