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1985 evinrude 90hp v4 VRO no compression

P

polariskid13

New member
hey all new to the forum, so yesterday went fishing and crusing at 30mph engine starts making a scraching sound,, no good our speed is slowly dropin to 25 mph then noise gets louder, stop check plugs and the right bottom cylinder plug had metal shavings on the top (N):( we continue to run it,, shoiuld have stopped noise gets louder and warning buzzer comes on. BEEEEEEEP........BEEEEEEEP..........BEEEEEEP just trying to figure which code that is, no oil or overheat. the engine was pumping water out the tell tale fine the beep came after we pumped the oil bulb so we were thinking an air bubble? but it started b4 that. anyway got home all cyliders have 130-140 psi except one with metal shaving which has zero?? sad day as it was an amazing engine just have a few questions like is it ok to replace one piston and bore it out or do all have to be done do to imbalance? and which beeper is that b/c it happened once last year but it was BEEEP BEEP BEEEP continuous not long and paused then it ran fine for 2 weeks. so any help on to what happened would be appriciated ,,we took the oil out at end of season if that means anythin but always have and refilled full this season it was not low oil as it was full
 
Just add it to the long list of motors that likely failed due to broken piston rings.-------------Very, very common.-----------Pull the head and inspect.----------------Ok to do one cylinder with oversize piston and rings.--------------Automatic oil injection is not automatic if it is not maintained / checked.-------Best to mix at 50:1
 
thanks for the reply now it makes sense why so many ppl scrap the oil injection and run mix atleast that way u know tis getitn oil, so u think just broken rings caused it?
 
Sorry I can not see , hear or feel the motor in question.----Took an 88 -110 HP apart today.------Broken rings on 2 pistons.-----------Don't know how many times I have seen this typical failure over the last 40 years
 
ya makes sense i just want to know the cause b/c i dont wanna have to rebuilt it twice idk if it would be rings like all the other clyinders comp was fine but the plugs did not have much oil except the bottom right ill have to rip into it and see what the deal is thanks for your help it has been such a good boat otherwise and worked great for 20+ years with only replacement being the fuel pump 3 years ago
 
If you popped the cylinder that provides crankcase pulses to the VRO, that would explain the no oil delivery alarm. That's a pretty robust motor. figure out what went wrong or you'll be doing it again. I always top off the oil as opposed to draining. The air bubble you create by draining can cause issues. I do drain the gas though.
 
Just to get you thinking....if no oil due to VRO failure, why no damage to the other three cylinders?

More likely is lean on one cylinder only due to dirty HS jet in that carb. Burns up one cyl., leaving the others OK.
 
thanks for your help and postin above^^ i thoguhtr of that very issue plugged jet b/c its only one it makes sense to me but im in hischool with not much experinece. dad didnt think so but ur info is much appriciated well see the cause when we rip it apart
 
I agree daselbee--- My thought was that cylinder leaned out or whatever, then the cyl popped. Once there was no compression, there's nothing to run the VRO pump if that is the cyl that provides the pulses.

Definately agree that a true oil delivery failure would have wiped out the whole powerhead. Either way, mix the gas till VRO is proven. Run the consumption test at both idle and WFO before switching to clear fuel.
 
The piston rings in these motors wear and side clearance quickly increases !-------The tapered ring then breaks from being hammered at full throttle .-------------See this all the time!!--------------Without regular maintenance the VRO can not be trusted.---------------These units need to be checked and maintained.
 
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