OMC Stringer 3.0 ticking

recess · May 29, 2005

1976 Grady White Gulfstream with a 3.0 ltr OMC electric stringer, new fuel pump, new fuel filter. Idles, runs up to about 2500 rpm's great. Good steady runner. Trolled offshore for 3 hours, no problem But, when pushed to WOT, roughly 3500, after about 4-5 minutes, start to hear what sounds like a tin can in the engine compartment, and RPM/s slowly drop off (lean knock???). When I pull the throttle back, she idles and runs great (no noise), but anything up above 3k runs her out of fuel, or at least I think that's what is happening. I just changed the fuel filter/water seperator, but not sure about float level in carb. I'm planning on dumping the fuel filter to see what comes out. Next step would be the carb to check float level. Am I missing anything. Thanks.

Bondo · May 29, 2005

Re: OMC Stringer 3.0 ticking

But, when pushed to WOT, roughly 3500,

You're running 1000rpms Below Recommended WOT..........

start to hear what sounds like a tin can in the engine compartment,

That's Detonation,...........Little Bit's,+ Pieces of Your Engine going Out the Exhaust........ I'll bet there's little pieces of your pistons All Over the electrodes of your spark plugs........ Pouring Raw Gasoline Down the Throat of the Carb., From a 5 gal. Can,...... Isn't going to Richen it Enough to Fix This.................

recess · May 29, 2005

Re: OMC Stringer 3.0 ticking

What caused it? I eventually plan to yank this thing out and put a bracket and outboard on it. Sounds like I may be doing it sooner than I thought? I bought it last winter with this in mind, but hoped to play a little this summer before working the conversion. What tests should I do to determine extent of damage? Thanks Rodbolt. I usually spend my summers at 5.5 MP but daughter and friends have the place for the summer. So, gotta play in Va. Beach.

Bondo · May 29, 2005

Re: OMC Stringer 3.0 ticking

I Guess the 1st place I'd Look is,... What's the Prop Pitch ?? Dock boat, or Trailer boat ?? Has it Ever ran at 4200rpm or Better ?? Has it ever Ran, Right ??

recess · May 30, 2005

Re: OMC Stringer 3.0 ticking

Bought the boat last year. Best I could get was 3500 rpm. Boat was in water at some time of its life as bottom is painted and thouroughly worn. Now shes is trailered. Guy before states it runs great up to 29 mph. (Imagine that.) Had it out last year, but kept running into minor repair problems that prevented me from running it up for extended periods. The prop is 14X17 SS. Yesterday finally got to sea trials for extended time. The ticking is not that loud, and as soon as it happened, I backed it down to idle. Checked guages. Temp, oil, volts, all reading good. Tried it again. Ran it up and again after about 5 minutes watched RPMs to match when the sound appeared. Sure enough, a light ticking, almost alike a washer rattling; rpm's slowly dropping. So, backed it off again. Trolled and cruised under 2500 rpm's for the rest of the day and all went great. She starts right up after setting the choke and 2 primes fo the throttle. There is a Tempo Fuel Filter/water separator on it. Could this be restricting the flow? Is it big enough? New filter last week. I will check that later today and see what's in it. Thanks

Bondo · May 30, 2005

Re: OMC Stringer 3.0 ticking

1st thing is to get a Smaller Prop on it.......... You've Got To get the RPMs Up Higher..... I don't do OMCs,.. But My 1st Guess is possibly, You have Too Tall of a Ratio in the drive,.... You've only got 1 more step Down in props,+ I Doubt a 15" is going to be Near Enough to get the RPMs back up to where they Need to Be......... I Still Doubt you're dealing with Strictly a Fuel Issue.......... Ayuh,... Your Fuel Filter/Seperator is Fine.....As long as it's got a Fresh Filter...

recess · May 30, 2005

Re: OMC Stringer 3.0 ticking

Thanks Bondo. I thought RPM's should be higher so I picked up a 14 X 16. I will put that one on and try that. What are max RPM's for this little engine? The original owners manual recommends 3800 to 4200, but not sure what motor that would be for as the manual covers all the '76 models.

