Engine Coupler Problem?

M

myoldboat2

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Joined
Jun 3, 2007
RO Number
26606
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135
Hello -

I have a 1970's Mercruiser 140 hp with a Mercruiser I (or maybe I-R) outdrive. After starting for the frist time since winterization last fall, the drive wouldn't shift into forward or reverse, there was a thumping noise from the rear of the engine, and the engine temp started climbing. I was able to determine that nothing in the outdrive was turning. By watching the splined shaft that connects the outdrive U-joint to the engine coupler, I could see that it was basically not turning--just erratic movement, maybe turning 3/4 turn in 30 seconds. I removed the outdrive. The U-joint and splined shaft look OK. The outdrive seems to work fine in forward and reverse when I turn the U-joint by hand. When I run the engine with the outdrive off, it runs great, and there is no longer any thumping noise.

Do you think the engine coupler has failed? Or could it be something else, as scary as the end of the crankshaft breaking? Do I need to pull the engine to even be able to inspect the coupler?

Also, does it look like the splined shaft was inserted far enough into the coupler? Some of the splines were showing. I have read that the wrong combination of drive/bellhousing/transom can result in not enough spline engagement, but I'm not sure how far it should engage.

Thanks in advance for any advice you can offer.

My advice to you would be to stop posting garbage links. I'll be too happy to just erase anything you might have to say if you don't.
 
Hi. I have a 1991 Merc 4.3L with Alpha 1 gen 2. When the boat was 3 years old, my coupler went out. The engine had to be pulled to repair the problem---a very expensive repair! While doing some research, I discovered that Merc had discontinued the zert fitting which lubed the coupler in 1991. We installed an aftermarket zert fitting and have had no problems since. Make sure that coupling gets lubed every year!
 
Good pics for a change...your drive coupler is toast. The little metal shavings in your drive shaft splines are whats left of your engine coupler. The drive shaft splines are hardened steel...the engine coupler is aluminum. You did pretty good getting this much time off it...I'd also check the engine alignment, that driveshaft should be all-in when connected.

Engine has to come out for the coupler replacement.
 
Thanks for the quick replies, guys. Assuming I can borrow a hoist, do you think pulling the engine and replacing the coupler is something I can do myself? In the past, I have pulled the lower unit, replaced the water pickup pump, removed and cleaned the engine manifold, replaced the exhaust shutter, pulled the carb, pulled the engine water pump, replaced the fuel tank and lines, and reworked the electrical system. These things seem to be pretty easy compared to pulling the engine.

I have a friend who owns the tools needed to reinstall the outdrive. I think that includes the engine alignment tool, but I'll have to check with him.

Normally I would take this in, but it's spring so the marina is very backed up, and I'd like to have the boat working 10 days from now. And it'd be nice to save some money.

I have the Mercruiser repair manuals and a Clymer manual.

Thanks.
 
Yup, That's an oldie. Is that some kind of early deck boat or something?

More'n likely you spun the hub or splines. In any case you'll have to pull the engine. You've done enuff that you would be able to tackle the job. a 4 cylinder is light enuff that you'll be able to fab a frame outta 4x4's.
 
This thread deserves an award.....That is the best asked question I have ever seen - pics and all! Nice...
 
Thanks for all the replies. Our boat is an old pontoon boat. We like the 140 because it allows us to pull kids on a tube, skis or a wakeboard.

(edit: Cleaned this up--I've ordered a drive installation kit with the gaskets and o-rings, plus new nuts for the coupler, drive mounting and trim cylinders. And I ordered a new V-belt, as long as the engine will be out.)

About 3 years ago I had a mechanic replace the belt. I assume he had to loosen one front engine mount. I know he did not pull the outdrive. Would his replacing the belt have messed up the engine alignment? (Yes, I have not had the alignment checked each year--I am a very bad person... I believe I will be doing that each year from now on.)

That's all for now. :)

Thanks for the advice.
 
Good questions and good answers so far. I would think that from what you have been able to do so far you could replace the coupler yourself. I have replaced one and pulled an engine twice. I found a simple engine hoist rented from a tool rental place worked on my 21 foot cuddy cabin with a small block V8 when it was on my trailer. They can often get under the boat -- but over the gunnel --- just take some measurements and go find a rental unit. Do the normal things for moving any engine -- making sure you don't move it so far to break any wiring or hoses, you may not have to totally disconnect everything. There is no need to lift it very far or out of the boat. The bolts holding the engine down have washers under them -- don't loose them and make sure to get them back correctly. Get a basic Mercruiser manual if you don't have one from an aftermarket source. I would use loctite on the coupler bolts, and torgue them properly. If you do it all well you should probably never have to do it again. If all is in alignment it should last 5-10 years, or maybe even more, but a filed coupler is not uncommon. Good luck in your project.
 
Thanks for the input, DaleG. I've located a local rental hoist, or I may build one out of wood as suggested by jtybt. As long as the engine is up, I'm going to put on a new starter and an oil drain hose, so I may want to take my time with my own "hoist" (it will be plenty strong). The new coupler nuts (#11-34933) are those elastic stopnuts--would you still loctite the metal threads? I do use a torque wrench for all of these things. I'm really anal about that.

