sonic28

35 fountain twin 496's the rear two center plugs how do you people get to them?

Raylar

Why are you changing plugs. these are platunum tipped plugs and if they are running ok they should just about outlast the engine and the boat?

Best Regards,
Ray @ Raylar

clpbs

Thay are diffacult to get but can be done. I have seen several engines with those plugs that fail between 200 and 300 hours. The #7 plug is the hardest.

sonic28

hi Ray
thank you, you stand correct I thought I had a bad plug and found out is was a wire.I changed one plug and said I have to change all what a mistake that was.I had to pull the fresh water tank on the port side and the holding tank on the starboard side.I just have a problem with the rear two in the center do to the fact I am a little portlie lol on me.So who was the brain child that said size matters not in this case.
regards Paul

verbi69

A tech deep at Merc suggested they should be changed every year...

techman

They are also in the business of selling parts, what do you think they are going to say?

I'm with Ray, why change them if there is no reason to think they are not working. How many times do they actually fire over the lifetime of a marine motor? Think of how often your car's plugs fire and you probably don't touch those for the life of the car!

Griff

I thought merc recommended changing them at like 300hrs.

clpbs

I think in our area it may have something to do with the saltwater use. My shop has had three boats in six months with some bad plugs.

stevesxm

then there is something else wrong. modern plugs with modern ignition , in nominal circumstance should last exactly as ray says.

hillbilly24

The only real valid reason for changing platinum plugs is that even the best quality stainless plugs will eventually corrode and then it is a real pain to get them out. For boats that sit in the saltwater or in any salt environment I recommend changing them every couple years regardless of hours. If you have to pay some one to extract one plug that snaps at the base it will cost alot more then a set of plugs.