one sideof the V4, the plugs are rusting

[bob johnson]

My Johnson V4 1995 vintage ocean runner 115 hp has had the straboard side plug bodies rusting badly while the port side has no rust. I use the motor in salt water, maybe 20 times a year... I am thinking it MIGHT be because the port side runs much hotter at idle than the starboard side, and thus the heat removes more moisture...at cruise both heads are the same 100 degrees...

do you guys think the reason is the temps??? or is there some type of electrolysis going on I don't understand?? there is no leak in the cover!!!

bob

 

[oldboat1]

Boy, that looks to me like exterior corrosion. I've seen plugs like that on parts motors in Maryland, stuff that had sat out -- presumably in salt air. No salt water corrosion or evidence of leakage around the t.stat cover on that side?

 

[bob johnson]

Boy, that looks to me like exterior corrosion. I've seen plugs like that on parts motors in Maryland, stuff that had sat out -- presumably in salt air. No salt water corrosion or evidence of leakage around the t.stat cover on that side?

no! there really isn't any corrosion visible on the motor, partly because when you don't run the motor the gas evaporates that's in the carbs and the oil runs down onto everything, plus maybe two of the carb bowls have that leaky BB... not bad.....but the motor looks pretty clean corrosion wise... the t stats are dry...zero leak.... the gasket on the motor cover is great! , not folded... although most things on this motor are stainless steel or painted aluminum or plastic....there is like zero regular steel!!....so it would be hard to get corrosion.....

bob

 

[oldboat1]

I wouldn't suspect electrolysis or heat damage/effect, unless there's evidence elsewhere as well. Obviously pretty severe corrosive effect, of some kind. If it were mine, I would start with a fresh set of plugs and check after each use -- see if I could catch changes in progress. Other than that.....

 

[emdsapmgr]

You've got two different plugs on each side of that engine. I'd figure out just which plugs go in it first...

 

[bob johnson]

You've got two different plugs on each side of that engine. I'd figure out just which plugs go in it first...

all four plugs are QL78YC , that's the plug I have used from day one 5 years ago.. and I am pretty sure is the one called for...although I think they list another plug as optional..QL77 something

bob

 

[dingbat]

I had a similar issue . Turned to be a small leak in the thermostat circuit. Replaced all the hoses in the circuit and the problem went away

 

[fhhuber]

Check your thermostat housings for leaks...

again

 

[bob johnson]

will have to give that a check after I run her wide open for a little bit.....see if water is getting past that o ring. BOB

 

[tommarvin]

Free factory outboard service manuals at www boatinfo.no/lib/library.html.

Click your make, find your outboard, find the plugs. We have a Force 125 they say NGK -BUHX surface gap, I've read surface gaps are better for outboards?
If interested go to NGK.com, see if they have a surface gap plug for your motor.

 

[bob johnson]

Free factory outboard service manuals at www boatinfo.no/lib/library.html.

Click your make, find your outboard, find the plugs. We have a Force 125 they say NGK -BUHX surface gap, I've read surface gaps are better for outboards?
If interested go to NGK.com, see if they have a surface gap plug for your motor.

the gap wasn't the issue...motor ran great..... I have always heard that the J-E of the 90s always ran better on champion plugs....

bob

 

[racerone]

Is the spray coming off the hull / motor the same on starboard and port sides ?--------Does the cowling have the louvered air intakes ?

 

[bob johnson]

Is the spray coming off the hull / motor the same on starboard and port sides ?--------Does the cowling have the louvered air intakes ?

the motor has the louvers up top on each side ... the spray would dynamically be the same....I am guessing.... IT MIGHT be possible the transducer sends up a spray on the suspect side( starboard), but in memory I don't see it hitting the cowling.......that seems more plausible than the leaky t-stat...because there is never any water inside the cowling or on the heads or down below the heads on the inside of the lower cowling...that I can ever remember....now that I have noticed it...( in the 5 previous years I cant remember this happening)...I plan to monitor it more...

bob

 

[Chris1956]

I think it is external corrosion as well. Somewhere there is a leak where salt water can get to the plug bases.

 

[bob johnson]

put the plugs back in today and took a closer look...sure enough there was a leak out of the thermostst seat!!!

thanks for the replies !

bob