I'm pretty confused about the stern drive model number. I see information on "I" drives that says through the early 1980's. Then I see listings that say the "I" was only from the 1960's, and that mine is a "120/140" sterndrive defined based on serial number. The manuals I have say that the "I-R" wasn't put out until 1984. So I've assumed my 1970's drive is a "I". Does any of this make sense?
 
1970 120/140 is an typeI. On the port side of the upper drive case, just above the upper/lower separation, you may have a couple SS screws that look like the fill/vent screws. That would ID the drive as an earlier typeI, when both cases were separate(not connected by an oil passage). One screw IS a vent for the lower case, the other screw locks the water pump body in place.
 
Thanks. That would make sense. I believe this is a 1974 sterndrive. Based on your reply and a page in the Clymer manual, I think it is the "Late Model I". My sterndrive has an oil passage between the drive housing and the gear housing (I remember putting in the small seal when changing the water pump). The Clymer manual shows a sketch of the two different bell housings, and mine matches the "Late Model I Bellhousing and Gasket", and uses only one gasket instead of two. So I guess the correct name for my sterndrive is "Late Model I". Great! I've always wondered about that.

I've been reading the manuals in advance (it's been raining here) and I have another question. The Clymer manual (which I sometimes don't trust) says to use water-resistant gasket sealant on the drivehousing/bellhousing gasket, but the Mercruiser manual doesn't mention sealant. Should I use sealant, and if so, which do you recommend?

Also, for the 2-4-C Marine Lubricant and Engine Coupler Spline Grease, do you use the Mercruiser/Quicksilver products or another brand? I usually try to stay with the original products, but I don't know if I can get all of this from the local marina (and of course I forgot to add them to my boatfix parts order).

Thanks.
 
Yup! I noticed you have the removable strainer on the raw water intake which comes on on the later typeI and alpha/mr models,too.

Use a light smear of ultrablack silicone gasket sealer on the gaskets but if the surfaces are clean and smoothe, you don't need it but yours has some age to it.(I have a '73 and '78)

I've bought 2 tubes of 24C over the last 18 years so a tube lasts a long time. I once bought one tube of merc spline grease but at $25, never again. You can get it from boatfix for around $7-$8(sierra brand)
 
And just to answer a previous question -- No I would not use loctite on a Nyloc nut --
unless I have reused that nut, which is not supposed to be reused, quite a few times so the Nyloc isn't doing anything -- now who would do that???
good luck
 
Not checking and adjusting the alignment could have easily hastened the couplers demise. When you put the engine back in, make sure you replace all the rear engine rubber mounting hardware.
 
Thanks for all the replies.

I'm having a hard time figuring out the engine mount drawing (below). Only part #43 is listed with the word "Rubber" in the part name. Which are the rubber mounting parts?

Also, is there a way to "convert" the Mercruiser part numbers to equivalent Sierra numbers? I see some engine mounts on boatfix.com, but they come up "pg. 0".

Thanks.

CRUISER6857315.GIF
 
#19(2) are the rear motor mounts. There's an inner and outer steel sleeve with a rubber insert between. There are two versions of the rear motor mounts. The inner sleeve is knurled on one version. You'll have to look up the application.
 
Thanks. I guess the left and right mounts really are different. Here is what I've found for #19:

32832 MOUNT, FLYWHEEL HOUSING (LEFT) $39 / boatfix $31
Is there a Sierra or other aftermarket for the left engine mount 32832?

99297A1 MOUNT, FLYWHEEL HOUSING (RIGHT) No longer made, limited availability $25 / boatfix $24
-- order 865329A02 $33 / boatfix $26
Sierra Part Number: 18-2193 boatfix $17

They tried very hard to make these motor mounts very confusing.

Should I replace the rubber mounts in the front? Is that just:

#30 Mount, Front Mounting Bracket $23 / boatfix $19
Is there a Sierra or other aftermarket for this?

#43 Washer, Rubber - Front Mounting Bracket Adjusting Stud $2.50 / boatfix $2

Last question -- I really should replace these rubber mounts, right? I suppose it doesn't make sense to go through all this and plop it down on old mounts. But the cost is adding up... :(

Thanks.
 
Sorry for adding another reply, but I'm trying to plan the job. Here is what I plan to do with the engine out:

1. Coupler
2. Starter
3. V-belt
4. Oil drain hose & oil filter
5. Motor mounts

Is there anything else obvious that I should do while it's out?
Just fyi, I had the manifold and exhasut elbow off recently and cleaned them out.
And the exhaust shutter is new.

A dumb question... does anyone ever wire an extra v-belt into place so if one breaks you can get the spare on without pulling a front engine mount? Or am I missing something about how the belt is replaced with the engine in place?

Anyway, the motor mount questions are probably more pressing for me at this time, but I thought I'd get these out there.

I'm starting to understand why some of these jobs cost a grand or two at a marina...
 
I've replaced the rear mounts a couple of times but I don't remember them costing so much or any difference in left/right. I'll do some investigating and get back to you. I get the kits which include all parts(bolts and washers)
 
Sounds good. I looked at some of those kits but didn't see the actual rubber mount in them. I will wait for your next reply.

Are the front mounts not usually replaced?
 
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