OMC 302 Jumping 6 inches

[bianchija]

I was watching my engine yesturday while a friend of mine increased the RPM's of my OMC 302 engine and the front jumps about 6 inches. Is this normal for those engines, or do I have issues with my engine mounts? If I do, does anyone have any ideas as to where I can get parts like that? Thanks.

 

[Boomyal]

Re: OMC 302 Jumping 6 inches

Ya better hook a chain to it. Leave lots of slack in the rope so it won't rip your deck cleat off when the motor goes overboard. <br /><br />Seriously, if your motor does not have a power trim assy, at the front, then you are in jeopardy. You should be able to watch the mounts pulling away from the stringers as you rev it. Sounds like your motor mount stringer are history.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

Great!!! Do you have any idea where I can look for stringers. Thanks so much for the help.

 

[Boatin Bob]

Re: OMC 302 Jumping 6 inches

Wow Joe...if thats whats happening I wouldn't run it anymore, your alignment must be out now and you run the risk of destroying your coupler, gimbal bearing, u-joints. Your engine mounts could be bolted to a bracket and it in turn should be lag bolted to the stringers.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

I found this engine below that looks much like mine. This might give you an idea as to what I'm looking at.<br /><br /> http://cgi.ebay.com/ebaymotors/ws/e...tem=2479551619&category=50442&sspagename=WDVW <br /><br />I'll take a look and the entire assembly tonight. I just wanted to verify that it's not normal for the front of the engine to jump 6 inches. My only concern as far as not running it is that it only happens in the water while in gear. If it's not in gear its going to be hard to see that problem, correct?

 

[rybad]

Re: OMC 302 Jumping 6 inches

I guess to answer your basic question. The engine SHOULD NOT be moving AT ALL. This will quickly destroy the drive train into the outdrive (misalignment).<br /><br />Hopefully, your mounts are bad and no the stringer. If I had bad stringers under the engine mounts, I'd get a new boat.<br /><br />Good luck.

 

[a.d.mobile]

Re: OMC 302 Jumping 6 inches

WO boys this is a stringer! no alignment here! joe remove engine hood so you can see good and look for the movement. my guess is a engine mounted trim system that has failed and the cylinders are letting the engine come up. must check all problems out corectly and describe the tipe of product carefully or someone will have you change a transome cable,esa module and grease u-joints before you figure out if it has one or not.

 

[Boomyal]

Re: OMC 302 Jumping 6 inches

Originally posted by JoeAB:<br /> Great!!! Do you have any idea where I can look for stringers. Thanks so much for the help.

Before you jump to conclusions, you have not identified the type of OMC setup you have. If it has four identical motor mount pads, two on the motor (as pictured) and two on the intermediate housing, then you have an OMC Stringer of one variety or the other. Make sure the the bolts, that attach the mount to the engine are in. Make sure that the large bolts from the mounting bracket to the mounting foot are in place. If all is well there then you have a rebuild looming in your future. There is no such thing just getting stringers. If your mount stringers are rotten then you probably have more issues under the floorboards.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

Ok, I'm starting to figure out what you are all saying. Believe it or not, it's a Boston Whaler, 1978 revenge. I understand the stringer aspect now and am concerned about it, however I think it’s attached differently and not into the stringers. It’s almost like they built a special platform for the mounts. Yes, it does have four mounts, but the fact that the front of the engine is what’s lifting points me to the front mounts, or those that are in the middle of the engine. <br /><br />I’m thinking I could try turning the lag screws that are holding the engine down. If those turn there’s my problem. If not, I thought I might try lifting the engine with a 2 x 4 and see if I could see something wrong with the mounts themselves. What do you think?

 

[Boomyal]

Re: OMC 302 Jumping 6 inches

most likely the 'feet' are pulling up away from the floor when you rev it under load. That's putting a whole lot of load on the rear mounts. There is only a half inch rubber washer between the foot and the mount coming off of the intermediate housing. That does not allow for much motion before something else rips out or breaks. You will probably find that the lag holes are stripped and or the threads have rusted away. Either way it means wet, rotted wood. Not sure how BW's were constructed but as they are still in business you could find out from them.

 

[skicat]

Re: OMC 302 Jumping 6 inches

I had this same problem 12 years ago on a 302 190hp omc 1977. The stringers were rotted out leaving nothing for the lag bolts to tighten into. I hoisted the engine up, cut away the fiberglass that surrounded the stringers and put in new pressure treated lumber for stringers, bolted them down and re fiberglassed it back together. I dont know if this is the proper way to do it, but it worked for three years until I sold the boat.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

Sskicat, thanks for the advice. I've been thinking all day about how I would fix it...great idea. Let me look into this after work. I'll let you know if it is in fact the stringers. Based on all these responses it sounds like it's the only thing it could be.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

I just got off the phone with a friend of mine that watched the mounts at one point and he said they are not pulling out. He said it's something in the mount itself, but that he doesn't know enough about them to understand exactly what is going on. He said it's also jumping more like 3 inches. Any thoughts?

 

[Boomyal]

Re: OMC 302 Jumping 6 inches

If yours are like the mounts pictured in the ebay site motor, you have a cast bracket that screws to the block (2 bolts), that bracket bolts onto the foot with one approximate 5/8 in diameter bolt, with some 2 1/2 inch spacer washers and a rubber pad in between. the foot then lag bolts to the stringers.(3 lags) It's that simple. If all the bolts are in place then the motor has to be lifting off of the stringer, bracket and foot included. No other options.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

Thank you Boomyal. I'll check to make sure it's all there and check the lag screws to see if they are loose.

 

[skicat]

Re: OMC 302 Jumping 6 inches

On my omc 302 Ford, The front engine mounts had hydraulics to trim the engine and outdrive. If your mounts are not coming loose from the stringers, perhaps the hydraulics are bad and allowing the engine to move freely. Open your engine cover and trim the engine up and down to see if it is working.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

Interesting question Skicat. You can't trim the OMC outdrive that I have, but I never thought about the engine. The boat does have a trim switch, but it hasn't worked since I got the boat last summer, so I'm not sure what it goes to. The only problem with this is that I've never seen evidence of hydrualics anywhere. <br /><br />On a side note, I checked the lag screws and they are tight. They don't seem to be the problem. Unfortunately it's difficult to see the inner workings of the mount itself so I'm not sure where I stand with that. I need to get an enginer hoist or something to lift it up.

 

[Boomyal]

Re: OMC 302 Jumping 6 inches

Look at the mounts on the ebay engine. If you have hydraulic trim apparatus on your engine it will not have those two mounts, mid-motor. As I alluded to in my first response "unless you have power trim" which uses a cross bar front mount attached to the front timing cover. If you have this mount arraingment but do not have all of the rest of the tilt mechanism, this could be responsible for the movement.

 

[bianchija]

Re: OMC 302 Jumping 6 inches

The mounts are mid motor. Is there a way to attach pictures to this?

 

[Boomyal]

Re: OMC 302 Jumping 6 inches

Go to Myfishing pictures.com:<br /><br /> http://www.myfishingpictures.com/index.php <br /><br />Register, sign in, go to 'upload' pictures and pull the pic off of your HD. Once uploaded, copy the link and come on back over to iboats, do your reply, hit the image button and paste the picture link into the box. Hit ok, and add reply and you should have your pic displayed on your post.<br /><br />