OMC Ford Cobra 5.8 Loud Knock & ticking 1989

SharpeCon

Seaman Apprentice
Joined
May 28, 2009
Messages
41
Hello,

Hoping someone can help me determine what has happened to my engine. Here is what happened: I have had my 1989 Bayliner Cierra 2755 Sunbridge for about a month, I have had it out over 10 times since, it has run great. Had it out over the weekend, I hit a huge wave & nearly caught air, came down hard. I quickly slowed down on the throttle, went slow for about 20 mins due to a no wake zone. After no wake I throttled up to wot. right as soon as I got above 3000 rpms, I heard a loud couple of knock, or rapping sounds from the engine compartment, I immediately brought it to an idle, checked engine for obvious signs of damage, I found nothing, although there was a ticking noise coming from the crankcase on one side. I was about 3 miles from my marina so I slowly made my way back to the slip with no further problems. It was dark by the time I got back so I did no futher investigation. The next day, I checked the oil, which seemed a bit dirty, added about 2/3 of a can of seafoam, & decided to see if it was still acting up. It ran fine at around 2000 rpms, as soon as I got around 2900 & up on plane I heard ONE knock sound, about 30 seconds later, there was a sudden cut out in the engine & what sounded like a backfire. Again, I slowed down to an idle, and limped back to my slip. I have not done a compression test, checked spark plugs, or any tests for that matter. I do not know much about this engine yet. Looking for someone to tell me what might be going on?

Thanks
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: OMC Ford Cobra 5.8 Loud Knock & ticking 1989

Popped a spark plug wire loose creating an intermittent or high speed miss. Cracked a distributor cap as free play in the shaft pushed up the rotor and it struck the cap, loose accessory braket (alternator for example), battery bouncing around, just to name a few odd-ball things. Remove the engine cover and have someone with some engine knowledge ride with you while watching the engine to try and identify what's making the noise. If you almost caught air, you may have and when the prop got a bite again the coupler may be in the beginnings of failure.
 

SharpeCon

Seaman Apprentice
Joined
May 28, 2009
Messages
41
Re: OMC Ford Cobra 5.8 Loud Knock & ticking 1989

Update,

Checked the spark plugs, found a wire that was off one of the plugs! Connected it back up, enigne no longer ticks! I believe this will solve the problem. Thanks for the reply Silvertip!
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,133
Re: OMC Ford Cobra 5.8 Loud Knock & ticking 1989

Update,

Checked the spark plugs, found a wire that was off one of the plugs! Connected it back up, enigne no longer ticks! I believe this will solve the problem. Thanks for the reply Silvertip!

Danm,.... Yer Good Silvertip,.... If there's an electrical spark to be found,... Yer Right on it.... ;)
 
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