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I have a yamaha 130 and the other day it stopped firing on one cylinder. Carbs are clean and gunk free, fuel filter is clean and new primer bulb. All cylinders have spark. I did a compression check and three have 120 psi and the one not firing has maybe 20 psi. The piston moves up and down so the rod isn't broken. I'm thinking maybe the piston rings went bad.
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Is there a question you are asking?
Stuck rings due to piston damage would be my 1st thought, but maybe broke ring.
Time to open it up and have a look to see what happened -
Sorry my question was what else could be causing the loss of compression. I plan on opening it up tomorrowComment
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Broken rings, hole in piston, score in the cylinder walls, etc.
As suggested, open it up and take a look. It is not going to fix itself (don't think so anyway).Comment
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Never worked on an outboard before have mainly done just car engines, can you replace the piston and rings without total disassembly of the motor?Comment
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Maybe a good idea to have a Yamaha dealer double-check your low compression reading with their equipment and possibly do a bore scope into that cylinder to try identify the problem before ripping into the motor....If it was stuck rings and just maybe a treatment with Ringfree might loosen it up?....just an idea...good luck!Originally posted by Salt Gobbler View PostComment
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first and foremost, remove the head on the low compression side, this will allow you to see of the bore and piston is shot, or the head gasket is blown, beware of broken bolts when dismantling!Comment
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is it a 2 stroke? Is so can you take the exhaust side cover off and look in the cylinder? if so you'll see if the piston and rings are scored...Comment
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could you physically get a piston ot and back in without total disassembly?
possibly but it would be a junk engine in about 10 minutes.
no way you could align the rodcaps correctly much less bore,hone and chamfer the cylinders then clean all the debris before reassembly.Comment
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I soaked all the head bolts to take it off with PB Blaster and I still broke a bolt. Anyone have any ideas or techniques on how to get the rest out?Comment
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Did the bolt break off at the bolt hex head or flush with block? Try to loosen the others just a bit, spray blaster into gap between head and bolt, tighten bolt, back out and repeat...the idea is to try and get the pentreating lube into the threads.... Only thing left is to go ahead, remove what you can, and get the broke ones out after head is off, you'll be able to soak with blaster, and hopefully get vise grips, or hammer punch, or drill them out....Last edited by mackwrench; 08-14-2013, 09:17 PM.Comment
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I have used an electric impact gun with good success. Start slowly and let it wack on the bolt for a period of time, then have at it with the gun. The vibration seems to help free the threads within the block.Originally posted by Salt Gobbler View Post
Another trick is to heat the block around the bolt with a hot air gun. Then chill the bolt using some dry ice. The bolt will shrink and the block will expand, hopefully breaking the threads loose.
When you get the head off, notwithstanding how many bolts break or not, let us know what the cylinder walls look like.
What is the age of this motor by the way? The model year will do. ThanksComment
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Hi, new to the forum. Was searching for my answer and this post is the closest I got. I have a pair of '89 130's (130ETXF) that are quite old. Today I had to pull a head off since my thermostat housing screws broke. Plus I wanted to replace the internal zinks, head gasket and just take a peak. In pulling the head, 4 out of the 10 bolts snapped, flush at the block. Looking back, I wish I'd used my electric impact.
My question is how is the best way to extract these bolts without doing damage? If drilling, how big of a bit do I use for the #8 bolts? Is simply drilling them in the center enough to break them out?
Thanks for any and all advice.
ChrisComment
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