Low compression in first cylinder

[ken_kaniff]

Got my boat back from the repair shop. It had the plugs replaced, seafoamed, carbs rebuilt, you know... made lake ready. Was told it still has low compression in the first cylinder and the only way to fix it is to rebuild the engine. And since I won't spend the $1500 to get that fixed he said just to use it. That it will eventually need rebuilding. Also said it had a lean idle spit. Is there anything I can do? Am I likely to just blow an engine at the lake and be stranded? the compression was 105 in the first cylinder while all the others were around 120.

 

[tashasdaddy]

Re: Low compression in first cylinder

ask him if he looked at the reed valves. what motor is it.

 

[nightstalker]

Re: Low compression in first cylinder

Give us the year, model, etc. and see what the forum gurus have to say. I know everyone looks for compression no greater than 10 pounds between the cylinders, but lets see what a 15 pound difference brings.
nightstalker

 

[fishmen111]

Re: Low compression in first cylinder

Did he check the head gasket?

 

[Benny1963]

Re: Low compression in first cylinder

pull the head with low comp head gaskets are cheap
check for scuffing . but may need better decarb .
may be head gasket .ever been run hot .
check reeds
good luck bennyb .

 

[ken_kaniff]

Re: Low compression in first cylinder

It is a 1978 evinrude 115 model #115899. I'll have to check on the reed valves but he is closed on sat.

 

[Dhadley]

Re: Low compression in first cylinder

You're within the 15 lb variance but just barely. If you're sure the guy did a decarb I'd take look at head gaskets (change the water deflectors while you're there). If you paid to have it all "lake ready" it shouldn't have come back with a lean sneeze. I'm not sure I'd be convinced he did a drcarb.

What plugs did he put in?

 

[ezeke]

Re: Low compression in first cylinder

Reeds don't have anything to do with a compression test. The best bet is to pull the cylinder head and check for a leaking head gasket and see if the cylinder is damaged. If the cylinder is damaged, it will just get worse and could make the block unusable.

 

[tashasdaddy]

Re: Low compression in first cylinder

thanks, exeke, i miss read this "Also said it had a lean idle spit. " read it as a carb spitting. gotta slow down.

 

[ezeke]

Re: Low compression in first cylinder

Lean spit could have a lot to do with reeds TD, that was not my intended message - sorry if I misspoke.

 

[Theoutdoorsman]

Re: Low compression in first cylinder

Let's back up for just a minute......... Was the lean sneeze/spit present before you took the boat to the shop? If not, I'd suspect a fuel restriction. Possibly a kinked fuel line or maybe a loose clamp. Something along those lines. If it were mine, I'd be waaaay more concerned with the sneeze/spit, whichever it is, than the compression right now. Does the outboard spit fuel from a carb as it's idling? This would indicate a possible reed problem. Or is it more like a hickup or cough? These guys need a wee bit more information from you before they can actually pinpoint the problem area and suggest a method to fix it. I totally agree with Dhadley on this. If you paid to have it "lake ready", it should have gone home with you "lake ready" and without the "spitting". I would suggest doing your own decarb, $10 at best with some SeaFoam from NAPA, and install some new champion plugs afterwards($12). My memory fails me or I'd recite the exact ones you need. QL77JC4's gentlemen? For about $25 and the decarb method, listed here at iBoats in the frequently asked questions forum, you will KNOW that your decarb has been done and been done correctly. Who knows, your compression issue might just be erased. As far as the sneeze/spit concern, bring some more information to the table and watch the wheels of these great minds turn. Your in the right place to solve your own problem!!! These guys rock!!!