Engine won’t go into drive after hitting sand bar

[jpormen]

I have a 1992 20 foot chaparral with mercruiser 5.0 alpha 1 outdrive not sure if it’s gen 1 or 2. Boat only has 191 hours on it

Last weekend i hit my prop on the sand bar, i immediately shut it up. When i went to leave i push boat out into deeper water, it fired right up but would not go into gear and sounds like i have a knocking noise towards the back on the motor/drive area. I pulled the prop and the hub is fine and the prop shaft spins true and no play. It would shift into gear on the water and stay running but the prop wouldn’t spin. When i got home the next day, the boat started fine but now when i try to shift inot gear it dies. I noticed today that there is fresh metal shavings under the starboard side of the motor. Here is a video where you can kind of hear the knocking noise. I’m trying to narrow down what it can be so i can decide if i want to try to tackle this my self or find a shop.
https://youtu.be/Y2RzPUmxkX0

 

[Bt Doctur]

guessing you took out the coupler

 

[GA_Boater]

Probably stripped the splines out of the coupler.

A wee bit of advice - The fire extinguisher under the doghouse isn't a good location. If you ever need to use it for an engine fire, are you going to reach into a ball of fire to get it? And if the motor is running, a panic situation isn't a good time to sticking hands and fingers near spinning pulleys and belts. It looks like it should be checked to see if it's still charged, too.

Back to your toothless splines.

 

[jpormen]

Probably stripped the splines out of the coupler.

A wee bit of advice - The fire extinguisher under the doghouse isn't a good location. If you ever need to use it for an engine fire, are you going to reach into a ball of fire to get it? And if the motor is running, a panic situation isn't a good time to sticking hands and fingers near spinning pulleys and belts. It looks like it should be checked to see if it's still charged, too.

Back to your toothless splines.

i actually have three other exitinguishers on board, the last owner went over board. Two of the floor are still charged in good. I haven’t checked the other two. i will check the one in the motor to see if it’s even good anymore.

Is the coupler hard to replace? I’m assuming I’m have to pull the drive?

 

[Bt Doctur]

shift into fwd and remove the drive , look for long aluminum needles stuch to the input shaft by the grease.
Then get a flashlight and look in at the coupler, you should see the splines if there are any.
Prep motor for removal, lift up ,remove rear housing, read bushings and replace the rear bushings. There the leading failure from misalignment remove flywheel bolts and remove and replace coupler or remove the 3 mounting bolts from the flywheel and replace the coupler. Install engine, realign, install drive

 

[alldodge]

Looks to me as a halon extinguisher, has a heat sensor to set off

 

[jpormen]

Can y’all give me a rough guestiment on what a shop might charge to replace the coupler? If it involves pulling the engine and the drive, it’s more of a project than i want to tackle.

 

[Rick Stephens]

Can y’all give me a rough guestiment on what a shop might charge to replace the coupler? If it involves pulling the engine and the drive, it’s more of a project than i want to tackle.

Kind of depends on the shop and how hard it is to get the carpeted stuff away blocking access to the back of the engine. With access to the motor, it is about an hour out and an hour back in. Can be less even, last time I did mine in 45 minutes total, out and back in and fired up, but I had just installed it and had all the tools and the tractor sitting there. There are other variables as well, like the risers get pulled off and we find erosion of the water jacket, or pitting that needs a lot of cleanup to reinstall. Or the rubber connectors are burnt a bit from a past overheat. Or exhaust shutters toasted. Stuff like that can pop up making the repair get costlier as a mechanic does a simple coupler.

 

[jpormen]

Kind of depends on the shop and how hard it is to get the carpeted stuff away blocking access to the back of the engine. With access to the motor, it is about an hour out and an hour back in. Can be less even, last time I did mine in 45 minutes total, out and back in and fired up, but I had just installed it and had all the tools and the tractor sitting there. There are other variables as well, like the risers get pulled off and we find erosion of the water jacket, or pitting that needs a lot of cleanup to reinstall. Or the rubber connectors are burnt a bit from a past overheat. Or exhaust shutters toasted. Stuff like that can pop up making the repair get costlier as a mechanic does a simple coupler.

If i knew it was 100 percent the coupler and nothing else i wouldn’t mind trying to tackle it. I just don’t want to spend 3 days tearing into it and not realizing that something else is messed up. If i can get a shop to do it for Under $1000 I’ll be pretty happy.

