1985 90hp Evinrude - spark plug metal shavings

[basser01]

just got a used 1985 90hp evinrude vro. A closer inspection turned up metal shavings (likely aluminum) around the outside of two of the spark plugs from the upper cylinders. haven't fired up the motor yet and likely won't until this is solved. No shavings around the lower two cylinders. Is this a rebuild issue?

 

[Joe Reeves]

Re: 1985 90hp Evinrude - spark plug metal shavings

You say "around the outside of two of the spark plugs". This sounds like you're saying that the aluminum shavings are exposed when the spark plugs are installed.... that is the shavings are on the outer porcelin portion of the plugs and ARE NOT on the threaded electrode portion of the plugs inside the cylinder. If this is correct, I have no idea where the shavings came from and you'll need to inspect the engine closer.

If on the other hand, the shavings are internal.... remove the cylinder heads for a closer inspection. A compression check should tell the story if this (internal shavings) is the case.

 

[levi_tsk]

Re: 1985 90hp Evinrude - spark plug metal shavings

look IN the spark plug hole and see if you see shavings.... someone my have put a helicoil in the spark plug hole and not cleaned up the outside when they were done and this leads me to believe that they probably got some of those shaving inside the cylinder and if so and you run it itll frag itself ... you may not need a rebuild but you probably wanna pull the heads off if you see shavings inside the cylinder through the spark plug hole and honestly id take em off even if i didnt see anything through the hole because it may not be on the piston but below the spark plug hole on the bottom of the cylinder
post up a pic if you would please

 

[levi_tsk]

Re: 1985 90hp Evinrude - spark plug metal shavings

look IN the spark plug hole and see if you see shavings.... someone my have put a helicoil in the spark plug hole and not cleaned up the outside when they were done and this leads me to believe that they probably got some of those shaving inside the cylinder and if so and you run it itll frag itself ... you may not need a rebuild but you probably wanna pull the heads off if you see shavings inside the cylinder through the spark plug hole and honestly id take em off even if i didnt see anything through the hole because it may not be on the piston but below the spark plug hole on the bottom of the cylinder
post up a pic if you would please

joe types faster than me

 

[basser01]

Re: 1985 90hp Evinrude - spark plug metal shavings



This is the most in focus I could get. They seem to be fairly large - maybe 1/16th to 1/8th in size, silver and slightly curled. There is a whole crap load of them. They seem to be on the outside, thought the spark plug thread was kind of "cruddy" in the threads.

 

[basser01]

Re: 1985 90hp Evinrude - spark plug metal shavings



Here is the spark plug from that cylinder as well.

 

[levi_tsk]

Re: 1985 90hp Evinrude - spark plug metal shavings

hmm did you peek inside the spark plug hole towards the piston?

how do the threads look in the holes do they look a little stripped?

 

[trendsetter240]

Re: 1985 90hp Evinrude - spark plug metal shavings

If I were you I would pull all the plugs, take a clean shop rag and remove as much of the shavings as you can. Be careful not to get any shavings into the cylinder. Clean the threads on the plugs too and check if they are stripped.

Then do a compression test. That will tell you if the problem is interal or not.

 

[emdsapmgr]

Re: 1985 90hp Evinrude - spark plug metal shavings

As trendsetter mentioned, possible those shavings are due to cross-threaded spark plugs. If the head threads are damaged, you may need to put helicoils in both plug holes.

 

[basser01]

Re: 1985 90hp Evinrude - spark plug metal shavings

So the threads on the plugs look fine but the threads on the motor look a bit stripped and sad. I can't see any of the debris inside the cylinder (for as far as I can see in there. I will do a compression test today then.

 

[jeffersondodson561]

Re: 1985 90hp Evinrude - spark plug metal shavings

View attachment 96471

Here is the spark plug from that cylinder as well.

Threads look a little cross threaded...What is that white residue, is that something you put on (lithium grease)?

 

[levi_tsk]

Re: 1985 90hp Evinrude - spark plug metal shavings

As trendsetter mentioned, possible those shavings are due to cross-threaded spark plugs. If the head threads are damaged, you may need to put helicoils in both plug holes.

but pull the heads off to do it -you dont want shavings inside the cylinder

 

[Cofe]

Re: 1985 90hp Evinrude - spark plug metal shavings

Over torquing spark plugs will cause this to happen. The aluminum threads are eventually pulled out by the steel spark plug threads. You will need to remove the head and install heli-coils. Heli-coils properly installed are a stronger than original option.

 

[levi_tsk]

Re: 1985 90hp Evinrude - spark plug metal shavings

Over torquing spark plugs will cause this to happen. The aluminum threads are eventually pulled out by the steel spark plug threads. You will need to remove the head and install heli-coils. Heli-coils properly installed are a stronger than original option.

agreed WAY stronger just make sure you get the stainless steel ones or youll have mess at the end of the season

 

[basser01]

Re: 1985 90hp Evinrude - spark plug metal shavings

So you guys were totally right. It turns out that the previous owner had put in helicoils on the top two cylinders and they both came out with the spark plugs. In the pictures you can see the difference between the normal spark plug on the left and the one with the helicoil still threaded on it. Also, you can see the diameter difference between the two spark plug holes - one normal and the other after having its helicoil ripped out via spark plug! Thanks so much for the help!

 

[levi_tsk]

Re: 1985 90hp Evinrude - spark plug metal shavings

thats kinda what i meant when i said youd have a mess.... are they rusted down onto the plugs?

whatcha gonna do now???

 

[basser01]

Re: 1985 90hp Evinrude - spark plug metal shavings

Just wanted to give the follow-up to what we did. So after searching through several manufacturers of spark plug thread insert, I found the exact ones that were used to "fix" this motor. I installed them per instructions and she fired right up. I am keeping a few spare inserts in the on board tool box just in case I get a fouled plug in one of those cylinders and the insert again comes out with the spark plug. Problem solved.