Alignment problems 1988 OMC Cobra 3.0

[StorminNormin]

Hello All,

I have read all the posts on engine alignment, and still have an issue. I took the motor out to change the coupler and the starter motor, and have re-installed it. After adjusting the front mount higher, and setting the gimbal bearing (I think I got it set) I had the alignment tool going in and out with ease. Grease marks seemed heaviest on the top and on the (port) side, and light on the bottom and starboard side, but it went in like butter. I rotated the engine 180 degrees, and the tool went half way in and jammed. A Friend's guess was a rotten transom/stringers or bad rear mounts. I noticed when I put the front mounts back in and I aligned the mount with the old holes, and put the lag bolts back in. One went in tight, and was basically stripped. Also, it seemed to me the front of the engine could go 1-2mm either way and these bolts would still go in. Also, the bolt in the starboard rear mount went down with the nut as I tightened it. This left the bottom bolt down about 1/2 inch and the lower washer loose, even though the top nut was torqued to spec. I tried a few times and the same. I could not get a wrench in to hold the bottom bolt, so I held the top of the bolt with pliers, and tighten the nut with a wrench. Got the bolt snug, but not tight. (Top nut is tight) Looks OK, and I don't know if that bolt needs to be tight, or just the top nut.

I was assured that the coupler I bought was taken off a working boat. Guy was an older retired marine tech, and I don't think he would lie to me. It looked fine to me.

The transom seems fine in and out when hit with a hammer, but I really don't know what I am looking for.

At witts end with this job, and would appreciate any help.

 

[Bluestream]

Re: Alignment problems 1988 OMC Cobra 3.0

I would think if the transom were rotten you would not get it to line up at all.

I would place my "guess" on a bad coupler.

 

[Haffiman]

Re: Alignment problems 1988 OMC Cobra 3.0

If you just by turning the engine 180 degrees gets from an 'aligned' engine to an 'non-aligned', it is a coupler problem.

 

[wire2]

Re: Alignment problems 1988 OMC Cobra 3.0

Can you move the engine at all, by levering it with a 2x4?

 

[dubs283]

Re: Alignment problems 1988 OMC Cobra 3.0

I was assured that the coupler I bought was taken off a working boat.

you bought a used coupler?? why??

the cost of a new coupler is well worth the price of knowing you have a new part

The transom seems fine in and out when hit with a hammer, but I really don't know what I am looking for.

to see if the transom is rotten, stand on the cavitation plate on the drive and "bounce" up and down - just like your uncle would stand on the bumper of his grand marquis to test the shocks

if the boat/trailer moves with your bouncing, or everything remains solid - the transom is okay

if just the drive moves and you see flexing in the transom area - rotten transom

 

[StorminNormin]

Re: Alignment problems 1988 OMC Cobra 3.0

Guys, the boat was an $1100 purchase with trailer, and I spend more time looking at the engine and outdrive than I did the boat. As such, I didn't want to pay $300 for a new coupler for this boat which I have never driven. I had to sell my beloved Sea-Ray a few years ago following a divorce, and basically this is what I can afford right now.

The out drive is off right now for service, so I can't do the stand on test, but the floor has some soft spots, and after extensive reading on other people's experience here, I am willing to bet there is rot in the transom. There are hairline cracks in the gel coat around the outdrive. This Four Winns boat does not seem to have the quality I have had in my other boats.

As for the front mounts, I loosened them off and tried to move the engine, and it is fixed firm by the rear mounts, so this is no longer a worry.

The rear mounts look fine, but how do I test them. I assume they need to come out for a visual exam?

It looks like I was sold a bad coupler, as I don't know what else it could be. If transom was rotted I should be able to get it aligned at least temporarily.

 

[Haffiman]

Re: Alignment problems 1988 OMC Cobra 3.0

Install the alignment tool as far in as possible.
Put some weight on it, up/down/sideways.
The coupler has a rubber hub, and may be slightly 'off', just like a prop hub that sometimes need the prop to be tightened to center properly.
Pull the tool out, grease the tip and re-install.
Adjust the engine, then again turn the engine 180 degrees and check if still same problem.

