1982 Mercruiser 260 Dead?

[sr225]

1982 Sea Ray 225 Express Cruiser w/ Mercruiser 260

Bought one month ago. Limited history and hours unknown. Boat looks like it has been used very little.

Changed plugs, filters, oil, batteries. Boat ran GREAT for one month.


Then...running at 4500 RPM two days ago when boat began to slow. Loud pinging noise from engine bay. Sounded like metal hitting the valve cover in sync with the RPMs. RPMS began to fall to 3500 at WOT. I cut back throttle and engine struggled to keep 2500 RPM.

RPMS ans speed fell off and engine stuggled to idle.

Oil pressure and temp were fine.

I turned engine off. No visible damage. But engine would not refire.


I have checked fuel, spark, etc. All seem fine.

Any ideas of where to start?

 

[HT32BSX115]

Re: 1982 Mercruiser 260 Dead?

Howdy,

From your description it sounds like a detonation event.

You might get your hands on a compression gage kit (available at most autoparts store for a noominal fee) and check the compression.

You'll be looking for one or more cyls with low (or zero) compression.

If you find a cyl with zero compression, yes the 260 is "dead".

Compression is a good place to start based on what you describe.


Good luck!


Rick

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

Thanks for the info Rick, as bad is it may be.

I will check the compression and go from there.

Would a "detonation" event not have shown on the oil pressure guage?

 

[HT32BSX115]

Re: 1982 Mercruiser 260 Dead?

Would a "detonation" event not have shown on the oil pressure guage?

Um....oil pressure gages show OIL PRESSURE.


Detonation could have been the audible "pinging" you heard. In a car it can happen when you use regular gas when premium is REQUIRED, or the timing is advanced too far, there's heavy carbon deposits on spark plug, valves, pistons etc or when the engine is heavily loaded at low rpm.....there's other reasons.

http://www.misterfixit.com/deton.htm

Detonation can destroy an engine pretty quickly if it's allowed to do it heavily loaded (like Marine engines usually are) AND 4500 RPM would be at or near WOT (Wide-open-throttle) for most marine engines.....

I'm not saying this is absolutely what happened in your case but, from your description it "sounds" like it!

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

Thanks. Great link.

Appreciate your input.

Steve

 

[180shabah]

Re: 1982 Mercruiser 260 Dead?

How long were you running it at 4500RPM?

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

Maybe a couple of minutes. I had just fired up to return home.

 

[FreeBeeTony]

Re: 1982 Mercruiser 260 Dead?

Sounds like it was a horrible death............

You may see evidence on the condition of the plugs when you remove them for the compresion test.

Will the engine still turn over with the starter?

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

The engine cranks fine and wants to fire. But will not start.

No unusual sounds.

 

[FreeBeeTony]

Re: 1982 Mercruiser 260 Dead?

Stupid Question...........are you getting fuel?

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

I had just changed the fuel filter the day before. So is suspected that might be the problem.

Last night I took the breather off and it appeared to get fuel though slighlty restricted. I went to take the fuel filter off and it was TIGHT! I suspect some type of vacum lock. (is that possible). I had planned to return tonight w/ a filter wrench to investigate further.

If it was starving for fuel would it make such a noise and act in that manner?

 

[FreeBeeTony]

Re: 1982 Mercruiser 260 Dead?

Maybe became very LEAN @ WOT and was pinging???

Not really sure.........never heard an engine run out of gas @ WOT.

Just a guess on my part.

What do you mean it appeared to be getting fuel???

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

I took the breather off and pumped the throttle to prime the engine.

I cranked several times. Given the amount of throttle I was giving it I suspected more fuel and more vapor. You could see it was "getting" some fuel but very little vapor and a slow flow of fuel to carb.

In the past , if I really pumped the throttle..you would get the strong odor of gas. Not so now.

 

[FreeBeeTony]

Re: 1982 Mercruiser 260 Dead?

Were you looking into the carb while someone else "Pumped the throttle"??..........you should see 2 streams of fuel when the throttle is pumped.....if you are alone, then disconnect the throttle cable and operate the throttle linkage by hand while looking down the carb.

Just my $0.02...........not sure if this is the right path but I would make sure you have fuel first.

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

Got the guage.

Cylinder # 2 = No compression.

Plug was shredded. I suspect a broken valve or rod.

RIP 350.

Pricing engines. OUCH.

Thanks for all the input.

Steve

 

[HT32BSX115]

Re: 1982 Mercruiser 260 Dead?

Sorry to hear it. If the plug is "shredded", you probably have a hole in the piston.... It's sounding a lot more like a severe detonation now...

 

[Bondo]

Re: 1982 Mercruiser 260 Dead?

It's sounding a lot more like a severe detonation now...

Ayuh,.... Probably caused by a Lean condition.....

 

[FreeBeeTony]

Re: 1982 Mercruiser 260 Dead?

Would be interested in seeing a pic of that plug........

Sounds a little like the death of my 350..........lifter hanging up, piston hitting valve and, the rest is history.............

 

[sr225]

Re: 1982 Mercruiser 260 Dead?

I will get a pic of the plug (motor porn) this weekend and post.

Any recommendations on a vendor of a remanufactured 350 motor. Prices on the web are all over the place ($850-$2,000). Anybody to avoid?

Thanks Steve