Strange ticking noise, odd, look

[ryanr623]

1970 Mercruiser 120. At low throttle engine purrs like a kitten. After a couple minutes at 3/4 throttle the engine starts to tick. When throttled down to low, it does it for about a minute and stops. The strange part is that it is, or at least sounds like, it's coming from the spark arrestor. I originally thought it was an exhaust leak, but it stops after going to low throttle after a minute. Any ideas?

 

[ryanr623]

Re: Strange ticking noise, odd, look

anyone?

 

[ryanr623]

Re: Strange ticking noise, odd, look

No one?

 

[Uraijit]

Re: Strange ticking noise, odd, look

Leaking spark plug wire? Valve train noise?

Hard to say without looking at it.

 

[ryanr623]

Re: Strange ticking noise, odd, look

I also thought it could be pinging, but usually pinging is sparattic, this is very consistent when it happens, like an exhaust leak.

 

[captk]

Re: Strange ticking noise, odd, look

Oil over full, Or breaking down?

 

[chiefalen]

Re: Strange ticking noise, odd, look

Spray some wd 40 around the base of the carb see if you have a leak.Also the vacuum tube.

Only other thing maybe just maybe a rocker arm loose? Needs a adjustment?

Maybe i said.

 

[APPALOOSA2]

Re: Strange ticking noise, odd, look

I know on my 120 i get a ticking from the other side of the engine, the fuel pump. Very slight and normal.

 

[chiefalen]

Re: Strange ticking noise, odd, look

Me too fuel pump makes a ticking noise.

 

[bigbob_FTW]

Re: Strange ticking noise, odd, look

I've always heard that tick in my 120, but assumed it was a loose rocker arm. I'll have to listen closer.

 

[chiefalen]

Re: Strange ticking noise, odd, look

Another thing these ain't new boats. 30+ years on the original posters boat.

We should thank g-d they still run.

Mine rusted out the head. Got a head waiting for gaskets.

However still runs good, good compression.

Hows the compression on the 70's 120?

 

[chiefalen]

Re: Strange ticking noise, odd, look

What am i saying almost 40 years on the 70's boat.

 

[APPALOOSA2]

Re: Strange ticking noise, odd, look

Mine runs like a swiss watch. I still use the points and condenser and this motor doesn't make a full revolution and its running. Running a 15x 21 prop on a 18 ' Starcraft Holiday full fuel 2 people and gear hits 42 on gps, and sips fuel doing it.......nice...
20' i/o glass with a 350 chevy sits next to the barn, it's a fuel hog.

 

[ryanr623]

Re: Strange ticking noise, odd, look

Turns out my spark arrestor top was loose. what an idiot i am lol