How To Replace Engine Coupler Mercruiser

This is a step by step as best as I can make it on how to replace the engine coupler, sometimes called a drive coupler, in a mercruiser powered boat. This process will be generally the same for all mercruiser engines.

[@Arcturian1111]

I had a very weird knocking noise that came from the flywheel/ coupler area with the sterndrive off. It turned out, I had two loose coupler nuts/studs. I have a Merc 3.0 IO. , this video helped me out tremendously. Thanks again.

[@JC-uh6dy]

Great video, thanks for the info. After thinking I had a spun hub I realized it was bigger then that and found out I also had a bad coupler. So now I’m forced to take apart everything you did and thanks to your great video it’ll make it a lot easier. Thanks again

[@thestigmach1984]

Glad ik could help any questions feel free to ask and I'll do my best to answer

[@johnhuizinga5309]

Awesome video taught me everything I needed to learn about that out drive and motor coupling ... very clear and explained every thing very well. Thank you for this video I really appreciate it!!!

[@leonardrice2830]

Awesome real world experience you've documented!👍

[@dryan8377]

God bless you for this. I have to go thru this exact same procedure to replace my drive flange on my mercruiser 898, with a perfectly running chevy 305. Wow. Now I know exactly what to expect. Thank you so much for your dedication to help others!

[@thestigmach1984]

Happy I could help you

[@dryan8377]

@@thestigmach1984 Finally got it done in an hour yesterday. I built a six foot wide wooden gantry out of doubled 2x4's, with a harbor freight chain hoist. Took me a while to figure out it was a two piece boat, so I had to cut out the top of the back end (which is hidden with a flip up top cover). Removal and reinstall was surprisingly easy!

[@davesenor3146]

Awesome video! Just found it. Swapping out engines on my sons SeaRay. Just got the bad engine out and will be installing the new used) one. This will help a lot.

[@davelambardo6464]

Very good video overall. Clear camera work and complete descriptions. I am in middle of a 4cyl. Oil leak and this video has been helpful for tear down

[@nelloagostini4389]

good video lot of useful info, good on you for putting the flywheel back in the same position. A lot of people don't realize that the entire rotating assembly is balanced including the flywheel and balancer they mast go back in the same position.

[@rastagrastag9496]

Very informative thank you so much for being so detailed 👍👍👍👍👍👍

[@aarondunne3519]

Hell Yes!! Thanks for giving me the confidence to tackle this!

[@melbigelow1200]

Found my rear motor mount loose enough to turn on 1990 454 Bravo 2, thank you! never seen the backside of our engines! Now I just need to figure out my next step!

[@davidg1950]

Did you have a bad motor mount or a problem with the support system under the metal motor mount. Or was the mounting bolts just loose?

[@mrpaom0307]

Thanks for sharing your knowledge! ❤

[@crisprtalk6963]

great video man! Thanks.I really wish you had a tripod for the camera. One day I will need this.

[@jkgkjgkijk]

I learned so much from this. You rip the mask off the hidden crap that is a mystery. Thank you!👍

[@leesire]

Thanks so much for making this diy video. I’ll need it. I just bought a 87 Thunder Craft with a 120 hp Mercruiser. I don’t know if the boat floats or runs. I know, crazy. I knew better too. Just loved the boat!

[@thestigmach1984]

I've been there. My first boat was like that. Good luck

[@leesire]

thestigmach1 Was there anything else wrong with the boat? Did you use it last summer?

[@thestigmach1984]

@@leesire needed floor replaced. I used it two summers then traded it for a bigger one. Was very reliable

[@leesire]

thestigmach1 congratulations!

[@gregangulo7439]

I like all your explained thanks

[@closniev2939]

Easiest way to install and remove studs with out a stud remover or installer is to use 2 of the nuts you already removed. Install the 1st in the opposite direction and 1 in the regular direction so that they mate together. Tighten them against each other use a wrench on the inner 1 and you are all set the stud start to rotate. No special tools needed and the stud can be reused and reinstalled in the same manner

[@davidg1950]

GREAT job on the video and very in-depth. I do wish I had seen you remove the engine. But there ar other sites that show that process. I have a 1991 Mariah 1900Z 19 foot with a 4.3L and when I got it I knew it had a bad coupler. I contacted a Marine parts supply and was told from my Serial # that mine had the Triangular Coupler. And from another site I found that if your drive shaft only has 2 O-rings that it will not accept the triangular coupler. So don't take a parts seller's word as gospel. They make mistakes. My problem was caused by a rotten motor mount support. And also from a very poor job of trying to fix it by a marine repair shop. I wonder how many others have found crappy fixes done by marinas. I would like to here if any one else has had the same experience and how they fixed the bad support issue??