 

[alldodge]

It doesn't take 3 days of tear down, the motor comes out as one unit after disconnecting, hoses, wires and cable, then front a rear mounts. The flywheel cover is removed and then the coupler

Sence all the noise is gone with the drive off, it could very well be in the bearing or drive and not the coupler.

 

[Rick Stephens]

So two ways to go at this - either you want to service and maintain and repair your boat or you want to pay someone. I don't see it being feasible to straddle that fence for very long. If you do it yourself, you need a few special tools, an alignment bar right out the chute. And right now, to make a decision easier, you need to take a look at the drive shaft and see if the splines are full of metal and grease mixed into a paste, and use a flashlight to look though the gimbal bearing and see if the splines are existing on the coupler end. All suggestions that were recommended earlier and allow you to know whether or not you're likely to need a coupler.

If you're going to take it to a shop, then all this discussion is somewhat moot.

 

[jpormen]

Well i did some research today and found out the drive is incredibly easy to remove. I had mine off in about 5 mins with no issues. First time ever removing an outdrive.

Unfortunately it looks to be the engine coupler. There were no noticeable shavings but the shaft teeth you could tell have been rubbing metal and there was no teeth inside at all and you can tell where they were rubbed down. I tried to get a photo. The gimbal bearing looks fine and spun free. The u-joints also appear to be fine. I am goin to call some local shops and see what kind of pricing i am looking at for a shop to do it. I do have some family and friends willing to help me replace coupler if shops are too expensive


On the way down to the lake we got in a wreck and the boat shifted forward about a foot on the trailer but did not cause any damage to the boat that i have found yet. Do you think that cause the motor to get out of alignment? Or was it probably me hitting the prop on the sand bar?

 

[alldodge]

On the way down to the lake we got in a wreck and the boat shifted forward about a foot on the trailer but did not cause any damage to the boat that i have found yet. Do you think that cause the motor to get out of alignment? Or was it probably me hitting the prop on the sand bar?

In most all cases the coupler goes slowly over time from lack of maintenance. The drive should be removed every year or at least every 2 and inspect it, change fluid and check alignment. Yours hasn't been done in a while so it just gave up.

The wreck didn't help but should not have changed anything, but the sand bar probably finished the job, due to it was so worn at the time

 

[Rick Stephens]

Definitely falls into the realm of stuff that just happens around boats. Nice part of just replacing a coupler is you don't need to be set up to remove the motor from the hull altogether. All you need is disconnect it, pick it up and move it far enough towards the bow to turn it and pull the flywheel cover. Lots less required in the way of movable lift capabilities.

 

[Bt Doctur]

Without removing the drive yearly you will never know about the alignment until its too late. Misalignment from:
rotted stringers, rotted transom, transom flex
failed rear motor mounts
failed front mounting nuts, loose front mounting nuts

 

[jpormen]

I call a few shops and they are saying 1200-1400 for parts and labor. I have an uncle who is a mechanic and is willing to help me pull the motor and replace the coupler. I know there are two style of couples. My motor is a 1992 mercruiser mcm 5.0 serial oD827519, i believe i need mercruiser part number 18643A7. Which is the triangle style coupler. Can anyone help me verify this? Also I’m seeing alignment bars for like $20-30 bucks? Is this about a standard price?

 

[alldodge]

Your correct on parts, and do believe you can also use the full round one 8M0098795 but unable to verify for sure. Think the triangle was replaced by the round. So far as the alignment bar, the price is right, just make sure your buying one (if from ebay) that has sold a lot of them with good feed back

https://www.mercruiserparts.com/bam/subassembly/31719/1014/270

The link above shows both couplers for the serial number range

 

[nola mike]

Doesn't look like that drive shaft has much grease on it...when was the last time it was off/serviced?

 

[jpormen]

So i got my alignment tool delivered and my new coupler. I will be tackling this project with my dad and uncle on Saturday using annover head hoist at my dads factory. My uncle was curious if we need to replace any seals or gaskets when we pull the motor? Such as the exhaust gasket or anything else? I did order a new outdrive gasket. Any tips or tricks to make this job go smoother?

 

[wellcraft-classic210]

Not aware of any engine gaskets being required assuming your not pulling risers etc.


--If their is any surface rust where the rubber exhaust coupler's go it can cause small leaks // best to repaint if needed or at-least wire brush.

--Its a great time to fix any oil leaks and or aged rubber hoses // Whats the age of bellows set and impeller ?

--Separate front engine mounts at large nuts -- ( avoid the turning the lag bolts into the stringers )

--Take pics of any wiring an d mark the wires well for re-assembly

The experts my have added tips --