Thought it was the coupler, but now...?

[Augie56]

Mercruiser MC-1, 1979 vintage, with GM 305 V8, 228 HP

Long story short, last time out on Lake Erie the driver of my boat ran the outdrive into rocks and after the last *bang* happened, the engine spun up freely and no more forward or reverse. Luckily, my brother was behind us by a few minutes with his boat and was able to tow us in.

At first, I thought it was the coupler. I was able to run it on muffs at home, but I only ran it for a minute because I saw that it wasn't taking any water in. After shutting engine down, I engage forward and reverse from the controls, and each time the prop would click in one direction and lock in the other. I though, great...outdrive is OK, must be coupler.

Yesterday, I began disassembly of the stern area of boat. Removed batteries, and all other fiberglass sun platform pieces. I was able to inspect the coupler, and it felt intact. So I then made a mark on the input shaft (inserted into the coupler) and repeated the same test engaging forward and reverse and trying to rotate prop by hand. This time, same clicking but I was able to budge the prop in the opposite direction. No grinding noise, but a faint groan could be heard when rotating prop in the locked direction. Each time I did this, I went back into the boat and checked the input shaft position, and it never moved.

So I'm now thinking something did break in the outdrive, but I don't think it's anything that has to do with the gear shifting. My question is : what is the most likely thing that would've broken free? I'm going to drain the outdrive and take the lower unit off tonight (shift FWD completely first) to see if I can determine what let go. Ideas? Suggestions?

In one breath, I'm relieved I probably won't have to pull the engine, but in another breath I'm thinking an outdrive repair may cost more than a new coupler. Oh well, Break Out Another Thousand, right?

 

[81 Checkmate]

Re: Thought it was the coupler, but now...?

I would first pull the top cap on the outdrive and look at the gears...
Drain the outdrive fluid and check for metal.....

Then go from there....

A outdrive is proly gona be cheaper than the coupler. If it's a coupler you have to pull the motor to replace.

Let us know what you find!

 

[TilliamWe]

Re: Thought it was the coupler, but now...?

an outdrive repair may cost more than a new coupler. Oh well, Break Out Another Thousand, right?

Technically it'll cost more, but it will be a lot easier and faster to replace a drive than replacing a coupler. $1400 SEI brand new replacement drives, sold right here on iboats. 3 year no-fault warranty. Hitting that object the next time is even covered!

 

[haulnazz15]

Re: Thought it was the coupler, but now...?

The only caveat that I would add it that the coupler isn't likely to spin while the boat is on muffs, there simply isn't enough load put on the input shaft when out of the water. The other item you might check is the prop hub, to ensure you didn't spin that either.

 

[Augie56]

Re: Thought it was the coupler, but now...?

Thanks for the replies, guys. I would think that prop hub and transmission shifting is all OK with putting it in forward and reverse and checking prop rotation (proper clicking in one direction and engaging in other when rotating prop by hand). I know for certain that the impeller isn't spinning when on muffs, which means one of the two main vertical shafts (one in each half of case) isn't spinning.

A lot less labor (for me) to remove and repair an outdrive than it would be for me to pull the engine...but the cost of whatever broke will certainly be more than a $175 coupler.

 

[MarkSee]

Re: Thought it was the coupler, but now...?

At first, I thought it was the coupler. I was able to run it on muffs at home, but I only ran it for a minute because I saw that it wasn't taking any water in.

...so in addition to the other comments, if you weren't getting any water going through for "a minute", could the shaft turning the impeller be bent but regardless, running for more than several seconds destroys the impeller.

Hopefully the hit did not rip apart the water connection inside the bellhousing and it really is just a SEI drive you need.

Mark

edit: guess I took too long typing that and you posted about the impeller

 

[HT32BSX115]

Re: Thought it was the coupler, but now...?

A outdrive is proly gona be cheaper than the coupler. If it's a coupler you have to pull the motor to replace.

Um, last time I checked, a coupler can be bought for a "coupl'a" hundred dollars......... I don't think you can buy a drive that cheep!

If you're going to replace a drive, and pay someone to do it, it won't be just the cost of the drive there'll be labor there too......

You can EASILY R&R an SBC in your garage by making a simple hoist using 4x4 lumber etc......

Long story short, last time out on Lake Erie the driver of my boat ran the outdrive into rocks and after the last *bang* happened, the engine spun up freely and no more forward or reverse. Luckily, my brother was behind us by a few minutes with his boat and was able to tow us in.

Now having said all of the above, you don't always "spin' a coupler when you drive the drive into the rocks. But if you have not checked the alignment or lubed the splines in many years and there's even a question on the coupler, I would replace it along with the new drive.

My last one (coupler) went 39 years before failing with no warning at the lake. They don't last forever!

