Mercruiser I/O loss of power

[skyking_22]

Update from previous post: http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=24;t=000101;p=1#000019 <br /><br />I have had 3 different shops look at my boat. To date I have had 3 new sets of plugs, wires, router/cap assy, and coil. The newest addition is the frequent breaking of bolts and brackets. I have changed the PS/Alt bracket twice, lower alt bracket four times, tensioner pully and bracket twice, tensioner pully bolt four times (sheared off) this is a grade 8 bolt, and all they ever say is it must be a bad plug wire. The boat has the factory prop installed, and when new the boat would do 4800 RPM & 40 mph @ WOT. now it only does 4000 RPM & 25 MPH @ WOT. I am really getting frustrated, I can only go about 12 miles before some sort of bracket of bolt breaks. The engine @ WOT makes a noise similar to pinging, but it is not pinging, this is a different sound. Has anyone ever run into this?

 

[H2o steve]

Re: Mercruiser I/O loss of power

Bob, your boat is possessed, (sp?) you'll have to burn it..thats what I had to do! my troubles left! then my wife started acting wierd too. I started to burn her, but then she left. <br />I read your (post) posts. I am not familer w/your engine design, but the bracket thing intrests me. is this a serpentine style belt? or conventional V belt/s? is it possibile that your haromonic balancer sheared it's key? (hence the timing trouble, backfire, loss of power, etc.<br />There were some great previous posts re your situ. the dist. advance, mech/vacuum, i would suspect as well as H20 in the gAs. Does your $oat utlize a Q-jet carb? These have lead plugs in the bottom witch become loose and leak. I can spend your money as quick as my ex wife. keep in post so we can all learn, sl

 

[qystan]

Re: Mercruiser I/O loss of power

The breakage is consistent with fatigue induced type of failure. <br /><br />To induce such, you need a continuous cyclic type of load and for 12 miles to do damage it must be very significant.<br /><br />Not mentioned is whether it has 1 serpentine or 2 v-belts. You may want to try the following, they're just guesses:<br /><br />If it is 2 belts and it occurs with both the p/s pump and alternator, the source must be the engine. Single belt, then it can be any one of the rotating units.<br /><br />1. Look for eccentricity/wobbly/out of round bearings of the pulleys. For a 2-belt arrangement it can only be the main pulley. For single belt, check all pulleys. Try insp with engine running, be very very careful around operating equipment, hair, fingers, clothes and loose objects.<br /><br />2. If the pulleys are ok, the other possiblity is that the engine is running with cyclic speed variations. The pinging like noise appears to support this. A compression check may help point to weak cylinder(s) that can cause this. Look at the plugs to identify any possible bad cylinders. From the severity, it would be a few cylinders with additive effects. <br /><br />Good luck.

 

[skyking_22]

Re: Mercruiser I/O loss of power

I agree it is possessed but, with the price of gas I can't afford to burn it. The belt is a serpentine type. The carb is a plain 2 BBL it is the Mercruiser Thunderbolt V ignition system. I have also changed the fuel/water filter several times with no resolve. I will have to inspect the pulleys.

 

[skyking_22]

Re: Mercruiser I/O loss of power

Well, I pitched a fit with Mercruiser and they agreeded to send a factory rep out to look at my boat. I will update the post when I hear more.