bottom cyclinder reading zero compression

rodster

Seaman
Joined
Jul 21, 2002
Messages
58
I have 125 force 1988 and i had no problems in last 6 years until last weekend i noticed hard starting a staling a low idle. i took a compression test and i noticed bottom cyclinder reading zero and i also noticed oil build up in the lower carburator. What is my problem and what causes this to happen? please help before i am taken for a ride on the mechanics path of assumptions$$$$$$$.
 

wilde1j

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Apr 15, 2002
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5,964
Re: bottom cyclinder reading zero compression

I would first try using a decarb product on the hope it's possibly a stuck piston ring. If that doesn't help, pull the head and inspect the cylinder bore. A broken ring will show up as scoring at the break. If the bore is clean, you may have a blown head gasket. You'll need a new one anyway.<br />Good luck!
 

rodster

Seaman
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Jul 21, 2002
Messages
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Re: bottom cyclinder reading zero compression

thanks wildone, but i think its too late. i just got a phone call from the marina and cyclinder 1,3 are fine but 2/4 are bad which is tells me that it lower cyclinder of each carburator are problematic. <br /><br />questions:<br /><br />1-how does one decarb?<br /><br />2-if i need a rebuild should i change all pistons<br />because their are rumours about force's having bad manufactured pistons and supposively their are new and improved ones available? <br /><br />3-how much will this cost me to do.<br /><br />thanks guys
 

wilde1j

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Re: bottom cyclinder reading zero compression

OMC dealers have a aerosol product called Engine Tune, Merc dealers a similar product. It's sprayed into the carb throats w/ engine at a fast idle until all used. Then wait at least an hour ,or overnight is even better, and run the motor hard for about 15 minutes to blow the crap out. Directions on the can. NAPA dealers sell a product called Sea Foam --- same stuff, but you provide the sprayer. Cost is < $10.<br /><br />If the cylinder is scored and needs a boring, new piston and ring set plus soft parts, you're looking at major $'s, although it's acceptable marine practice to rework only the bad hole, which can save some money. Most of the cost is teardown and assembly labor. Cost is a function of local labor cost - around here it's around $75/hr- and this is probably an 8 to 10 hour job.<br /><br />By the way, what were the actual compression readings? Sounded like you had only one bad.
 

rodster

Seaman
Joined
Jul 21, 2002
Messages
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Re: bottom cyclinder reading zero compression

wildone..<br /><br />The first mechanic checked only the 1st cyclinder and it read 125psi,and the 4th cyclinder read zero.??<br /><br />My brothers mechanic (#2) took over the task a he did a leak-down test and read 1st/3rd leaking 20% and the 2nd/4th leaking 80% which isn't good news. I still don't know if he took it apart to see whats causing the leak, either ring problems, cyclinder damage, pistons ruined?<br />TO be honest are force motors worth rebuiding because i have a opportunity to get a 2year old 4stroke merc but its only a 90hp rather than my 125 force. If i go that route i'm afraid it will not provide enough power.?!@#$%^&*liner cobra)<br /><br />please comment<br />rodel
 
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