Problems with 5.0 L OMC cobra

[Coors]

Re: Problems with 5.0 L OMC cobra

you have multiple problems.
Check the compression next.

 

[mcleaves]

Re: Problems with 5.0 L OMC cobra

Key word "Quick"
Ok Ok I'll say it "head gasket"

Yup.. Like I said,follow the steam... Give up on the ignition for now. That's a red herring. You may have problems there, but a head gasket will cause EXACTLY what you are complaining about, and you have evidence that there is a problem with them.

 

[Don S]

Re: Problems with 5.0 L OMC cobra

Since you are in the Norfolk, Virginia area, you will see some steam coming out of the exhaust. It's hot exhaust into cold water, happens all the time, so does carb ice. I had it today on a boat I was running, rebuilt engine, new manifolds and risers, new impeller, running 140? and there is white smoke (Steam) coming from the warm water out the exhaust. IT was 49? outside and the engine runs perfectly.
Melted wires will cause your engine to miss etc, and may even damage the ign. module. But till your run it and check the riser temp with one of those IR temp guns, don't go blaming a bad manifold or riser just yet.
IF that was the problem, when it starts missing and sputtering, shut it off and look at the plugs. If there is water it will be beaded up on and in the spark plug.

 

[mcleaves]

Re: Problems with 5.0 L OMC cobra

Some steam yes, but it sounds like it gets worse the longer he runs. When I've seen this it's the leak in the gasket expanding and letting water into the cyl.

I guess is depends on how bad it's getting.


M

 

[JCF350]

Re: Problems with 5.0 L OMC cobra

Pick up coil in the distributor? Happened to me enough (autos) that I don't change the module with out changing this also. Didn't have them yet when I worked on little boats.

 

[agibson]

Re: Problems with 5.0 L OMC cobra

Yes I see the steam when the thermostat opens and starts mixing with the cold water from the hose. I did notice yesterday that even after setting for 2 hours it would start but miss and quit after 10 min. Temp when it quit was about 110 degrees. Like I said it starts fine after setting all night and runs about 20 minutes and then starts missing and finally stalls out. The more I attempt to start it the worse it gets and shorter amount of time it runs.

 

[Don S]

Re: Problems with 5.0 L OMC cobra

When it stops running and won't restart, check for spark. Then we will have a direction to go. So far you haven't really tried any of the suggestions, so everyone is still in the guessing state.
Time to start isolating possibilities one at a time. It's called troubleshooting.

 

[agibson]

Re: Problems with 5.0 L OMC cobra

I have pulled the coil wire after it has quit and can hear it sparking. Today I ran her this morning and as always ran for about 20 then quit. I left the water running to it , pulled the coil wire and cranked it for a while, then pulled the spark plugs they were brownish black with no water. Also pulled the risers and found no evendence of water in the exhause jackets. After all that I started again, and it ran about 7 minutes and quit, never got above 120 degrees. This one is really kicking my butt !!!!!

 

[mcleaves]

Re: Problems with 5.0 L OMC cobra

So you touched two areas today and now the problem is worse. I doubt it was the man/risers making it worse. My bet is you have a bad wire(s) or plug(s) where heat is expanding some connection point(s).

The coil work was yesterday and it ran for the usual 20 minutes this morning. I understand you played with the wires and plugs after that and it ran worse right?

M

 

[agibson]

Re: Problems with 5.0 L OMC cobra

Well finally got a good spark tester and it looks like when the motor starts to miss 3-4 cyls are not firing. Guess it is time to by a new inginition module

 

[Don S]

Re: Problems with 5.0 L OMC cobra

Maybe not the module, many times the coil tower can crack due to bad wires, and when it warms up a little, it will start arcing to the nearest small terminal on the coil.
Don't get me wrong, it can still be the module, but I would sure check the coil and plug wires first.

 

[agibson]

Re: Problems with 5.0 L OMC cobra

Thanks....all ready replaced the coil, so I feel it must be the module at this point. I have been all through this boat ,batteries, altenator, manifolds, water in plugs after running, risers, wiring from front to back.

 

[Coors]

Re: Problems with 5.0 L OMC cobra

Not the the coil, the distributer cap; they crack/ get carbon tracking on them.

 

[Don S]

Re: Problems with 5.0 L OMC cobra

Not the the coil, the distributer cap; they crack/ get carbon tracking on them.

So does the coil, that is why I said COIL.
Even a new coil will quickly develop a crack if the plug wires are bad.

 

[mcleaves]

Re: Problems with 5.0 L OMC cobra

You don;t say if you replaced the wires..

Even if so they could be bad.. Wouldn't be the first time someone has repalced something that was DOA

M

 

[JCF350]

Re: Problems with 5.0 L OMC cobra

While your at the module check the pickup coil with an ohm meter should measure 500 to 1500 ohms check it when the engine shuts down also.

 

[agibson]

Re: Problems with 5.0 L OMC cobra

Mine doesn't have a pick up coil, it is all one unit, has 2 leads coming out going to the coil. Here is a link to the one I have

http://bpi.ebasicpower.com/c/OMC9L/Ignition+Modules+for+OMC

 

[a70eliminator]

Re: Problems with 5.0 L OMC cobra

Oh sheds new light on the subject, yep yep I'll bet that module is bad they're prone to damage if the key accidently left on, get the pertronix ignitor II which is imune to key left on syndeome, also being an OMC you'll have the ignition cutout switch, it's the micro switch actuated by the shift lever, as it passes neutral the ignition gets interupted momentarily to assist in a smooth shift for the gearcase, that switch has a retrofit to work with your style ignition.

Ok I opened a whole nother can o worms hope someone else can clarify my suspicions?

 

[Coors]

Re: Problems with 5.0 L OMC cobra

So does the coil, that is why I said COIL.
Even a new coil will quickly develop a crack if the plug wires are bad.

I thought he said he had replaced the coil already.

 

[agibson]

Re: Problems with 5.0 L OMC cobra

Thanks I would love to covert to the Pertronic Ignitor 2 , but I don't see one on the internet that will fit my dist. I have a ford Prestoline 7806 4C dist. All I saw was points conversion kits.