2 spark plugs rusted, 2 not!!

[bob johnson]

I have a 1995 johnson 115 ocean runner. ...60 degree looper. I recently bought out a marinas parts room and was going to install some of the hundreds of spark plugs i aquired. On the starboard side both metal hexs on the spark plugs were rusted badly. But on the port side both plugs were clean as can be. One thing that comes to mind , is that the starboard head runs hotter than the port. if i idle or motor slowly the starboard head can run up to 170 and even 180 at times.. but the port seldom goes about 150.

when i run over 3000 rpm the heads cool to 100 or so.

does anyone know why the one sides plugs are rusting...is that a clue for me??

i am thinking that i may be running a tad lean there and might go trun the idle mixture a little.

thanks

bob

 

[boobie]

Re: 2 spark plugs rusted, 2 not!!

Any chance of a very small water leak when the mtr is running ??

 

[JB]

Re: 2 spark plugs rusted, 2 not!!

Don't those two cylinders share a head gasket? A compression test might reveal a small gasket failure.

 

[Home Cookin']

Re: 2 spark plugs rusted, 2 not!!

could be a leak at the tell-tale,or even a by-passed tell-tale port (happened to me). The rust was on the outside, right?

 

[bob johnson]

Re: 2 spark plugs rusted, 2 not!!

the heads dont use gaskets they have an O-ring around the permiter of the bore on each cylinder.the water would have to flow out of the thermostat cap, to run down the outside of the head....Ill check on that...i replaced the thermostat with another used one I tested in the kitchen, the same day i replaced the plugs...seemed to have been a good seal....motor is clean otherwise....

bob

 

[bob johnson]

Re: 2 spark plugs rusted, 2 not!!

could be a leak at the tell-tale,or even a by-passed tell-tale port (happened to me). The rust was on the outside, right?

yes the hex to remove the plug is what rusted....there is no tell tale....per se...on the lower section in between the heads ( below the electrical compnents is an opening that the water stream comes out of...there is a fitting there for a garden hose..it is way below my rusty plugs


this motor is NOT a crossflow...it is a mid 90's and later designed V4 looper ( 60 degree)

bob

 

[Home Cookin']

Re: 2 spark plugs rusted, 2 not!!

OK I re-read your firs tpost; the rust did not occur on your watch. Could be anything, but points to some splash or spray of salt water onto the outside of the engine block. No telling what the previous owner did. As a salt water boater I can tell you it's not all that unusual and just as easily could mean nothing. I think you are spending time trying to find and solve a problem that might not exist. Stuff rusts. Maybe nothing more than a leaky cowl while the motor is tilted up.

But here's what happened to me, just in case: my mid-80's johnson 70 originally had the tell-tale port coming out toward the bottom of the water jacket. They redesigned and put a port at the top (like all motors you see now) and plugged off the bottom one with a rubber plug. Unbeknownst to me, that rubber plug failed, so I was driving around bathing the inside of the motor with salt water. Got some rust from it on the outside of the plugs, and elsewhere.

So something like that could have happened; the upper tell-tale tube may have cracked or got as pin hole or sprayed/dripped some when someone was working on it or trying to get it unclogged. Only takes once. Just as easy could have been during a thermostat repair, etc.

 

[bob johnson]

Re: 2 spark plugs rusted, 2 not!!

OK I re-read your firs tpost; the rust did not occur on your watch. Could be anything, but points to some splash or spray of salt water onto the outside of the engine block. No telling what the previous owner did. As a salt water boater I can tell you it's not all that unusual and just as easily could mean nothing. I think you are spending time trying to find and solve a problem that might not exist. Stuff rusts. Maybe nothing more than a leaky cowl while the motor is tilted up.

But here's what happened to me, just in case: my mid-80's johnson 70 originally had the tell-tale port coming out toward the bottom of the water jacket. They redesigned and put a port at the top (like all motors you see now) and plugged off the bottom one with a rubber plug. Unbeknownst to me, that rubber plug failed, so I was driving around bathing the inside of the motor with salt water. Got some rust from it on the outside of the plugs, and elsewhere.

So something like that could have happened; the upper tell-tale tube may have cracked or got as pin hole or sprayed/dripped some when someone was working on it or trying to get it unclogged. Only takes once. Just as easy could have been during a thermostat repair, etc.

thanks for the reply, the motor is not new to me, I have had it for 4 years now. I installed the plugs myself last year. doesnt apprear to be spray from the water, as nothing else is showing those conditions. My question basically was...is that rust a sign of an engine condition possibly...

since i also have that side heating up more than the other side! BUT i will remove the hood and run the motor to verify that the plugged water port isnt leaking.... it probably is nothing.. I know a lot of guys here have delt with motor repairs for years and the more you have worked on stuff the more you see all the possible issues.
bob

 

[Home Cookin']

Re: 2 spark plugs rusted, 2 not!!

the metal on spark plugs will rust way before anything else, since it is not marine quaility. It is not a sign of engine condition. you nailed it when you said "probably nothing." enjoy your boat.