1994 evinrude 120 V4 loud knocking

[rodeomanrides]

I have an Evinrude 120 and over the past few weekends i noticed it was not running like it should. I was still getting around 58 MPH but the motor just didnt seem like it was running right. After about a 20 minute run at WOT i noticed an intermitent beep indicating low oil so i filled up the oil reservior (yes it was low but not out.) and ran the boat for 15 minutes or so with no alarm however it just seemed not to have the power it had earlier so i decided to change the spark plugs. When I pulled the first one i noticed it did not have any gap to it at all. Now the engine has a rather loud knocking at WOT but i have no decrese in speed or RPM's and the engine still cranks and pumps water like normal. The motor has always smoked a lot but that goes away after it warms up so i know it is getting oil... I fear the worst has happened....any advise on what to look for

 

[metriccrescentwrench]

Re: 1994 evinrude 120 V4 loud knocking

Well, that plug didn't re-gap itself, it had to have had some help. It's time to pull the head and see what's going on. Post some photos of what you find.

EDIT to add: And for goodness sakes, don't run the engine any more until you get this figured out, you'll just make matters worse.

 

[rodeomanrides]

Re: 1994 evinrude 120 V4 loud knocking

I am pulling the head this afternoon... If the piston has come apart shouldnt there be some other symptoms of failure? What exactly am i looking for once the head is pulled?

 

[metriccrescentwrench]

Re: 1994 evinrude 120 V4 loud knocking

Doubtful that the piston has come apart. More likely something like chunks of a broken ring flailing around inside the cylinder. Just post photos and a description of what you find, the experts here have seen it all before.

 

[V153]

Re: 1994 evinrude 120 V4 loud knocking

Check compression.