Electrode burning off one plug

[duttonv]

I have a 1976 Evinrude 115HP outboard.<br /><br />The top right plug after idling melts the electrode off after 15 to 20 minutes at idle speed. The other 3 plugs are fine. What do you think the problem is?<br /><br />Dutton<br />

 

[Dhadley]

Re: Electrode burning off one plug

Welcome!!<br /><br />What plugs are you using?

 

[duttonv]

Re: Electrode burning off one plug

Champion

 

[Dhadley]

Re: Electrode burning off one plug

OK.<br /><br />Which Champion?

 

[duttonv]

Re: Electrode burning off one plug

from the box<br />828ql77jc4

 

[Dhadley]

Re: Electrode burning off one plug

Good. <br /><br />How does the motor idle? Good? Fast? Is it hard to start?<br /><br />Whats the history of it? Been sitting? Did any of the run characteristics changed just before this?

 

[duttonv]

Re: Electrode burning off one plug

How does the motor idle? Good? Fast? Is it hard to start?<br /><br />Whats the history of it? Been sitting? Did any of the run characteristics changed just before this? <br /><br />motor idles fine<br />I bought the motor 4 years ago and have used it at least one day of every summer weekend since with no problems<br /><br />No run charastics changed. We were towing one of the kids on a tube and it started acting up 2 weeks ago. limped home with 1 cylinder missing.<br /><br />Replaced plugs and went back out everything fine.<br /><br />This weekend (plugs have 8 hours on them) ran fine for 1 hour, slowed down to idle (left motor running to inflate tube from 12V pump) and went to tow tuber and 1 cylinder missing. Limped home checked plugs 3 OK same one the bent electrode was much smaller on the bent side.<br /><br />Thank you for your time here I know this was alot of information

 

[Dhadley]

Re: Electrode burning off one plug

Thats the info we need. <br /><br />First lets check compression to make sure we dont have a damaged cylinder now.<br /><br />If the compression is OK, pop the flywheel off to make sure the key isnt sheared.<br /><br />If the key is good, check the timing on #1 with your timing light. Make sure it doesnt go past 28 at any rpm. Check it as close to wot as you can. If, at any prm, it does go past 28 then shut down right away.<br /><br />Good luck!

 

[duttonv]

Re: Electrode burning off one plug

thank you<br /><br />I will check all of that this weekend.<br /><br />My boat is at the beach 2 hours away.<br /><br />Thank you.

 

[Dhadley]

Re: Electrode burning off one plug

At the beach? Sounds like a good reason to skip work!! Lol!<br /><br />Good luck!

 

[duttonv]

Re: Electrode burning off one plug

yea<br /><br />skipped work on friday<br /><br />can't do it again today.

 

[duttonv]

Re: Electrode burning off one plug

hi<br /><br />did the test you recommended.<br /><br />Timing is 24 degress<br />compression in each cyl is 120 120 120 122 in the cyl that has the plug problem<br /><br />Had a digital temp gauge (spot temp) with me<br /><br />two left cyl are 109 degrees at idle and the two right were 120 degreees thought that was odd.

 

[Solittle]

Re: Electrode burning off one plug

If the timing is OK I would suspect a defective plug - repalce it and monitor.

 

[duttonv]

Re: Electrode burning off one plug

replaced plugs this past weekend <br /><br />the OLD set of plugs had maybe 4 hours of run time.<br /><br />same plug top right cyl was starting to do the same thing. build up around the electrode insulator and the tip was starting to look odd. like it was drying out.<br /><br />ALSO my manual from the manuafcturer says gap the plugs @ .040 and Boat US says .030. Which is right?<br /><br />Dutton

 

[JB]

Re: Electrode burning off one plug

Moving to Johnson/Evinrude Troubles

 

[corm]

Re: Electrode burning off one plug

Hi,<br />.40 is the correct gap. You have a rather different problem that could be several things.<br />Is that coil case cracked if not you could swap two coils around to see if the spark problem follows the coil. You could also look down the plug hole to see if the top of the piston is clean. If it is you may have a little water getting in the cyl(comp does not indicate this) turning to steam on combustion which is very corrosive and could erode the electrode away. Or you could have a overheat problem (don't seem like it@120 deg) which would make the piston top look like grey sand. you may want to check your varitherms(thermostats) to see if right one is not opening fast enough or far enough...mmmmmmm..<br /><br />I've talked myself out of these being solutions.<br />Other than swapping the coils for info, the other things are probably a non issue.<br /><br />Dhadly, I hope is comming up with a good idea for you. He is good. I'm going to watch this thread with interest.

 

[duttonv]

Re: Electrode burning off one plug

Thanks to all <br /><br />I will be back at my boat this weekend and try swapping the coils and looking at the top of the piston.<br /><br />That is bad that Boat US says .030 gap on the plug.<br /><br />I hope I did not do anything to the motor having the .030 gap. The new plugs I installed this past weekend are set at .040.<br /><br />Maybe that was the problem?

 

[clanton]

Re: Electrode burning off one plug

The latest sparkplug and gap from OMC Bombardier is QL77JC4/L77JC4 gapped at .030. Dated February 2003.

 

[Hooty]

Re: Electrode burning off one plug

What are the chances of you posting a foto or two of one of those burned plugs? If you have trouble posting it, email it and I'll post it.<br /><br />c/6<br /><br />Hooty

 

[Hooty]

Re: Electrode burning off one plug

Another thing. You and I may be related. My grandfather was born in the "Elias Vaught Cabin" in the 1880's.I think it was near Somerset, Ky. His name was E.M.Dutton.<br /><br />c/6<br /><br />Hooty