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how tightt should spark plugs be??

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MCC, if your boat is equipped with catalytic converters I woud rethink fogging the engine. All of the comments that I have read from everyones mechanics (including the brand new school trained mechanic from where I bought my boat) says not to fog the engine because it could potentially damage the "cats". As for the plugs, I am not sure about exact torque specs but I anti-seize the threads on my plugs, run them in until snug then add an 1/8 to a 1/4 turn so the crush rings can do their jobs.

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I second not fogging each cyclinder individually. Even without cats, you can easily add too much fogging oil and have issues. I would introduce the fogging oil in through the throttle body while the motor is running.

I always torque my plugs down to 10 foot pounds. Every automotive technical manual that I have ever read stated between 8 and 13 foot pounds. I couldn't find the exact number for the indmar so I went with 10. Antisieze compound is also a good idea.

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If your boat has catalytic converters you should still fog the engine but it should be done different than a standard motor.

Standard motors you can fog the engine with it running down the throttle body. A catalyst equipped motor should still be fogged (you still need to protect the piston rings on the cylinder walls) each cylinder one by one. What Indmar does not want to happen is getting raw fogging oil on the catalyst then letting it sit all winter long. Fogging oil will get on the catalyst when the engine is started on the spring but they will get hot enough to burn any residual oil off so no damage will happen.

In my opinion winterization is the most important service you can do on your boat and engine.

Here is the torque specifications for spark plugs on a Indmar engine copied right out of the service manual.

Initial installation on a new cylinder head 30 Nm or 22 lb ft

All Subsequent Installations 15 Nm or 11 lb ft

If the cylinder head is aluminum (LS1, LT1, LQ9, or Hammerhead) Anti Seize should always be used.

post-4023-076784000 1317918278_thumb.jpg

Hope this helps you out


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thks for the info,

i got sta bil fogging oil from bakes,

need to get anti seize..

now is there a tool that shows me how tight i am getting with the sparks???

might sound stupid but its all numbers to meif i dont know how tights it each numbers means..


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Thanks for posting that info Paul ... it saved me from having to do it!!!

Any time Larry! Great having you on the boards too making sure people get the right information!

Hope all is well! See you at service training this winter


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