5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next Step?

[Bl@ck Pe@rL]

5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next Step?

Due to a coil arching problem (arch between term wire and coil to distrib cap wire) I replaced the coil, distrib cap and rotor on my port 5.7L 2007 Mercruiser on '96 Proline. After less than an hour of run time, the arching is back.

I have pulled the coil-to-distrib cap wire off the stbd motor (which runs) and still have the archning, from what I have read, sounds like my next step is to check/replace spark plugs and spark plug wires.

Looking for a "warm-fuzzy" that I am on the right track. One other variable in this is my raw water washdown tubing and live-well tubing is directly over this Port motor and I did notice some drips from this tubing down on to the motor. And we were running the washdown and live-well when the motor shutdown after the 1 hour of run time.

Thanks in advance!
Jon

 

[Don S]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Is this a carbed engine? Thunderbolt V ignition?

Sounds like you have a faulty plug wire or spark plug. High resistance causes the arc. Usually a cracked coil tower. Are you sure all the plug wires are on the spark plugs?

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Thanks Don, it's a carbed engine with a standard ignition system that came with the motor.

When I replaced the coil, distib cap & rotor, I pulled the wires off each plug and put some dielectric stuff in the plug wire caps, and re-installed the wires on the plugs. I did pull one plug it it looked OK. Motor has less than 50 hours on in it.

One thing I did not do, was paint the coil connections with that black rubbery stuff, wonder if that is allowing some leakage?

 

[Don S]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Brand new parts can fail.

One thing I did not do, was paint the coil connections with that black rubbery stuff,

Merc uses that to keep moisture out, not electricity in.

Check the resistance in the wires and change the plugs.

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Thanks Don, greatly appreciate the info/advice, I'm off the the parts store $$ then to the Marina, then hopefully out on the water

 

[MikDee]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Are you sure they are resistor spark plugs? If not strange things electrical can happen (arcing).

 

[P 0 P E Y E]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

You replaced parts to correct a problem but the problem did not change?

Looks like you can still change parts till you find the problem. Not always the most economical and efficient method of troubleshooting.

1. When you bought replacement parts did you use OEM parts for that engine. Part numbers the manufacture specs out, or did you use the parts you took off for a match? Just throwing that out there cause the preexisting problem still exists.

2. Change the plugs too...would be a good idea.

 

[P 0 P E Y E]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Forgot to suggest

I would inspect all spark plugs as a window into the sole of the engine,,,,YUCK

Check the plugs, see if they have a nice, neutral Grey color.

Check for water on the plugs
Check the oil to see if chocolate milk is on the menu

Go lights out at night an look for flash over on the wires and plugs

 

[Fun Times]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Do you know if the spark plug wires are stock or after market? What color are they? It almost sounds like you have the wrong type of wire or boot to cover the coil tower and the spark is leaking past the boot or you have too damaged "boot" wires if I am reading this right and the spark is going to the ground side of the coil right? Or am I way off here:redface:

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Thanks for the all the greta responses, spent all day trying to figure our why after cleaning my battery terminals, my engine died, when I turned the ingnition key not even a buzzer noise, found a breaker on the engine "mercathode" thing that had trip, so I back to spark plug and wire replacement.

Thanks for all the great responses, here's my $0.02:


boat teck ->Do you know if the spark plug wires are stock or after market?

Resp -> The wires are stock, came with motor (blue color):

P 0 P E Y E -> OEM Part?, Forgot to suggest -> plugs, oil, nightime engine look;

Resp -> I replaced with "Quicksilver Parts" , plan to pull the plugs today and change oil next avail,


MikDee ->Are you sure they are resistor spark plugs? If not strange things electrical can happen (arcing).

Resp -> The plugs are AC Delco 41-883,

Thanks Again!
Jon

 

[MikDee]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Resp -> The plugs are AC Delco 41-883,

Thanks Again!
Jon

Are they AC MR43T, or MR43TS, Marine resistor plugs, or an equivalent, it don't sound like it?
That's the standard marine plug.
And , or, it could be the wrong spark plug wire type as boat teck mentioned.

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

MikDee - When I pulled one of the plugs, "AC Delco 41-883" was the info on the plug ; I have box of replacement plugs that I got from the owner I bought the boat from and they are AC MR43T;

As far as the "Quicksilver" Coil, Distib cap and rotor, are good?

Also, where can I find info on the right spark-plug wires?

 

[Fun Times]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

http://www.acdelco.com/parts/sparkplugs/identification.jsp Here is a link to help you see what plugs you had and what you have now, To me MikDee is right you might have the wrong plug in the engine. You are running A platinum and you should only need the MR43t To be sure of this try looking at the flame arester [air cleaner] It should tell you what the spark plug number you need as long as it is still stock. Also here is another link you could look at that has boat spark plugs to look and buy from if you want to help give you an idea. http://www.boatersland.com/acplugs.html And here is a link of what your engine part numbers will be for you spark plug wires The color of the wires I believe are right Also try reading the plug wire to see if it has a merc name on it.http://www.mercruiserparts.com/Show...=50&bdesc=Distributor+and+Ignition+Components

 

[Bl@ck Pe@rL]

Update '07 5.7L Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching

Update '07 5.7L Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching

Just finished changing plugs and wires and coil is still arching. So my "replace parts" trouble-shooting method (to date have rotor, distrib cap, spark plug wires, and spark plugs) did not provide me a quick hitter, only a big dent in the wallet. ad:

Any suggestions on where to go from here?

Thanks in advance,
Jon

 

[MikDee]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Is this a carbed engine? Thunderbolt V ignition?

Sounds like you have a faulty plug wire or spark plug. High resistance causes the arc. Usually a cracked coil tower. Are you sure all the plug wires are on the spark plugs?

The only other thing I can think of, is like what Don said, take a close look at the coil top (tower) for any fine hairline cracks? If not, there might be residue, or a leftover carbon track (or path) on there, that will cause arcing. Clean it good with alcohol, or acetone, and don't get any finger prints on it, then put it back together and try it.

By the way, if there's no "R" in the plug number, usually it means they're not resistor plugs.

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Thanks, I'll check the coil today

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Bubba - No anti-sieze on the plugs; Good idea about the over voltage to the coil, one reason I haven't swapped coils from the operational stbd motor;

How do I check voltage at the coil, across the two leads on the coil?

 

[Bl@ck Pe@rL]

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Re: 5.7L '07 Merc - Coil Arching -> Coil/Distib/Roto Replaced & Still Arching: Next S

Thanks.

The thing about electricity it likes to go to the path of least resistance, given that I have replaced everything in the circuit -> coil to distib cap to rotor to wires to plugs) just seems odd it still jumps/archs across the coil;

Looking at the schematics, there is a sensor in the distibutor that the metal tab on the disk part of the rotor pass by which I have not replaced