2000 mercury 90 knock

[classic015]

I have a 2000 mercury power force 90 2 stroke.took off across lake it died... started it up had a knock took off again ran good then died again, started and had a knock. took to the shop they did a compresson check had 1 dead hole.<br />Something about never decarbing the motor. I bought this boat new had maybe 50-60 hours on it.<br />Will decarbing now give me back the dead hole?

 

[jetdriven]

Re: 2000 mercury 90 knock

Can you post the compression values that the shop measured?<br />With the knocking and all, I suspect that there may be some piston damage. If it were mine, I would pull the head off and inspect the cylinder and piston for damage before running it any further.

 

[classic015]

Re: 2000 mercury 90 knock

They did not give me the compresson ratos just showed me the #3 piston was 0

 

[Hooty]

Re: 2000 mercury 90 knock

If nr. 3 was "0", I doubt decarb will bring it back.You can sorta check it out yourself by removing all the sparkplugs, ground all the plug wires and spin the engine with the starter and putting your thumb over nr. 3 sparkplug and see if it really has "0" compression.<br /><br />c/6<br /><br />Hooty

 

[Walker]

Re: 2000 mercury 90 knock

If it still has the same plugs in it check the plugs for aluminum on the plug surface and electrode. If you find any then you can bet you need a rebuild.

 

[dmessy]

Re: 2000 mercury 90 knock

A zero would indicate either the piston wasn't moving( broke rod, end cap) or a hole in the piston( usually will still show some compression). Do what Hooty said 1st, followed by Jetdriven's suggestion. Either way expect to spend a chunk of dough to either repair or replace. Something in a can won't fix it...<br />PS- did you buy an extended(5 yr)warrenty??