smoke coming from outdrive...

[benlh77]

'84 Mercruiser 5.7 898...<br />I took the boat for it's first run today and noticed a couple complications. Around 2000 rpm's there is a loud knocking that shakes the boat. It comes and goes at higher rpm's and the funny thing is, when in a "medium" left turn it completely goes away everytime and the boat sounds beautiful. After a while, I noticed smoke coming from behind the engine, out from the outdrive passage. Could this be the gimbal bearing? U-joints? Appreciate any help...

 

[benlh77]

Re: smoke coming from outdrive...

Also, I noticed gear oil in the bilge...

 

[Don S]

Re: smoke coming from outdrive...

You are probably in the process of loosing your outdrive. If you have gear lube coming into the boat, it's because it's in the ujoint bellows and not in the drive. When it's not in the drive, the gears and the bearings are running dry and destroying themselves. That oil is also washing the grease out of the gimbal bearing and ujoints. The cause of the whole problem is most likely a hole in the ujoint bellows which allowed water into the bellows which got to the input shaft and rusted it, which ground the input shaft seal away and made it leak. The water also destroyed the gimbal bearing and ujoints due to rust and with all the heat a rusty bearing causes, it makes the gear lube from the drive leaking oil from the input shaft get hot and smoke.<br />But that is just an educated guess.

 

[benlh77]

Re: smoke coming from outdrive...

Thanks Don, you have always helped me and I appreciate that. Do you think if I installed new ujoints, gimbal bearing and seals, it would make a difference?

 

[benlh77]

Re: smoke coming from outdrive...

And obviously the bellows. What other seals should I replace?

 

[Don S]

Re: smoke coming from outdrive...

I don't even know if that is your problem, I am only guessing because I can't see it first hand.<br />I would drain what's left of the gear lube and look at it. Don't expect any good news.<br />Then pull the drive and look. <br />Then you will have SOME idea of exactly what is going on.