I've got a 2003 25 horse Merc 4 stroke and I have yet to change the plugs on this motor. I've never had any problems with the motor but I am kind of wondering if maybe I should change the plugs as they are over 5 years old.

When I winterized my motor this fall I noticed the are starting to get some build up which is why I'm thinking it's time for a change.

My big question is should I be able to just go to my local Merc dealer, get new plugs and just swap them out? Do I need to do anything prior to putting in the plugs? Check the gap? Or should this already be correct since they are going to be Merc plugs?

Any help is greatly appreciated. I'm getting anxious for the soft water!

Thanks,

Dave

Ask the dealer if they are pre gapped - most are in the automotive market dont know about boats for sure. I always put a dab of Die Electric Grease between the plug and boot to resist corrosion etc.

Shouldnt be too big of a project but 5 years YES its time to RnR.

5 years!!  I change my plugs twice a year.  Am I doing it too often??

I just talked to my dealer and he said that they have pre-gapped ones for my motor.

I haven't changed mine do to most of my trips are on no wake lakes/electric only lakes and I rarely get a chance open my boat up if even start the big motor.

I'm going to get some new plugs tonight!

Boxes get droped in shipment and in merchandizing. Always check the gap, it takes five seconds. Why would you not?  

5 years!! I change my plugs twice a year. Am I doing it too often??

I put in new plugs every spring. I only use Autolite. Always check/set gap before installing. Happy fishing.

~B.A.S.S.~N.A.F.C.~BoatU.S.~

I just talked to my dealer and he said that they have pre-gapped ones for my motor.

I haven't changed mine do to most of my trips are on no wake lakes/electric only lakes and I rarely get a chance open my boat up if even start the big motor.

I'm going to get some new plugs tonight!

Stop at an auto parts store and get a set of feeler gauges so you can check the gap. For less than $20 you will be able to put in new plugs every year or every other year. Read the owners manual and see how often they recommend.

Also I am NOT a marine mechanic but I have been told that a steady diet of low RPM running is harder on plugs than normal running.

Thanks for all the advice everyone.

One more question, how do you go about adjusting the gap if need be?  I've never done that before?

Also I am NOT a marine mechanic but I have been told that a steady diet of low RPM running is harder on plugs than normal running.

Thanks for all the advice everyone.

One more question, how do you go about adjusting the gap if need be? I've never done that before?

It's actually quite simple. I suggest you buy a spark plug gapping tool at NAPA auto parts and ask the counter man to show you how to do it.     Happy fishing.

~B.A.S.S.~N.A.F.C.~BoatU.S.~