 

[StorminNormin]

Re: Alignment problems 1988 OMC Cobra 3.0

Install the alignment tool as far in as possible.
Put some weight on it, up/down/sideways.
The coupler has a rubber hub, and may be slightly 'off', just like a prop hub that sometimes need the prop to be tightened to center properly.
Pull the tool out, grease the tip and re-install.
Adjust the engine, then again turn the engine 180 degrees and check if still same problem.

Never thought that could be done. As it is, if I get the motor lined up as good as I can, (tool goes in and out like butter) then when the engine is rotated, the tool goes in about half way into the coupler, then I feel resistance, and I can get it all the way in with force. So it can't be out by much.

I spoke with the guy who sold the coupler to me, and he claims it is fine. (not that that means anything)

Can I assume that if I can get it aligned at least in one spot that the motor mounts are fine? Would a bad motor mount not mean no alignment at all?

Also, I drove the boat for 15 mins, would that help to center the spline in the rubber coupler, or would it just ruin my gimbal bearing?

 

[Haffiman]

Re: Alignment problems 1988 OMC Cobra 3.0

I would just have aligned it up, installed the drive, taken a trip, pulled the drive and re-checked.

 

[sea wolf]

Re: Alignment problems 1988 OMC Cobra 3.0

I would just have aligned it up, installed the drive, taken a trip, pulled the drive and re-checked.

Which would result in damage to the coupler if the alignment is off.

 

[sea wolf]

Re: Alignment problems 1988 OMC Cobra 3.0

Never thought that could be done. As it is, if I get the motor lined up as good as I can, (tool goes in and out like butter) then when the engine is rotated, the tool goes in about half way into the coupler, then I feel resistance, and I can get it all the way in with force. So it can't be out by much.

I spoke with the guy who sold the coupler to me, and he claims it is fine. (not that that means anything)

Can I assume that if I can get it aligned at least in one spot that the motor mounts are fine? Would a bad motor mount not mean no alignment at all?

Also, I drove the boat for 15 mins, would that help to center the spline in the rubber coupler, or would it just ruin my gimbal bearing?

Why don't u just pull the engine & check the coupler? The drive is off & it's not that big of a deal to pull a 3.0. This may be a dumb question, but you are tightening the mounts before you rotate the engine, correct?

 

[Bluestream]

Re: Alignment problems 1988 OMC Cobra 3.0

If he pulled the engine, how would he check the coupler? Sounds like it lines up perfect, then goes out a few thousands of an inch when rotated. Visual inspection won't revel being out that small amount.

 

[Haffiman]

Re: Alignment problems 1988 OMC Cobra 3.0

Which would result in damage to the coupler if the alignment is off.

If the coupler is already 'damaged' it does not matter!!
My guess, with plenty of grease on the splines it will 'align' itself after a short run provided the problem is not caused by a defective engine mount. That again is not likely the problem, as the only thing 'moving' when rotating the engine is the coupler.
I have experienced similar with brand new couplings, a question of 'running in'.

 

[StorminNormin]

Re: Alignment problems 1988 OMC Cobra 3.0

I think I will install the drive and run it for a bit. May even be able to run it on the muffs for 30 mins. I have read every post on alignment here, and there seems to be no conclusion on an issue like this. One guy kept buying new couplers and they were out and he returned them all. Given how they are made with a spline inserted into a rubber bushing, there's no way they are all going to centered perfect down to a thousand of an inch.

As for the rear mounts, they looked fine but I don't know how to check them. When I tightened the rear nuts they don't seem to squish down the rubber at all, The nuts just tighten on the bolt. Again, I think if a rear mount was bad the coupler would not line up at all.

I have a pic of the rear mounts, and will post it as soon as I can