Stator Autopsy on 1987 Mercury

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Posts: 77
Joined: Fri Oct 16, 2015 1:08 am
Location: SoCal/SoNev

Stator Autopsy on 1987 Mercury

Postby pcrussell50 » Mon Aug 12, 2019 9:52 pm

On a 1987 Mercury 2.0-liter150-HP:

In another thread I complained about a miss fire at idle, but the engine ran very nicely at medium and high RPM without a miss. It was suggested that the first culprit to look at might be the stator, so I got a new Mercury Quicksilver stator.

Upon examination of my old stator, in addition to the red and blue wires having that soft rubbery noodle feel—the big thing—the two yellow wires had hard dried, discolored, cracked away insulation. I wonder if they got hot?

Has anyone seen this failure mode before?


Posts: 7326
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula

Re: Stator Autopsy on 1987 Mercury

Postby jimh » Tue Aug 13, 2019 7:30 am

The yellow wires from the stator coil assembly were probably the high-current alternator windings feeding the rectifier. In addition to the ambient heat from the under-flywheel location, the wiring was being heated by resistive losses in carrying the high current. The inference that the dry and cracked insulation was due to heat is very likely correct.

Posts: 417
Joined: Thu Jul 11, 2019 1:31 pm
Location: south Tampa Bay area

Re: Stator Autopsy on 1987 Mercury

Postby biggiefl » Tue Aug 13, 2019 9:46 am

Very common in older Mercs. Lucky it made it this long.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll: