mercruiser 454 and Bravo I HELP!

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duckman

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I have an 89 Mercruiser 7.4 MPI with a bravo I, I apparently need to replace gimble bearing (clicking in neutral and in gear, and pretty good vibration), how big of a deal is this? I do about 95% of maintenance on my cars (from Oil Changes to suspension, drive shafts, PS Pumps, Ignition, etc)Would it be possible to do it while the boat is on a hydrahoist? How much does a Bravo I Drive weigh ( I assume I have to pull the drive?)<br /><br />Second question, all of the sudden yesterday I've lost alot of power, seem to have a backfire, and possibly loss of a couple of cylinders, I noticed spark arc from the coil to the negative terminal on the coil, even though there was dielectric grease on the terminals, I can hear a pronounced "tick". The strangest event is sometimes when trimming the outdrive I get a loss of power and a backfire (this is relatively consistant), but sometimes doesn't do anything.... all of these events happen ONLY when the boat is in gear, in neutral I've (cautiously) taken her up to 3000 RPM with no problems... I'm assuming a tune up / compression test is in order, but do I have to take the exahust manifold's off to get to the plugs (I can't see them in the drive area) Any special tips/tricks on the plug wire/plug change and compression test?<br /><br />Last, where can I get a manual FAST? Like overnight? Amazon can't get me one for 3-4 weeks!<br /><br />Last, last, is it ok (assuming we get the ignition issue worked out) to drive with a gimble going out? (4th of july weekend and all!)<br /><br />Thanks so much! In advance!
 

Walter

Senior Chief Petty Officer
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Jul 3, 2001
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Re: mercruiser 454 and Bravo I HELP!

Until you've accurately diagnosed the cause/source of the noise and vibration you believe is coming from your gimball bearing...I'd suggest you consider some dock side parties vs. long cruises. It's possible you have a u-joint failing...you wouldn't want that coming apart!<br />Although I can sympathize with your plight (no boat on July 4), I think you're running a significant risk of seriously damaging your outdrive. Of course...my opinion is based on the info you've provided. Heck...for all I know maybe the vibration you feel is your stern line wrapped around the prop!<br /><br />If you plan to tackle these repairs yourself, then a factory manual is a must! Where you'll get your hands on one in short order? I haven't a clue. Perhaps you could take a bottle of good hooch down to your local MerCruiser mechanic and ask to borrow one...<br /><br />I'm not familiar enough with the big blocks to say what you'll need to do re: tune up, etc. Again...that's where the factory manual comes in. However, I'd think you could tell whether you can access the plugs without removing the exhaust manifold simply by looking.<br /><br />Good luck and Happy July 4th.<br /><br />Walt
 

duckman

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Joined
Jun 27, 2001
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Re: mercruiser 454 and Bravo I HELP!

after reading the task and tool list from lowerunits.com, we've decided to have the gimble done by a pro... boat will be docked until gimble is replaced...<br /><br />Thanks
 

Walter

Senior Chief Petty Officer
Joined
Jul 3, 2001
Messages
787
Re: mercruiser 454 and Bravo I HELP!

If it weren't for a Merc tech buddy of mine...I'd have really struggled with many of the repairs I've made to my outdrive. It's great to learn from someone who knows best how to do the job. <br /><br />Unless you're prepared with the tools, parts, and knowledge...what you were considering would have been a difficult task. I think your decision to refer those repairs to a pro is a good call. Hopefully you'll be back on the water soon!<br /><br />Happy 4th!<br /><br />Walt
 
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