2002 70BETO Overheating Alarm at idle

[Stuy1980]

Hey Guys
I seem to have a over heating alarm going off when i run the motor at idle. Everything seems to fine when traveling along its only when i come to idle the alarm goes off afyer about 5min. I have only had the boat 1 month.
I have changed impeller + gaskets, thermostat + gasket, and spark plugs. Ive also flushed to cooling system so there is no blockage.
It is peeing water as normal..
Any ideas or help where to go from here would be appreciated ?
Cheers

[Sequoiha]

More than likely the pressure control valve stuck open. ( aka poppet valve)

[Stuy1980]

Hey Sequoiha,
Apparently this motor doesnt have a PRV.
Ive looked all through the service manual and parts catalogue and can't find it.
So think i can rule that out

[ausnoelm]

Did you replace the entire water pump or just the impeller? can sometimes make a big difference, especially of the housing is shot.

[Stuy1980]

Hey ausnoelm
I only did the impeller and gaskets.
The water pump housing looked ok but i guess i could swap that out and see what happens.

[Jason2tpa]

Just so I'm clear, when you're in gear idling the high temp alarm activates? But alarm is not activated while cruising on plane?

[Stuy1980]

Yep alarm comes on when not in gear but motor running.
No alarm when cruising on plane.

[cpostis]

Stuy:
Might want to pull the lower and check to see that all water tube dampers and seals are present and in place properly. The items I am speaking of are # 1, 4, and 16 in the following diagram. Note, this diagram is from a US 70TLRA, your non-US 70BETO may be the same or not.

[IMG]70TRLA.WP.TubeSealsDampers by Charles Postis, on Flickr[/IMG]

[Jason2tpa]

Yep alarm comes on when not in gear but motor running.
No alarm when cruising on plane.

How about when in-gear, idle speed? Alarm or no alarm?

[Stuy1980]

Hey cpostis..
Ive had the lower unit off and i cant see any damper or seals on the water pick up tube. So maybe its not getting enough water at low rpm..
Have order these and will install.. thanks for the tip.👍

Hey Jason.
No alarm when in gear.

[rodbolt17]

if the water tube(damper in jinglish) seal is not in the housing, guess what.
it overheats at low speeds.
like I have pointed out. the 60 and 70 two strokes use a high volume low pressure system.
it is the only system Yamaha specifically recommends NOT to use a water pressure guage.
however that housing left japan with the seal in place.
a replacement housing has no seal.
someone most likely replaced the housing and failed to swap over the parts.

[Stuy1980]

Thanks Rodbolt.
Ive ordered the seals as there is non in the top of the water pump.
When they arrive ill take some pics and post them up for anyone else who needs them for reference.
Cheers

[JPJ]

Stuy,

Did you ever get the new parts and install them. I am having similar issues but I have all the seals required. My 1992 Pro 60 heats up at *****ing speed but at idle it stays in the recommended heat range.

Thanks,
JPJ

[JPJ]

Bueller, Bueller...anyone. I should also mention everything in the water pump ,Plastic shrould, cup, impeller...Was replaced with OEM parts. Does anyone have any insight as to what might cause it to run hot while *****ing only?


JPJ

[Stuy1980]

Hey JPJ
I did get the parts and have installed them. Ive ran the motor on muffs for about 10min and no alarm.
Weather has been pretty average lately in Sydney so havent had a chance to take it for a proper run, but when i do ill let you know..