Serial Number: 2B125401 MERCURY 250DFI L PROXS Gen-2 TM
Lots of great feedback and advice. First year with new to us Z20. Purchased boat with 67 hours, it currently has 135.
Shutting it down for the year (Michigan). Was told the 100 hour service was completed but as always , trust but verify.
The lower unit oil appears it was the original and not changed so that got fresh quart of High Performance Lube. Easy peasy! Seeing that, I thought what about plugs. I guess at 67 hours they wouldn't/shouldn't change them. I pulled the first plug and realized right away they had some black overspray from the factory paint so they were original. Time to go those get swapped too which was pretty straight forward. Love the fuel line suggestion to get em' started.
My question is they look a little sooty to me and that tells me it might be running a little rich? Now since I've owned it we are using the "cocktail" and changed to the preferred DFI. Could some of the carbon be a combination of the oil and no fuel treatment. I'm pretty sure previous owner just ran it. The plug change made a difference, just sounds, idles and runs better.
87 octane?
Verify temps are coming up to 125 before putting it on the pad
high octane fuel, stats stuck open, excessive low speed operation all would cause the plugs to look that, also if some one has been shifting it in and our of gear with key on could put it into break in mode (double oil)
Service intervals are annually (every 365 days) or 100hrs whichever occurs first so plugs were due by hours alone. Those plugs look like the engine was/is run mostly under 2500rpm, no way for you to know what previous owner did unless you get a printout from a dealer. If possible, should try to end your day on the water with a run at or near WOT for 15 - 20mins.
Great tips guys. yeah it was a 2016 that only had 67 hours, The dealer did share the hours with me and it was babied. Not so much anymore.
As mentioned lots of good advice we always let it come up to temp using the vessel view before it's hammer down and always run it hard coming in too and yes its always 87 octane.
Those plugs don't look bad at all considering their extended use. Also, if you were idling before they were removed, the engine will run it's DIRTIEST at IDLE and WOT.
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