1992 Marlin 3.0L OMC Cobra clanking noise when putting in gear

[1992Marlin3.0lOMC]

Hello all,

Forgive me if I am bringing up a topic that has been addressed, I recently purchased a 1992 Marlin 3.0L HO OMC Cobra from the original owner. I took the boat out and it clearly has an issue under load (the carb was recently rebuilt) but that is not my main concern. Every time I shift in gear there is a metal clanking noise that goes away once engaged. I am an automotive mechanic and I know it is hard to repair something you do not understand so I ordered the repair manual and I am planning on checking the oil in the drive and check for debris as well as check the shift linkage. The noise is rather alarming and greatly subsides when I remove the propeller, I greased the propeller and retightened everything and the noise didn't change. Below is a link to a video I created (sorry for the whining kid in the background). Below is the items that were replaced at a shop from 04/2013. I find it hard to believe the mechanic would have released the boat with these concerns as it was tested in the water and I heard the noise right away.
The boat runs fine in neutral with no noises, I am a big boy and can work on it myself with the manual but I am no boat expert. I am not going to take the boat out until I figure this out. I had a 1996 Chaparral 180 Le before and it never made this noise. The noise is present regardless if I slowly put it in gear or if I put in gear fast and is present in reverse and forward.

Any thoughts are appreciated, here is a link to my video: https://www.youtube.com/watch?v=ozglrT4bU-c&feature=youtu.be

Thank you all!

 

[alldodge]

No OMC expert but I know this one, it's the lower shift cable that needs replacing and adjusting. The mechanic should have thought about it but like most of the mechanics I run there one of three types. (1) Cannot fix anything but charge like they can, (2) Can fix the problem but only fix what there told to do or asked to do, (3) Can fix the problem and are sharp enough to advise why it happened and offer advise to remedy. Sounds like you had a number 2 guy/shop. Once the cable is replaced and adjusted it will go in and out of gear real smooth

 

[1992Marlin3.0lOMC]

Thanks for the reply, reading your response is a sigh of relief for me (I know there is no guarantee you are right and the boat may have other issues), shift linkage makes sense. I hope nothing was damaged from all the usage. The original owner did not know much about the mechanical side of the boat so they could have had this concern for a while. The manual will be in next week and I will probably wait until I can read the entire section before I mess something up. Thanks again for taking the time to help me out on this one. Just remembered the guy said they had the throttle cable replaced before they sold the boat (may be relevant), sorry that slipped my mind and was not in the maintenance records he gave me.

 

[1992Marlin3.0lOMC]

Another question, do you think I could just adjust the cable or is this a sign the cable is bad?

 

[Lou C]

I agree with the above response, the noise is a sign that the dog clutch is not fully engaging either fwd or reverse gear. The fact that is does it more with the prop on, suggests that the weight of the prop causes it to make the noise more distinctly. I bet they didn't even water test this boat. If they did, they would have noticed the shifting problem immediately. This can be caused by several things: an out of adjustment transom shift cable, sticky bell crank in the pivot housing, defective (sticky corroded inside) transom shift cable, mis adjusted remote cable from the control.
As a test you can (WITH THE ENGINE OFF) try this:
have someone up a the helm, to shift the remote control. You are at the stern of the boat, and you spin the prop, have them shift from neutral to fwd (you can feel if the dog clutch fully engages the gear, it will not ratchet but lock in solid). Do the same in reverse. If it does not lock in either or both gears, then the boat has to go to someone who knows how to set up OMCs. If it does lock in both gears, the problem might be in the cable that goes from the remote control to the engine shift lever.
When I do a Cobra, I start with the drive off. I measure the shift rod height first. Then, I disconnect the transom shift cable at the engine end and the pivot housing end. I measure the drag on the cable in both directions with a fish scale. It should not exceed 2.5 lbs. If it does you need a new cable. Then I install the special tool that holds the bell crank at 90* on the pivot housing and go up and adjust the cable with the special cable tool, on the engine end. After that, I tighten the cable retainer on the bellcrank end at the pivot housing. Next I reinstall the drive, and adjust the remote control cable on the engine shift lever. Its not hard but you have to know what you are doing and you do need the special tools (at least the holder and cable tool, the shift rod height can be measured with regular tools if you are careful). Google Midnight Wolf OMC tools, he has the 2 main ones you need and all the instructions, if you want to do this yourself.

 

[1992Marlin3.0lOMC]

Lou C, thank you for the response, that test sounds simple enough for me to do. On another note, I drained the drive oil today and didn't see anything alarming just minor shavings that I am no to worried about and think if my concern was in the drive I would have seen chunks (Fluid was black). Also I pulled what looks like a fairly common rookie mistake, I pulled the wrong plug and I guess this is a mystery plug and you know the rest the back piece fell into the drive. It turned out to be a good thing, I just pulled the drive off and the U-joints needed some grease. I will be putting it back together and filling the drive (from the bottom until the fluid reaches the center hole, then plugging the center hole and then until it reaches full on the dipstick). After it is all put back together I will do the test you recommend. Thanks again!