I would think that prop hub and transmission shifting is all OK with putting it in forward and reverse and checking prop rotation (proper clicking in one direction and engaging in other when rotating prop by hand). I know for certain that the impeller isn't spinning when on muffs, which means one of the two main vertical shafts (one in each half of case) isn't spinning.

Something is broken inside the drive. You'll be replacing/rebuilding the drive. The SEI is a pretty good choice.

 

[Augie56]

Re: Thought it was the coupler, but now...?

Thanks for all the advice. I do know that with running the engine on muffs, ALL of the water is pushed out from under the muffs...none of it is getting drawn up into the engine...that tells me the impeller is not spinning. And since the impeller was relatively new and working 100% at the moment just before the accident, I strongly believe one or both of the vertical shafts in the outdrive is not spinning with the engine. Also, forward and reverse engage correctly, but with engine running, there is no engagement noise and no prop motion...again, outdrive gears are not rotating with engine.

At first, I thought coupler. But after observing no input shaft rotation after manually rotating prop with forward and/or reverse engaged (against the engagement direction...which I shouldn't have been able to do in the first place), I'm almost certain something is busted in the outdrive...sheared splines, broken gear, spun hub, something....I'll know more when I remove my damaged prop, and then if necessary, remove the outdrive.

 

[81 Checkmate]

Re: Thought it was the coupler, but now...?

Um... yea a coupler is around a couple hundred dollers...

But not or have the facility..nor the know how/tools..ect to pull a motor to change the coupler! But end up having to pay the labor for someone to do it..... But one can replace the outdrive fairly easy with a new SEI or used drive.

 

[TilliamWe]

Re: Thought it was the coupler, but now...?

If you're going to replace a drive, and pay someone to do it, it won't be just the cost of the drive there'll be labor there too......

You can EASILY R&R an SBC in your garage by making a simple hoist using 4x4 lumber etc......

Paying someone to unbolt 6 bolts and the pin through the rams is pretty pointless. (and not that expensive) And that labor is WAY easier than making a hoist with 4X4s etc...

 

[Augie56]

Re: Thought it was the coupler, but now...?

I really would much rather work with removing/replacing a lower unit, upper unit, or both RATHER than pulling a 900lb boat engine.

I'll now more tonight when I drain the outdrive gear oil and have a look at upper unit gears and prop hub. The more I read up about this problem, though, the more I really doubt it's a spun prop hub or coupler. With the engine running, I get *zero* cooling water movement, no shift engagement in FWD or REV (no prop motion or "clunk") and no unusual gear noise. With the engine off, I can engage FWD and REV with no problem. But when counter-rotating the prop by hand in gear (against gear engagement), I am able to turn the prop using a bit of force. This leads me to think maybe I have a weakened prop hub ALONG WITH a broken gear or shaft somewhere in the outdrive. I'll have to mark the prop and hub before testing in gear tonight to know for sure. Stay tuned...

 

[FLAT RATE]

Re: Thought it was the coupler, but now...?

I think the MC-1's have a "break away" spot on the verticle shaft near the water pump, a spot that is machined a little smaller to act as a sacrificial joint as to not cause any other damage in the drive. Had one several years ago and that was the issue.

 

[Augie56]

Re: Thought it was the coupler, but now...?

Thanks, FLAT. I found the symptoms in this thread to be identical to my problem :

http://forums.iboats.com/mercruiser...er-outdrive-doesnt-engage-problem-582287.html

 

[skyking897]

Re: Thought it was the coupler, but now...?

Suprised no one asked, but what about your insurance?

 

[Bondo]

Re: Thought it was the coupler, but now...?

I think the MC-1's have a "break away" spot on the verticle shaft near the water pump, a spot that is machined a little smaller to act as a sacrificial joint as to not cause any other damage in the drive. Had one several years ago and that was the issue.

Ayuh,.... Right Idea, wrong area, 'n reason though....

My guess is the vertical shaft of the lower unit, Snapped off at the upper o-ring groove....

Drop the lower unit, 'n you'll know...

 

[Augie56]

Re: Thought it was the coupler, but now...?

Thanks to the insight. I took advantage of the mild weather lately to get some other things done outside....I haven's disassembled the outdrive yet. If it is, in fact, a snapped lower unit vertical shaft....is the shaft something I can replace myself, or am I looking at either a new lower unit (SEi) or having a marine mechanic rebuild mine? Just wondering how much Christmas money I need to reserve to get this done!

 

[Bondo]

Re: Thought it was the coupler, but now...?

Thanks to the insight. I took advantage of the mild weather lately to get some other things done outside....I haven's disassembled the outdrive yet. If it is, in fact, a snapped lower unit vertical shaft....is the shaft something I can replace myself, or am I looking at either a new lower unit (SEi) or having a marine mechanic rebuild mine? Just wondering how much Christmas money I need to reserve to get this done!

Ayuh,... I doubt you'll be rebuildin' it yerself,...

Lotsa Special Tools needed...