GRINDING when trying to start newly rebuilt 1996 Mercruiser 5.7L

[floydf]

I have a VERY frustrating problem. I've looked through several pages in your forum, but didn't see a similar issue.<br /><br />I just bought a 1996 Chaparral that has a rebuilt 5.7L Mercruiser engine that only has about 10 hours of use on it with a Bravo III lower unit. On the way home from the previous owner's house, after going fine for about 30 minutes, the engine sputtered and died. After a lot of troubleshooting (and turning the engine over numerous times after adding gas thinking it had run out of gas) and then downloading the schematics, we found that there wasn't 12 volts across the coil. After checking the whole wiring system, we finally found tonight that it was the (-) that was lost. The idiots at the marina just screwed down the black lead from the ignition amplifier to some shiny painted metal, making the screw head and threads the only ground path. As soon as I tried to remove the screw, the head popped off. So, we connected everything back together and moved that ground point. That got my coil working.<br /> <br />Now, the problem. I tried to start the engine and it turned over for about 5-10 seconds and it did briefly try to fire. But, right after that, each time I tried to start the engine, moving the throttle a few time with the engine disengaged, it will turn over for a second and then make a loud metal-to-metal SCARY sound. Several times, after that short turn-over the engine would quit turning over. I switched one of the batteries out with a fresh one, but no change. I'm an Electrical Engineer so I could understand the circuiting, but this is VERY frustrating! The marina said I could have the boat towed all the way back to them, but it would be over a month before they could look at it. After seeing their wiring job, I don't want to take it back to them. Do you have any ideas what I can check or do? I'm sure that the other night, and tonight, the throttle was messed with multiple times because we thought the boat had run out of gas. Tonight, it sounded almost like the engine was getting engaged (I'm not sure; it just sounded bad!). The previous owner asked the marina to replace almost everything, and said he hadn't had a problem in the couple of times he took the new engine out. Any suggestions you could give would be GREATLY appreciated!<br /> <br />Thanks again!<br /> <br />Floyd

 

[anesthes]

Re: GRINDING when trying to start newly rebuilt 1996 Mercruiser 5.7L

The ground on the coil should goto the ignition box, or dist. In any event, its a pulsed ground (pulses when coil fires).<br /><br />I'm not really sure about your grinding issue. I recommend you get a breaker bar, and socket, and turn the motor over by hand while someone else inspects hte boat. It could be something as simple as astarter, or it could be an outdrive problem. <br /><br />If you rule out the starter, I'd then remove all the accesory belts, and try turning it. IF not, then remove all the spark plugs.. IT should turn over REALLY easy. If not, then I'd take the out drive off. Try to turn it outside the boat. If it turns freely, try the motor again. <br /><br />If the motor won't turn over w/outdrive removed, and plugs removed, belts removed; you have an internal engine problem. <br /><br />-- Joe

 

[vinney]

Re: GRINDING when trying to start newly rebuilt 1996 Mercruiser 5.7L

The starter used on that engine is a new style gear reduction starter. If there is any reason for the engine not to turn freely it will break the starter drive or nose cone on the starter. The older starter would bent a conn rod. The new style starter will fail befor you bend a conn. rod. Over fueling the engine or water in the cylinder will hydo the engine and break the starter drive or nose cone. If the engine back fires or if you were running the boat and lost ignition its possible to pull water in thru the exhaust. Pull the plugs and disconnect the ignition and turn the engine over to make sure cylinders are clear of water or fuel. You may need to change the starter first.

 

[floydff]

Re: GRINDING when trying to start newly rebuilt 1996 Mercruiser 5.7L

Well, after almost 3 months, the boat may FINALLY be getting out of the marina soon. They let it sit for 2 months, assuming the water came in through the exhaust manifolds. They finally, reluctantly, took it apart to see the manifolds and gaskets were fine. But, the water sitting in there that long destroyed the engine. So, ANOTHER engine has been installed. It's only going up to 4000 rpm, so they have ordered another knock module to see if that fixes the problem.<br /><br />Now, the next problem...The lower unit of the Bravo III is badly pitted/corroded. I want to get the boat out of there first, but know that work will need to be done soon. Any suggestions on where to order another expensive item, or can just the gear housing be replaced? Thanks!

 

[tommays]

Re: GRINDING when trying to start newly rebuilt 1996 Mercruiser 5.7L

well the pitting will happen to any drive if it is not protected from galvanic corrosion<br /><br />a unit like a bravo 3 with the big ss props is very hard to protect it is supposed to have a mercathode system which runs off the battery full time but if the system has wireing problems or a bad shorepower connection it cant work correctly<br /><br />since it is from 1996 i have no idea if your zink anodes are still(they need to be new every season) in good condtion or the mercathode is still working <br /><br />if you dont get it fixed a drive can allmost melt away in the water<br /><br />i dont know the full story but it sounds like it would be hard for you to find a worse service center<br /><br />tommays

 

[floydff]

Re: GRINDING when trying to start newly rebuilt 1996 Mercruiser 5.7L

I'm sure the cathodic protection needs to be replaced. But, I'm sure the average consumer would not believe that they should be replaced "every few WEEKS" if the boat was left in the water, according to the Service Manager. Also, even though it has one Mercathode, I wouldn't think the average consumer would assume it needs TWO, as Mercruiser recommends for that model. They even recommend different cathode material depending on what type of water you are in; which is bad since I'm in both salt and fresh water.<br /><br />Any recommendations on where to order the new parts??