One Clean Plug

[JOHN81859]

I Have A 1978 1150 Mercury outboard,I Did a Compression check On
My Motor, All In The 132 + Range. But The # 6 Plug Was Very Clean
The Motor Has Been Sitting About 4 Years, All Wireing Is Bad
What Should I Do Next. It Runs And Starts
Thank You In Advance

 

[Chris1956]

Re: One Clean Plug

When the #6 spark plug is clean, you likely have water intrusion. Water intrusion can be caused by a bad lower crankshaft seal or a bad exhaust water jacket cover or gasket. Both are a drag to replace, with the crankseal change out easier.

 

[JOHN81859]

Re: One Clean Plug

Thank You For Your Reply
Is This Something I Can Do?
I Have My Manual

 

[JOHN81859]

Re: One Clean Plug

How Can I Be Sure That Water Intrusion Is The Problem?
Is There A Test I Can Run?
Before I Take The Power head Off?
Is It Possible That My #6 Cylnder Is Not Fireing

 

[Chris1956]

Re: One Clean Plug

Test the spark on #6. If the spark is good, switch plugs and see if the new plug gets real clean. That is the best test...

Get a merc Service manual for the repair.

 

[JOHN81859]

Re: One Clean Plug

Thank You For Your Experience, It Is Very Appreciated