[@mechRuud]

VERY IMFORMATIVE , BEST VIDEO I'VE SEEN

[@riverlife2246]

awesome video thank you

[@eclipser2004]

Great video. very informative. Have to do a front crankshaft seal on a 135hp 4 cylinder mercruiser. Might as well do front base pan and gasket as well as timing chain I suppose. Maybe rear crank seal too- not sure. But the engine is coming out for the winter so might as well do all of it . It's 19 years old

[@Lonchpad1]

What did you find when replacing your front mail seal, Mine is leaking as well. I was thinking that it might be bad main bearings causing the front main seal to leak, Update?

[@eclipser2004]

@@Lonchpad1 No. Bearings are fine. This is a common problem with this GM based 4 cylinder. It is the old GM 2.5 liter 4 cyl bored out to 3 liters basically.

[@paulzarobell2753]

What about OMC 5.0 is it the same as fords 302

[@M4dex]

I’ve learned a lot thanks.

[@hunterm.172]

Any idea where I can get new flexplate/couple bolt? Two of mine snapped

[@bert5390]

Great video. I was trying to change the shift bellows by myself and got the shift cable stuck in between the coupler and bell housing. I have the engine ready to hoist up as that’s the only way I can think to get it unstuck. Will for sure need a new shift cable as I had to cut this one. Anyone ever had this problem or any advice? Thanks!!

[@grndhg86d]

Great video

[@DerekIwasiuk]

Very helpful

[@roocket6]

So you changed the pre-alpha transom gimbal assembly for a alpha one. but did you keep the mercruiser 305 230? I have a sea ray V225 cuddy but with a mercruser 305 next generation with the screws on top valve cover. I have problems with the hydraulic steering system. and last year I bought an alpha one setendrive. complete with transom gimbal assembly and trim pump but I only installed the outdrive; From what I could see it can be installed completely. Now I have to do some repairs to the transome. I have rotten wood and it needs to be repaired, in addition to some damage next to the drain plug that also needs to be repaired. then I will have time to install the alpha one gimbal assembly right? Tank you so much.

[@knowyuhgrow420]

Thanks for sharing

[@CodyEmersonFilms]

My prop will no longer spin enough to move the boat, I have very fine metal shavings in the bilge and a clanking/grinding noise coming from that area of the boat? Are these symptoms of a bad coupler?

[@eagle5720]

I have a 17 foot larson with a volvo penta 3.0 gs and volvo penta sx drive but i have a problem i want to fix, the gimbal need to remove and reseal cause i have a little bit of leak and i used some marine sealant n seal the outside around transome area but it work but when I work go in rough water n get alot of beaten it leaks again and other issue is where the engine mount screw down is sinking and did put a bigger bolt in it with some woodfilling. Want to take on the project but I think I'm going need atleast a second person on a project like this .

[@elizabethmetzloff720]

Nice video. You are in my neck of the woods. Like to redo my 3.7l engine and out drive . might have some questions for you.

[@robertadams8340]

Flywheel install? Can you explain the installation process.

[@willytv275]

Hi, I'm doing this repair now - on basically the same boat you have (mine is a 1983 SRV197). I noticed you pulled the carb off of the engine. Is that necessary?

[@KINGREABO]

I know that its kinda late but if you had taken a pair of vise grips and chomped down on the smooth surface on the engine side, then brace against something to keep the grips and or nut in place, then just unscrew it. The nut on the other side is a little harder in my opinion.

[@FawxNewsNetwork]

I wish you could fix my coupler🤷🏼‍♂️ experience is everything.

[@TMcD3]

Previous owner bagged that boat. Corrosion everywhere and SeaRays are notorious for rotted stringers.Was that coupler destroyed from rotted engine mount stringers? I like the newer SeaRays but buyer beware.

[@hunterm.172]

@12:30 it’s funny you say “The last thing you want is your Coupler coming off on you” lol I bought a boat and I suspected I spun bearing but come to find out two of these flexplate bolts had backed out and we’re laying in my pan and the fly wheel was hitting them making it sound like a bad crank bearing-I’m very surprised they werent any loctite/thread sealant and after seeing this video seems like that was just a standard thing to not add which is very surprising

[@davidg1950]

What year is your Sea Ray? I know that they changed the style of coupler around 1993 0r close to that. I have a 1991 and I also get conflicting answers to which coupler that it takes. Thanks for such a helpful video!!!! Keep up the good info!

