Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

[MistaBoatahMan]

Hello everybody and thank you in advance for taking your time to read this.
I recently purchased a 1985 SeaRay Citation with a Mercruiser 3.0L 140hp linked to an Alpha-One Outdrive. The boat has been sitting for years. It initially presented with a bog on hard accleration but new filters and an accelerator pump solved that, well.......
On the last outing everything was working/sounding fine except for a screeching noise coming from the engine which happened just before the boat would plane out ~15-20mph. This was accompanied by a burnt rubber smell, and smoke. I watched the belt while this would happen and it wasn't coming from the front of the engine. It appeared to be coming from the back of the engine. This was also accompanied by a slipping or lack of power from the boat. I kept the boat under 5 mph and made my way to shore. During this time the engine was shaking pretty vigorously but sounded fine.
Could this be the engine coupler? if so, why burnt rubber? If not, any ideas on what it could be?
This would be a repair I am doing myself and I am no foreigner to pulling out engines so advice on how to fix this problem would be greatly appreciated.

Thanks for your time!:redface:

 

[Don S]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Yep, you need a new coupler.
Go up to the Adults only sticky at the top of this forum, and download an OEM service manual for your engine and drive. You're gonna need it.

 

[JustJason]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Agreed, its a coupler. Its common for them to let go when engine alignment is not done annually.

 

[Fishermark]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Could this be the engine coupler? if so, why burnt rubber?

As mentioned above, it is the coupler. There is a rubber hub which acts as a shock absorber or damper I suppose. When it gives way, it has a burnt rubber smell like you notice.

This would be a repair I am doing myself and I am no foreigner to pulling out engines so advice on how to fix this problem would be greatly appreciated.

The actual replacement of the coupler is fairly straight forward. You will need to pull the engine and remove and replace the coupler.

The bigger issue is what caused it to go bad? A misaligned engine is the most common cause.

Then you have to ask what caused the engine to be misaligned. Ah! Now is where you have to poke and prod and investigate. It could be the fiber washers at the rear engine mount have softened over the years.... or it could be the stringers are rotten and have allowed the engine to shift... bottom line is you need to identify and fix the cause - then align the engine - then you are good to go boating!

 

[Don S]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Any time I have to replace a coupler on a Mercruiser, the rear engine mounts in the flywheel cover get replaced. The can get soft and allow too much engine movement causing coupler failure.
This is also a good example of why the engine alignment should be checked yearly. Just to make sure nothing has happened.

 

[MistaBoatahMan]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Thanks for all the info guys and I have a few more questions. Is it possible that since the boat is 24 years old that the coupler has met its last day?
Additionally, while I have the engine and outdrive out, what other high-use/high-wear things might I anticipate replacing that will be easy to access during this time?

Sharing your knowledge is greatly appreciated.

 

[joncrisler]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Thanks for all the info guys and I have a few more questions. Is it possible that since the boat is 24 years old that the coupler has met its last day?
Additionally, while I have the engine and outdrive out, what other high-use/high-wear things might I anticipate replacing that will be easy to access during this time?

Sharing your knowledge is greatly appreciated.

If the alignment is perfect and kept perfect, I have seen them last 20 years and 2000 hours on the engine. They might last longer but I am just going by what I personally witnessed.

If you are pulling the engine, you might consider replacing the gimble bearing, possibly the bellows. If you do not have a remote oil drain, have the drain hose installed in the pan- the part is only like $25. have the exhaust manifolds inspected as well.

 

[fat fanny]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Also for what it cost's you might as well replace the oil pump since this is the perfect time with the engine out and any other gaskets seals and hoses as well as a fresh coat of paint. Man I would research the heck out of this project and do what ever I could with these conponents out of the boat. Good luck and post back with results and work performed for knowledge sharing.

 

[Fishermark]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Also for what it cost's you might as well replace the oil pump

Are you suggesting he replace the oil pump in the engine? If so, I am not sure why you would suggest that. That's not something that one would replace "just because the engine is pulled."

I would agree it is a good time to freshen the paint up and add a coat of anti-corrosion spray. Especially if it is a salt water boat.

Check the things like the bilge pump, etc and replace anything like that while it is easy to access.

It might be time to replace the shifter cable if there is even a hint that is is starting to get stiff and hard to move.

 

[Bondo]

Re: Mercruiser 3.0 140 Alpha 1 Burnt Rubber Smell

Also for what it cost's you might as well replace the oil pump since this is the perfect time with the engine out

Ayuh,... In the Motor,..?? Why,..??

MistaBoatahMan,....
Closely inspect the exhaust system,... All the Rubber parts,... Shutters, etc....
While the coupler was Slippin',... The Impeller wasn't turnin'....
A lack of water flow will Fry the Rubber stuff in No time......