Overheat alarm comes on after engine at idle for 4-5 mins. If moving, even at slow speeds, it stays cool enough to keep alarm from coming on. Just had new water pump placed. Mechanic said the old one was installed incorrectly (washers were placed in wrong position?) The overheat has happened before at idle, but was remedied with new pump 2 years ago. Does this sound like wrong/bad impellar installed or something else like thermostats/poppet valves? Engine is a 2000 yamaha saltwater series. Thanks.
So the engine cooled fine for two years with the washers installed wrong, now with a new pump installed it runs hot at idle?? Something don’t sound right!!
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It is the 150 hp saltwater series. The mechanic took off the lower unit and the water pump was properly installed…The thermastats were working appropriately as well. Apparently , the poppet valve was not opening and closing properly at idle speeds (?is there one or two). There was some sand around the valve and he also adjusted the spring. He let in run at idle and this seems to have fixed it. I told him to go ahead and just replace the valve even though it seems to work fine after the adjustment. Several years ago I ran across a sand bar and sucked up a bunch of coarse sand. After that incident, it overheated but was remedied with a new water pump. Hard to imagine that sand is still in there and causing the problem, but that is the only time she has been run across shallow water.
Ben Miller
pressure relief (aka poppet) valve is notorious for causing low rpm overheat issues
sand can stay in the system for a really long time
Man, I miss the old days I used to feed my 25 hp merc a steady diet of sand and pluff and it never complained…
“I fish therefore I lie”
2006 Mckee Craft 185 Bay Classic 150 Yamaha
God blessed those old merc 25s!
quote:
Originally posted by chris Vpressure relief (aka poppet) valve is notorious for causing low rpm overheat issues
sand can stay in the system for a really long timewww.teamcharlestonmarine.com
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My Yamaha ProV-200 always gets hot if I idle at 700RPM or lower for more than 5 minutes. Hard to troll for trout at 800RPM (especially when the water is cool and the Trout are moving slow).
Chris - you think this is the pressure-relief/poppet valve? I have replaced the thermostats and even ran without them for a long time. Have changed the water pump religiously for years as well. All with no improvement. Now I must keep it at 800RPM or more if I idle fr more than 5 minutes (shrimping, getting bait, leaving my creek, Shem Creek) to avoid the heat & buzzer.
Thanks, Captain Ross
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T Top, my engine idles after warmed up @ 600 rpm. After replacing the poppet, I let it run @ idle for 20 mins with lower unit in barrell and no overheat. Hope this helps.
Ben Miller
quote:
Originally posted by Miller TimeT Top, my engine idles after warmed up @ 600 rpm. After replacing the poppet, I let it run @ idle for 20 mins with lower unit in barrell and no overheat. Hope this helps.
Ben Miller
Good to know - have to get a poppet valve then. Just thought my ProV ran hot since its been hopped up a bit.
Thanks, Captain Ross
http://T-Topless.com folding, stainless steel T-Top fits most center console boats
http://ShadowTop.com entry level (Do-It-Yourself) T-Topless kit
http://Montauk-T-Topless.com for Boston Whaler Montauk, Dauntless or Outrage
http://Flats-Top.com Shade for Flats Boats
http://RNR-Marine.com/Canvas.shtml Original OEM factory replacement Sunbrella canvas for Sea Pro, Sea Boss, McKee Craft, Key West, Sea Hunt, Cobia, Sea Fox, Pioneer, Everglades, Tidewater, Mariah, Cobia, Caravelle, Baha Cruisers & Palmetto Custom.</font id=“size1”>
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quote:
Originally posted by chris Vremove and clean poppet valve
www.teamcharlestonmarine.com
www.joinrfa.org
Roger that … will do this week …
I can’t imagine how sand or dirt got in there 
Thanks Chris!
Thanks, Captain Ross
http://T-Topless.com folding, stainless steel T-Top fits most center console boats
http://ShadowTop.com entry level (Do-It-Yourself) T-Topless kit
http://Montauk-T-Topless.com for Boston Whaler Montauk, Dauntless or Outrage
http://Flats-Top.com Shade for Flats Boats
http://RNR-Marine.com/Canvas.shtml Original OEM factory replacement Sunbrella canvas for Sea Pro, Sea Boss, McKee Craft, Key West, Sea Hunt, Cobia, Sea Fox, Pioneer, Everglades, Tidewater, Mariah, Cobia, Caravelle, Baha Cruisers & Palmetto Custom.</font id=“size1”>
Drop your top and go T-Topless! T-Topless@RNR-Marine.com