Went to change spark plugs on 225HP optimax and found 2-different plug sizes???

[GC3]

So I have 2004 225HP Optimax S/N-OT921915

I went to change the plugs today and pulled the bottom and middle-right side (looking from the back) plugs and they where NGK ILFR6G-E. *** These are 1/4" longer then the 4-correct plugs***

These where the first 2-plugs I pulled and I thought damn I got the wrong plugs.

Then I pulled rest and the other 4 plugs where NGK IZFR5G. Correct plugs

Can one of the Mercury Techs on here give me some info on this? I AM PRETTY CONFIDENT THAT ALL SERVICE WORK PRIOR TO ME BUYING IT WAS AT A MERCURY DEALER. Why would it have the 2-different plugs? I bought the boat 3 years ago FROM A FRIEND and have not used it much the last 2 years but when I did it ran great. This spring and summer I have had more time to fish and have been out at least 3 weekends a month since March. It was running great all year till 2-weeks ago when it would take forever to get on plane. Then It would run ok. It had no power to put it on the trailer either. I thought maybe it was loaded up and fouled a plug because I have been night fishing all summer-5MPH max at night here. So with all the idling I thought maybe I fouled a plug. They did not look fouled though. Thanks for any info.

[JOE54]

IZFR5G is correct number ,cant explain reason someone would have done this

[EuropeanAM]

Those other two plugs are for a 4-stroke... and had no business in your Optimax. Good catch on getting them replaced.

[GC3]

Hi Don, Could they cause damage? After talking to my buddy I bought the boat from. All work was done at our local Ranger?Mercury dealer (where he purchased the boat new at) so there mechanic did this. Why would they do this?? Any thoughts? Engine did have Power head replaced 5 years ago. Thanks

[JOE54]

any evidence of piston contact, why ;;;; hurry up , no no better , dont care , pay attention

[EuropeanAM]

This had to have been an error on the part of the technician. Perhaps he had plugs for two different engines sitting there on his bench, or perhaps they were mixed up by the Parts Person, or perhaps-perhaps-perhaps.

Regardless, the installer is the one responsible to install the correct parts, gap the plugs correctly, and torque them to the correct specification.

"Wrong spark plugs in motor" is one of the very first classroom "bugs" a technician will encounter in training.

If there was no evidence of contact, run it for a while and check compression (basic indicator of whether problems exist).

[GC3]

Thank You Don, No evidence of contact. Thankfully. It seems to run fine now. It was fine all summer then on labor day It would not get on plain or have any power to load on trailer. I changed the spark plugs and fuel filter and ran this past weekend and it seems to be all good. I think I got really lucky.

[GC3]

Thanks Joe

[GC3]

Don, on a side note. when using your mercury additive cocktail. Do you use the Optimax oil when adding straight to fuel tank? and is the 150:1 4 oz to every 5 gallons of gas? Thanks again

[castforcash]

Don, on a side note. when using your mercury additive cocktail. Do you use the Optimax oil when adding straight to fuel tank? and is the 150:1 4 oz to every 5 gallons of gas? Thanks again

Use premium plus

[EuropeanAM]

^^^^ For the 150:1, absolutely use Premium PLUS.