Hi guys - I work at a car dealership where we believe that preventive maintenance makes the engines and transmission last longer. I have my Bravo 1 drives serviced (change gear oil, remove drive and re-align) at the start of every season. My motors are 7.4 MPI's 310 hp. I blew the upper in one drive after about 500 hours which I thought was kind of weird considering I'm easy on the sticks and I have the drives regularly serviced. Am I doing something wrong or am I on track? Thanks..

Id be happy to get 500 hours out of any moving boat part.

Just like in your dealership, even with preventative maintenance, sometimes stuff just breaks. But you do move the chances in your favor by doing so.

Thanks for the replies guys

Can you be more specific about the damage that was done in the upper. That is the only way to determine a course of action. At 310hp I suspect that the preload on the tapered bearings was loose enough to cause a problem. The gears themselves can last a long time if the gear mesh is kept inline.

Hope that helps.
Dick

I had over 650 hours on a pair of bravos behind 496 Mags never an issue. Just did oil changes every year. Getting the boat out of water and not getting out of the throttle can take out an upper in the matter of 30 seconds no matter how often you change the oil too.

mr. gadgets, the gears in the upper were missing teeth off of them.

32,
Was there ever a case of shock loading the gears? That can fracture the teeth and cause a failure. Typically the 310hp doesnt impose that much of a load on the B1 gears. At some point the bearings loosen up and cause the pinion to walk over the driven gear. This could cause broken teeth. Look at the inside of the snout where the pinion gear bearings ride. If there is a ridge there, it shows signs of loss of preload. And it could be what caused your problem. At 450hrs, if you can turn the input shaft with little drag, things are pretty loose inside. Without looking at it, it is all speculation, but that may have been the situation in your case.
Other wise shock loading will weaken and eventually break the teeth.

Dick

I was aware of the shock loading destroying gears so I'm very easy on them in that respect for sure. It happened on a day where i was crusing at 3,000 - 3,500 rpm's for about a total of 5 hours during the day. Damage is done, just wanted to try and prevent any other. Thanks for the replies

Well one question is, how wet is the hull at that rpm? If the boat is still very wet and the 310 makes decent torque in the middle, it can stress the gears. Max load in that range, possibly.
Dick