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aq151 blown again

T

tlacey1

New member
ok i have a big problem i blew the 2nd 151 the same way looks like the counter balance shaft broke and it messed up the works,same place the #4 piston got to be something wrong???????
 
At what RPMs do you usually run this engine? Continuous operation at RPMs over 60% of max WOT RPMs ( assuming that MAX WOT RPMS are within the maximum specified range) usually a recipe for short engine life.
 
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I have a aq151/290od in my 20ft citation,Volvo recommends max rpm 55-5700rpm,ive ran mine all day at5 to 5500rpm,what are you running?if your over this range you may need to change props!!
 
I've had twins for 20 years in a heavy offshore boat. I cruise at 4100 rpm and rarely go higher. They've been great motors for me except for a few design issues, heat exchanger design could be better, exhaust port #4 corrodes badly. Best thing I ever did was replacing the exhaust manifolds with bronze ones. They never corrode!
 
What kind of oil are you using??these engines need a oil with ptfe in it for the cam especially.Its only in racing brand oils now because it has been found to damage catalic converters in cars,yep another emmission thing,first our gas gets f*** up,now our oil.So if you dont run racing oil you better be using a PTFE addittive.That could be a factor for engine damage.
 
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