OMC 1.6 Seadrive Running Rough

[strombolichef]

Engine overheated one time, shut it down, then replaced all head gaskets, thermos, waterpump, plugs, wires.

Now it runs rough sometimes however always starts on first turn of key. Idle sounds good most of the time, probably in the 3000+ range it runs rough.

Any chance that the flywheel movement or small movements in the throttle linkage during this process caused a little problem with the timing?

Also there is a leak in the gearcase, replaced plug gaskets and rear seals, if I dont use the engine at high speed a lot, and keep the oil changed often is there any kind of damage that will happen to gearcase?

I dont feel like removing the waterpump again to replace the seals if its not critical.

 

[Solittle]

Re: OMC 1.6 Seadrive Running Rough

Do a compression check & post the results.

Have you checked spark to all 4 cyl? You should get a bright snap that jumps a 3/8" gap.

Start with the basic troubleshooting & go from there.

 

[strombolichef]

Re: OMC 1.6 Seadrive Running Rough

Solittle....thank you for helping.

checked compression as you recommended
Left side top 137
Left bottom 137
Right top 142
Right Bottom 148


Spark good, plugs re gapped, very black, with some oil on them.

Thanks for helping, I will continue based on the next advice I get.

Still always starts instantly.

Bob

 

[Solittle]

Re: OMC 1.6 Seadrive Running Rough

Take it out and when it starts to run rough squeeze the primer bulb and see what it does. What you are doing is trying to isolate the problem to spark or fuel. What rpm's are you getting at WOT? Does it smooth out when you get over 3,000 rpm?

Compression is just fine.

Is this a "new" engine to you?

I have a pair of 1987 1.6L Sd. The engine is pretty much the same as a non Sd engine. If you are going to keep this pupply I recommend that you get the OMC shop & parts manuals.

 

[strombolichef]

Re: OMC 1.6 Seadrive Running Rough

I have the manuals, am fine with mechanicals, just not really aware of how the electricals work too much.

It does seem to even out a bit when I squeeze the fuel bulb, the motor never evens out WHEN its running rough, (but it doesnt always do it).. rarely, I will push the throttle to WOT and it just bogs down, then after some playing around up down up down with the throttle, it will come to life and run strong and push the boat up to a plane.

I am getting the RPMS 5600 with boat trimmed right at WOT when its running sweet.

It seems like something small, an adjustment or maybe a little dirt in carb? what do you think. What should I look at next.

Yes the engine is new to me. I am not sure how long I will keep it. Thanks

 

[Solittle]

Re: OMC 1.6 Seadrive Running Rough

At this point your symptoms point to crud in the carbs. They are not difficult to rebuild. Lots of info here on iboats on how to do it. My only suggestion is to use high pressure air (not rattle cans) to blow out all of the internal passages after you soak it.

 

[strombolichef]

Re: OMC 1.6 Seadrive Running Rough

will do that next. thanks.

 

[strombolichef]

Re: OMC 1.6 Seadrive Running Rough

just to finish this, ran old gas out of tank, put in some fuel additive, and problem fixed.
thanks

 

[flabum]

Re: OMC 1.6 Seadrive Running Rough

Did this problem begin right after the overheat? If so, check the torque on the coils. The coils sometime melt when you overheat the motor and can loosen. If they are melted and loose, remove them and give them a close inspection. If any are severely melted, replace them.

 

[Solittle]

Re: OMC 1.6 Seadrive Running Rough

Thanks for the feedback - I wish others would do it more often.