low compression #'s

[HotLava]

Skirt some oil into the cyclinder through the spark plug hole, re-measure. If the reading goes up, it's rings, if it doesn't, could be valve seals or head gasket,

 

[cosander]

low compression #'s

86 170 mercruiser has <br /> <br />145 #1<br />75 #2<br />90 #3<br />90 #4 <br />This boat sat for about 4 yr with out being ran. what would be the most probable cause for these numbers? I am hoping it is just a gasket but I doubt it could be some thing that cheap. Where do I go from here?

 

[vipzach]

Re: low compression #'s

Could be a gasket, could also be piston rings

 

[wake5150]

Re: low compression #'s

I didn't get the impression from your original message that the boat wouldn't run.<br /><br />I'd guess that it should probably run, even with this crappy compression? Have you diagnosed fuel and ignition systems yet? <br /><br />Make sure your getting wet plugs and a spark. Best not to do so at the same time

 

[cosander]

Re: low compression #'s

I put oil in the cyls and no change.

 

[cc lancer]

Re: low compression #'s

Cylinder walls rusted from sitting, and now the rings can't seal, leaking head gasket, valves not sealing the combustion chamber.<br /><br />If you have a 6 gallon tank, mix a heavy mix of Marvel Mystery oil and gas, get out on the water and run the engine, then do another compression check. I have had reasonable luck doing this, but there is no prefect way to get the compression up if the rings can't seal.

 

[cosander]

Re: low compression #'s

I wish I could get the motor to start co I could decarbonize it. Anything else that I am missing? Is it possible for this engine to run with these numbers?

 

[cosander]

Re: low compression #'s

ok I guess I jumped the gun I am geting no spark from the coil.

 

[cosander]

Re: low compression #'s

ok I got spark (points were a bit corroded) Now the carb is dripping fuel keeping the engine flooded where can I find the carb rebuild kit and all fuel filters?

 

[vipzach]

Re: low compression #'s

NAPA usually has a pretty good selection of marine parts, what carb do you have?

 

[jeff13601]

Re: low compression #'s

You might just be able to take the carb apart and clean it. Could be rust or dirt. Check the float and needle

 

[cosander]

Re: low compression #'s

I have the 2 bbl I am not sure of any other ways to identify it

 

[cosander]

Re: low compression #'s

Thankyou everyone I never thought I would get this things started. After I let the cylinders dry out from being flooded I primed it with a shot of gas and it fired. A huge cloud of black smoke came out and after that I realized the exhaust was coming from the inside of the boat. So my question now is where can I find the best deal on new exhaust bellows?