 

[Lou C]

Something does not make sense... You paid for syn gear oil in April, it should not be black 4 months later. They had the drive off, re sealed it and gave it back to you shifting like that? I'm almost sure they never water tested that boat.

I'd want my money back, you have an OD full of black oil that does not shift right, that you can't use the way it is.

BTW when you fill the OD with oil you should be doing it this way: Drain with the top, bottom and middle plugs out. Use new fiber washers. Replace the bottom most plug. Put the top cap plug (dip stick) in but do not screw it down. Fill it slowly from the middle plug (it is on the right side of the OD as you face it from the rear near the joint between the lower and upper gear cases). Pump slowly till it reads full on the dip stick. It should take about 2 qts. When it reads full screw the dip stick in. Remove the gear oil pump and replace the drain plug. Loosen the top dipstick, let it sit for a bit to allow any air bubbles to escape. Check the level again and if needed top it off by the dip stick hole. I use the Merc Hi Performance Gear oil, its easy to find anywhere and works great in the Cobra.

 

[Lou C]

No Title

 

[1992Marlin3.0lOMC]

I recently purchased the boat and that is a receipt from the original owner, I am convinced the shop took him. I bought the oil yesterday and the guy told me to fill it from the bottom until it comes out the middle, then cap the middle and fill until it reaches the dipstick so I did it like that, do you think that will be a problem? I haven't taken it out yet so it wouldn't be a big deal to redo it but the process sounds similar. I only ran it in my driveway with the muffs on briefly to see if the clank noise changed, which it did not. He also sold me the mercruiser oil, when I asked twice about the filling process he seemed annoyed. Haha, not trying to be an annoying new guy but I don't want to screw something up and pulling the wrong plug was a reality check to check twice and not assume. Thank you for the response.

 

[Lou C]

The 'guy' never read an OMC shop manual, as I have.....lol......do it my way and not worry. Since you have the oil in there already, if its been sitting for a while, spin the prop shaft by hand, to allow any possible air bubbles to go to the top, and then check it with the dipstick. If its OK, then run it on the muffs briefly, check it again. I don't know if that way is OK really, I always did it the way they said in the OMC shop manual. It should have taken about 2 qts, if you put in a lot less then you have to add it with the pump at the middle fill plug.

 

[Idlespeedonly]

Drain it with all 3 plugs out, and refill it per the factory service manual.
Dont even run it on the muffs.
doing it any other way is just stupid.

 

[1992Marlin3.0lOMC]

Filled the system, it took 2 quarts ran it with muffs on and rechecked the level and it needed almost 1/4 of a quart more. I took the boat out Saturday and with the prop all the way down there is no clanking noise, for now I will stop messing with it in my driveway and if I hear anything abnormal when the boat is in the water I will dig back into it. Thank you all for the help!

 

[sea wolf]

I've owned my Cobra for over 20 yrs. & I've never filled it any other way then what the omc manuel says. Which is the middle plug. The mechanic who told you otherwise doesn't know squat about Cobra drives. Just sayin...................

 

[HT32BSX115]

I've owned my Cobra for over 20 yrs. & I've never filled it any other way then what the omc manuel says. Which is the middle plug. The mechanic who told you otherwise doesn't know squat about Cobra drives. Just sayin...................

Howdy, Well, to be fair, there are "some" that fill a dog clutch Cobra from the bottom until it runs out of the "Correct" (middle) fill port, THEN they continue filling it from that port until full.

That technique has been used successfully by many people for so long that everyone thinks it's the "right" way. including these guys........ http://www.sterndrive.info/id270.html

While it does appear to work, and you probably will not "hurt" the drive doing it that way, OMC is VERY clear about how to fill a dog-clutch Cobra. I REALLY don't like even explaining that technique because someone will invariably try it and screw it up by just filling their drive like a Mercruiser with catastrophic results.

It's a COBRA. Fill it FROM the OMC designated "FILL" (middle) port.


Let me also add that if the drive actually DOES go into gear "smartly" in the water, Then the "dogs" are probably not "rounded" (btw, DO NOT TRY TO SHIFT IT SLOWLY!!)

If it doesn't go into gear "smartly" out of the water, that clicking noise with minimal mass on the propshaft (the prop), indicates that your lower shift cable is likely not moving correctly(due to corrosion, binding etc) .......... as LouC so correctly explained.

Do not let it go for long as it will start doing it in the water as the shift cable gets harder and harder to move........ and the subsequent wear on the clutch dogs will permanently damage them!


Cheers,


Rick