HELP! Mercruiser 260 dead?

[sr225]

1982 Sea Ray 225 Express Cruiser w/ Mercruiser 260

Bought one month ago w/ limited hx. Hours unknown.

Changed plugs, oil, filters, batteries. Boat ran great for one month. Absolutely perfect.

Last weekend I was cruising at 4500 rpm when a knocking nosse started coming from the engine bay. Sounded like someone hitting the valve cover with a wrench in sync with the rpms.

RPMs began to fall even w. WOT. RPMS fell steadily to 2500 and ran for about two minutes. Noise continued whole time. If given throttle RPMS would not increase.

Oil pressure and temperature where fine.

I eventually turned off engine and it would not refire.

Any ideas?

 

[captmello]

Re: HELP! Mercruiser 260 dead?

Sounds like something busted doesn't it.

Do a compression test and see what you get.

How long were you "cruising" at 4500 RPM? Thats tough on that old motor.

 

[HT32BSX115]

Re: HELP! Mercruiser 260 dead?

Last weekend I was cruising at 4500 rpm when a knocking nosse started coming from the engine bay. Sounded like someone hitting the valve cover with a wrench in sync with the rpms.

Hmm,

Ok, second post for the same problem?

Last post you said you you were at 4500RPM for

Maybe a couple of minutes.

Now it's "Cruising"?

If you were "cruising at 4500", that would probably take nearly wide-open throttle (WOT)

While it's ok to run at WOT for a couple of min, (most of us would limit WOT runs to a min or less) If you had old gasoline or a mis-timing issue, That would be prime case for detonation.

I would start with looking at the plugs. (since you have to pull them for the compression check)


By the way it works better if you keep your posts together instead of starting another one for the same issue......(the exception is when it get hyjacked or runs so long that everybody forgets what the original question is!!!)




Cheers,

Rick