Spinning off engine coupler 3.0 HO omc 1993

[Rookie 132]

Need some help here. I have a 1993 Caravelle bowrider 1750. I had it in the shop because the engine started slipping while out on the water. Once the engine was removed, the coupler had broken loose. The engine was completely torn down and everything looked good, so they re installed the coupler and put it back together. Next time out, rode around for about 45 minutes and the engine coupler started slipping again. Same thing... this time shop ordered and installed a new coupler. Third time out 20 minutes in...same thing. I noticed the engine vibrates about two inches side to side when running in nuetral. Any ideas on why it keeps throwing couplers???? My mechanic is stumped, wanting to tear the engine down again and make sure all part #'s in the motor match to the original #'s I think he's reaching. What could cause this? I have heard a bad motor mount can cause vibration, but I would think it would be something major if I can't make it over 30 minutes without problems. The shaft was removed from the coupler to the outdrive and showed to be true on a lathe also. Please help on this one. Boat's been in the shop on and off 9 months. This is a 4 cyl OMC cobra I/O with about 300 hours on it.

 

[Bondo]

Re: Spinning off engine coupler 3.0 HO omc 1993

Ayuh,.... Bad motor mounts,..??
Bad transom mounting,..??
Was it Aligned when replaced,..??

Where, Exactly is it failing,..??

 

[DBreskin]

Re: Spinning off engine coupler 3.0 HO omc 1993

I noticed the engine vibrates about two inches side to side when running in nuetral.

If the motor is vibrating that much it seems you have problems with both poor motor mounts and rough idle. If the motor is moving that much it must be tearing up the driveline, which is not designed to tolerate that much movement.

 

[Don S]

Re: Spinning off engine coupler 3.0 HO omc 1993

I would be worried about your mechanic as well. Why he wants to tear down the engine every time there is something wrong, and why he would reinstall a defective coupler. Even the worst shop should understand couplers slipping, and that there is no repairing them, and they don't heal.
Before you let these guys take the engine apart, how about having them do some troubleshooting, like compression checks, leakdown tests, maybe valve adjustments. Timing, dwell, carb and fuel system. You know, basic troubleshooting. Besides, there aren't part numbers on every part in an engine so they can verifiy if it's OEM or not.
I would be finding a new shop.

 

[Rookie 132]

Re: Spinning off engine coupler 3.0 HO omc 1993

Thanks for the tips. To answer the alignment question, it was aligned when the new coupler was installed. Also, not sure if this provides any more info,but there was more vibration after the new coupler was installed than the old one. BAd news on this for me is that I paid for this when I picked it up the first time. So the money is gone and I'm either stuck with this guy fixing it or eating it twice to take it somewhere else.
Thanks

 

[Don S]

Re: Spinning off engine coupler 3.0 HO omc 1993

I would be curious to know if after doing the alignment, they turned the engine 180? and rechecked the alignment. I have found many couples bad right out of the box this way. It's both OEM parts, and aftermarket parts.
If they are aligned to a bad coupler and not checked at 90, 180 and 270, then you have no way of knowing if the coupler was bad or not.
If it was bad, and the adjusted the alignment to fit a defective coupler, then it would vibrate, and it would go bad in a hurry.
That is why I have learned to install the engine, bolt it down, then check the alignment at all angles to make sure the coupler is ok. THEN and ONLY THEN do I finish installing the engine.

 

[intrepidvoyager]

Re: Spinning off engine coupler 3.0 HO omc 1993

run the engine less the coupler ....you could have an engine that is seriously out of balance .....these 3.0 engines are takeoff's of the old iron duke which was notorious as the shake, rattle and roll engine. Was there engine vibration when you first started the engine ?????

also you should check that the coupler is itself aligned and that the splined sleeve is true and not at an angle to the coupler body.

also check that the coupler is indexed to the fly wheel ....

as your mechanic is at an impass he should be willing to pull the engine ..tie it to a skid ..start it with the coupler and rig up a pointer on the coupler sleeve and see whats going on.

also check your gimbal bearing and universals ...if there is slop there your drive shaft will be moving off center as it rotates.

also check that there is no play in the gimbal ring and pivot housing.

good luck ...let us know

 

[Don S]

Re: Spinning off engine coupler 3.0 HO omc 1993

start it with the coupler and rig up a pointer on the coupler sleeve and see whats going on.

That is what turning the engine 0?-90?-180?-270? and checking the alignment checks.
If the alignment changes the coupler is faulty.

 

[intrepidvoyager]

Re: Spinning off engine coupler 3.0 HO omc 1993

or the coupler is not indexed to the flywheel.

seems to me the first thing is to start with the engine ...if it has a serious vibration due to parts weight imbalance ...like if 2 of the rods are at max allowable over blueprint weight and the other 2 are at max underweight and there are other balance issues ..ie harmonic balancer, etc you can end up with a nasty vibration at the coupler.

You can't tell this without running the engine and see what's happening to the coupler.

if the front of the engine is vibrating sideways 1/4 of and inch that will make at least the same if not more at the outside edge of the coupler .

 

[zbnutcase]

Re: Spinning off engine coupler 3.0 HO omc 1993

No, they are NOT takeoffs of the Iron Duke!!!!!!!!!!! WHEN WILL PEOPLE LEARN THAT WAS A PONTIAC ENGINE???? These are CHEVROLET engines! QUIT CALLING THEM THAT!!!!

 

[Rookie 132]

Re: Spinning off engine coupler 3.0 HO omc 1993

I will pass the info along to him and see if we can get it lined out. Thanks for the help

 

[intrepidvoyager]

Re: Spinning off engine coupler 3.0 HO omc 1993

hey nutcase thats interesting ....i had one in my VEGA !!! now let me see is that pontiac vega or chevrolet vega ...

who cares ...some of those engines shook like hell ... i AM SURE THE ORIGINAL POSTER IS MORE INTERESTED in what's happening to HIS engine than hearing about the whose engine plant made the original GM 4 banger !

Come to think of it I think they were made .....and still are ...in Mexico...Ole!!


ooops ...here we go again .......