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471 cracked sleeves

seagull04

New member
"I have a 471 in a 39ft trawle

"I have a 471 in a 39ft trawler.After working all night I was steaming home and it lost revs and stopped.Got it going,went home.It had a surge at idol not to bad.Worked 2 more nights.Had motor checked to find no.2 sleeve cracked.Has less than 800 hrs since rebuild.Mechanic recommended reco motor which I bought.Marine gear-blower etc put on new motor.When started it had a small surge at idol.Went to work and on way out less than 1/2 hr motor lost revs and stopped same as last time.Got it going,lots of black smoke till it started and kept going with a little smoke,idoled home.Found no.2 sleeve craked again.Has anyone got an idea please"
 
TO CRACK A SLEEVE THERE MUST B

TO CRACK A SLEEVE THERE MUST BE A SEIZED PISTON THIS IS MORE THEM LIKLY CAUSED FROM OVER HEATING IF SO THERE MAY BE A CRACKED CLY HEAD. WHAT DO THE OTHER CYL LOOK LIKE?
 
"The other cylinders are fine

"The other cylinders are fine as they were in the first motor.The sleeves in both motors cracked right around through the holes and could be seen clearly when inspection plates were removed,the piston is black and the rings don't appear broken.Motors both ran at around 140-145 degrees,quiet good I thought.
Thanks Alex"
 
The problem could be you have

The problem could be you have the wrong liner size. which causes the liner to chatter in the block and doesnt transfer heat from piston/liner to the block efficiently. The liner to block clearance is .006 on std liners. hope this helps just wanted to throw my two-cents in
 
The first motor was reconditio

The first motor was reconditioned and lasted less than 800hrs when it cracked it's no.2 sleeve.I then bought this reconditioned motor and put the blower and marine manifolds on to it from last motor and it lasted less than 3hrs and cracked the no.2 sleeve.
Thanks Alex
Also thanks mikey every 2 cents helps.
 
I will have the liner checked

I will have the liner checked and the manifold pressure tested and see if one of these are causing the problem.Also is there a max and min or recommended running temp for a 471 marine motor.
Thanks Alex
 
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