Bondo · May 30, 2005

Re: OMC Stringer 3.0 ticking

I have No Clue as to What OMC Wanted,..........Like I said,.. I Don't Do OMCs...... Every 3.0l I've Ever Seen, Needs to be Able to run up to 4200/4600RPMs, WOT..... To have Any Power down low in the RPMs,+ To Run Right............ Now,....... I'm NOT saying you Should run it at those speeds all the time,..... But,.. It'll Run Much Better, at 3500RPMs,.. If it Can get to those #s...........

recess · May 30, 2005

Re: OMC Stringer 3.0 ticking

I just checked plugs, and they look good. I had never checked the carb, but when I push the throttle lever full forward to where it stops, the butterfly is only open about 75%. Should it be straight up and down???? Could this be part of the problem? If I readjust the throttle linkage, that should allow me to get RPM's up. I intend to take carb off next week, check the float, and double check timing once I get full throttle adjusted. Any advice would be helpful.

Bondo · May 30, 2005

Re: OMC Stringer 3.0 ticking

Ayuh,........... You may well have Found the Problem.............

Boatist · May 30, 2005

Re: OMC Stringer 3.0 ticking

I would also loosen or remove the fuel cap. You could have a fuel vent that is plugged up so as you run WOT the suction builds up in the tank and caused the carb to run low on fuel so you are running very lean. I have a 1980 OMC 400 Stringer, HP140, 3.0L, 181 Cubic inch and it RPM range is 4200 to 4600. After I could no longer get leaded fuel mine also would ping at WOT after warmed up unless I ran 92 octain fuel. The Owner manual call for 87 octain leaded fuel. I did some work on the head and installed a slightly thicker head gasket and it no longer pings. My boat is a 1980 Crestliner Aluminum and weights 2800 pounds dry and is a 21 foot by 92 inch beam mofided V hull. I have two props I use a 13 inch by 19 pitch OMC #389510 I use in the ocean and also areas where where make longer runs in rough water. This prop on my rig turns 4200 at WOT and gets 38 MPH. Second Prop is a 13 3/8 inch by 17 Pitch OMC #389948 stainless I use in smaller lakes and rivers where we tend to start and stop more offten but not travel near as far. This prop turns 4600 RPMS at 35 MPH. I hope this info can help you. You might try one of the decarb two cycle sprays like OMC Engine Tuner or Napa Seafoam deep creep. at lease mine has not pinged since I removed the head and cleaned it of carbon replaced one valve and installed a little thicker head gasket. Also timing for my engine is 4 degrees BTDC and dwell is 31 to 34 degrees, compression 130 PSI.

recess · May 31, 2005

Re: OMC Stringer 3.0 ticking

Where, or how, did you get a thicker head gasket? Is this an OMC part? I am running regular octane, so I may try loading it up with hightest and do a sea foam cleaning. Worked wonders on my outboard, never thought about if for this one. My boat weights in around 3200lbs. so I should see comparable results, or at least, now I know what I should be looking for as far as performance and specs.

Boatist · May 31, 2005

Re: OMC Stringer 3.0 ticking

I ordered it from Johnson Marine over the phone. It is a OMC head gasket. I not sure if it was standard gasket or not. I had talk to OMC rep at one of the boat shows. Main questions I had was what to do now that Leaded fuels are no longer available and that has slight ping at high rmps. I remember his suggestion to try a higher octain and detuning the engine by useing a thicker gasket but do not remember geting a part number. So I guess not sure about the gasket but the gasket was different style. I also should mention that when I replaced the valve I had other valves ground or polished. At time I ask about hardened vlave seat and the cost as still worried about the no lead fuel. Did not end up changing any valve seats. Also did not have the head flatened like I normaly would. Not too much help but can tell you my engine does not ping with either prop now. However I usually do not run anywhere around WOT except to test for a few minutes. I normaly curise at 3000 to 3200 RPMS in the 25 to 30 mph range. I am also not sure if your 1976 and my 1980 engines are the same as my factory book only covers 1980 engines. Good Luck

OMC Stringer 3.0 ticking

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