used_to_own_a_mastercraftOPRamp RegularCharlotte, NC19 posts, joined Jun 2025
#1
first jet boat after eleven years with a MasterCraft X-Star. 2019 Yamaha AR195, single 1.8, 140 hours, bought used in May from a guy in Mooresville. Lake Norman.
twice now, idling back to the ramp at Blythe Landing through the no wake zone, the overheat alarm has gone off. both times hot afternoons, the water feels like a bathtub. as soon as i get on plane it clears. never once in the morning. is the 1.8 just marginal at idle in 88 degree water, or am i missing something obvious?
the lake was down a couple of feet earlier in June, Duke Energy posts the levels on duke-energy.com, and the shallow coves by the landing have grass in them.
J
rotax_shop_jenPump GuruOrlando, FL61 posts, joined Jun 2025
#2
on the Yamaha 1.8 boats the cooling water comes off the jet pump. at idle the pump moves a lot less water, so anything partly blocking the intake shows up first at idle, in hot water, exactly like you describe. alarm at idle, clears on plane. my first guess is grass on the grate.
if the grate is clean, look at the cooling water line and fitting off the pump, they can pack up with grass and sand. thermostat is possible but it is way down the list.
P
impeller_nerdPump GuruLake Elsinore, CA77 posts, joined Jun 2025
#3
Lake Elsinore in July is 85 degrees and green, so i have opinions on this one. at idle it is weeds on the grate most of the time. the moment you get on plane the flow blows them off, which is why the alarm goes away.
trick: in deep water just before the no wake zone, bump it into reverse for a second or two. that backflushes the grate. then idle in. do not do that over the grass beds or you just pick up a fresh load.
S
sandbar_weekendsSandbar CaptainTampa, FL33 posts, joined Jun 2025
#4
Tampa Bay in August, same thing with turtle grass. i keep a cheap boat hook with the tip bent over so i can clear the grate from the swim platform without getting wet. will not work on every hull though, the grate on an AR195 sits pretty far forward.
G
used_to_own_a_mastercraftOPRamp RegularCharlotte, NC19 posts, joined Jun 2025
#5
got in the water at Blythe Landing last night after the fireworks crowd left and felt around the grate. a softball of hydrilla wound through the grate bars. pulled it off, idled the whole way back to the ramp to test, temps normal. tried the reverse trick twice this morning and it works too.
so a jet boat is a vacuum cleaner for lake weeds. noted.
T
twin_engine_dadSandbar CaptainCoeur d'Alene, ID29 posts, joined Jun 2025
#6
late, but one more for the next person who finds this: if it ever alarms at idle with a clean grate, check the engine temp sender connector before you start buying thermostats. our port engine threw a false overheat for a month and it was a green crusty connector. cleaned it, dielectric grease, done.
Log in to reply. No account yet? Ask a mod for one, it takes a day or two.