[@thestigmach1984]

It was an 85 or 86 I believe. I dont have it anymore. There was conflicting part numbers for mine as well between the round one and the triangle one. I took my phone with video on record and stuck it back there to record what it looked like before I ordered parts. You can see what it looks like without pulling the motor

[@Hitech82]

The only time this happened to me the transom was rotted out causing engine to go out of alignment when under power.

[@croskey20101]

How long did this job take you total? Great video and saved it to my playlist of boat repair videos!

[@thestigmach1984]

Total of 10 hrs alone. I've done it in as little as 6 on one that was recently apart and maintained and in my own garage. Just because less fighting with stuck things and things not lining up and I know where all my tools are.

[@Rodman712]

Very good and helpful video. Do you know if the engine mounts in a 4.3 V6 boat will accept a 5.0 V8?

[@thestigmach1984]

Been awhile since I messed with that stuff but rear mounts for sure front mounts 95%. Google V8 swap S10. Same engine swap you're trying to do and will tell if front mounts need changed.

[@masonsebastaincomedy]

What year and what boat? Im getting ready to do this same project on a 1978 Bellboy with the 898 mercruiser.

[@thestigmach1984]

This was in a 1985 searay 19ft with a 230mercruiser. The process will be the same for all alpha and pre alpha drive mercruisers.

[@tshelton010]

When you took it out the first time and it was spinning but not going anywhere, did you smell burning rubber?

[@thestigmach1984]

I did not but guys I talked to said that can be a symptom of this. On mine the metal splines stripped out. If the rubber bit separated from the metal you could be getting rubber burning.

[@Tomsmus]

So loosening the 2 front engine mount bolts and the 2 in the rear allows the motor to just slide off the splines? I have to pull mine out and this I'm not sure about.

[@thestigmach1984]

Are you pulling the engine or the outdrive?

[@Tomsmus]

@@thestigmach1984 I pulled the engine. And have since reinstalled the replacement.

[@WarrenDJr]

When the engine was pulled out, did you bother checking the rubber mounts in the bell housing? Now's the Time to check and replace

[@thestigmach1984]

Yes I did. Mine were in good shape

[@willytv275]

Also, didn't mention this earlier - but I swapped the original MCM228 out for a 5.7 (350 CI) reman ten years ago and was doing great until I sheared the engine coupling last week. Newer engine has 450 hours on it and I have always checked alignment when I had the drive off and greased the splines regularly. Each time the alignment seemed to be pretty well perfect as I could push alignment tool all the way in with two fingers and minimal pressure. That said, when it sheared last week I was heavily loaded with six adults and lots of gear. I'm thinking that certainly contributed to the failure. Plus, I run a stainless prop (no flexing with SS) and the newer engine has quite a bit of power (~270 HP) relative to the lame 305. Besides what I mentioned above, is there ANYTHING else you can think of that may have caused the coupling to fail? I had ten relatively good years but I for sure don't want to go through this again.

[@thestigmach1984]

@@willytv275 being under heavy load I wonder if there's a weak spot in the stringers causes the engine to twist. They used these on big blocks before the bravo came out and still use them on the small block 350s with 260hp.

[@willytv275]

@@thestigmach1984 Hello and thanks for the reply. I wondered if maybe the engine is moving around some. However, I have tapped around on the flooring and the mount pedestals and all seems to be pretty solid. The boat is old obviously but has always been stored under roof and I open it up and let it dry out really well after each outing. I purchased some new rear mount bushings as those have never been replaced. I’m thinking that may be part of my problem. I plan to install them as soon as I get the engine out.

[@willytv275]

@@thestigmach1984 Hey, how are you doing today? Follow up to my last post - I’m expecting a new coupling to be delivered today. The one that failed was an aftermarket and this time I’m going back with OEM Mercruiser. Cost is twice that of aftermarket, but I want to get the best possible part. I’m planning to pull the engine this week and do the coupling swap. One thing to note, I did check my alignment yesterday and it is still spot on. Your comments regarding the stringers, do concern me, however. That said, since the alignment is still in good shape, I found that at least somewhat encouraging. Bottom line, I was overloaded and running a 21 pitch prop, which did not help matters. I should have switched to my 19 before that outing, or better yet, kicked a few people out of the boat. Please let me know if you have any other thoughts or advice…

[@meganperry5307]

Remember to position drive in forward gear for removal and installation. always use a new gasket and install dry, use a little grease on the O rings to hold in place, with all surfaces clean you will have a tight seal. The use of chaulk just makes it a B for the next guy.

[@thestigmach1984]

I've been using RTV on these for years and never have a leak and dont have a problem removing when it's time for maintenance. Theres a big difference between rtv and caulk. Seems like I mentioned the forward gear part but may have forgotten to say that.

[@meganperry5307]

@@thestigmach1984 I use the word caulk loosely, referring to any and all sealers/adhesives. It's just a lot of work to remove from surfaces, and I'm usually the one stuck doing it. I've installed many using quicksilver and sierra gaskets dry without any come backs.

[@thestigmach1984]

@@meganperry5307 with the black stuff I use it's a matter of tear it off. I've never had to actually use tools to remove the rtv. Everyone has a method but this is the method I found to work best

[@rickccorbett]

Just got a '98 SeaRay 250DA and experienced the same problem last night. About to attempt this repair and found your video incredibly helpful. Any major differences between 350 & 454 Merc? PS - I hope you invest in a tripod for future videos ;)

[@Natter20002]

I have that same boat. 454 B2. 1995 though.

[@marshall8898]

Is there a way to check coupler without removing engine? I have an omc cobra will only do 10 mph everyone keeps saying it’s the coupler

[@thestigmach1984]

@@marshall8898 not that I know of. Sounds like the coupler

[@PARKERBROTHERSPLUMBING]

How did you get the coupler off when the bolts are undone? mine are stuck

[@thestigmach1984]

Give er hell is the best thing I can give you. Luckily mine weren't badly stuck. You may have to find a way to wedge the flywheel so the motor doesn't turn while you are cranking on it

[@bradbenson1355]

thestigmach1, do you know if it's possible for that coupler to just kinda go bad? Everything I read says they are all or nothing. I developed a bad vibration and a tinkling sound coming from the rear of the engine. I pulled the outdrive thinking it was my u-joint or gimbal bearing, which I just replaced when I did the bellows, but they are both fine. When I reach around the back of the engine, the rubber ring part of the coupler is uneven, it sticks out more on one side than the other. When I bump the engine, the deformity moves with the motor. Can the rubber fail and let the splines shift? The alignment tool does not slide in. It goes in a little bit and makes the coupler clunk in and out about 1/8" when I push and pull on it. I'm sure the coupler must be bad but I hate to do all that work if that's not the problem. Thanks SO much for your super helpful video!

[@thestigmach1984]

It sounds like the coupler is going bad. I have heard of the rubber bit shifting from wear and age. Sounds like the engine is out of line as well. The part isn't expensive. Id put a new one in and make sure you have the engine aligned perfectly. May save you from being stranded in the water like i was with this boat

[@bradbenson1355]

@@thestigmach1984 Thanks! Through all of my highly scientific Google research, I couldn't figure out if it was possible for that thing to shift or not.

[@robrector9456]

I just came across this video my motor mout broke causing motor to lean heard a noise coming from coupler area pulled out drive off still here noise . will the coupler only make noise when out drive is hooked up

[@thestigmach1984]

A failed coupler yes. It could be hitting on the housing or even loose from the engine itself. Definitely need to pull the engine and have a look at whats going on.

[@robrector9456]

@@thestigmach1984 Thank you for the quick response I'll look into that I just hope the noise isn't coming from internally

[@johnwehunt4305]

Did you look at the triangle style coupler over the crankshaft mount coupler?

[@thestigmach1984]

They're a different style and length not swappable

[@johnwehunt4305]

@@thestigmach1984 Did you find out what the sbc 1 pc rms coupler part number? Their seems to be so much deceptive and secrecy to find correct part.

[@thestigmach1984]

@@johnwehunt4305 it's going to depend which one you have. Only way I know of is to shove your phone in there and video it so you can see if it's round or triangle. Then should be able to search for you r year and that style. Sierra marine is helpful even if you don't buy it from them. I don't remember or have those part numbers anymore

[@dennisbalsarick9727]

Great Job, Imformative, But Just a Little To Much Explanation for Me. I Guess Because I Have Some Knowledge Already 👍

[@rawebonics9914]

It always starts with I just bought this boat lmao

[@shawncharon6876]

Would a bad coupling give me a whining noise my boat sounds like it needs to be greased sounds like the baron is rubbing and it’s not the gimbal bearing Just had all that replaced The noise is coming from behind The bell housing

[@thestigmach1984]

Possible. Does it still drive? Odds are the coupler is fine if it still drives. The bearing may have been installed incorrectly. Was it aligned when the bearing was installed? Could cause some nasty stuff as well.

