84 Mercury 150 blackmaxx clunk and grind

[84Ranger]

Hi there everyone.....I have a problem with my 84 mercury 150 blackmax that when shifting into gear it really grinds and makes clunking noise....clunk noise sound like the prop was hitting bottom but it not.....sometime when shift into forward there will be some clunk noise like metal bang and jerk that whole boat like it trying to engage and I have to keep trying until it engage and it will shift into gear....im not shifting into gear slow but that noise Im hearing tell me something is wrong.....than yesterday i took out the boat and it did it again and this time it will not go in gear at all in forward or reverse...but will grind really bad and at time will engage into gear but will still have the grinding noise......even in netural there will be a loud rattle/knocking noise like a rod knocking ......and than it die. I try to start it the motor but it will not crank as the motor will not turn at all.....starter engage but the motor will not turn..........so loaded the boat and came home.....once i got home I try to start it again and it started but still with the same rattle/knocking noise....noise seem to be coming from the lower end.....and will not shift into forward and reverse...just grinds really bad....any ideas on wut could it be.......broken shaft.....????????

 

[fishdog4449]

Re: 84 Mercury 150 blackmaxx clunk and grind

it could be your shift cable is not adjusted right. it may not be pushing the dog all the way into gear. either way, check it. but you may have already damaged the gears or dog trying to shift it. check your lu oil for shavings.

 

[BF]

Re: 84 Mercury 150 blackmaxx clunk and grind

Sounds like a major lower unit failure. Yes it could be a broken/twisted driveshaft but it could be some other failure too. Maybe a bearing or gear broke and some chunks got munched up in the gears.

Whatever the case, there is not likely to be an inexpensive fix. There's really no way to know what it is until you (or someone else) starts taking it apart.

I have the lower unit on my 150 sitting in my basement right now. When I took the water pump off, the drive shaft came out in my hand. (it's not supposed to do that) So, in my case it's really easy to tell the failure was that the driveshaft broke right above the pinion gear.

Unless you already know how a lower unit works, I highly recommend that you get some kind of service manual and do some reading. Even if you take into a shop, at least then you'll understand what they're talking about. Around here, a total lower unit rebuild can easily hit $2-3000. Used units in working condition go for $1000-1500 here (if you can find one). I managed to find the correct internals for mine on ebay (used parts) for a total of ~$300. But I still need to buy a new water pump and base, and put it all together.

good luck.

addition... <to confirm if the lower unit is really in bad shape, drain the oil and see if it has chunks/filings it.... >

 

[84Ranger]

Re: 84 Mercury 150 blackmaxx clunk and grind

thanks guys.....I look into it and keep yall posted.....thanks again

 

[j_martin]

Re: 84 Mercury 150 blackmaxx clunk and grind

Hi there everyone.....I have a problem with my 84 mercury 150 blackmax that when shifting into gear it really grinds and makes clunking noise....clunk noise sound like the prop was hitting bottom but it not.....sometime when shift into forward there will be some clunk noise like metal bang and jerk that whole boat like it trying to engage and I have to keep trying until it engage and it will shift into gear....im not shifting into gear slow but that noise Im hearing tell me something is wrong.....than yesterday i took out the boat and it did it again and this time it will not go in gear at all in forward or reverse...but will grind really bad and at time will engage into gear but will still have the grinding noise......even in netural there will be a loud rattle/knocking noise like a rod knocking ......and than it die. I try to start it the motor but it will not crank as the motor will not turn at all.....starter engage but the motor will not turn..........so loaded the boat and came home.....once i got home I try to start it again and it started but still with the same rattle/knocking noise....noise seem to be coming from the lower end.....and will not shift into forward and reverse...just grinds really bad....any ideas on wut could it be.......broken shaft.....????????

I HATE IT WHEN IT DOES THAT!!!

 

[84Ranger]

Re: 84 Mercury 150 blackmaxx clunk and grind

I took my lower unit off and start the motor and the knocking noise is gone.....
ran it for 10 second....no noise........rotate the driveshaft and it will not turn freely.....but will turn with some force and u can feel that the gear is either broken or something came apart......even when shift into forward and turning the shaft u can feel the gear slipping and the prop will not turn...so the gearing is broken....well how how do I take out the drive shaft...remove the water pump and it will not come off.....should the bearing be remove first or is there something else I miss.....or do it need a puller

 

[BF]

Re: 84 Mercury 150 blackmaxx clunk and grind

something else I miss.....or do it need a puller

Hi again,

What you need is a service manual. The merc one specific to your motor is best, but you can also get a more generic one. I have a seloc one, and it's not bad. Often the pict's are of some other model, but the point is the same.

No you don't pull the driveshaft out. You have to remove the bearing carrier (the one around the prop shaft), the reverse gear/bearing, the prop shaft. Then you need to remove the pinion nut on the bottom of the driveshaft, then the pinion gear, then the driveshaft will pull out. Then you can remove the fwd gear and bearing.

Some special tools are needed for several of these steps, but if you're persistent (=stubborn) you can bodge together something that will work. It can be slow and frustrating. You need a manual, then you can decide whether you're still in your comfort zone to proceed.

Good luck.

Oh, and were there chunks of metal, or lots of filings in the oil?