What would be an average on the hour meter before a rebuild is needed ? Looking at two boats with 300x motors , 05 with 340 hrs and 03 with 155 hrs. I know anything can happen , just looking for some input. I was told around 250 hrs be ready to rebuild. I understand there are alot of variables that come into play here just wanting to check all angles. Thanks
The first thing would be a leak -down test it will gave you the numbers if the motor need to be rebuild ?
I have around 340 on mine and no where near ready for a rebuild..
<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Largemouthlou »</td></tr><tr><td class="quote">I have around 340 on mine and no where near ready for a rebuild..</td></tr></table>
+1
Recommend (at a minimum):
-Compression test AND Leak-down test
-Printouts from the Computer Diagnostic System of Run History, and Freeze Frame (Fault) History
-Gearcase check
-Maintenance history (and needs) review
-Of course- a test run on the water to confirm proper operation.
Although that's well above average hours, it's really not the HOURS that are critical. What's far more important is HOW THE ENGINE WAS SERVICED, RUN, AND TREATED DURING THOSE HOURS.
If in good shape- and properly maintained, there should be MANY, MANY hours left in EITHER of these engines you're considering.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
What would be acceptable numbers on compression and leak down ? Thanks again guys
Compression: There's no real correct "book" answer. May range from 110-135 psi (varies... and the engines actually seem to "gain" compression after break-in). Main thing to watch here is VARIANCE.... preferably no more than 10% variance in compression.
LEAKDOWN is a better measure. Anything much above 5% is an indication that there may be problems in that bore/cylinder.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
We have a friend down here that has a Ally with a 300X on it with well over 600 hours
Jason
I have read of motors having 1000+ I truly hope that I can get more than 350
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