[@shawncharon6876]

@@thestigmach1984 It’s funny it only makes the noise when it’s in the water I can hook up the paddles in my yard turn the water on start the boat and it won’t make the noise it’s a whining noise I had the gimbal bearing and all new Bellows done this spring my gimbal bearing was fine but he replaced it while he had it open anyways The noise is coming from the area of the coupling around that bell housing it’s a loud whining noise there is a grease fitting on that shaft right before the bell housing i’ve tried grease in that too I just know pulling the motor is a big job

[@shawncharon6876]

@@thestigmach1984 it was making a whining noise before I had all that work done I thought maybe it was the gimbal bearing but obviously it wasn’t it’s still making the noise and I had a in-home boat mechanic come to me very well known in my state very recommended on Facebook so I know his work was good just couldn’t get the boat to make the noise in the yard when he was here like I said it only makes a whining noise when it’s in the water

[@Arcturian1111]

I'm getting a weird sound coming from the coupler area with the sterndrive off. Any greasing or maintenance for this? A Video of sound is enclosed below. Any ideas what this could be, the splines look fine on the drive shaft of the outdrive. The Inside of the coupler spline seem fine when feeling it with my hand. kzbin.infoejTgRw6c_rQ?feature=share

[@thestigmach1984]

Am I understanding right that the drive is removed from the boat? Sounds to me like ujoints but wouldn't make sense if it's removed. Unfortunately it sounds like it needs to come out and see what's banging around in there. Could it be low end knock? Hard to tell in a video.

[@Arcturian1111]

Stern was off. It was a loose coupler. I had to order a new coupler because a few of the studs got compromised from it being loose and the coupler holes were eggshaped from the looseness and friction. I'll need 2 studs now to replace also. There not cheap in price.

[@bwagenberg]

Do you own a torque wrench? How do you attach to an engine stand? Pretty good video. You had kids for a reason... to hold the camera, or rams.

[@thestigmach1984]

I do have a torque wrench but the only thing that would be useful for that is the cooler itself and theres no way of getting torque wrench on those bolts. What are you wanting to attach to the engine stand.

[@brandonprettyman269]

Reason it happened was probably because floor is rotten were motor is and engine become unsigned from sinking

[@tylermason218]

Boy hope you never have to replace that couple again using red loctite on those nuts. Shoulda used blue on the nut side

[@johnpritchett2330]

Would that being bad cause your engine to run hot to mine doind the same thing other than its cause engine to run hot

[@cliffsallee7717]

@@johnpritchett2330 Yours is probably a busted rubber inside the coupler and your not getting enough water from the outdrive up to the engine , Thats what mine was

[@chumrobarge1018]

All that gasket maker and you didn’t seal the shifter pivot

[@bodyshotjake7475]

What engine is this?

[@thestigmach1984]

Mercruiser 230hp the 5.0 v8 engine

[@bodyshotjake7475]

@@thestigmach1984 thanks

[@bodyshotjake7475]

@@thestigmach1984 what would a job like this cost?

[@thestigmach1984]

@@bodyshotjake7475 not sure never checked into it call around different shops to get estimates

[@davidg813]

Really need to get a tripod so that the people can actually see what you're doing ,, what good is a video if its goes like ..I wish I could show you this part but I can't.

[@thestigmach1984]

Come hold the camera for me so I can. Most other people seem to have figured it out and found it helpful.

[@davidg813]

@@thestigmach1984 it was helpful I was only suggesting that because it would be helpful more to be able to see and a tripod would serve that purpose free up both your hands I'm about to change out an engine a 305 engine and I have a lot of research even though I have pulled one before you can never know too much ,,the other one was a small 4-cylinder MerCruiser

[@brandonprettyman269]

Lol ready to roll your a fool for beleiving that look at that boat looks like previous did zero matienence to that thing

[@sosume5]

Everything but changing an engine coupler. 45 minute video with 40 minutes of boring waisted extra talk

[@thestigmach1984]

Can you make a better video?

[@heffedirte6243]

If it dries fast, put the lid back on it while you are picking up the camera and turning it on and talking. Good job besides that. I dislike waste

[@sarahbaines4951]

You talk too much

[@thestigmach1984]

Would you rather I not explain what I'm showing you?

[@TTURocketDoc]

Ignore this troll